This study investigates the potential of Prosopis cineraria Leaves Powder(PCLP)as a biosorbent for removing lead(Pb)and zinc(Zn)from aqueous solutions,optimizing the process using Response Surface Methodology(RSM).Pro...This study investigates the potential of Prosopis cineraria Leaves Powder(PCLP)as a biosorbent for removing lead(Pb)and zinc(Zn)from aqueous solutions,optimizing the process using Response Surface Methodology(RSM).Prosopis cineraria,commonly known as Khejri,is a drought-resistant tree with significant promise in environmental applications.The research employed a Central Composite Design(CCD)to examine the independent and combined effects of key process variables,including initial metal ion concentration,contact time,pH,and PCLP dosage.RSM was used to develop mathematical models that explain the relationship between these factors and the efficiency of metal removal,allowing the determination of optimal operating conditions.The experimental results indicated that the Langmuir isotherm model was the most appropriate for describing the biosorption of both metals,suggesting favorable adsorption characteristics.Additionally,the D-R isotherm confirmed that chemisorption was the primary mechanism involved in the biosorption process.For lead removal,the optimal conditions were found to be 312.23 K temperature,pH 4.72,58.5 mg L-1 initial concentration,and 0.27 g biosorbent dosage,achieving an 83.77%removal efficiency.For zinc,the optimal conditions were 312.4 K,pH 5.86,53.07 mg L-1 initial concentration,and the same biosorbent dosage,resulting in a 75.86%removal efficiency.These findings highlight PCLP’s potential as an effective,eco-friendly biosorbent for sustainable heavy metal removal in water treatment.展开更多
Adsorption of Neutral Red (NR) onto peanut husk in aqueous solutions was investigated at 295 K. Experiments were carried out as function of pH, adsorbent dosage, contact time, and initial concentration. The equilibriu...Adsorption of Neutral Red (NR) onto peanut husk in aqueous solutions was investigated at 295 K. Experiments were carried out as function of pH, adsorbent dosage, contact time, and initial concentration. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, and Toth isotherm models. The results indicated that the Toth and Langmuir models provided the best correlation of the experimental data. The adsorption capacity of peanut husk for the removal of NR was deter...展开更多
A heavy metal contaminated soil sample collected from a mine in Chonnam Province of South Korea was found to be a source of heavy metal adsorbing biosorbents. Chemical analyses showed high contents of lead （Pb） at 3...A heavy metal contaminated soil sample collected from a mine in Chonnam Province of South Korea was found to be a source of heavy metal adsorbing biosorbents. Chemical analyses showed high contents of lead （Pb） at 357 mg/kg and cyanide （CN） at 14.6 mg/kg in the soil. The experimental results showed that Penicillium sp. MRF-1 was the best lead resistant fungus among the four individual metal tolerant fungal species isolated from the soil. Molecular characterization of Penicillium sp. MRF-1 was determined using ITS regions sequences. Effects of pH, temperature and contact time on adsorption of Pb（Ⅱ） by Penicillium sp. MRF-1 were studied. Favorable conditions for maximum biosportion were found at pH 4 with 3 hr contact time. Biosorption of Pb（Ⅱ） gradually increased with increasing temperature. Efficient performance of the biosorbent was described using Langmuir and Freundlich isotherms. Adsorption kinetics was studied using pseudo first-order and pseudo second-order models. Biosorbent Penicillium sp. MRF-1 showed the maximum desorption in alkali conditions. Consistent adsorption/desorption potential of the biosorbent in repetitive cycles validated the efficacy of it in large scale. SEM studies given notes on surface modification of fungal biomass under metal stress and FT-IR results showed the presence of amino groups in the surface structure of the biosorbent. In conclusion, the new biosorbent Penicillium sp. MRF- 1 may potentially be used as an inexpensive, easily cultivatable material for the removal of lead from aqueous solution.展开更多
Kinetics and isotherms of Triton X-100 sorption on soil,base-extracted soil（BE）,humic acid（HA） and humin（HM） were investigated respectively to get better understanding on characteristics of the surfactant sorpti...Kinetics and isotherms of Triton X-100 sorption on soil,base-extracted soil（BE）,humic acid（HA） and humin（HM） were investigated respectively to get better understanding on characteristics of the surfactant sorption onto different soil organic matters（SOMs）.It was demonstrated that the kinetics results could be satisfactorily described by the pseudo-second order model.The half of the time to reach equilibrium（t1/2） for different sorbents followed the sequence of soil 〉 HA 〉 BE 〉 HM.Furthermore,the calculated equilibrium sorption capacity（Ceq） was found in the sequence of HA 〉 BE 〉 HM 〉 soil,which agreed well with the experimental results.The isotherms of Triton X-100 sorption on soil and HA could be well described by the S-type isotherm,but BE and HM by the L-type.The isotherms of all the four sorbents were found reasonably fitted to the Langmuir equation.The Kd value,defined as the ratio of Triton X-100 in sorbent and in the equilibrium solution for given concentrations,generally followed the order of HM 〉 HA 〉 soil 〉 BE.Separated HM and HA showed high affnity for Triton X-100,but the HA and HM in soil and BE were tightly bounded by the minerals.Thus,the HA on the soil surface might dominate the sorption,whereas the bounded HM would play a key role upon the surfactants being penetrated inside the soil.展开更多
The Microcystis aeruginosa(MA) was immobilized on sodium alginate and used as biosorbent for removal of Cd(Ⅱ) ions from aqueous solution.The biosorption process is pH dependent,and the optimum biosorption was observe...The Microcystis aeruginosa(MA) was immobilized on sodium alginate and used as biosorbent for removal of Cd(Ⅱ) ions from aqueous solution.The biosorption process is pH dependent,and the optimum biosorption was observed at pH 6.0 with the biosorption capacity of 98.38 mg/g.Among Langmuir,Freundlich and Temkin isotherm models,the Freundlich and the Temkin isotherm fit well with the experimental data.Cd(Ⅱ) ions biosorption follows the pseudo-second-order kinetic model.The rate controlling mechanism study reveals that film diffusion is the rate-limiting step and intraparticle diffusion is also involved in biosorption.Thermodynamic parameters,such as Gibbs free energy(ΔG°),the enthalpy(ΔH°) and entropy(ΔS°) were calculated,and revealed that the biosorption process is spontaneous,exothermic and random.Furthermore,the immobilized MA can be regenerated using 0.1 mol/L HCl solutions.展开更多
In this research miswak leaves, agriculture wastes, available in large quantity in Saudi Arabia, was used as low-cost adsorbent for removing methylene blue (MB) dye. Equilibrium behavior of miswak leaves was investiga...In this research miswak leaves, agriculture wastes, available in large quantity in Saudi Arabia, was used as low-cost adsorbent for removing methylene blue (MB) dye. Equilibrium behavior of miswak leaves was investigated by performing batch adsorption experiments. The effects of [MB] 0, pH, contact time and adsorbent dose were evaluated. An alkaline pH (10.6) was favorable to the adsorption of MB dye. Adsorption isotherm models, Langmuir, Freundlich and Temkin were used to simulate the equilibrium data. Langmuir equation was found to have the highest value of R2 compared with other models. Furthermore, it was found that miswak leaves have a high adsorptive capacity towards MB dye (200 mg/g) and show favorable adsorption of MB dye with separation factor (RL < 1). In addition, pseudo-first- order, pseudo-second order and intra-particle diffusion were used to study the kinetics of MB adsorption onto miswak leaves. Adsorption process undergoes pseudo-second order kinetic as proved by the high value of R2 and the low value of sum of squared error (SSE percentage). Results indicated that intra-particle diffusion is not the limiting step, and the adsorption process is spontaneous as indicated by the negative value of the .展开更多
The removal of cobalt ion from aqueous solution by Acacia nilotica leaf carbon(HAN), is described. Effect of p H,agitation time and initial concentration on adsorption capacities of HAN was investigated in a batch mod...The removal of cobalt ion from aqueous solution by Acacia nilotica leaf carbon(HAN), is described. Effect of p H,agitation time and initial concentration on adsorption capacities of HAN was investigated in a batch mode. The adsorption process, which is p H dependent, shows maximum removal of cobalt in the p H range 5 for an initial cobalt concentration of 50 mg·L–1The experimental data have been analyzed by using the Freundlich, Langmuir,Temkin and Dubinin–Radushkevich isotherm models. The batch sorption kinetics have been tested for a pseudofirst order, pseudo-second order and Elovich kinetic models. The rate constants of adsorption for all these kinetic models have been calculated. Results showed that the intraparticle diffusion and initial sorption of Co(Ⅱ) into HAN was the main rate limiting step. The adsorption of cobalt ion was confirmed through instrumental analyses such as scanning electron microscope(SEM) and Fourier transform infrared spectroscopy(FTIR). The desorption and recycling ability of HAN were also found. We conclude that HAN can be used for the efficient removal of cobalt from aqueous solution.展开更多
Knowing methane desorption characteristics is essential to define the contribution of adsorbed gas to gas well production.To evaluate the synthetic effect of a clay stabilizer solution on methane desorption kinetics a...Knowing methane desorption characteristics is essential to define the contribution of adsorbed gas to gas well production.To evaluate the synthetic effect of a clay stabilizer solution on methane desorption kinetics and isotherms pertaining to Longmaxi shale,an experimental setup was designed based on the volumetric method.The objective was to conduct experiments on methane adsorption and desorption kinetics and isotherms before and after clay stabilizer treatments.The experimental data were a good fit for both the intraparticle diffusion model and the Freundlich isotherm model.We analyzed the effect of the clay stabilizer on desorption kinetics and isotherms.Results show that clay stabilizer can obviously improve the diffusion rate constant and reduce the methane adsorption amount.Moreover,we analyzed the desorption efficiency before and after treatment as well as the adsorbed methane content.The results show that a higher desorption efficiency after treatment can be observed when the pressure is higher than 6.84 MPa.Meanwhile,the adsorbed methane content before and after treatment all increase when the pressure decreases,and clay stabilizer can obviously promote the adsorbed methane to free gas when the pressure is lower than 19 MPa.This can also be applied to the optimization formulation of slickwater and the design of gas well production.展开更多
The adsorption properties, including the adsorption isotherms, thermodynamics and kinetics, of 1-amino-2- naphthol-4-sulfonic acid (1,2,4-acid) onto weakly basic resin ND900 are investigated. Both the Langmuir and Fre...The adsorption properties, including the adsorption isotherms, thermodynamics and kinetics, of 1-amino-2- naphthol-4-sulfonic acid (1,2,4-acid) onto weakly basic resin ND900 are investigated. Both the Langmuir and Freundlich equations can give a good fit to the adsorption isotherms, which indicates an endothermic and a favorable adsorption in our study range. A high yield in elimination of about 45.21 %-97.28% is obtained for the tested adsorption systems. The capacity and affinity of the adsorption increase with temperature, due to the phenomena of 'solvent-motivated' effects. The value of is 51.59 kJ/mol, which indicates a chemical adsorption and then expects the poor desorption property of ND900. The negative value of indicates the spontaneous nature of the adsorption process, and the positive value of shows the increased randomness at the solid/solution interface during the adsorption process. The value of the adsorption rate constant lower than 0.013 min-1 is indicative of a slow adsorption rate. The intra-particle diffusion must be one of the rate limiting steps.展开更多
In this research dobera leaves (DL), an agricultural waste, available in large quantity in south region of Saudi Arabia, were used as low-cost adsorbent for removal of metal ions such as Pb(II). Batch operation was us...In this research dobera leaves (DL), an agricultural waste, available in large quantity in south region of Saudi Arabia, were used as low-cost adsorbent for removal of metal ions such as Pb(II). Batch operation was used to study the equilibrium behavior of DL. The effects of initial concentration of Pb(II), solution pH, contact time and adsorbent dose were evaluated. To study the kinetics of adsorption of Pb(II) onto DL, pseudo-first-order, pseudo-second-order and intra-particle diffusion were used. Adsorption process undergoes pseudo-second-order kinetic as proved by the high value of R2. Furthermore, to design the equilibrium data of adsorption of process, four adsorption isotherm models such as Langmuir, Freundlich Temkin and Dubinin-Radushkevich (D-R) were used. It is found that Langmuir equation has the highest value of R2 (0.999) compared with other models. In presences of a mixture of Pb(II)/Ni(II), DL were found to be selective for Pb(II) ions with a high adsorptive capacity of 83 mg/g and show favorable adsorption with RL < 1. In addition, preliminary results indicate that DL are very effective adsorbent for the removal of Pb(II) ions (>90%) from drinking water with less competition of other ions present in water.展开更多
The adsorption isotherms of four activated carbons （Norit Rill, Chemviron BPL, Monolit, and Ambersorb-572） have been examined by nitrogen adsorption at 77.5 K. A method for adsorption potential distribution calculat...The adsorption isotherms of four activated carbons （Norit Rill, Chemviron BPL, Monolit, and Ambersorb-572） have been examined by nitrogen adsorption at 77.5 K. A method for adsorption potential distribution calculation has been proposed based on the adsorption isotherms. This distribution provides information about possible changes in the Gibbs free energy caused by the energetic and geometrical heterogeneities of an activated carbon as well as by the adsorbate-related entropic effects. The general character of the adsorption potential distribution is clearly visible by its simple relation to the micropore and mesopore distribution,展开更多
We show that most of the empirical or semi-empirical isotherms proposed to extend the Langmuir formula to sorption (adsorption, chimisorption and biosorption) on heterogeneous surfaces in the gaseous and liquid phase ...We show that most of the empirical or semi-empirical isotherms proposed to extend the Langmuir formula to sorption (adsorption, chimisorption and biosorption) on heterogeneous surfaces in the gaseous and liquid phase belong to the family and subfamily of the BurrXII cumulative distribution functions. As a consequence they obey relatively simple differential equations which describe birth and death phenomena resulting from mesoscopic and microscopic physicochemical processes. Using the probability theory, it is thus possible to give a physical meaning to their empirical coefficients, to calculate well defined quantities and to compare the results obtained from different isotherms. Another interesting consequence of this finding is that it is possible to relate the shape of the isotherm to the distribution of sorption energies which we have calculated for each isotherm. In particular, we show that the energy distribution corresponding to the Brouers-Sotolongo (BS) isotherm [1] is the Gumbel extreme value distribution. We propose a generalized GBS isotherm, calculate its relevant statistical properties and recover all the previous results by giving well defined values to its coefficients. Finally we show that the Langmuir, the Hill-Sips, the BS and GBS isotherms satisfy the maximum Bolzmann-Shannon entropy principle and therefore should be favoured.展开更多
Equilibrium adsorption studies for detoxification of Congo Red (CR) dye from single component model wastewater by powdered watermelon rinds and neem leaves adsorbents were carried out with the view to test the applica...Equilibrium adsorption studies for detoxification of Congo Red (CR) dye from single component model wastewater by powdered watermelon rinds and neem leaves adsorbents were carried out with the view to test the applicability of the adsorption process to Langmuir, Freundlich, Temkin, Dubinin-Radushkevich and Harkins-Jura isotherm models. The values of correlation coefficient, R2 (0.9359 - 0.9998), showed that all the experimental data fitted the linear plots of the tested isotherm models. Dubinin-Radushkevich’s monolayer maximum adsorption capacity qD (20.72 - 26.06 mg/g) is better than Langmuir’s qm (18.62 - 24.75 mg/g) for both adsorbents with the capacities higher for adsorption on watermelon rind than on neem leaves. Values of Langmuir separation factor (RL) suggest unfavourable adsorption processes (i.e. chemisorption) of the dye on both the adsorbents, while Freundlich constant (nF) indicates unfavourable process only for CR adsorption onto neem leaves. The Dubinin-Radushkevich’s mean free energy of adsorption, E (0.29 - 0.32 kJ/mol), suggests physical adsorption processes. Values for Temkin’s heat of adsorption, bT (-0.95 to 0.74 kJ/mol), also show physical adsorption process.展开更多
In this study, adsorption of Congo red dye onto activated carbon prepared from Jujube (Ziziphus Mauritiania) seeds with phosphoric acid as the activating agent was investigated. Batch adsorption studies were carried o...In this study, adsorption of Congo red dye onto activated carbon prepared from Jujube (Ziziphus Mauritiania) seeds with phosphoric acid as the activating agent was investigated. Batch adsorption studies were carried out to study the influence of contact time, adsorbent dosage and initial dye concentration on the adsorption. The data was analysed using pseudo-first order and pseudo-second order kinetic models. The pseudo-second order kinetic model was found to describe the adsorption more effectively with a perfect correlation coefficient of unity. The rate constant, K was obtained as 0.182 (g/mg min) and the calculated qe (9.81) is very close to the experimental value (9.78). A high correlation coefficient obtained when the data was analysed with the intraparticle diffusion rate equation, revealed the presence of intraparticle diffusion in the adsorption process even though it is not the sole controlling step as shown by the value of the intercept (C ≠ 0). Isotherm studies showed that there is high correlation in each case when the data was modelled with Langmuir, Freundlich, Temkin and Dubinin-Radushkevic isotherm models but the best fit was obtained with the Freundlich model with R2 = 0.9991, adsorption capacity, KF = 19.73 (mg/g)(mg/L)1/n and n = 1.563 indicating the adsorption is favourable and occurs on a heterogeneous surface by multilayer. The study showed that activated carbon from jujube seeds is an effective adsorbent for the removal of Congo red dye from solution.展开更多
The Polanyi-Dubinin equation was used to predict adsorption isotherms for eight organic vapors at 25℃ and for two organic vapors at 25℃, 40℃ and 60℃ on activated carbon in this analysis. The theoretical affinity c...The Polanyi-Dubinin equation was used to predict adsorption isotherms for eight organic vapors at 25℃ and for two organic vapors at 25℃, 40℃ and 60℃ on activated carbon in this analysis. The theoretical affinity coefficient, β, was calculated by three methods (molar volume, molecular parachor and electronic polarization) based on nonpolar and polar reference vapors.展开更多
Monolayers of porphyrin and phthalocyanine at the air-water interface were studied bymeans of film balance and Brewster angle microscopy (BAM). ResultS showed that the final point ofcompression isotherm and that of re...Monolayers of porphyrin and phthalocyanine at the air-water interface were studied bymeans of film balance and Brewster angle microscopy (BAM). ResultS showed that the final point ofcompression isotherm and that of recompression isotherm were coincident or not coincidentdepending on the target pressures. Results were discussed in terms of the morphology of monolayersobserved by BAM.展开更多
In this work, the potential of natural and pretreated palm tree trunk (PTT) as agents for adsorption of an organic dye, 2,6-dichlorophenolindophenol (2,6-DCPIP) from aqueous solutions was probed. Natural and acetic ac...In this work, the potential of natural and pretreated palm tree trunk (PTT) as agents for adsorption of an organic dye, 2,6-dichlorophenolindophenol (2,6-DCPIP) from aqueous solutions was probed. Natural and acetic acid treated PTT were characterized by Fourier transform infrared (FT-IR) spectroscopy and by the point of zero charge (pzc). The biosorption of 2,6-DCPIP was investigated in batch mode using natural and treated PTT. This study was achieved by highlighting several parameters such as the contact time, biosorbents dosage, the initial concentration of 2,6-DCPIP, the pH of the solution, the ionic strength and the interfering ions. The results showed that 2,6-DCPIP was successfully adsorbed from aqueous solutions by natural and treated PTT. The equilibrium was attained after 40 minutes for treated PTT and 20 minutes for natural PTT. The maximum capacity of adsorption was obtained at pH = 2. The adsorption isotherms were investigated and it was found that the experimental data were best described by the Dubinin-Radushkevich isotherm for the natural PTT (R2 = 0.979) and by the Temkin isotherm for the treated PTT (R2 = 0.976). The maximum adsorption capacities determined by Langmuir isotherm were found as 108.932 and 157.233 μmol·g–1 for natural and treated PTT, respectively. The adsorption kinetics was analyzed and was best described by the pseudo-second order model (R2 ≥ 0.998). The diffusion mechanism was studied and the result showed that external mass transfer is the main rate controlling step. The desorption of 2,6-DCPIP is favorable in alkaline medium.展开更多
In this study, coconut husk cellulose was employed as a cost-effective and environmentally friendly adsorbent to eliminate methylene blue (MB) dye from aqueous solutions. The successful development of response surface...In this study, coconut husk cellulose was employed as a cost-effective and environmentally friendly adsorbent to eliminate methylene blue (MB) dye from aqueous solutions. The successful development of response surface methodology paired with a central composite design (RSM-CCD) enabled the optimization and modelling of the adsorption process. The study investigated the individual and combined effects of three variables (pH, contact time, and initial MB dye concentration) on the adsorption of MB dye onto coconut husk cellulose. The developed RSM-CCD model exhibited a remarkable degree of precision in predicting the removal efficiency of MB dye within the specified experimental parameters. This was demonstrated by the strong regression parameters, with an R<sup>2</sup> value of 99.79% and an adjusted R<sup>2</sup> value of 99.6%. The study depicted that the optimal parameters for attaining a 98.8827% removal of MB dye using coconut husk cellulose were as follows: an initial MB dye concentration of 30 mg∙L<sup>−1</sup>, contact time of 120 minutes, and pH 7 at a fixed adsorbent dose of 0.5 g. The Freundlich isotherm model provided the most satisfactory description of the equilibrium adsorption isotherms, suggesting that MB dye adsorption onto coconut husk cellulose occurs on a heterogeneous surface. The experimental results demonstrated a strong agreement with the pseudo-second-order kinetics model, indicating that the number of active sites present on the cellulose adsorbent predominantly influences the adsorption process of MB dye. Additionally, the adsorbent made from coconut husk cellulose exhibited the potential to be reused, as it retained its efficiency for a maximum of three cycles of adsorption of MB dye. The results of this study show that coconut husk cellulose has the potential to be an effective and sustainable adsorbent for removing MB dye from aqueous solutions.展开更多
Ferrite nanoparticles (FNPs) have attracted considerable attention due to their diverse applications in wastewater treatment. This study focused on synthesizing non-stoichiometric copper ferrite magnetic nanoparticles...Ferrite nanoparticles (FNPs) have attracted considerable attention due to their diverse applications in wastewater treatment. This study focused on synthesizing non-stoichiometric copper ferrite magnetic nanoparticles (CuFNPs) through co-precipitation and microwave methods. The synthesized adsorbents were characterized using techniques such as X-ray diffraction (XRD), vibration sample magnetometry (VSM), and scanning electron microscopy (SEM). XRD analysis revealed crystallite sizes ranging from 24 to 31 nm for all samples. Furthermore, adsorption experiments were performed to investigate the impacts of several factors, including dye concentration, contact time, adsorbent dosage, and pH, on the removal efficiency of Alizarin Yellow R (AYR) dye. The CuFNPs (5) sample achieved a maximum removal efficiency of 98.90% at a dye concentration of 50 ppm, pH 2, and an equilibrium time of 90 minutes. The kinetic investigation demonstrated that the adsorption of AYR dye onto the nanoparticles adhered to a pseudo-second-order (PSO) model. The adsorption equilibrium data were most accurately described by the Langmuir isotherm model, although the Freundlich model was also evaluated. The CuFNPs (4) sample showed superparamagnetic behavior with a saturation magnetization value of 58.28 emu/g. The antibacterial activity of the synthesized CuFNPs was evaluated against four bacterial strains, including gram-positive, gram-negative, and pathogenic fungal yeast. Results showed that the CuFNPs (5) sample demonstrated significant effectiveness against both gram-negative bacteria (E. coli, P. aeruginosa) and gram-positive bacteria (S. aureus, B. cereus), as well as the pathogenic fungal yeast C. albicans.展开更多
文摘This study investigates the potential of Prosopis cineraria Leaves Powder(PCLP)as a biosorbent for removing lead(Pb)and zinc(Zn)from aqueous solutions,optimizing the process using Response Surface Methodology(RSM).Prosopis cineraria,commonly known as Khejri,is a drought-resistant tree with significant promise in environmental applications.The research employed a Central Composite Design(CCD)to examine the independent and combined effects of key process variables,including initial metal ion concentration,contact time,pH,and PCLP dosage.RSM was used to develop mathematical models that explain the relationship between these factors and the efficiency of metal removal,allowing the determination of optimal operating conditions.The experimental results indicated that the Langmuir isotherm model was the most appropriate for describing the biosorption of both metals,suggesting favorable adsorption characteristics.Additionally,the D-R isotherm confirmed that chemisorption was the primary mechanism involved in the biosorption process.For lead removal,the optimal conditions were found to be 312.23 K temperature,pH 4.72,58.5 mg L-1 initial concentration,and 0.27 g biosorbent dosage,achieving an 83.77%removal efficiency.For zinc,the optimal conditions were 312.4 K,pH 5.86,53.07 mg L-1 initial concentration,and the same biosorbent dosage,resulting in a 75.86%removal efficiency.These findings highlight PCLP’s potential as an effective,eco-friendly biosorbent for sustainable heavy metal removal in water treatment.
基金the China PostdoctoralScience Foundation (No. 20070420811)the Edu-cation Department of Henan Province in China (No.200510459016)
文摘Adsorption of Neutral Red (NR) onto peanut husk in aqueous solutions was investigated at 295 K. Experiments were carried out as function of pH, adsorbent dosage, contact time, and initial concentration. The equilibrium adsorption data were analyzed by Langmuir, Freundlich, Temkin, Dubinin-Radushkevich, and Toth isotherm models. The results indicated that the Toth and Langmuir models provided the best correlation of the experimental data. The adsorption capacity of peanut husk for the removal of NR was deter...
基金supported by Agricultural R&D Promotion Center,South Korea (No. 060101001)
文摘A heavy metal contaminated soil sample collected from a mine in Chonnam Province of South Korea was found to be a source of heavy metal adsorbing biosorbents. Chemical analyses showed high contents of lead （Pb） at 357 mg/kg and cyanide （CN） at 14.6 mg/kg in the soil. The experimental results showed that Penicillium sp. MRF-1 was the best lead resistant fungus among the four individual metal tolerant fungal species isolated from the soil. Molecular characterization of Penicillium sp. MRF-1 was determined using ITS regions sequences. Effects of pH, temperature and contact time on adsorption of Pb（Ⅱ） by Penicillium sp. MRF-1 were studied. Favorable conditions for maximum biosportion were found at pH 4 with 3 hr contact time. Biosorption of Pb（Ⅱ） gradually increased with increasing temperature. Efficient performance of the biosorbent was described using Langmuir and Freundlich isotherms. Adsorption kinetics was studied using pseudo first-order and pseudo second-order models. Biosorbent Penicillium sp. MRF-1 showed the maximum desorption in alkali conditions. Consistent adsorption/desorption potential of the biosorbent in repetitive cycles validated the efficacy of it in large scale. SEM studies given notes on surface modification of fungal biomass under metal stress and FT-IR results showed the presence of amino groups in the surface structure of the biosorbent. In conclusion, the new biosorbent Penicillium sp. MRF- 1 may potentially be used as an inexpensive, easily cultivatable material for the removal of lead from aqueous solution.
基金supported by the National Basic Research Program (973) of China (No. 2007CB407202)
文摘Kinetics and isotherms of Triton X-100 sorption on soil,base-extracted soil（BE）,humic acid（HA） and humin（HM） were investigated respectively to get better understanding on characteristics of the surfactant sorption onto different soil organic matters（SOMs）.It was demonstrated that the kinetics results could be satisfactorily described by the pseudo-second order model.The half of the time to reach equilibrium（t1/2） for different sorbents followed the sequence of soil 〉 HA 〉 BE 〉 HM.Furthermore,the calculated equilibrium sorption capacity（Ceq） was found in the sequence of HA 〉 BE 〉 HM 〉 soil,which agreed well with the experimental results.The isotherms of Triton X-100 sorption on soil and HA could be well described by the S-type isotherm,but BE and HM by the L-type.The isotherms of all the four sorbents were found reasonably fitted to the Langmuir equation.The Kd value,defined as the ratio of Triton X-100 in sorbent and in the equilibrium solution for given concentrations,generally followed the order of HM 〉 HA 〉 soil 〉 BE.Separated HM and HA showed high affnity for Triton X-100,but the HA and HM in soil and BE were tightly bounded by the minerals.Thus,the HA on the soil surface might dominate the sorption,whereas the bounded HM would play a key role upon the surfactants being penetrated inside the soil.
基金Project(41271332) supported by the National Natural Science Foundation of ChinaProject(11JJ2031) supported by the Natural Science Foundation of Hunan Province,China+1 种基金Project(2012SK2021) supported by the Science and Technology Planning Program of Hunan Province,ChinaProject(CX2012B138) supported by the Hunan Provincial Innovation Foundation for Postgraduate,China
文摘The Microcystis aeruginosa(MA) was immobilized on sodium alginate and used as biosorbent for removal of Cd(Ⅱ) ions from aqueous solution.The biosorption process is pH dependent,and the optimum biosorption was observed at pH 6.0 with the biosorption capacity of 98.38 mg/g.Among Langmuir,Freundlich and Temkin isotherm models,the Freundlich and the Temkin isotherm fit well with the experimental data.Cd(Ⅱ) ions biosorption follows the pseudo-second-order kinetic model.The rate controlling mechanism study reveals that film diffusion is the rate-limiting step and intraparticle diffusion is also involved in biosorption.Thermodynamic parameters,such as Gibbs free energy(ΔG°),the enthalpy(ΔH°) and entropy(ΔS°) were calculated,and revealed that the biosorption process is spontaneous,exothermic and random.Furthermore,the immobilized MA can be regenerated using 0.1 mol/L HCl solutions.
文摘In this research miswak leaves, agriculture wastes, available in large quantity in Saudi Arabia, was used as low-cost adsorbent for removing methylene blue (MB) dye. Equilibrium behavior of miswak leaves was investigated by performing batch adsorption experiments. The effects of [MB] 0, pH, contact time and adsorbent dose were evaluated. An alkaline pH (10.6) was favorable to the adsorption of MB dye. Adsorption isotherm models, Langmuir, Freundlich and Temkin were used to simulate the equilibrium data. Langmuir equation was found to have the highest value of R2 compared with other models. Furthermore, it was found that miswak leaves have a high adsorptive capacity towards MB dye (200 mg/g) and show favorable adsorption of MB dye with separation factor (RL < 1). In addition, pseudo-first- order, pseudo-second order and intra-particle diffusion were used to study the kinetics of MB adsorption onto miswak leaves. Adsorption process undergoes pseudo-second order kinetic as proved by the high value of R2 and the low value of sum of squared error (SSE percentage). Results indicated that intra-particle diffusion is not the limiting step, and the adsorption process is spontaneous as indicated by the negative value of the .
文摘The removal of cobalt ion from aqueous solution by Acacia nilotica leaf carbon(HAN), is described. Effect of p H,agitation time and initial concentration on adsorption capacities of HAN was investigated in a batch mode. The adsorption process, which is p H dependent, shows maximum removal of cobalt in the p H range 5 for an initial cobalt concentration of 50 mg·L–1The experimental data have been analyzed by using the Freundlich, Langmuir,Temkin and Dubinin–Radushkevich isotherm models. The batch sorption kinetics have been tested for a pseudofirst order, pseudo-second order and Elovich kinetic models. The rate constants of adsorption for all these kinetic models have been calculated. Results showed that the intraparticle diffusion and initial sorption of Co(Ⅱ) into HAN was the main rate limiting step. The adsorption of cobalt ion was confirmed through instrumental analyses such as scanning electron microscope(SEM) and Fourier transform infrared spectroscopy(FTIR). The desorption and recycling ability of HAN were also found. We conclude that HAN can be used for the efficient removal of cobalt from aqueous solution.
基金supported by the China Scholarship Council(No.201908505143)the Chongqing Research Program of Basic Research and Frontier Technology(No.cstc2017jcyj AX0290/No.cstc2018jcyj AX0563)。
文摘Knowing methane desorption characteristics is essential to define the contribution of adsorbed gas to gas well production.To evaluate the synthetic effect of a clay stabilizer solution on methane desorption kinetics and isotherms pertaining to Longmaxi shale,an experimental setup was designed based on the volumetric method.The objective was to conduct experiments on methane adsorption and desorption kinetics and isotherms before and after clay stabilizer treatments.The experimental data were a good fit for both the intraparticle diffusion model and the Freundlich isotherm model.We analyzed the effect of the clay stabilizer on desorption kinetics and isotherms.Results show that clay stabilizer can obviously improve the diffusion rate constant and reduce the methane adsorption amount.Moreover,we analyzed the desorption efficiency before and after treatment as well as the adsorbed methane content.The results show that a higher desorption efficiency after treatment can be observed when the pressure is higher than 6.84 MPa.Meanwhile,the adsorbed methane content before and after treatment all increase when the pressure decreases,and clay stabilizer can obviously promote the adsorbed methane to free gas when the pressure is lower than 19 MPa.This can also be applied to the optimization formulation of slickwater and the design of gas well production.
基金The work is financially supported by the National Natural Science Foundation of China (No. 20274017)
文摘The adsorption properties, including the adsorption isotherms, thermodynamics and kinetics, of 1-amino-2- naphthol-4-sulfonic acid (1,2,4-acid) onto weakly basic resin ND900 are investigated. Both the Langmuir and Freundlich equations can give a good fit to the adsorption isotherms, which indicates an endothermic and a favorable adsorption in our study range. A high yield in elimination of about 45.21 %-97.28% is obtained for the tested adsorption systems. The capacity and affinity of the adsorption increase with temperature, due to the phenomena of 'solvent-motivated' effects. The value of is 51.59 kJ/mol, which indicates a chemical adsorption and then expects the poor desorption property of ND900. The negative value of indicates the spontaneous nature of the adsorption process, and the positive value of shows the increased randomness at the solid/solution interface during the adsorption process. The value of the adsorption rate constant lower than 0.013 min-1 is indicative of a slow adsorption rate. The intra-particle diffusion must be one of the rate limiting steps.
文摘In this research dobera leaves (DL), an agricultural waste, available in large quantity in south region of Saudi Arabia, were used as low-cost adsorbent for removal of metal ions such as Pb(II). Batch operation was used to study the equilibrium behavior of DL. The effects of initial concentration of Pb(II), solution pH, contact time and adsorbent dose were evaluated. To study the kinetics of adsorption of Pb(II) onto DL, pseudo-first-order, pseudo-second-order and intra-particle diffusion were used. Adsorption process undergoes pseudo-second-order kinetic as proved by the high value of R2. Furthermore, to design the equilibrium data of adsorption of process, four adsorption isotherm models such as Langmuir, Freundlich Temkin and Dubinin-Radushkevich (D-R) were used. It is found that Langmuir equation has the highest value of R2 (0.999) compared with other models. In presences of a mixture of Pb(II)/Ni(II), DL were found to be selective for Pb(II) ions with a high adsorptive capacity of 83 mg/g and show favorable adsorption with RL < 1. In addition, preliminary results indicate that DL are very effective adsorbent for the removal of Pb(II) ions (>90%) from drinking water with less competition of other ions present in water.
基金Natural Science Foundation of Guangdong Province (No. 36566)
文摘The adsorption isotherms of four activated carbons （Norit Rill, Chemviron BPL, Monolit, and Ambersorb-572） have been examined by nitrogen adsorption at 77.5 K. A method for adsorption potential distribution calculation has been proposed based on the adsorption isotherms. This distribution provides information about possible changes in the Gibbs free energy caused by the energetic and geometrical heterogeneities of an activated carbon as well as by the adsorbate-related entropic effects. The general character of the adsorption potential distribution is clearly visible by its simple relation to the micropore and mesopore distribution,
文摘We show that most of the empirical or semi-empirical isotherms proposed to extend the Langmuir formula to sorption (adsorption, chimisorption and biosorption) on heterogeneous surfaces in the gaseous and liquid phase belong to the family and subfamily of the BurrXII cumulative distribution functions. As a consequence they obey relatively simple differential equations which describe birth and death phenomena resulting from mesoscopic and microscopic physicochemical processes. Using the probability theory, it is thus possible to give a physical meaning to their empirical coefficients, to calculate well defined quantities and to compare the results obtained from different isotherms. Another interesting consequence of this finding is that it is possible to relate the shape of the isotherm to the distribution of sorption energies which we have calculated for each isotherm. In particular, we show that the energy distribution corresponding to the Brouers-Sotolongo (BS) isotherm [1] is the Gumbel extreme value distribution. We propose a generalized GBS isotherm, calculate its relevant statistical properties and recover all the previous results by giving well defined values to its coefficients. Finally we show that the Langmuir, the Hill-Sips, the BS and GBS isotherms satisfy the maximum Bolzmann-Shannon entropy principle and therefore should be favoured.
文摘Equilibrium adsorption studies for detoxification of Congo Red (CR) dye from single component model wastewater by powdered watermelon rinds and neem leaves adsorbents were carried out with the view to test the applicability of the adsorption process to Langmuir, Freundlich, Temkin, Dubinin-Radushkevich and Harkins-Jura isotherm models. The values of correlation coefficient, R2 (0.9359 - 0.9998), showed that all the experimental data fitted the linear plots of the tested isotherm models. Dubinin-Radushkevich’s monolayer maximum adsorption capacity qD (20.72 - 26.06 mg/g) is better than Langmuir’s qm (18.62 - 24.75 mg/g) for both adsorbents with the capacities higher for adsorption on watermelon rind than on neem leaves. Values of Langmuir separation factor (RL) suggest unfavourable adsorption processes (i.e. chemisorption) of the dye on both the adsorbents, while Freundlich constant (nF) indicates unfavourable process only for CR adsorption onto neem leaves. The Dubinin-Radushkevich’s mean free energy of adsorption, E (0.29 - 0.32 kJ/mol), suggests physical adsorption processes. Values for Temkin’s heat of adsorption, bT (-0.95 to 0.74 kJ/mol), also show physical adsorption process.
文摘In this study, adsorption of Congo red dye onto activated carbon prepared from Jujube (Ziziphus Mauritiania) seeds with phosphoric acid as the activating agent was investigated. Batch adsorption studies were carried out to study the influence of contact time, adsorbent dosage and initial dye concentration on the adsorption. The data was analysed using pseudo-first order and pseudo-second order kinetic models. The pseudo-second order kinetic model was found to describe the adsorption more effectively with a perfect correlation coefficient of unity. The rate constant, K was obtained as 0.182 (g/mg min) and the calculated qe (9.81) is very close to the experimental value (9.78). A high correlation coefficient obtained when the data was analysed with the intraparticle diffusion rate equation, revealed the presence of intraparticle diffusion in the adsorption process even though it is not the sole controlling step as shown by the value of the intercept (C ≠ 0). Isotherm studies showed that there is high correlation in each case when the data was modelled with Langmuir, Freundlich, Temkin and Dubinin-Radushkevic isotherm models but the best fit was obtained with the Freundlich model with R2 = 0.9991, adsorption capacity, KF = 19.73 (mg/g)(mg/L)1/n and n = 1.563 indicating the adsorption is favourable and occurs on a heterogeneous surface by multilayer. The study showed that activated carbon from jujube seeds is an effective adsorbent for the removal of Congo red dye from solution.
文摘The Polanyi-Dubinin equation was used to predict adsorption isotherms for eight organic vapors at 25℃ and for two organic vapors at 25℃, 40℃ and 60℃ on activated carbon in this analysis. The theoretical affinity coefficient, β, was calculated by three methods (molar volume, molecular parachor and electronic polarization) based on nonpolar and polar reference vapors.
文摘Monolayers of porphyrin and phthalocyanine at the air-water interface were studied bymeans of film balance and Brewster angle microscopy (BAM). ResultS showed that the final point ofcompression isotherm and that of recompression isotherm were coincident or not coincidentdepending on the target pressures. Results were discussed in terms of the morphology of monolayersobserved by BAM.
文摘In this work, the potential of natural and pretreated palm tree trunk (PTT) as agents for adsorption of an organic dye, 2,6-dichlorophenolindophenol (2,6-DCPIP) from aqueous solutions was probed. Natural and acetic acid treated PTT were characterized by Fourier transform infrared (FT-IR) spectroscopy and by the point of zero charge (pzc). The biosorption of 2,6-DCPIP was investigated in batch mode using natural and treated PTT. This study was achieved by highlighting several parameters such as the contact time, biosorbents dosage, the initial concentration of 2,6-DCPIP, the pH of the solution, the ionic strength and the interfering ions. The results showed that 2,6-DCPIP was successfully adsorbed from aqueous solutions by natural and treated PTT. The equilibrium was attained after 40 minutes for treated PTT and 20 minutes for natural PTT. The maximum capacity of adsorption was obtained at pH = 2. The adsorption isotherms were investigated and it was found that the experimental data were best described by the Dubinin-Radushkevich isotherm for the natural PTT (R2 = 0.979) and by the Temkin isotherm for the treated PTT (R2 = 0.976). The maximum adsorption capacities determined by Langmuir isotherm were found as 108.932 and 157.233 μmol·g–1 for natural and treated PTT, respectively. The adsorption kinetics was analyzed and was best described by the pseudo-second order model (R2 ≥ 0.998). The diffusion mechanism was studied and the result showed that external mass transfer is the main rate controlling step. The desorption of 2,6-DCPIP is favorable in alkaline medium.
文摘In this study, coconut husk cellulose was employed as a cost-effective and environmentally friendly adsorbent to eliminate methylene blue (MB) dye from aqueous solutions. The successful development of response surface methodology paired with a central composite design (RSM-CCD) enabled the optimization and modelling of the adsorption process. The study investigated the individual and combined effects of three variables (pH, contact time, and initial MB dye concentration) on the adsorption of MB dye onto coconut husk cellulose. The developed RSM-CCD model exhibited a remarkable degree of precision in predicting the removal efficiency of MB dye within the specified experimental parameters. This was demonstrated by the strong regression parameters, with an R<sup>2</sup> value of 99.79% and an adjusted R<sup>2</sup> value of 99.6%. The study depicted that the optimal parameters for attaining a 98.8827% removal of MB dye using coconut husk cellulose were as follows: an initial MB dye concentration of 30 mg∙L<sup>−1</sup>, contact time of 120 minutes, and pH 7 at a fixed adsorbent dose of 0.5 g. The Freundlich isotherm model provided the most satisfactory description of the equilibrium adsorption isotherms, suggesting that MB dye adsorption onto coconut husk cellulose occurs on a heterogeneous surface. The experimental results demonstrated a strong agreement with the pseudo-second-order kinetics model, indicating that the number of active sites present on the cellulose adsorbent predominantly influences the adsorption process of MB dye. Additionally, the adsorbent made from coconut husk cellulose exhibited the potential to be reused, as it retained its efficiency for a maximum of three cycles of adsorption of MB dye. The results of this study show that coconut husk cellulose has the potential to be an effective and sustainable adsorbent for removing MB dye from aqueous solutions.
文摘Ferrite nanoparticles (FNPs) have attracted considerable attention due to their diverse applications in wastewater treatment. This study focused on synthesizing non-stoichiometric copper ferrite magnetic nanoparticles (CuFNPs) through co-precipitation and microwave methods. The synthesized adsorbents were characterized using techniques such as X-ray diffraction (XRD), vibration sample magnetometry (VSM), and scanning electron microscopy (SEM). XRD analysis revealed crystallite sizes ranging from 24 to 31 nm for all samples. Furthermore, adsorption experiments were performed to investigate the impacts of several factors, including dye concentration, contact time, adsorbent dosage, and pH, on the removal efficiency of Alizarin Yellow R (AYR) dye. The CuFNPs (5) sample achieved a maximum removal efficiency of 98.90% at a dye concentration of 50 ppm, pH 2, and an equilibrium time of 90 minutes. The kinetic investigation demonstrated that the adsorption of AYR dye onto the nanoparticles adhered to a pseudo-second-order (PSO) model. The adsorption equilibrium data were most accurately described by the Langmuir isotherm model, although the Freundlich model was also evaluated. The CuFNPs (4) sample showed superparamagnetic behavior with a saturation magnetization value of 58.28 emu/g. The antibacterial activity of the synthesized CuFNPs was evaluated against four bacterial strains, including gram-positive, gram-negative, and pathogenic fungal yeast. Results showed that the CuFNPs (5) sample demonstrated significant effectiveness against both gram-negative bacteria (E. coli, P. aeruginosa) and gram-positive bacteria (S. aureus, B. cereus), as well as the pathogenic fungal yeast C. albicans.
