Humins,as a group of by-products formed through the condensation and coupling of fragment intermediates during lignocellulosic biomass refining,can cause numerous negative effects such as the wastage of carbon resourc...Humins,as a group of by-products formed through the condensation and coupling of fragment intermediates during lignocellulosic biomass refining,can cause numerous negative effects such as the wastage of carbon resources,clogging of reactor piping,deactivation of catalyst,and barriers to product separation.Elucidating the generation mechanism of humins,developing efficient inhibitors,and even utilizing them as a resource,both from the perspective of atom economy and safe production,constitutes a research endeavor replete with challenges and opportunities.Orbiting the critical issue of humins structure and its generation mechanism from cellulose and hemicellulose resources,the random condensation between intermediates such as 5-hydroxymethylfurfural,furfural,2,5-dioxo-6-hydroxyhexanal,and 1,2,4-benzenetriol etc.were systematically summarized.Additionally,the presence of lignin in real biorefining processes further promotes the formation of a special type of humins known as"pseudo-lignin".The influences of various factors,including raw materials,reaction temperature and time,acid-base environment,as well as solvent systems and catalysts,on the formation of humins were comprehensively analyzed.To minimize the formation of humins,the design of efficient solvent systems and catalysts is crucial.Furthermore,this review investigates the approaches to value-added applications of humins.The corresponding summary could provide guidance for the development of the humins chemistry.展开更多
In this paper,experiments were carried out to investigate the retention of liquid hydrocarbons in kerogen type Ⅰ.The study focuses on the mudstone from the Lucaogou Formation in the Junggar Basin of China.To prepare ...In this paper,experiments were carried out to investigate the retention of liquid hydrocarbons in kerogen type Ⅰ.The study focuses on the mudstone from the Lucaogou Formation in the Junggar Basin of China.To prepare samples of kerogen with varying degrees of maturity,artificial pyrolysis was used.Swelling experiments with three different types of liquid hydrocarbons were then conducted.The results revealed that the peak swelling adsorption capacity of type Ⅰ kerogen for liquid hydrocarbons occurred at Easy%R_(o)=1.07.Additionally,the kerogen showed a selective ability to retain aromatic hydrocarbons throughout the entire process compared to alkane.The order of hydrocarbon expulsion from source rocks was established as follows:short-chain alkanes>cycloalkanes/long-chain alkanes>aromatics with alkyl groups>polycyclic aromatic hydrocarbons.This study also developed a model for evaluating the swelling capacity of kerogen.This model was capable of evaluating the total swelling state of liquid hydrocarbons without considering the adsorption state,which was not possible in previous experimental work.According to this model,the swelling ability of long-chain alkanes and polycyclic aromatic hydrocarbons in type Ⅰ kerogen was high,while the swelling ability of cycloalkanes was weak,and most of them existed in the form of adsorption.This study suggests that paraffin and asphaltenes may affect the expulsion of shale oil and heavy oil in the form of swelling state,particularly in immature source rocks.This finding provides a new direction for research on hydrocarbon source rock evaluation and unconventional oil exploration.展开更多
As the main factor influencing the flow and preservation of underground fluids,wettability has a profound impact on CO_(2)sequestration(CS).However,the influencing factors and internal interaction mechanisms of shale ...As the main factor influencing the flow and preservation of underground fluids,wettability has a profound impact on CO_(2)sequestration(CS).However,the influencing factors and internal interaction mechanisms of shale kerogen wettability remain unclear.In this study,we used molecular dynamics to simulate the influence of temperature,pressure,and salinity on wettability.Furthermore,the results were validated through various methods such as mean square displacement,interaction energy,electrostatic potential energy,hydrogen bonding,van der Waals forces,and electrostatic forces,thereby confirming the reliability of our findings.As temperature increases,water wettability on the surface of kerogen increases.At CO_(2)pressures of 10 and 20 MPa,as the temperature increases,the kerogen wettability changes from CO_(2)wetting to neutral wetting.As the CO_(2)pressure increases,the water wettability on the surface of kerogen weakens.When the pressure is below 7.375 MPa and the temperature is 298 or 313 K,kerogen undergoes a wettability reversal from neutral wetting to CO_(2)wetting.As salinity increases,water wettability weakens.Divalent cations(Mg2+and Ca2+)have a greater impact on wettability than monovalent cations(Na^(+)).Water preferentially adsorbs on N atom positions in kerogen.CO_(2)is more likely to form hydrogen bonds and adsorb on the surface of kerogen than H_(2)O.As the temperature increases,the number of hydrogen bonds between H_(2)O and kerogen gradually increases,while the increase in pressure reduces the number of hydrogen bonds.Although high pressure helps to increase an amount of CS,it increases the permeability of a cap rock,which is not conducive to CS.Therefore,when determining CO_(2)pressure,not only a storage amount but also the storage safety should be considered.This research method and results help optimize the design of CS technology,and have important significance for achieving sustainable development.展开更多
This study investigated the hydrocarbon source rock potential of the Late Cretaceous Mamu and Nkporo formations in the Asaga-Ohafia Axis,Afikpo Basin,southeastern Nigeria,using integrated facies analysis,organic geoch...This study investigated the hydrocarbon source rock potential of the Late Cretaceous Mamu and Nkporo formations in the Asaga-Ohafia Axis,Afikpo Basin,southeastern Nigeria,using integrated facies analysis,organic geochemical and palynofacies data.Five lithofacies were identified:dark grey shale,oolitic limestone,heterolithic mudstone/sandstone,laminated bioturbated sandstone,and calcareous mudstone,indicating estuarine,deltaic,and shallow marine depositional environments.Total organic carbon(TOC) contents range from 1.47 to 2.40 wt%,which reflects moderate to good organic richness.For the Mamu Formation,kerogen composition is dominated by Type Ⅱ/Ⅲ,composed of 30 %-50 %amorphous organic matter(AOM),5 %-10 % liptinite,30 %-50 % vitrinite,and 10 %-20 % inertinite.Spore coloration and Thermal Alteration Index(TAI:3-3+) suggest thermal maturity within the oil window(Ro:0.80 %-1.50 %).In contrast,the Nkporo Formation shows comparable kerogen composition(20 %-45 % AOM,0-20 % liptinite,and 40 %-65 % vitrinite) but lower maturity(TAI:2-2+;Ro:0.45 %-0.80 %).Rock-Eval pyrolysis further supports these findings.The Mamu Formation displays higher Hydrogen Index,favorable Tmax,and Production Index values,confirming its maturity and oil and gas-prone potential.Palynological assemblages,including marine dinoflagellate cysts(Mamu Formation) and freshwater algae/fungal spores(Nkporo Formation),align with the inferred depositional settings.Thus,the Mamu Formation is the more prolific source rock,characterized by superior organic quality and thermal maturity.展开更多
Twenty-three progressive extractions were performed to study individual humic acids (HAs) and humin fractions from a typical black soil (Mollisol) in Heilongjiang Province, China using elemental analysis and spectrosc...Twenty-three progressive extractions were performed to study individual humic acids (HAs) and humin fractions from a typical black soil (Mollisol) in Heilongjiang Province, China using elemental analysis and spectroscopic techniques. After 23 HA extractions the residue was separated into high and low organic carbon humin fractions. HA yield was the highest for the first extraction and then gradually decreased with further extractions. Organic carbon (OC) of the humin fractions accounted for 58% of total OC …展开更多
Kerogen plays an important role in shale gas adsorption,desorption and diffusion.Therefore,it is necessary to characterize the molecular structure of kerogen.In this study,four kerogen samples were isolated from the o...Kerogen plays an important role in shale gas adsorption,desorption and diffusion.Therefore,it is necessary to characterize the molecular structure of kerogen.In this study,four kerogen samples were isolated from the organic-rich shale of the Longmaxi Formation.Raman spectroscopy was used to determine the maturity of these kerogen samples.Highresolution transmission electron microscopy(HRTEM),13 C nuclear magnetic resonance(13 C NMR),X-ray diffraction(XRD)and Fourier transform infrared(FT-IR)spectroscopy were conducted to characterize the molecular structure of the shale samples.The results demonstrate that VReqv of these kerogen samples vary from 2.3%to 2.8%,suggesting that all the kerogen samples are in the dry gas window.The macromolecular carbon skeleton of the Longmaxi Formation kerogen is mainly aromatic(fa’=0.56).In addition,the aromatic structural units are mainly composed of naphthalene(23%),anthracene(23%)and phenanthrene(29%).However,the aliphatic structure of the kerogen macromolecules is relatively low(fal*+falH=0.08),which is presumed to be distributed in the form of methyl and short aliphatic chains at the edge of the aromatic units.The oxygen-containing functional groups in the macromolecules are mainly present in the form of carbonyl groups(fac=0.23)and hydroxyl groups or ether groups(falO=0.13).The crystallite structural parameters of kerogen,including the stacking height(Lc=22.84?),average lateral size(La=29.29?)and interlayer spacing(d002=3.43?),are close to the aromatic structural parameters of anthracite or overmature kerogen.High-resolution transmission electron microscopy reveals that the aromatic structure is well oriented,and more than 65%of the diffractive aromatic layers are concentrated in the main direction.Due to the continuous deep burial,the longer aliphatic chains and oxygen-containing functional groups in the kerogen are substantially depleted.However,the ductility and stacking degree of the aromatic structure increases during thermal evolution.This study provides quantitative information on the molecular structure of kerogen samples based on multiple research methods,which may contribute to an improved understanding of the organic pores in black shale.展开更多
There is a dearth of information about the distribution of trace elements in kerogen from shale rocks despite several reports on trace element composition in many shale samples. In this study, trace elements in shale ...There is a dearth of information about the distribution of trace elements in kerogen from shale rocks despite several reports on trace element composition in many shale samples. In this study, trace elements in shale rocks and their residual kerogens were determined by inductively coupled plasma–mass spectrometry. The results from this study show redox-sensitive elements relatively concentrated in the kerogens as compared to the shales. This may be primarily due to the adsorption and complexation ability of kerogen, which enables enrichment in Ni, Co, Cu, and Zn. For the rare earth elements(REEs),distinct distribution characteristics were observed for shales dominated by terrigenous minerals and their kerogen counterparts. However, shales with less input of terrigenous minerals showed similar REE distribution patterns to their residual kerogen. It is speculated that the distribution patterns of the REEs in shales and kerogens may be sourcerelated.展开更多
Organic-rich shale resources remain an important source of hydrocarbons considering their substantial contribution to crude oil and natural gas production around the world. Moreover, as part of mitigating the greenhou...Organic-rich shale resources remain an important source of hydrocarbons considering their substantial contribution to crude oil and natural gas production around the world. Moreover, as part of mitigating the greenhouse gas effects due to the emissions of carbon dioxide （CO2） gas, organic-rich shales are considered a possible alternate geologic storage. This is due to the adsorptive properties of organic ke- rogen and clay minerals within the shale matrix. Therefore, this research looks at evaluating the seques- tration potential of carbon dioxide （CO2） gas in kerogen nanopores with the use of the lattice Boltzmann method under varying experimental pressures and different pore sizes. Gas flow in micro/nano pores differ in hydrodynamics due to the dominant pore wall effects, as the mean free path （λ） of the gas molecules become comparable to the characteristic length （H） of the pores. In so doing, the traditional computational methods break down beyond the continuum region, and the lattice Boltzmann method （LBM） is employed. The lattice Boltzmann method is a mesoscopic numerical method for fluid system, where a unit of gas particles is assigned a discrete distribution function （/）. The particles stream along de- fined lattice links and collide locally at the lattice sites to conserve mass and momentum. The effects of gas-wall collisions （Knudsen layer effects） is incorporated into the LBM through an effective-relaxation- time model, and the discontinuous velocity at the pore walls is resolved with a slip boundary condition. Above all, the time lag （slip effect） created by CO2 gas molecules due to adsorption and desorption over a time period, and the surface diffusion as a result of the adsorption-gradient are captured by an adsorption isotherm and included in our LBM. Implementing the Langmuir adsorption isotherm at the pore walls for both CO2 gas revealed the underlying flow mechanism for CO2 gas in a typical kerogen nano-pore is dominated by the slip flow regime. Increasing the equilibrium pressure, increases the mass flux due to ad- sorption. On the other hand, an increase in the nano-pore size caused further increase in the mass flux due to free gas and that due to adsorbed gas. Thus, in the kerogen nano-pores, CO2 gas molecules are more adsorptive indicating a possible multi-layer adsorption. Therefore, this study not only provides a clear un- derstanding of the underlying flow mechanism of CO2 in kerogen nano-pores, but also provides a potential alternative means to mitigate the greenhouse gas effect （GHG） by sequestering CO2 in organic-rich shales.展开更多
Original organisms are the biological precursors of organic matter in source rocks. Original organisms in source rocks are informative for oil-source rock correlation and hydrocarbon potential evaluation, especially f...Original organisms are the biological precursors of organic matter in source rocks. Original organisms in source rocks are informative for oil-source rock correlation and hydrocarbon potential evaluation, especially for source rocks which have high-over level of thermal maturity. Systematic identification of original organism assemblages of the Lower Paleozoic potential source rocks and detailed carbon isotopic composition of kerogen analyses were conducted for four outcrop sections in the Tarim basin. Results indicated that the original organism assemblages of the lower part of the Lower Cambrian were composed mainly of benthic algae, whereas those of the Upper Cambrian and the Ordovician were characterized by planktonic algae. Kerogen carbon isotopic data demonstrated that the δ13 Ckerogen values of source rocks dominated by benthic algae are lower than-34‰, whereas the δ13 Ckerogen values of source rocks dominated by planktonic algae are higher than-30‰ in general. We tentatively suggested that the carbon species those are utilized by algae and the carbon isotopic fractionation during photosynthesis are the major controls for the δ13 Ckerogen values in the Lower Paleozoic source rocks in the Tarim basin. Correlating the δ13 C values of oils exploited in the Tarim basin, the original organism assemblages, and δ13 Ckerogen values of source rocks, it implied that the Lower Paleozoic oils exploited in the Tarim basin should be sourced from the source rocks with original organism assemblages dominated by planktonic algae, and the hydrocarbon sourced from the Cambrian benthic algae should be of great exploration potential in future. Original organism assemblages in source rocks can provide important clues for oil-source rocks correlation, especially for the source rocks with high thermal maturity.展开更多
Kerogen is known as an important organic part for absorbing and forming shale gas whose absorption function,especially mechanical and tribological properties,has not been fully revealed.Here,we use Fourier transform i...Kerogen is known as an important organic part for absorbing and forming shale gas whose absorption function,especially mechanical and tribological properties,has not been fully revealed.Here,we use Fourier transform infrared(FTIR) and X-ray photoelectron spectroscopy(XPS) analysis to reveal the chemical structure of kerogen.We report the first study of the adhesion and friction behavior of kerogen using atomic force microscope(AFM) Nanoman technology.Our finding reveals the friction of kerogen is decreased at higher pressure while is inhibited at increased temperature,and friction decreases logarithmically as the sliding speed increases.The weakened of Al-O linkage at high temperature have great influence on the decrease of friction forces between kerogen and alumina pellet.This finding lays the mechanism for understanding the dynamic adhesion behavior of kerogen in frictions,therefore attracting increasing interests from scientists,researchers,petroleum engineers and investors.展开更多
Pore structure characterization and its effect on methane adsorption on shale kerogen are crucial to understanding the fundamental mechanisms of gas storage,transport,and reserves evaluation.In this study,we use 3D sc...Pore structure characterization and its effect on methane adsorption on shale kerogen are crucial to understanding the fundamental mechanisms of gas storage,transport,and reserves evaluation.In this study,we use 3D scanning confocal microscopy,scanning electron microscopy(SEM),X-ray nano-computed tomography(nano-CT),and low-pressure N2 adsorption analysis to analyze the pore structures of the shale.Additionally,the adsorption behavior of methane on shales with different pore structures is investigated by molecular simulations.The results show that the SEM image of the shale sample obviously displays four different pore shapes,including slit pore,square pore,triangle pore,and circle pore.The average coordination number is 4.21 and the distribution of coordination numbers demonstrates that pores in the shale have high connectivity.Compared with the adsorption capacity of methane on triangle pores,the adsorption capacity on slit pore,square pore,and circle pore are reduced by 9.86%,8.55%,and 6.12%,respectively.With increasing pressure,these acute wedges fill in a manner different from the right or obtuse angles in the other pores.This study offers a quantitative understanding of the effect of pore structure on methane adsorption in the shale and provides better insight into the evaluation of gas storage in geologic shale reservoirs.展开更多
Shale oil formations contain both inorganic and organic media.The organic matter holds both free oil in the pores and dissolved oil within the kerogen molecules.The free oil flow in organic pores and the dissolved oil...Shale oil formations contain both inorganic and organic media.The organic matter holds both free oil in the pores and dissolved oil within the kerogen molecules.The free oil flow in organic pores and the dissolved oil diffusion in kerogen molecules are coupled together.The molecular flow of free n-alkanes is an important process of shale oil accumulation and production.To study the dynamics of imbibition process of n-alkane molecules into kerogen slits,molecular dynamics(MD)simulations are conducted.Effects of slit width,temperature,and n-alkane types on the penetration speed,dynamic contact angle,and molecular conformations were analyzed.Results showed that molecular transportation of n-alkanes is dominated by molecular structure and molecular motion at this scale.The space-confinement conformational changes of molecules slow down the filling speeds in the narrow slits.The n-alkane molecules with long carbon chains require more time to undergo conformational changes.The high content of short-chain alkanes and high temperature facilitate the flow of alkane mixtures in kerogen slits.Results obtained from this study are useful for understanding the underlying nanoscale flow mechanism in shale formations.展开更多
Stimulated shale reservoirs consist of kerogen,inorganic matter,secondary and hydraulic fractures.The dispersed distribution of kerogen within matrices and complex gas flow mechanisms make production evaluation challe...Stimulated shale reservoirs consist of kerogen,inorganic matter,secondary and hydraulic fractures.The dispersed distribution of kerogen within matrices and complex gas flow mechanisms make production evaluation challenging.Here we establish an analytical method that addresses kerogen-inorganic matter gas transfer,dispersed kerogen distribution,and complex gas flow mechanisms to facilitate evaluating gas production.The matrix element is defined as a kerogen core with an exterior inorganic sphere.Unlike most previous models,we merely use boundary conditions to describe kerogen-inorganic matter gas transfer without the instantaneous kerogen gas source term.It is closer to real inter-porosity flow conditions between kerogen and inorganic matter.Knudsen diffusion,surface diffusion,adsorption/desorption,and slip corrected flow are involved in matrix gas flow.Matrix-fracture coupling is realized by using a seven-region linear flow model.The model is verified against a published model and field data.Results reveal that inorganic matrices serve as a major gas source especially at early times.Kerogen provides limited contributions to production even under a pseudo-steady state.Kerogen properties’influence starts from the late matrix-fracture inter-porosity flow regime,while inorganic matter properties control almost all flow regimes except the early-mid time fracture linear flow regime.The contribution of different linear flow regions is also documented.展开更多
Kerogen types exert a decisive effect on the onset and capacity of hydrocarbon generation of source rocks.Lacustrine source rocks in the Liaohe Western Depression are characterized by thick deposition,high total organ...Kerogen types exert a decisive effect on the onset and capacity of hydrocarbon generation of source rocks.Lacustrine source rocks in the Liaohe Western Depression are characterized by thick deposition,high total organic carbon(TOC)content,various kerogen types,and a wide range of thermal maturity.Consequently,their hydrocarbon generation potential and resource estimation can be misinterpreted.In this study,geochemical tests,numerical analysis,hydrocarbon generation kinetics,and basin modeling were integrated to investigate the differential effects of kerogen types on the hydrocarbon generation potential of lacustrine source rocks.Optimized hydrocarbon generation and expulsion(HGE)models of different kerogen types were established quantitatively upon abundant Rock-Eval/TOC/vitrinite reflectance(R_(o))datasets.Three sets of good-excellent source rocks deposited in the fourth(Es4),third(Es3),and first(Es1)members of Paleogene Shahejie Formation,are predominantly types I-II_(1),II_(1)-II_(2),and II-III,respectively.The activation energy of types I-II_(2)kerogen is concentrated(180-230 kcal/mol),whereas that of type III kerogen is widely distributed(150-280 kcal/mol).The original hydrocarbon generation potentials of types I,II_(1),II_(2),and III kerogens are 790,510,270,and 85 mg/g TOC,respectively.The Ro values of the hydrocarbon generation threshold for type I-III source rocks gradually increase from 0.42%to 0.74%,and Ro values of the hydrocarbon expulsion threshold increase from 0.49%to 0.87%.Types I and II_(1)source rocks are characterized by earlier hydrocarbon generation,more rapid hydrocarbon expulsion,and narrower hydrocarbon generation windows than types II_(2)and III source rocks.The kerogen types also affect the HGE history and resource potential.Three types(conventional,tight,and shale oil/gas)and three levels(realistic,expected,and prospective)of hydrocarbon resources of different members in the Liaohe Western Depression are evaluated.Findings suggest that the Es3 member has considerable conventional and unconventional hydrocarbon resources.This study can quantitatively characterize the hydrocarbon generation potential of source rocks with different kerogen types,and facilitate a quick and accurate assessment of hydrocarbon resources,providing strategies for future oil and gas exploration.展开更多
In this study,the kerogen of oil shale from Moroccan Tarfaya deposits was isolated and the changes in the initial organic matter during the removal of the mineral matrix were examined.Chloroform extraction of the oil ...In this study,the kerogen of oil shale from Moroccan Tarfaya deposits was isolated and the changes in the initial organic matter during the removal of the mineral matrix were examined.Chloroform extraction of the oil shale increases the intensity of the peaks in the X-ray diffractograms.Infrared spectra and X-ray diffractograms reveal the presence of mineral,calcite,quartz,kaolinite,and pyrite in the mineral matrix of the oil shale.Hydrochloric and hydrofluoric acids dissolution do not alter the organic matter.The nonisothermal weight loss measurements indicate that thermal decomposition of the isolated kerogen can be described by first-order reaction.A single kinetic expression is valid over the temperature range of kerogen pyrolysis between 433K and 873K.Furthermore,the results indicate that the removal of mineral matter causes a decrease in the activation energies of the pyrolysis reactions of oil shale.展开更多
High-quality source rocks in saline lacustrine or marine sedimentary environments often show early peak petroleum generation and enhanced hydrocarbon yields,which have conventionally been attributed to organosulfur-en...High-quality source rocks in saline lacustrine or marine sedimentary environments often show early peak petroleum generation and enhanced hydrocarbon yields,which have conventionally been attributed to organosulfur-enhanced thermal decomposition of kero gen.However,there is increasing awareness that the coexisting inorganic salts,particularly sulfates,might also contribute to the acceleration of petroleum generation.In this study,we investigated the influence of sulfates on the thermal decomposition of kerogen sampled from the Pingliang Formation in the Ordos Basin.Our results demonstrate that the kerogen samples mixed with sulfate generate more hydrocarbons with a lower peak production temperature than their sulfate-free counterparts.Detailed chemical analysis revealed that the presence of sulfates significantly facilitated the generation of resins and asphaltenes at temperatures below 350℃,corresponding in our simulations to the early stage of petroleum generation(Easy%R_o <1.0%).We hypothesize that sulfates can promote the fragmentation of kerogen via direct thermochemical oxidation into a complex mixture of bitumen components that consist mostly of compounds typically encountered in the classical resin and asphaltene fractions.The findings reveal a new reaction paradigm between sulfates and organic macromolecules that could offer useful guidance in the exploration for low-maturity oils.展开更多
Lignite-derived humin(CHM)was extracted from raw coal in Heihe City,China,producing calcium-modifed lignite-derived humin(Ca-CHM)by Ca(OH)_(2).The physical and chemical performances of CHM and Ca-CHM were analyzed wit...Lignite-derived humin(CHM)was extracted from raw coal in Heihe City,China,producing calcium-modifed lignite-derived humin(Ca-CHM)by Ca(OH)_(2).The physical and chemical performances of CHM and Ca-CHM were analyzed with SEM,^(13)C spectra and XPS techniques.The results show that Ca-CHM exhibited weaker aliphatic,more aromatic polar compared with CHM,which improves the adsorption capacity for Cd(Ⅱ).XPS analysis indicates that Ca(Ⅱ)has been loaded onto Ca-CHM successfully after modifcation.This batch adsorption experiments report the adsorption performance of CHM and Ca-CHM for Cd(Ⅱ).The adsorption process of CHM and Ca-CHM for Cd(Ⅱ)conform to pseudo-second-order model,which is chemical adsorption,and the adsorption data presented good fts to the Langmuir model.The maximum adsorption amount(Q_(m))of Cd(Ⅱ)onto CHM and Ca-CHM by the Langmuir model is 15.29 mg/g and 41.84 mg/g,respectively.Based on the results of SEM,^(13)C spectra,and XPS analysis,we concluded that the main adsorption mechanism of Ca-CHM on Cd(Ⅱ)was ion exchange of Cd(Ⅱ)for Ca(Ⅱ),static-adsorbed and surface complexation.Therefore,Ca(Ⅱ)can be loaded on the surface of Ca-CHM by chemical modifcation,improving the adsorption capacity of materials in aqueous solutions.展开更多
文摘Humins,as a group of by-products formed through the condensation and coupling of fragment intermediates during lignocellulosic biomass refining,can cause numerous negative effects such as the wastage of carbon resources,clogging of reactor piping,deactivation of catalyst,and barriers to product separation.Elucidating the generation mechanism of humins,developing efficient inhibitors,and even utilizing them as a resource,both from the perspective of atom economy and safe production,constitutes a research endeavor replete with challenges and opportunities.Orbiting the critical issue of humins structure and its generation mechanism from cellulose and hemicellulose resources,the random condensation between intermediates such as 5-hydroxymethylfurfural,furfural,2,5-dioxo-6-hydroxyhexanal,and 1,2,4-benzenetriol etc.were systematically summarized.Additionally,the presence of lignin in real biorefining processes further promotes the formation of a special type of humins known as"pseudo-lignin".The influences of various factors,including raw materials,reaction temperature and time,acid-base environment,as well as solvent systems and catalysts,on the formation of humins were comprehensively analyzed.To minimize the formation of humins,the design of efficient solvent systems and catalysts is crucial.Furthermore,this review investigates the approaches to value-added applications of humins.The corresponding summary could provide guidance for the development of the humins chemistry.
基金financially supported by Guangdong Basic and Applied Basic Research Foundation(2023A1515011646)financially supported by the Director's Fund of Guangzhou Institute of Geochemistry,CAS(2022SZJ5T-06)Open Fund of SINOPEC Petroleum Exploration and Production Research Institute。
文摘In this paper,experiments were carried out to investigate the retention of liquid hydrocarbons in kerogen type Ⅰ.The study focuses on the mudstone from the Lucaogou Formation in the Junggar Basin of China.To prepare samples of kerogen with varying degrees of maturity,artificial pyrolysis was used.Swelling experiments with three different types of liquid hydrocarbons were then conducted.The results revealed that the peak swelling adsorption capacity of type Ⅰ kerogen for liquid hydrocarbons occurred at Easy%R_(o)=1.07.Additionally,the kerogen showed a selective ability to retain aromatic hydrocarbons throughout the entire process compared to alkane.The order of hydrocarbon expulsion from source rocks was established as follows:short-chain alkanes>cycloalkanes/long-chain alkanes>aromatics with alkyl groups>polycyclic aromatic hydrocarbons.This study also developed a model for evaluating the swelling capacity of kerogen.This model was capable of evaluating the total swelling state of liquid hydrocarbons without considering the adsorption state,which was not possible in previous experimental work.According to this model,the swelling ability of long-chain alkanes and polycyclic aromatic hydrocarbons in type Ⅰ kerogen was high,while the swelling ability of cycloalkanes was weak,and most of them existed in the form of adsorption.This study suggests that paraffin and asphaltenes may affect the expulsion of shale oil and heavy oil in the form of swelling state,particularly in immature source rocks.This finding provides a new direction for research on hydrocarbon source rock evaluation and unconventional oil exploration.
基金supported by the China Scholarship Council(Grant No.202306440152)the CNPC Science and Technology Major Project of the Fourteenth Five-Year Plan(Grant No.2021DJ0101)+1 种基金the Science Foundation of China University of Petroleum,Beijing(Grant No.2462022YXZZ007)the National Natural Science Foundation of China(Grant No.42102145).
文摘As the main factor influencing the flow and preservation of underground fluids,wettability has a profound impact on CO_(2)sequestration(CS).However,the influencing factors and internal interaction mechanisms of shale kerogen wettability remain unclear.In this study,we used molecular dynamics to simulate the influence of temperature,pressure,and salinity on wettability.Furthermore,the results were validated through various methods such as mean square displacement,interaction energy,electrostatic potential energy,hydrogen bonding,van der Waals forces,and electrostatic forces,thereby confirming the reliability of our findings.As temperature increases,water wettability on the surface of kerogen increases.At CO_(2)pressures of 10 and 20 MPa,as the temperature increases,the kerogen wettability changes from CO_(2)wetting to neutral wetting.As the CO_(2)pressure increases,the water wettability on the surface of kerogen weakens.When the pressure is below 7.375 MPa and the temperature is 298 or 313 K,kerogen undergoes a wettability reversal from neutral wetting to CO_(2)wetting.As salinity increases,water wettability weakens.Divalent cations(Mg2+and Ca2+)have a greater impact on wettability than monovalent cations(Na^(+)).Water preferentially adsorbs on N atom positions in kerogen.CO_(2)is more likely to form hydrogen bonds and adsorb on the surface of kerogen than H_(2)O.As the temperature increases,the number of hydrogen bonds between H_(2)O and kerogen gradually increases,while the increase in pressure reduces the number of hydrogen bonds.Although high pressure helps to increase an amount of CS,it increases the permeability of a cap rock,which is not conducive to CS.Therefore,when determining CO_(2)pressure,not only a storage amount but also the storage safety should be considered.This research method and results help optimize the design of CS technology,and have important significance for achieving sustainable development.
文摘This study investigated the hydrocarbon source rock potential of the Late Cretaceous Mamu and Nkporo formations in the Asaga-Ohafia Axis,Afikpo Basin,southeastern Nigeria,using integrated facies analysis,organic geochemical and palynofacies data.Five lithofacies were identified:dark grey shale,oolitic limestone,heterolithic mudstone/sandstone,laminated bioturbated sandstone,and calcareous mudstone,indicating estuarine,deltaic,and shallow marine depositional environments.Total organic carbon(TOC) contents range from 1.47 to 2.40 wt%,which reflects moderate to good organic richness.For the Mamu Formation,kerogen composition is dominated by Type Ⅱ/Ⅲ,composed of 30 %-50 %amorphous organic matter(AOM),5 %-10 % liptinite,30 %-50 % vitrinite,and 10 %-20 % inertinite.Spore coloration and Thermal Alteration Index(TAI:3-3+) suggest thermal maturity within the oil window(Ro:0.80 %-1.50 %).In contrast,the Nkporo Formation shows comparable kerogen composition(20 %-45 % AOM,0-20 % liptinite,and 40 %-65 % vitrinite) but lower maturity(TAI:2-2+;Ro:0.45 %-0.80 %).Rock-Eval pyrolysis further supports these findings.The Mamu Formation displays higher Hydrogen Index,favorable Tmax,and Production Index values,confirming its maturity and oil and gas-prone potential.Palynological assemblages,including marine dinoflagellate cysts(Mamu Formation) and freshwater algae/fungal spores(Nkporo Formation),align with the inferred depositional settings.Thus,the Mamu Formation is the more prolific source rock,characterized by superior organic quality and thermal maturity.
文摘Twenty-three progressive extractions were performed to study individual humic acids (HAs) and humin fractions from a typical black soil (Mollisol) in Heilongjiang Province, China using elemental analysis and spectroscopic techniques. After 23 HA extractions the residue was separated into high and low organic carbon humin fractions. HA yield was the highest for the first extraction and then gradually decreased with further extractions. Organic carbon (OC) of the humin fractions accounted for 58% of total OC …
基金supported by the National Science and Technology Major Project(2017ZX05035004–002)the National Natural Science Foundation of China(no.41702167)+1 种基金the Fundamental Research Funds for the Central Universities(No.2017CXNL03)the Scientific Research Foundation of the Key Laboratory of Coalbed Methane Resources and Reservoir Formation Process,Ministry of Education(China University of Mining and Technology)(No.2017–007)
文摘Kerogen plays an important role in shale gas adsorption,desorption and diffusion.Therefore,it is necessary to characterize the molecular structure of kerogen.In this study,four kerogen samples were isolated from the organic-rich shale of the Longmaxi Formation.Raman spectroscopy was used to determine the maturity of these kerogen samples.Highresolution transmission electron microscopy(HRTEM),13 C nuclear magnetic resonance(13 C NMR),X-ray diffraction(XRD)and Fourier transform infrared(FT-IR)spectroscopy were conducted to characterize the molecular structure of the shale samples.The results demonstrate that VReqv of these kerogen samples vary from 2.3%to 2.8%,suggesting that all the kerogen samples are in the dry gas window.The macromolecular carbon skeleton of the Longmaxi Formation kerogen is mainly aromatic(fa’=0.56).In addition,the aromatic structural units are mainly composed of naphthalene(23%),anthracene(23%)and phenanthrene(29%).However,the aliphatic structure of the kerogen macromolecules is relatively low(fal*+falH=0.08),which is presumed to be distributed in the form of methyl and short aliphatic chains at the edge of the aromatic units.The oxygen-containing functional groups in the macromolecules are mainly present in the form of carbonyl groups(fac=0.23)and hydroxyl groups or ether groups(falO=0.13).The crystallite structural parameters of kerogen,including the stacking height(Lc=22.84?),average lateral size(La=29.29?)and interlayer spacing(d002=3.43?),are close to the aromatic structural parameters of anthracite or overmature kerogen.High-resolution transmission electron microscopy reveals that the aromatic structure is well oriented,and more than 65%of the diffractive aromatic layers are concentrated in the main direction.Due to the continuous deep burial,the longer aliphatic chains and oxygen-containing functional groups in the kerogen are substantially depleted.However,the ductility and stacking degree of the aromatic structure increases during thermal evolution.This study provides quantitative information on the molecular structure of kerogen samples based on multiple research methods,which may contribute to an improved understanding of the organic pores in black shale.
基金financially supported by the National Natural Science Foundation of China (No. 41772117)the Strategic Priority Research Program of the Chinese Academy of Sciences (XDA14010103)the National Petroleum and Gas Projects of China (2017ZX05008002)
文摘There is a dearth of information about the distribution of trace elements in kerogen from shale rocks despite several reports on trace element composition in many shale samples. In this study, trace elements in shale rocks and their residual kerogens were determined by inductively coupled plasma–mass spectrometry. The results from this study show redox-sensitive elements relatively concentrated in the kerogens as compared to the shales. This may be primarily due to the adsorption and complexation ability of kerogen, which enables enrichment in Ni, Co, Cu, and Zn. For the rare earth elements(REEs),distinct distribution characteristics were observed for shales dominated by terrigenous minerals and their kerogen counterparts. However, shales with less input of terrigenous minerals showed similar REE distribution patterns to their residual kerogen. It is speculated that the distribution patterns of the REEs in shales and kerogens may be sourcerelated.
基金support of the Tertiary Oil Recovery Program (TORP)the Kansas Interdisciplinary Carbonates Consortium (KICC) at the University of Kansas
文摘Organic-rich shale resources remain an important source of hydrocarbons considering their substantial contribution to crude oil and natural gas production around the world. Moreover, as part of mitigating the greenhouse gas effects due to the emissions of carbon dioxide （CO2） gas, organic-rich shales are considered a possible alternate geologic storage. This is due to the adsorptive properties of organic ke- rogen and clay minerals within the shale matrix. Therefore, this research looks at evaluating the seques- tration potential of carbon dioxide （CO2） gas in kerogen nanopores with the use of the lattice Boltzmann method under varying experimental pressures and different pore sizes. Gas flow in micro/nano pores differ in hydrodynamics due to the dominant pore wall effects, as the mean free path （λ） of the gas molecules become comparable to the characteristic length （H） of the pores. In so doing, the traditional computational methods break down beyond the continuum region, and the lattice Boltzmann method （LBM） is employed. The lattice Boltzmann method is a mesoscopic numerical method for fluid system, where a unit of gas particles is assigned a discrete distribution function （/）. The particles stream along de- fined lattice links and collide locally at the lattice sites to conserve mass and momentum. The effects of gas-wall collisions （Knudsen layer effects） is incorporated into the LBM through an effective-relaxation- time model, and the discontinuous velocity at the pore walls is resolved with a slip boundary condition. Above all, the time lag （slip effect） created by CO2 gas molecules due to adsorption and desorption over a time period, and the surface diffusion as a result of the adsorption-gradient are captured by an adsorption isotherm and included in our LBM. Implementing the Langmuir adsorption isotherm at the pore walls for both CO2 gas revealed the underlying flow mechanism for CO2 gas in a typical kerogen nano-pore is dominated by the slip flow regime. Increasing the equilibrium pressure, increases the mass flux due to ad- sorption. On the other hand, an increase in the nano-pore size caused further increase in the mass flux due to free gas and that due to adsorbed gas. Thus, in the kerogen nano-pores, CO2 gas molecules are more adsorptive indicating a possible multi-layer adsorption. Therefore, this study not only provides a clear un- derstanding of the underlying flow mechanism of CO2 in kerogen nano-pores, but also provides a potential alternative means to mitigate the greenhouse gas effect （GHG） by sequestering CO2 in organic-rich shales.
基金funded by National Natural Science Foundation of China (Grant No. U1663201, 41472099 and 41872155)the Strategic Priority Research Program of the Chinese Academy of Science (Grant No. XDA14010404)CNPC innovation Foundation (2016D-5007-0102)
文摘Original organisms are the biological precursors of organic matter in source rocks. Original organisms in source rocks are informative for oil-source rock correlation and hydrocarbon potential evaluation, especially for source rocks which have high-over level of thermal maturity. Systematic identification of original organism assemblages of the Lower Paleozoic potential source rocks and detailed carbon isotopic composition of kerogen analyses were conducted for four outcrop sections in the Tarim basin. Results indicated that the original organism assemblages of the lower part of the Lower Cambrian were composed mainly of benthic algae, whereas those of the Upper Cambrian and the Ordovician were characterized by planktonic algae. Kerogen carbon isotopic data demonstrated that the δ13 Ckerogen values of source rocks dominated by benthic algae are lower than-34‰, whereas the δ13 Ckerogen values of source rocks dominated by planktonic algae are higher than-30‰ in general. We tentatively suggested that the carbon species those are utilized by algae and the carbon isotopic fractionation during photosynthesis are the major controls for the δ13 Ckerogen values in the Lower Paleozoic source rocks in the Tarim basin. Correlating the δ13 C values of oils exploited in the Tarim basin, the original organism assemblages, and δ13 Ckerogen values of source rocks, it implied that the Lower Paleozoic oils exploited in the Tarim basin should be sourced from the source rocks with original organism assemblages dominated by planktonic algae, and the hydrocarbon sourced from the Cambrian benthic algae should be of great exploration potential in future. Original organism assemblages in source rocks can provide important clues for oil-source rocks correlation, especially for the source rocks with high thermal maturity.
基金This project was supported by the National Natural Science Foundation of China(No.51875577)the Beijing Nova Program(No.2171100001117058)the Science Foundation of China University of Petroleum-Beijing(No.2462018BJC004)。
文摘Kerogen is known as an important organic part for absorbing and forming shale gas whose absorption function,especially mechanical and tribological properties,has not been fully revealed.Here,we use Fourier transform infrared(FTIR) and X-ray photoelectron spectroscopy(XPS) analysis to reveal the chemical structure of kerogen.We report the first study of the adhesion and friction behavior of kerogen using atomic force microscope(AFM) Nanoman technology.Our finding reveals the friction of kerogen is decreased at higher pressure while is inhibited at increased temperature,and friction decreases logarithmically as the sliding speed increases.The weakened of Al-O linkage at high temperature have great influence on the decrease of friction forces between kerogen and alumina pellet.This finding lays the mechanism for understanding the dynamic adhesion behavior of kerogen in frictions,therefore attracting increasing interests from scientists,researchers,petroleum engineers and investors.
基金The authors acknowledge financial support from the Science Fund for Creative Research Groups of the National Natural Science Foundation of China(No.51821092)the General Projects of the Natural Science Foundation of China(No.51674275)+1 种基金the Foundation of State Key Laboratory of Petroleum Resources and Prospecting,China University of Petroleum,Beijing(No.PRP/open-2003)Tianyu Wang acknowledges the China Scholarship Council for financial support during his visit to Harvard University.
文摘Pore structure characterization and its effect on methane adsorption on shale kerogen are crucial to understanding the fundamental mechanisms of gas storage,transport,and reserves evaluation.In this study,we use 3D scanning confocal microscopy,scanning electron microscopy(SEM),X-ray nano-computed tomography(nano-CT),and low-pressure N2 adsorption analysis to analyze the pore structures of the shale.Additionally,the adsorption behavior of methane on shales with different pore structures is investigated by molecular simulations.The results show that the SEM image of the shale sample obviously displays four different pore shapes,including slit pore,square pore,triangle pore,and circle pore.The average coordination number is 4.21 and the distribution of coordination numbers demonstrates that pores in the shale have high connectivity.Compared with the adsorption capacity of methane on triangle pores,the adsorption capacity on slit pore,square pore,and circle pore are reduced by 9.86%,8.55%,and 6.12%,respectively.With increasing pressure,these acute wedges fill in a manner different from the right or obtuse angles in the other pores.This study offers a quantitative understanding of the effect of pore structure on methane adsorption in the shale and provides better insight into the evaluation of gas storage in geologic shale reservoirs.
基金financially supported by the National Natural Science Foundation of China(Grant No.52004317,42090024)the Natural Science Foundation of Shandong Province of China(No.ZR2020ME091)+1 种基金the Fundamental Research Funds for the Central Universities(20CX06016A)the National Science and Technology Major Project(2017ZX05049-004)
文摘Shale oil formations contain both inorganic and organic media.The organic matter holds both free oil in the pores and dissolved oil within the kerogen molecules.The free oil flow in organic pores and the dissolved oil diffusion in kerogen molecules are coupled together.The molecular flow of free n-alkanes is an important process of shale oil accumulation and production.To study the dynamics of imbibition process of n-alkane molecules into kerogen slits,molecular dynamics(MD)simulations are conducted.Effects of slit width,temperature,and n-alkane types on the penetration speed,dynamic contact angle,and molecular conformations were analyzed.Results showed that molecular transportation of n-alkanes is dominated by molecular structure and molecular motion at this scale.The space-confinement conformational changes of molecules slow down the filling speeds in the narrow slits.The n-alkane molecules with long carbon chains require more time to undergo conformational changes.The high content of short-chain alkanes and high temperature facilitate the flow of alkane mixtures in kerogen slits.Results obtained from this study are useful for understanding the underlying nanoscale flow mechanism in shale formations.
基金supported by the Australian Research Council under Grant DP200101293UWA China Scholarshipsthe China Scholarship Council(CSC No.201707970011)。
文摘Stimulated shale reservoirs consist of kerogen,inorganic matter,secondary and hydraulic fractures.The dispersed distribution of kerogen within matrices and complex gas flow mechanisms make production evaluation challenging.Here we establish an analytical method that addresses kerogen-inorganic matter gas transfer,dispersed kerogen distribution,and complex gas flow mechanisms to facilitate evaluating gas production.The matrix element is defined as a kerogen core with an exterior inorganic sphere.Unlike most previous models,we merely use boundary conditions to describe kerogen-inorganic matter gas transfer without the instantaneous kerogen gas source term.It is closer to real inter-porosity flow conditions between kerogen and inorganic matter.Knudsen diffusion,surface diffusion,adsorption/desorption,and slip corrected flow are involved in matrix gas flow.Matrix-fracture coupling is realized by using a seven-region linear flow model.The model is verified against a published model and field data.Results reveal that inorganic matrices serve as a major gas source especially at early times.Kerogen provides limited contributions to production even under a pseudo-steady state.Kerogen properties’influence starts from the late matrix-fracture inter-porosity flow regime,while inorganic matter properties control almost all flow regimes except the early-mid time fracture linear flow regime.The contribution of different linear flow regions is also documented.
基金This research is supported by the Joint Fund of the National Natural Science Foundation of China(grant number U19B6003-02)the Cooperation Program of PetroChina Liaohe Oilfield Company(grant Number HX20180604)the AAPG Foundation Grants-in-Aid Program(grant number 22269437).This study has benefited considerably from PetroChina Liaohe Oilfield Company for data support.We also thank the editor and the anonymous reviewers for their professional suggestions and comments.
文摘Kerogen types exert a decisive effect on the onset and capacity of hydrocarbon generation of source rocks.Lacustrine source rocks in the Liaohe Western Depression are characterized by thick deposition,high total organic carbon(TOC)content,various kerogen types,and a wide range of thermal maturity.Consequently,their hydrocarbon generation potential and resource estimation can be misinterpreted.In this study,geochemical tests,numerical analysis,hydrocarbon generation kinetics,and basin modeling were integrated to investigate the differential effects of kerogen types on the hydrocarbon generation potential of lacustrine source rocks.Optimized hydrocarbon generation and expulsion(HGE)models of different kerogen types were established quantitatively upon abundant Rock-Eval/TOC/vitrinite reflectance(R_(o))datasets.Three sets of good-excellent source rocks deposited in the fourth(Es4),third(Es3),and first(Es1)members of Paleogene Shahejie Formation,are predominantly types I-II_(1),II_(1)-II_(2),and II-III,respectively.The activation energy of types I-II_(2)kerogen is concentrated(180-230 kcal/mol),whereas that of type III kerogen is widely distributed(150-280 kcal/mol).The original hydrocarbon generation potentials of types I,II_(1),II_(2),and III kerogens are 790,510,270,and 85 mg/g TOC,respectively.The Ro values of the hydrocarbon generation threshold for type I-III source rocks gradually increase from 0.42%to 0.74%,and Ro values of the hydrocarbon expulsion threshold increase from 0.49%to 0.87%.Types I and II_(1)source rocks are characterized by earlier hydrocarbon generation,more rapid hydrocarbon expulsion,and narrower hydrocarbon generation windows than types II_(2)and III source rocks.The kerogen types also affect the HGE history and resource potential.Three types(conventional,tight,and shale oil/gas)and three levels(realistic,expected,and prospective)of hydrocarbon resources of different members in the Liaohe Western Depression are evaluated.Findings suggest that the Es3 member has considerable conventional and unconventional hydrocarbon resources.This study can quantitatively characterize the hydrocarbon generation potential of source rocks with different kerogen types,and facilitate a quick and accurate assessment of hydrocarbon resources,providing strategies for future oil and gas exploration.
文摘In this study,the kerogen of oil shale from Moroccan Tarfaya deposits was isolated and the changes in the initial organic matter during the removal of the mineral matrix were examined.Chloroform extraction of the oil shale increases the intensity of the peaks in the X-ray diffractograms.Infrared spectra and X-ray diffractograms reveal the presence of mineral,calcite,quartz,kaolinite,and pyrite in the mineral matrix of the oil shale.Hydrochloric and hydrofluoric acids dissolution do not alter the organic matter.The nonisothermal weight loss measurements indicate that thermal decomposition of the isolated kerogen can be described by first-order reaction.A single kinetic expression is valid over the temperature range of kerogen pyrolysis between 433K and 873K.Furthermore,the results indicate that the removal of mineral matter causes a decrease in the activation energies of the pyrolysis reactions of oil shale.
基金supported by National Natural Science Foundation of China (No. 41403049)the Foundation of State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum (Beijing) (No. PRP/indep-3-1715)National Science and Technology Major Project during the 13th Five-Year Plan Period (2016ZX05007-002)。
文摘High-quality source rocks in saline lacustrine or marine sedimentary environments often show early peak petroleum generation and enhanced hydrocarbon yields,which have conventionally been attributed to organosulfur-enhanced thermal decomposition of kero gen.However,there is increasing awareness that the coexisting inorganic salts,particularly sulfates,might also contribute to the acceleration of petroleum generation.In this study,we investigated the influence of sulfates on the thermal decomposition of kerogen sampled from the Pingliang Formation in the Ordos Basin.Our results demonstrate that the kerogen samples mixed with sulfate generate more hydrocarbons with a lower peak production temperature than their sulfate-free counterparts.Detailed chemical analysis revealed that the presence of sulfates significantly facilitated the generation of resins and asphaltenes at temperatures below 350℃,corresponding in our simulations to the early stage of petroleum generation(Easy%R_o <1.0%).We hypothesize that sulfates can promote the fragmentation of kerogen via direct thermochemical oxidation into a complex mixture of bitumen components that consist mostly of compounds typically encountered in the classical resin and asphaltene fractions.The findings reveal a new reaction paradigm between sulfates and organic macromolecules that could offer useful guidance in the exploration for low-maturity oils.
基金supported by the National Key R&D Program of China(No.2020YFC1806504)Science and Technology Innovation and venture Fund of China Coal Technology and Engineering Group(No.2020-2-CXY001)We thank the editor and anonymous reviewers for their valuable comments.
文摘Lignite-derived humin(CHM)was extracted from raw coal in Heihe City,China,producing calcium-modifed lignite-derived humin(Ca-CHM)by Ca(OH)_(2).The physical and chemical performances of CHM and Ca-CHM were analyzed with SEM,^(13)C spectra and XPS techniques.The results show that Ca-CHM exhibited weaker aliphatic,more aromatic polar compared with CHM,which improves the adsorption capacity for Cd(Ⅱ).XPS analysis indicates that Ca(Ⅱ)has been loaded onto Ca-CHM successfully after modifcation.This batch adsorption experiments report the adsorption performance of CHM and Ca-CHM for Cd(Ⅱ).The adsorption process of CHM and Ca-CHM for Cd(Ⅱ)conform to pseudo-second-order model,which is chemical adsorption,and the adsorption data presented good fts to the Langmuir model.The maximum adsorption amount(Q_(m))of Cd(Ⅱ)onto CHM and Ca-CHM by the Langmuir model is 15.29 mg/g and 41.84 mg/g,respectively.Based on the results of SEM,^(13)C spectra,and XPS analysis,we concluded that the main adsorption mechanism of Ca-CHM on Cd(Ⅱ)was ion exchange of Cd(Ⅱ)for Ca(Ⅱ),static-adsorbed and surface complexation.Therefore,Ca(Ⅱ)can be loaded on the surface of Ca-CHM by chemical modifcation,improving the adsorption capacity of materials in aqueous solutions.
