The increasing pace of urbanization means that cities and global organizations are looking for ways to increase energy efficiency and reduce emissions. Combined cooling, heating, and power （CCHP） systems have the po...The increasing pace of urbanization means that cities and global organizations are looking for ways to increase energy efficiency and reduce emissions. Combined cooling, heating, and power （CCHP） systems have the potential to improve the energy generation efficiency of a city or urban region by providing energy for heating, cooling, and electricity simultaneously. The purpose of this study is to estimate the water consumption for energy generation use, carbon dioxide （CO2） and NOx emissions, and economic impact of implementing CCHP systems for five generic building types within the Atlanta metropolitan region, under various operational scenarios following the building thermal （heating and cooling） demands. Operating the CCHP system to follow the hourly thermal demand reduces CO2 emissions for most building types both with and without net metering. The system can be economically beneficial for all building types depending on the price of natural gas, the implementation of net metering, and the cost structure assumed for the CCHP system. The greatest reduction in water consumption for energy production and NOx emissions occurs when there is net metering and when the system is operated to meet the maximum yearly thermal demand, although this scenario also results in an increase in greenhouse gas emissions and, in some cases, cost. CCHP systems are more economical for medium office, large office, and multifamilv residential buildings.展开更多
CeO2‐ZrO2 (CeZr) and sulfated CeO2‐ZrO2 (S‐CeZr) catalysts were prepared for the selective catalytic reduction of NO with NH3. The CeZr catalysts exhibited higher activity at low temperatures (< 200°C) and ...CeO2‐ZrO2 (CeZr) and sulfated CeO2‐ZrO2 (S‐CeZr) catalysts were prepared for the selective catalytic reduction of NO with NH3. The CeZr catalysts exhibited higher activity at low temperatures (< 200°C) and lower activity at high temperatures (> 200 °C) than the S‐CeZr catalysts. The sulfation ofCeZr was studied in terms of surface acidity, redox properties and NO adsorption‐desorption bytemperature‐dependent experiments and in situ infrared spectroscopy. S‐CeZr displayed high concentrationsof acidic sites and increased surface acidities, but poor reducibility compared with CeZr.The high acidity of S‐CeZr was attributed to the presence of Br?nsted acid sites, arising mainly fromthe surface sulfates. Because the surface was covered with sulfate species, S‐CeZr showed lower NOadsorption and weaker oxidation ability than CeZr. The adsorption of NH3 on the Br?nsted acid sites restricted the reaction with NO at low temperatures, but the selective catalytic reduction cycle occurred easily at relatively low temperatures (150 °C), and the weakly bound nitrite was partially activated on the S‐CeZr catalyst at relatively high temperatures (300 °C). The catalytic mechanisms for the CeZr and S‐CeZr catalysts at 150 and 300 °C were also studied.展开更多
Activated red mud(RM)has been proved to be a promising base material for the selective catalysis reduction(SCR)of NOx.The inherent low reducibility and acidity limited its low-temperature activity.In this work,molybde...Activated red mud(RM)has been proved to be a promising base material for the selective catalysis reduction(SCR)of NOx.The inherent low reducibility and acidity limited its low-temperature activity.In this work,molybdenum oxide,tungsten oxide,and cerium oxide were used to reconfigure the redox sites and acid sites of red mud based catalyst.When activated red mud was reconfigured by cerium-tungsten oxide(Ce-W@RM),the NOx conversion kept above 90%at 219-480℃.The existence of Ce^(3+)/Ce^(4+) redox electron pairs provided more surface adsorbed oxygen(O_(α)) and served as a redox cycle.Positive interactions between Ce,W species and Fe oxide in red mud occurred,which led to the formation of unsaturated chemical bond and promoted the activation of adsorbed NH_(3) species.WO_(3) and Ce_(2)(WO_(4))_(3)(formed by solid-state reaction between Ce and W species)could provide more Brønsted acid sites(W-O modes of WO_(3),W=O or W-O-W modes of Ce_(2)(WO_(4))_(3)).CeO_(2) species could provide more Lewis acid sites.The Langmuir-Hinshelwood(L-H)routes and Eley-Rideal(E-R)routes occurred in the low-temperature SCR reaction on the Ce-W@RM surface.NH_(4)^(+) species on Brønsted acid sites,NH_(3) species on Lewis acid sites,bidentate nitrate and bridging nitrate species were key active intermediates species.展开更多
Vacuum ultraviolet(VUV) photolysis is recognized as an environmental-friendly treatment process. Nitrate(NO-3) and natural organic matter(NOM) are widely present in water source.We investigated trichloronitromethane(T...Vacuum ultraviolet(VUV) photolysis is recognized as an environmental-friendly treatment process. Nitrate(NO-3) and natural organic matter(NOM) are widely present in water source.We investigated trichloronitromethane(TCNM) formation during chlorination after VUV photolysis, because TCNM is an unregulated highly toxic disinfection byproduct. In this study:(1) we found reactive nitrogen species that is generated under VUV photolysis of NO-3react with organic matter to form nitrogen-containing compounds and subsequently form TCNM during chlorination;(2) we found the mere presence of 0.1 mmol/L NO-3can result in the formation of up to 63.96 μg/L TCNM;(3) we found the changes in pH(6.0-8.0), chloride(1-4 mmol/L), and bicarbonate(1-4 mmol/L) cannot effectively diminish TCNM formation;and,(4) we established the quantitative structure-activity relationship(QSAR) model,which indicated a linear relationship between TCNM formation and the Hammett constant(σ) of model compounds;and,(5) we characterized TCNM precursors in water matrix after VUV photolysis and found 1161 much more nitrogen-containing compounds with higher aromaticity were generated. Overall, this study indicates more attention should be paid to reducing the formation risk of TCNM when applying VUV photolysis process at scale.展开更多
The primary aliphatic amine Primene JM-T was investigated as a potential absorbent for H2S removal. The solubility of HzS in JM-T was measured at 298, 313,333,353, and 368 K with H2S partial pressures from 20 to 760 k...The primary aliphatic amine Primene JM-T was investigated as a potential absorbent for H2S removal. The solubility of HzS in JM-T was measured at 298, 313,333,353, and 368 K with H2S partial pressures from 20 to 760 kPa and HzS loading from 0.02 to 0.8 mol H2S per mol JM-T. Relevant physical properties, such as density, viscoslty and dielectric constant, ot the matenal were measured. ＇The thermodynamlc model with two-suttlX Margules equation was used to correlate the experimental vapor-liquid equilibrium data. Furthermore, the absorption mechanism in non-aqueous system is suggested and the difference between non-aqueous and aqueous absorption system is pointed out.展开更多
Accumulation of heavy metals in urban soil can pose adverse impacts on public health and terrestrial ecosystems. We developed a mass balance-based regression model to simulate the heavy metal accumulation in urban soi...Accumulation of heavy metals in urban soil can pose adverse impacts on public health and terrestrial ecosystems. We developed a mass balance-based regression model to simulate the heavy metal accumulation in urban soils as a function of time and to explore connections between metal concentration and urbanization processes. Concentrations of Cd and Zn in 68 residential soil samples in the urban area of Beijing were used. The background concentrations, the loss rates and the input fluxes of Cd and Zn in urban soils of Beijing during the last three decades were estimated using a regression of the time series of accumulations of the metals. Based on the regression estimates, we simulated the general trends of Cd and Zn accumulation in the soils from 1978 to 2078. The concentrations of Cd and Zn in urban soil generally increased with the population growth, vehicle use and coal consumption. The mean concentrations of Cd and Zn in urban soil of Beijing would increase by 3 fold over the next 70 years for the current development scenario. The mass balance-based regression approach, which is able to reconstruct the history data of urban soil pollution, provides fundamental information for urban planning and environmental management.展开更多
Ozonation of oxalate in aqueous phase was performed with a commercial activated carbon（AC）in this work. The effect of AC dosage and solution pH on the contribution of hydroxyl radicals（HOU） in bulk solution and ox...Ozonation of oxalate in aqueous phase was performed with a commercial activated carbon（AC）in this work. The effect of AC dosage and solution pH on the contribution of hydroxyl radicals（HOU） in bulk solution and oxidation on the AC surface to the removal of oxalate was studied. We found that the removal of oxalate was reduced by tert-butyl alcohol（tBA） with low dosages of AC,while it was hardly affected by tBA when the AC dosage was greater than 0.3 g/L. tBA also inhibited ozone decomposition when the AC dosage was no more than 0.05 g/L, but it did not work when the AC dosage was no less than 0.1 g/L. These observations indicate that HOUin bulk solution and oxidation on the AC surface both contribute to the removal of oxalate. HOU oxidation in bulk solution is significant when the dosage of AC is low, whereas surface oxidation is dominant when the dosage of AC is high. The oxalate removal decreased with increasing pH of the solution with an AC dosage of 0.5 g/L. The degradation of oxalate occurs mainly through surface oxidation in acid and neutral solution, but through HOUoxidation in basic bulk solution. A mechanism involving both HOUoxidation in bulk solution and surface oxidation was proposed for AC enhanced ozonation of oxalate.展开更多
Low-impact development （LID） technologies, such as bioretention areas, rooftop rainwater harvesting, a_nd xeris_caping can co_ntrol stormwater runoff, supply non-potable water, and landscape open space.TillS study e...Low-impact development （LID） technologies, such as bioretention areas, rooftop rainwater harvesting, a_nd xeris_caping can co_ntrol stormwater runoff, supply non-potable water, and landscape open space.TillS study examines a hybrid system （HS） that combines LID technologies with a centralized water system to lessen the burden on a conventional system （CS）. CS is defined as the stormwater collection and water supply infrastructure, and the conventional landscaping choices in the City of Atlanta. The study scope is limited to five single-family residential zones （SFZs）, classified R-1 through R-5, and four multi-family residential zones （MFZs）, classified RG-2 through RG-5. Population density increases from 0.4 （R-1） to 62.2 （RG-5） persons per 1,000 m2. We performed a life cycle assessment （LCA） comparison of CS and HS using TRACI 2.1 to simulate impacts on the ecosystem, human health, and natural resources. We quantified the impact of freshwater consumption using the freshwater ecosystem impact （FEI） indicator. Test results indicate that HS has a higher LCA single score than CS in zones with a low population density; however, the difference becomes negligible as population density increases. Incorporating LID in SFZs and MFZs can reduce potable water use by an average of 50%. and 25%,respectively.; however, water savings are negligible in zones with high population density （i.e., RG-5） due to the diminished surface area per capitaavailable for LID technoogies. The results demonstrate that LID technologies effectively reduce outdoor water demand and therefore would be a good choice to decrease the water consumption impact in the City of Atlanta.展开更多
Selective catalytic reduction （SCR） of NOx with NH3 is an effective technique to remove NOx from stationary sources, such as coal-fired power plant and industrial boilers. Some of elements in the fly ash deactivate ...Selective catalytic reduction （SCR） of NOx with NH3 is an effective technique to remove NOx from stationary sources, such as coal-fired power plant and industrial boilers. Some of elements in the fly ash deactivate the catalyst due to strong chemisorptions on the active sites. The poisons may act by simply blocking active sites or alter the adsorption behaviors of reactants and products by an electronic interaction. This review is mainly focused on the chemical poisoning on V2O5-based catalysts, environmental-benign catalysts and low temperature catalysts. Several common poisons including alkali/alkaline earth metals, SO2 and heavy metals etc. are referred and their poisoning mechanisms on catalysts are discussed. The regeneration methods of poisoned catalysts and the development of poison-resistance catalysts are also compared and analyzed. Finally, future research directions in developing poisoning resistance catalysts and facile efficient regeneration methods for SCR catalysts are proposed.展开更多
Our previous study proved that the acid-pretreatment process could efficiently activate red mud(RM)for the selective catalytic reduction(SCR)of NO_(x).However,in terms of the molding process,which is the key step dete...Our previous study proved that the acid-pretreatment process could efficiently activate red mud(RM)for the selective catalytic reduction(SCR)of NO_(x).However,in terms of the molding process,which is the key step determining whether it can be applied in large-scale industrial,the surface acidity and reducibility of catalyst always decreased dramatically,and part of surface area and pore structure were lost.In this study,we prepared monolithic honeycomb red mud(MHRM)catalysts with activated carbon(AC)as an accelerant and investigated the effect of AC on the MHRM.The results showed that the MHRM with 3 wt.%of AC(MHRM-AC3)exhibited the best SCR performance,and kept more than 80%NO_(x)conversion in the range of 325℃–400℃.Compared with the MHRM,MHRM-AC1,and HMRM-AC5,the MHRM-AC3 has more mesoporous and macroporous structures,which can provide more adsorption active sites.The AC significantly improved NH3 adsorption and surface reducibility,which was mainly due to the increase of the surface acid sites(especially the Brönsted acid sites),the concentration of Fe(II),and the surface adsorbed oxygen.The presence of more Fe(Ⅱ)enriched the surface oxygen vacancies,as well as the surface adsorbed oxygen,due to the charge imbalance and unsaturated chemical bond.And surface adsorbed oxygen exhibited more active than lattice oxygen owing to its higher mobility,which was conducive to NO_(x)reduction in the SCR reaction.展开更多
Thin-film composite (TFC) nanofiltration (NF) membranes were fabricated via the interfacial polymerization of piperazine (PIP) and 1,3,5-benzenetricart)oiiyl trichloride on polysulfone (PSf) support membranes blended ...Thin-film composite (TFC) nanofiltration (NF) membranes were fabricated via the interfacial polymerization of piperazine (PIP) and 1,3,5-benzenetricart)oiiyl trichloride on polysulfone (PSf) support membranes blended with K^+-responsive poly(N-isopropylacryamideco- acryloylamidobenzo-15-crown-5)(P(NIPAM-co- AAB15C5)). Membranes were characterized by attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscope, scanning electron microscope, contact angle, and filtration tests. The results showed that:(1) Under K^+-free conditions, the blended P(NIPAM-co-AAB15C5)/PSf supports had porous and hydrophilic surfaces, thereby producing NF membranes with smooth surfaces and low MgSO4 rejections;(2) With K^+ in the PIP solution, the surface roughness and water permeability of the resultant NF membrane were increased due to the K^+-induced transition of low-content P(NIPAM-co-AAB15C5) from hydrophilic to hydrophobic;(3) After a curing treatment at 95℃, the improved NF membrane achieved an even higher pure water permeability of 10.97 L·m^-2·h^-1 - bar1 under 200 psi. Overall, this study provides a novel method to improve the performance of NF membranes and helps understand the influence of supports on TFC membranes.展开更多
Red mud(RM),as an alkaline waste,was recently proved to be a promising substitute for the SCR catalyst.Dealkalization could improve the acidity and reducibility of red mud,which were critical for SCR reaction.However,...Red mud(RM),as an alkaline waste,was recently proved to be a promising substitute for the SCR catalyst.Dealkalization could improve the acidity and reducibility of red mud,which were critical for SCR reaction.However,the dealkalization effect depended on the reaction between acid solution and red mud.In this study,we realized the directional control of the chemical state of active sites through tuning the acid pretreatment(dealkalization)process.The pretreatment endpoint was controlled at pH values of 3–5 with diluted nitric acid.When the pH values of red mud were 3 and 5(CRM-3 and CRM-5),activated catalysts showed NOx conversion above 90%at 275℃–475℃.The high initial reaction rate,Ce^(3+)/(Ce^(3+)+Ce^(4+))ratio,and surface acidity accounted for the excellent SCR performance of CRM-5 catalyst.Meanwhile,more Fe^(3+) on the CRM-3 surface improved the NH_(3) adsorption.There was a strong interaction between Al and Fe in both CRM-5 and CRM-3 catalysts.DFT results showed that the adsorption capacity of the Al-O_(3)-Fe for NH_(3) and NO is stronger than that of Fe-O_(3)-Fe,which enhanced the NOx conversion of the catalyst.However,the almandine was formed in CRM-4,consumed part of Fe^(3+) and Al^(3+),and the interaction between Al and Fe was weakened.Also,deposited almandine on the catalyst surface covered the active sites,thus leading to lower NH_(3)-SCR activity.展开更多
Metal-organic frameworks(MOFs)are attractive for promising applications but plagued by difficult recovery and deployment due to their intrinsic nano/micro powder nature.Although significant efforts have been made to d...Metal-organic frameworks(MOFs)are attractive for promising applications but plagued by difficult recovery and deployment due to their intrinsic nano/micro powder nature.Although significant efforts have been made to develop separable solid matrixes for MOF supporting,the poor loading stability and durability of MOFs still challenge their engineering applications.Here,we present a facile and effective approach to fabricate MOF-based melamine foams(MFs)(denoted as MOFiths)with ultrahigh loading stability and operation stability,easy separation,and high-efficient performance for versatile robust applications.By adopting our approach,numbers of typical fragile MOFs characterized with wide ranges of particle size(from~nm to~μm)can be precisely incorporated into MFs with controllable loading ratios(up to~1,600%).Particularly,the produced MOFiths show excellent capacities for the highly effective and durable water purifications and acetalization reactions.100%of organic pollutants can be rapidly destructed within 10 min by MOFiths initiated Fenton or catalytic ozonation processes under five successive cycles while the maximum adsorption capacity of MOFiths toward Pb(II),Cd(II),and Cu(II)reaches to 422,222,and 105 mg·g^(-1),respectively.This study provides a critical solution to substantially facilitate the engineering applications of MOFs for long-term use in practice.展开更多
There were 30 speakers and the proceedings contained 28 abstracts that discussed the start-of-the art applications of sustainable chemical engineering [1]. We summarized topics that were discussed in the 28 abstracts ...There were 30 speakers and the proceedings contained 28 abstracts that discussed the start-of-the art applications of sustainable chemical engineering [1]. We summarized topics that were discussed in the 28 abstracts using the non-negative matrix factorization （NMF） algorithm. The ＂topics＂ were synthesized without reading the abstracts. Here we will not discuss the algorithm of NMF in detail because of the space limitation and please refer to references for the description of NMF [2,3]. Topic modeling will be more valuable as the number of the abstracts increases.展开更多
Polyvinylidene fluoride grafted with poly（ethylene glycol） methyl ether methacrylate （PVDF-g- PEGMA） was synthesized using atomic transfer radical polymerization （ATRP） at different reaction times （9 h, 19 h, a...Polyvinylidene fluoride grafted with poly（ethylene glycol） methyl ether methacrylate （PVDF-g- PEGMA） was synthesized using atomic transfer radical polymerization （ATRP） at different reaction times （9 h, 19 h, and 29 h）. The corresponding conversion rates were 10%, 20% and 30%, respectively. PVDF was blended with the copolymer mixtnre containing PVDF-g-PEGMA, solvent and residual PEGMA under different reaction times. In this study, we explored the effect of the copolymer mixture additives with different synthesis times on cast membrane performance. Increasing the reaction time of PVDF-g-PEGMA causes more PVDF-g-PEGMA and less residual PEGMA to be found in the casting solution. Incremental PVDF-g-PEGMA can dramatically increase the viscosity of the casting solution. An overly high viscosity led to a delayed phase inversion, thus hindering PEGMA segments in PVDF- g-PEGMA from migrating to the membrane surface. However, more residual PEGMA contributed to helping rnore PEGMA segments migrate to the membrane surface. The pure water fluxes of the blended membrane with reaction times of 9 h, 19 h, and 29 h are 5445 L. m 2.h I 1068 L- m 2.h land 1179 L.m 2.h I respectively, at 0.07 MPa. Delayed phase inversion can form smaller surface pore size distributions, thus decreasing the water flux for the membranes with PVDF-g-PEGMA at 19 h and 29 h. Therefore, we can control the membrane pore size distribution by decreasing the reaction time of PVDF-g-PEGMA to obtain a better flux performance. The membrane with PVDF-g-PEGMA at 19 h exhibits the best foulant rejection and cleaning recovery due to its narrow pore size distribution and high surface oxygen content.展开更多
Recent data reveals a staggering reality:as of 2020,approximately 3.6 billion individuals across the globe remain devoid of proper sanitation services[1].Worldwide governmental and nongovernmental organisations are de...Recent data reveals a staggering reality:as of 2020,approximately 3.6 billion individuals across the globe remain devoid of proper sanitation services[1].Worldwide governmental and nongovernmental organisations are dedicatedly engaged in the arduous task of ameliorating living standards by providing secure sanitation facilities.Nevertheless,a recurring challenge persists,with these initiatives frequently encountering setbacks,especially in rural areas.展开更多
Authors want to publish their work as soon as possible.However,the manuscript processing time increases if the manuscript does not meet the journal requirements.Our analysis of manuscripts submitted to Frontiers o f E...Authors want to publish their work as soon as possible.However,the manuscript processing time increases if the manuscript does not meet the journal requirements.Our analysis of manuscripts submitted to Frontiers o f Environmental Science&Engineering from November 2018 to July 2019 shows that the processing time was increased up to 33 days because the manuscripts:(1)had inconsistent formatting of citations,references,and units,(2)exceeded the word limit,(3)were missing information such as the graphical abstract,(4)plagiarized other papers,and(5)had too many tables and figures.Herein,we explain how authors can avoid these issues and decrease the manuscript processing time.展开更多
基金This work was partially supported by the Brook Byers Institute for Sustainable Systems, the Hightower Chair, Georgia Research Alliance, and grants （083604, 1441208） from the US National Science Foundation Program for Emerging Frontiers in Research and Innovation （EFRI）.
文摘The increasing pace of urbanization means that cities and global organizations are looking for ways to increase energy efficiency and reduce emissions. Combined cooling, heating, and power （CCHP） systems have the potential to improve the energy generation efficiency of a city or urban region by providing energy for heating, cooling, and electricity simultaneously. The purpose of this study is to estimate the water consumption for energy generation use, carbon dioxide （CO2） and NOx emissions, and economic impact of implementing CCHP systems for five generic building types within the Atlanta metropolitan region, under various operational scenarios following the building thermal （heating and cooling） demands. Operating the CCHP system to follow the hourly thermal demand reduces CO2 emissions for most building types both with and without net metering. The system can be economically beneficial for all building types depending on the price of natural gas, the implementation of net metering, and the cost structure assumed for the CCHP system. The greatest reduction in water consumption for energy production and NOx emissions occurs when there is net metering and when the system is operated to meet the maximum yearly thermal demand, although this scenario also results in an increase in greenhouse gas emissions and, in some cases, cost. CCHP systems are more economical for medium office, large office, and multifamilv residential buildings.
基金supported by the Science Fund for Yong Scholars at Changchun University of Science and Technology(XQNJJ-2014-15)~~
文摘CeO2‐ZrO2 (CeZr) and sulfated CeO2‐ZrO2 (S‐CeZr) catalysts were prepared for the selective catalytic reduction of NO with NH3. The CeZr catalysts exhibited higher activity at low temperatures (< 200°C) and lower activity at high temperatures (> 200 °C) than the S‐CeZr catalysts. The sulfation ofCeZr was studied in terms of surface acidity, redox properties and NO adsorption‐desorption bytemperature‐dependent experiments and in situ infrared spectroscopy. S‐CeZr displayed high concentrationsof acidic sites and increased surface acidities, but poor reducibility compared with CeZr.The high acidity of S‐CeZr was attributed to the presence of Br?nsted acid sites, arising mainly fromthe surface sulfates. Because the surface was covered with sulfate species, S‐CeZr showed lower NOadsorption and weaker oxidation ability than CeZr. The adsorption of NH3 on the Br?nsted acid sites restricted the reaction with NO at low temperatures, but the selective catalytic reduction cycle occurred easily at relatively low temperatures (150 °C), and the weakly bound nitrite was partially activated on the S‐CeZr catalyst at relatively high temperatures (300 °C). The catalytic mechanisms for the CeZr and S‐CeZr catalysts at 150 and 300 °C were also studied.
基金supported by the National Natural Science Foundation of China(21906090)the National Key Research and Development Program(2017YFC0210200,2017YFC0212800)Primary Research&Development Project of Shandong Province(2018GSF117034,2019JZZY020305).
文摘Activated red mud(RM)has been proved to be a promising base material for the selective catalysis reduction(SCR)of NOx.The inherent low reducibility and acidity limited its low-temperature activity.In this work,molybdenum oxide,tungsten oxide,and cerium oxide were used to reconfigure the redox sites and acid sites of red mud based catalyst.When activated red mud was reconfigured by cerium-tungsten oxide(Ce-W@RM),the NOx conversion kept above 90%at 219-480℃.The existence of Ce^(3+)/Ce^(4+) redox electron pairs provided more surface adsorbed oxygen(O_(α)) and served as a redox cycle.Positive interactions between Ce,W species and Fe oxide in red mud occurred,which led to the formation of unsaturated chemical bond and promoted the activation of adsorbed NH_(3) species.WO_(3) and Ce_(2)(WO_(4))_(3)(formed by solid-state reaction between Ce and W species)could provide more Brønsted acid sites(W-O modes of WO_(3),W=O or W-O-W modes of Ce_(2)(WO_(4))_(3)).CeO_(2) species could provide more Lewis acid sites.The Langmuir-Hinshelwood(L-H)routes and Eley-Rideal(E-R)routes occurred in the low-temperature SCR reaction on the Ce-W@RM surface.NH_(4)^(+) species on Brønsted acid sites,NH_(3) species on Lewis acid sites,bidentate nitrate and bridging nitrate species were key active intermediates species.
基金supported by Natural Science Foundation of Hunan Province (No. 2021JJ40066)National Natural Science Foundation (Nos. 51878257 and 52100007).
文摘Vacuum ultraviolet(VUV) photolysis is recognized as an environmental-friendly treatment process. Nitrate(NO-3) and natural organic matter(NOM) are widely present in water source.We investigated trichloronitromethane(TCNM) formation during chlorination after VUV photolysis, because TCNM is an unregulated highly toxic disinfection byproduct. In this study:(1) we found reactive nitrogen species that is generated under VUV photolysis of NO-3react with organic matter to form nitrogen-containing compounds and subsequently form TCNM during chlorination;(2) we found the mere presence of 0.1 mmol/L NO-3can result in the formation of up to 63.96 μg/L TCNM;(3) we found the changes in pH(6.0-8.0), chloride(1-4 mmol/L), and bicarbonate(1-4 mmol/L) cannot effectively diminish TCNM formation;and,(4) we established the quantitative structure-activity relationship(QSAR) model,which indicated a linear relationship between TCNM formation and the Hammett constant(σ) of model compounds;and,(5) we characterized TCNM precursors in water matrix after VUV photolysis and found 1161 much more nitrogen-containing compounds with higher aromaticity were generated. Overall, this study indicates more attention should be paid to reducing the formation risk of TCNM when applying VUV photolysis process at scale.
基金Supported by the National Natural Science Foundation of China(51178446,21206168)
文摘The primary aliphatic amine Primene JM-T was investigated as a potential absorbent for H2S removal. The solubility of HzS in JM-T was measured at 298, 313,333,353, and 368 K with H2S partial pressures from 20 to 760 kPa and HzS loading from 0.02 to 0.8 mol H2S per mol JM-T. Relevant physical properties, such as density, viscoslty and dielectric constant, ot the matenal were measured. ＇The thermodynamlc model with two-suttlX Margules equation was used to correlate the experimental vapor-liquid equilibrium data. Furthermore, the absorption mechanism in non-aqueous system is suggested and the difference between non-aqueous and aqueous absorption system is pointed out.
基金supported by the National Natural Science Foundation of China(No.41401588)supported by the State Scholarship Fund organized by China Scholarship Council+1 种基金the support from the Brook Byers Institute for Sustainable Systems,Hightower Chairthe Georgia Research Alliance at the Georgia Institute of Technology
文摘Accumulation of heavy metals in urban soil can pose adverse impacts on public health and terrestrial ecosystems. We developed a mass balance-based regression model to simulate the heavy metal accumulation in urban soils as a function of time and to explore connections between metal concentration and urbanization processes. Concentrations of Cd and Zn in 68 residential soil samples in the urban area of Beijing were used. The background concentrations, the loss rates and the input fluxes of Cd and Zn in urban soils of Beijing during the last three decades were estimated using a regression of the time series of accumulations of the metals. Based on the regression estimates, we simulated the general trends of Cd and Zn accumulation in the soils from 1978 to 2078. The concentrations of Cd and Zn in urban soil generally increased with the population growth, vehicle use and coal consumption. The mean concentrations of Cd and Zn in urban soil of Beijing would increase by 3 fold over the next 70 years for the current development scenario. The mass balance-based regression approach, which is able to reconstruct the history data of urban soil pollution, provides fundamental information for urban planning and environmental management.
基金supported by the National Natural Science Foundation of China (No. 21177130)the National Key Technology R&D Program (No. 2011BAC06B09)the Chinese Academy of Sciences Visiting Professorships for Senior International Scientists (No. 2009G2-28)
文摘Ozonation of oxalate in aqueous phase was performed with a commercial activated carbon（AC）in this work. The effect of AC dosage and solution pH on the contribution of hydroxyl radicals（HOU） in bulk solution and oxidation on the AC surface to the removal of oxalate was studied. We found that the removal of oxalate was reduced by tert-butyl alcohol（tBA） with low dosages of AC,while it was hardly affected by tBA when the AC dosage was greater than 0.3 g/L. tBA also inhibited ozone decomposition when the AC dosage was no more than 0.05 g/L, but it did not work when the AC dosage was no less than 0.1 g/L. These observations indicate that HOUin bulk solution and oxidation on the AC surface both contribute to the removal of oxalate. HOU oxidation in bulk solution is significant when the dosage of AC is low, whereas surface oxidation is dominant when the dosage of AC is high. The oxalate removal decreased with increasing pH of the solution with an AC dosage of 0.5 g/L. The degradation of oxalate occurs mainly through surface oxidation in acid and neutral solution, but through HOUoxidation in basic bulk solution. A mechanism involving both HOUoxidation in bulk solution and surface oxidation was proposed for AC enhanced ozonation of oxalate.
基金Acknowledgements This research was sponsored by the Brook Byers Institute for Sustainable Systems, Hightower Chair, and the Georgia Research Alliance at the Georgia Institute of Technology. This work was also supported by a grant for ＂Resilient Interdependent Infrastructure Processes and Systems （RIPS） Type 2： Participatory Modeling of Complex Urban Infrastructure Systems （Model Urban SysTems）,＂ （#0836046） from National Science Foundation, Division of Emerging Frontiers in Research and Innovations （EFRI）. The authors also acknowledge the support of Crittenden and Associates.
文摘Low-impact development （LID） technologies, such as bioretention areas, rooftop rainwater harvesting, a_nd xeris_caping can co_ntrol stormwater runoff, supply non-potable water, and landscape open space.TillS study examines a hybrid system （HS） that combines LID technologies with a centralized water system to lessen the burden on a conventional system （CS）. CS is defined as the stormwater collection and water supply infrastructure, and the conventional landscaping choices in the City of Atlanta. The study scope is limited to five single-family residential zones （SFZs）, classified R-1 through R-5, and four multi-family residential zones （MFZs）, classified RG-2 through RG-5. Population density increases from 0.4 （R-1） to 62.2 （RG-5） persons per 1,000 m2. We performed a life cycle assessment （LCA） comparison of CS and HS using TRACI 2.1 to simulate impacts on the ecosystem, human health, and natural resources. We quantified the impact of freshwater consumption using the freshwater ecosystem impact （FEI） indicator. Test results indicate that HS has a higher LCA single score than CS in zones with a low population density; however, the difference becomes negligible as population density increases. Incorporating LID in SFZs and MFZs can reduce potable water use by an average of 50%. and 25%,respectively.; however, water savings are negligible in zones with high population density （i.e., RG-5） due to the diminished surface area per capitaavailable for LID technoogies. The results demonstrate that LID technologies effectively reduce outdoor water demand and therefore would be a good choice to decrease the water consumption impact in the City of Atlanta.
基金This research was supported by the National Natural Science Foundation of China （Grant Nos. 21325731, 51478241 and 21407088）, and National High-Tech Research and the Development （863） Program of China （No. 2013AA065401） and the International Postdoctoral Exchange Fellowship Program of China （No. 20130032）.
文摘Selective catalytic reduction （SCR） of NOx with NH3 is an effective technique to remove NOx from stationary sources, such as coal-fired power plant and industrial boilers. Some of elements in the fly ash deactivate the catalyst due to strong chemisorptions on the active sites. The poisons may act by simply blocking active sites or alter the adsorption behaviors of reactants and products by an electronic interaction. This review is mainly focused on the chemical poisoning on V2O5-based catalysts, environmental-benign catalysts and low temperature catalysts. Several common poisons including alkali/alkaline earth metals, SO2 and heavy metals etc. are referred and their poisoning mechanisms on catalysts are discussed. The regeneration methods of poisoned catalysts and the development of poison-resistance catalysts are also compared and analyzed. Finally, future research directions in developing poisoning resistance catalysts and facile efficient regeneration methods for SCR catalysts are proposed.
基金the National Natural Science Foundation of China(Grant No.21906090)the National Key Research and Development Program(Nos.2017YFC0210200 and 2017YFC0212800)Primary Research&Development Project of Shandong Province(Nos.2018GSF117034 and 2019JZZY020305).
文摘Our previous study proved that the acid-pretreatment process could efficiently activate red mud(RM)for the selective catalytic reduction(SCR)of NO_(x).However,in terms of the molding process,which is the key step determining whether it can be applied in large-scale industrial,the surface acidity and reducibility of catalyst always decreased dramatically,and part of surface area and pore structure were lost.In this study,we prepared monolithic honeycomb red mud(MHRM)catalysts with activated carbon(AC)as an accelerant and investigated the effect of AC on the MHRM.The results showed that the MHRM with 3 wt.%of AC(MHRM-AC3)exhibited the best SCR performance,and kept more than 80%NO_(x)conversion in the range of 325℃–400℃.Compared with the MHRM,MHRM-AC1,and HMRM-AC5,the MHRM-AC3 has more mesoporous and macroporous structures,which can provide more adsorption active sites.The AC significantly improved NH3 adsorption and surface reducibility,which was mainly due to the increase of the surface acid sites(especially the Brönsted acid sites),the concentration of Fe(II),and the surface adsorbed oxygen.The presence of more Fe(Ⅱ)enriched the surface oxygen vacancies,as well as the surface adsorbed oxygen,due to the charge imbalance and unsaturated chemical bond.And surface adsorbed oxygen exhibited more active than lattice oxygen owing to its higher mobility,which was conducive to NO_(x)reduction in the SCR reaction.
基金the National Natural Science Foundation of China (Grant No.51678377)Sichuan University Outstanding Youth Foundation (2015SCU04A35)+1 种基金Applied Basic Research of Sichuan Province (2017JY0238)Key Projects in the Science & Technology Program of Hainan Province (zdkj2016022).
文摘Thin-film composite (TFC) nanofiltration (NF) membranes were fabricated via the interfacial polymerization of piperazine (PIP) and 1,3,5-benzenetricart)oiiyl trichloride on polysulfone (PSf) support membranes blended with K^+-responsive poly(N-isopropylacryamideco- acryloylamidobenzo-15-crown-5)(P(NIPAM-co- AAB15C5)). Membranes were characterized by attenuated total reflection Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscope, scanning electron microscope, contact angle, and filtration tests. The results showed that:(1) Under K^+-free conditions, the blended P(NIPAM-co-AAB15C5)/PSf supports had porous and hydrophilic surfaces, thereby producing NF membranes with smooth surfaces and low MgSO4 rejections;(2) With K^+ in the PIP solution, the surface roughness and water permeability of the resultant NF membrane were increased due to the K^+-induced transition of low-content P(NIPAM-co-AAB15C5) from hydrophilic to hydrophobic;(3) After a curing treatment at 95℃, the improved NF membrane achieved an even higher pure water permeability of 10.97 L·m^-2·h^-1 - bar1 under 200 psi. Overall, this study provides a novel method to improve the performance of NF membranes and helps understand the influence of supports on TFC membranes.
基金financially supported by the National Natural Science Foundation of China(Grant No.21906090)the National Key Research and Development Program of China(Nos.2017YFC0210200 and 2017YFC0212800)+1 种基金the Primary Research&Development Project of Shandong Province(China)(Nos.2018GSF117034 and 2019JZZY020305)The scientific calculations in this paper have been done on the HPC Cloud Platform of Shandong University(China).
文摘Red mud(RM),as an alkaline waste,was recently proved to be a promising substitute for the SCR catalyst.Dealkalization could improve the acidity and reducibility of red mud,which were critical for SCR reaction.However,the dealkalization effect depended on the reaction between acid solution and red mud.In this study,we realized the directional control of the chemical state of active sites through tuning the acid pretreatment(dealkalization)process.The pretreatment endpoint was controlled at pH values of 3–5 with diluted nitric acid.When the pH values of red mud were 3 and 5(CRM-3 and CRM-5),activated catalysts showed NOx conversion above 90%at 275℃–475℃.The high initial reaction rate,Ce^(3+)/(Ce^(3+)+Ce^(4+))ratio,and surface acidity accounted for the excellent SCR performance of CRM-5 catalyst.Meanwhile,more Fe^(3+) on the CRM-3 surface improved the NH_(3) adsorption.There was a strong interaction between Al and Fe in both CRM-5 and CRM-3 catalysts.DFT results showed that the adsorption capacity of the Al-O_(3)-Fe for NH_(3) and NO is stronger than that of Fe-O_(3)-Fe,which enhanced the NOx conversion of the catalyst.However,the almandine was formed in CRM-4,consumed part of Fe^(3+) and Al^(3+),and the interaction between Al and Fe was weakened.Also,deposited almandine on the catalyst surface covered the active sites,thus leading to lower NH_(3)-SCR activity.
基金This work was supported by the National Natural Science Foundation of China(No.22106141)the Key Research and Development Program of Zhejiang Province(No.2018C03004)+1 种基金the Scientific Launching Funding of Zhejiang Sci-Tech University and the Postdoctoral Program(No.TYY202103)of Zhejiang Sci-Tech University Tongxiang Research InstituteThe authors also acknowledge the support by the Brook Byers Institute for Sustainable Systems,Hightower Chair and the Georgia Research Alliance at the Georgia Institute of Technology.The views and ideas expressed herein are solely those of the authors’and do not represent the ideas of the funding agencies in any form。
文摘Metal-organic frameworks(MOFs)are attractive for promising applications but plagued by difficult recovery and deployment due to their intrinsic nano/micro powder nature.Although significant efforts have been made to develop separable solid matrixes for MOF supporting,the poor loading stability and durability of MOFs still challenge their engineering applications.Here,we present a facile and effective approach to fabricate MOF-based melamine foams(MFs)(denoted as MOFiths)with ultrahigh loading stability and operation stability,easy separation,and high-efficient performance for versatile robust applications.By adopting our approach,numbers of typical fragile MOFs characterized with wide ranges of particle size(from~nm to~μm)can be precisely incorporated into MFs with controllable loading ratios(up to~1,600%).Particularly,the produced MOFiths show excellent capacities for the highly effective and durable water purifications and acetalization reactions.100%of organic pollutants can be rapidly destructed within 10 min by MOFiths initiated Fenton or catalytic ozonation processes under five successive cycles while the maximum adsorption capacity of MOFiths toward Pb(II),Cd(II),and Cu(II)reaches to 422,222,and 105 mg·g^(-1),respectively.This study provides a critical solution to substantially facilitate the engineering applications of MOFs for long-term use in practice.
文摘There were 30 speakers and the proceedings contained 28 abstracts that discussed the start-of-the art applications of sustainable chemical engineering [1]. We summarized topics that were discussed in the 28 abstracts using the non-negative matrix factorization （NMF） algorithm. The ＂topics＂ were synthesized without reading the abstracts. Here we will not discuss the algorithm of NMF in detail because of the space limitation and please refer to references for the description of NMF [2,3]. Topic modeling will be more valuable as the number of the abstracts increases.
文摘Polyvinylidene fluoride grafted with poly（ethylene glycol） methyl ether methacrylate （PVDF-g- PEGMA） was synthesized using atomic transfer radical polymerization （ATRP） at different reaction times （9 h, 19 h, and 29 h）. The corresponding conversion rates were 10%, 20% and 30%, respectively. PVDF was blended with the copolymer mixtnre containing PVDF-g-PEGMA, solvent and residual PEGMA under different reaction times. In this study, we explored the effect of the copolymer mixture additives with different synthesis times on cast membrane performance. Increasing the reaction time of PVDF-g-PEGMA causes more PVDF-g-PEGMA and less residual PEGMA to be found in the casting solution. Incremental PVDF-g-PEGMA can dramatically increase the viscosity of the casting solution. An overly high viscosity led to a delayed phase inversion, thus hindering PEGMA segments in PVDF- g-PEGMA from migrating to the membrane surface. However, more residual PEGMA contributed to helping rnore PEGMA segments migrate to the membrane surface. The pure water fluxes of the blended membrane with reaction times of 9 h, 19 h, and 29 h are 5445 L. m 2.h I 1068 L- m 2.h land 1179 L.m 2.h I respectively, at 0.07 MPa. Delayed phase inversion can form smaller surface pore size distributions, thus decreasing the water flux for the membranes with PVDF-g-PEGMA at 19 h and 29 h. Therefore, we can control the membrane pore size distribution by decreasing the reaction time of PVDF-g-PEGMA to obtain a better flux performance. The membrane with PVDF-g-PEGMA at 19 h exhibits the best foulant rejection and cleaning recovery due to its narrow pore size distribution and high surface oxygen content.
基金supported by the National Key Research and Development Plan(2018YFC1903206)Youth Teacher International Exchange&Growth Program of USTB(QNXM20210029)Bill and Melinda Gates Foundation(OPP1157726).
文摘Recent data reveals a staggering reality:as of 2020,approximately 3.6 billion individuals across the globe remain devoid of proper sanitation services[1].Worldwide governmental and nongovernmental organisations are dedicatedly engaged in the arduous task of ameliorating living standards by providing secure sanitation facilities.Nevertheless,a recurring challenge persists,with these initiatives frequently encountering setbacks,especially in rural areas.
基金the Project for Outstanding Chinese Scientific Journals[2019-B10],which is funded by the China Association for Science and Technology.
文摘Authors want to publish their work as soon as possible.However,the manuscript processing time increases if the manuscript does not meet the journal requirements.Our analysis of manuscripts submitted to Frontiers o f Environmental Science&Engineering from November 2018 to July 2019 shows that the processing time was increased up to 33 days because the manuscripts:(1)had inconsistent formatting of citations,references,and units,(2)exceeded the word limit,(3)were missing information such as the graphical abstract,(4)plagiarized other papers,and(5)had too many tables and figures.Herein,we explain how authors can avoid these issues and decrease the manuscript processing time.
