共查询到20条相似文献,搜索用时 15 毫秒
1.
Yanxia Zhou Yiting Zhao Xiaoge Wu Weiqin Yin Jianhua Hou Shengsen Wang Ke Feng Xiaozhi Wang 《RSC advances》2018,8(55):31568
In this study, a facile one-step route was used to synthesize a novel magnetic mesoporous greigite (Fe3S4)-CTAB composite, which was utilized to remove hexavalent chromium (Cr(vi)). The optimized Fe3S4-CTAB0.75 composite with a CTAB dosage of 0.75 g possessed the maximum specific surface, showing the highest Cr(vi) adsorption capacity of 330.03 mg g−1. The mechanism analysis revealed that Fe(ii) and S(−ii) were critical for the reduction of Cr(vi). CTAB can promote the removal of Cr(vi) by Fe3S4-CTAB composites, possibly due to increased S(−ii) concentration, better dispersion of nanoparticles, and greater zeta potential. Besides, there is mild effect of Fe0 on Cr(vi) removal, which is confirmed by the disappearance of the Fe0 peak from the XPS analysis. The pseudo-second-order kinetic model could explain the Cr(vi) removal processes well. The adsorption of Cr(vi) at different initial concentrations was more consistent with a Langmuir isotherm. The existence of H+ was beneficial for Cr(vi) removal by Fe3S4-CTAB0.75. Our work confirmed that the obtained Fe3S4-CTAB0.75 composites exhibit considerable potential for Cr(vi) removal from aqueous solution.The presence of CTAB can promote the removal of hexavalent chromium from the Fe3S4-CTAB surface. 相似文献
2.
Spores of Aspergillus niger (denoted as A. niger) were used as a novel biosorbent to remove hexavalent chromium from aqueous solution. The effects of biosorbent dosage, pH, contact time, temperature and initial concentration of Cr(vi) on its adsorption removal were examined in batch mode. The Cr(vi) uptake capacity increased with an increase in Cr(vi) concentration until saturation, which was found to be about 97.1 mg g−1 at pH 2.0, temperature of 40 °C, adsorbent dose of 2.0 g L−1 and initial concentration of 300 mg L−1. Scanning electron microscopy, energy dispersive X-ray spectroscopy, field-emission transmission electron microscopy (FETEM), XPS and Fourier-transform infrared spectroscopy were applied to study the microstructure, composition and chemical bonding states of the biomass adsorbent before and after spore adsorption. The mechanisms of chromate anion removal from aqueous solution by the spores of A. niger were proposed, which included adsorption of Cr(vi) onto the spores followed by its reduction to Cr(iii). The reduced Cr(iii) was rebound to the biomass mainly through complexation mechanisms, redox reaction and electrostatic attraction. The removal of Cr(vi) by spores of A. niger followed pseudo-second-order adsorption kinetics. Monolayer adsorption of Cr(vi) was revealed by the better fitting of the Langmuir model isotherm rather than multilayer adsorption for the Freundlich model. The results indicated that A. niger spores can be used as a highly efficient biosorbent to remove Cr(vi) from contaminated water.Spores of Aspergillus niger (denoted as A. niger) were used as a novel biosorbent to remove hexavalent chromium from aqueous solution. 相似文献
3.
P. Nkuigue Fotsing E. Djoufac Woumfo S. Mezghich M. Mignot N. Mofaddel F. Le Derf J. Vieillard 《RSC advances》2020,10(34):20009
The present work addresses the development of simple, low-cost and eco-friendly cocoa-shell-based materials for efficient removal of heavy metal hexavalent chromium (Cr(vi)), and toxic nitrate (NO3−) from aqueous solution. A conventional treatment process was used to purify cocoa shell (CS) into an adsorbent, followed by chemical grafting of dendrimers to promote its surface properties for nitrate and Cr(vi) removal. The morphology, surface charge, structure and stability of the new adsorbent were investigated by scanning electron microscopy, Fourier transform infrared and UV-visible spectroscopies, zeta potential, X-ray photoelectron spectrometry, and differential scanning calorimetry. The successful chemical grafting of the dendrimer (polyethyleneimine, PEI) onto purified CS was confirmed. CS-T-PEI-P proved to be a very efficient candidate for the removal of nitrate and chromium(vi). Removal of the two pollutants at different initial concentrations and pH values was studied and discussed. Sorption of chromium and nitrate was found to obey 2nd-order kinetics and a Freundlich-type isotherm, affording an uptake adsorption of 16.92 mg g−1 for NO3− and 24.78 mg g−1 for Cr(vi). These results open promising prospects for its potential applications as a low cost catalyst in wastewater treatment.The present work addresses the development of simple, low-cost and eco-friendly cocoa-shell-based materials for efficient removal of heavy metal hexavalent chromium (Cr(vi)), and toxic nitrate (NO3−) from aqueous solution. 相似文献
4.
In this study, polyethylenimine-functionalized poly(vinyl alcohol) (PEI-PVA) films were prepared for the first time to remove aqueous Cr(vi). The results indicate that our PEI-PVA films have an excellent potential for Cr(vi) removal and their maximum removal capacity was 396.83 mg g−1. The optimized pH value was 2, the adsorption of Cr(vi) was fitted to the Langmuir model, and the kinetics of uptake could be described well by a pseudo-second-order rate model. Taking into account the simplified separation method of adsorbents and solutions, we used a PVA film as a carrier in which PEI-PVA microspheres were filled to obtain a PEI-PVA functionalized film (PPF). The PPF shows a great efficiency in the removal of Cr(vi) ions in solution, which can absorb and reduce the Cr(vi) ion concentration in the solution in 90 min. PPF has excellent selectivity and the removal efficiency of Cr(vi) ions in the presence of co-existing ions is not reduced. It also has good recycling properties; the removal efficiency remains at 77% over four cycles. The removal mechanism of Cr(vi) ions by PEI-PVA microspheres involves the reduction of the adsorbed Cr(vi) ions to Cr(iii) ions, which are less toxic.A PEI-PVA functionalized composite film has been developed to remove hexavalent chromium ion Cr(vi) from water by an adsorption–reduction mechanism. 相似文献
5.
This paper discusses the sorption characteristics of Pb(ii) and U(vi) on magnetic and nonmagnetic rice husk biochars. The porosity, specific surface area, hydrophobility, and reusability of biochar were effectively improved (1–2 times) after magnetic modification. The optimum adsorption conditions were as follows: biochar loading was 0.4 g L−1, pH value was 7.0, and anion strength of NO3− and PO43− were 0.01 mol L−1 for Pb(ii) and 0.04 mol L−1 for U(vi) respectively. Compared with U(vi), Pb(ii) had the faster adsorption rate and higher adsorption capacity on magnetic biochar (MBC). The adsorption experimental data were well fitted by pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption capacity of Pb(ii) and U(vi) on MBC was 129 and 118 mg g−1 at 328 K respectively, which was significantly higher than that of other sources biochars. Pb(ii) was mainly bonded to biochar by physisorption but the adsorption of U(vi) on biochar was mostly chemisorption. Fe oxides in MBC noticeably improved the ion exchange and complexation action between biochar and metal ion especially for U(vi). The experimental results confirmed MBC material can be used as a cost-effective adsorbent for the removal of Pb(ii) and U(vi) and can be separated easily from aqueous solution when application.This paper discusses the sorption characteristics of Pb(ii) and U(vi) on magnetic and nonmagnetic rice husk biochars. 相似文献
6.
In the present work, porous carbon was made from sewage sludge and hybrid liriodendron leaves, and modified with iron ions (Fe@LS-BC) carried out on Cr(vi) in aqueous solution from a single-component system and in competitive biosorption with methyl orange (MO) from a binary-component system. The iron ion-modified porous carbon (Fe@LS-BC) showed higher efficiency in the removal of Cr(vi) compared to porous carbon prepared by the co-pyrolysis of sludge and hybrid liriodendron leaves. The incorporation of the Fe element improved the ability of the material to redox Cr(vi), while imparting magnetic characteristics to the porous carbon and improving the reusability of the porous carbon. On the other hand, Fe@LS-BC exhibited a better pore volume, facilitating the contact of the material with Cr(vi) ions. The highest adsorption capacity was 0.33 mmol g−1, and the adsorption experimental results for the single-component and binary-component systems of Cr(vi) matched well with the Langmuir–Freundlich models. When the concentration of MO was 0.2 and 0.8 mmol L−1, respectively, the highest adsorption capacity of Cr(vi) was 0.35 and 0.46 mmol g−1 in the binary system. The positively charged N–CH3+ on the MO molecule promoted the electrostatic adsorption between HCrO4−, CrO42−, and Fe@LS-BC, and increased the adsorption potential of Cr(vi).Mechanism for the adsorption of hexavalent chromium and methyl orange in a binary system. 相似文献
7.
In this study, CMC–LDH beads were prepared and characterized using SEM, FTIR and TG analysis. The beads were applied for the removal of Cr(vi) from aqueous solution. The effects of adsorbent dosage, initial pH and initial concentration of Cr(vi) solution on Cr(vi) uptake were investigated in detail. Moreover, adsorption isotherms and adsorption kinetic models were employed to analyze the adsorption process, and a preliminary study of the reusability of the adsorbent was performed. The experimental results showed that the CMC–LDH beads could remove Cr(vi) from aqueous solution efficiently. When the initial concentration of the Cr(vi) solution was 100 mg L−1 and the adsorbent dosage was 12 g L−1, the removal efficiency of Cr(vi) reached 96.2%. After the CMC–LDH beads were reused 10 times, the removal efficiency of Cr(vi) still remained at 89.6%.CMC–LDH beads were prepared, characterized and applied for the removal of heavy metal ions in this study. 相似文献
8.
Azza Shokry Ayman El Tahan Hesham Ibrahim Moataz Soliman Shaker Ebrahim 《RSC advances》2019,9(67):39187
The aim of this study is to develop a ternary nanocomposite (NC) of polyaniline (PANI)/2-acrylamido-2-methylpropanesulfonic acid (AMPSA)-capped silver nanoparticles (NPs)/graphene oxide quantum dots (PANI/Ag (AMPSA)/GO QDs) as an efficient adsorbent for the removal of the highly toxic hexavalent chromium (Cr(vi)) from polluted water. PANI/Ag (AMPSA)/GO QDs NC was synthesized via in situ oxidative polymerization. The effects of pH, adsorbent dose, initial concentration, temperature, contact time, ionic strength and co-existing ions on the removal of Cr(vi) by PANI/Ag (AMPSA)/GO QDs were investigated. The PANI/Ag (AMPSA)/GO QDs NC (25.0 mg) removed 99.9% of Cr(vi) from an aqueous solution containing 60 mg L−1 Cr(vi) ions at pH 2. Energy dispersive X-ray (EDX) and inductively coupled plasma spectrometry (ICP) studies confirmed the adsorption of Cr(vi) and that some of the adsorbed Cr(vi) was reduced to Cr(iii). Cr(vi) removal by the PANI/Ag (AMPSA)/GO QDs NC followed the pseudo-second order kinetic model, and the removal was highly selective for Cr(vi) in the presence of other co-existing ions. In summary, the PANI/Ag (AMPSA)/GO QDs NC has potential as a novel adsorbent for Cr(vi).The aim is to develop a ternary nanocomposite of polyaniline/2-acrylamido-2-methylpropanesulfonic acid-capped silver nanoparticles/graphene oxide quantum dots as an efficient adsorbent for the removal of the highly toxic hexavalent chromium (Cr(vi)) from polluted water. 相似文献
9.
In this study, Fe/Ni nanoparticles supported by a novel fly ash-based porous adsorbent (FBA-Fe/Ni) for Cr(vi) and Pb(ii) removal were investigated. In order to enhance the reactivity of zero-valent iron (ZVI), ZVI particles were deposited on the surface or in the inner pores of FBA as a support material and Ni nanoparticles were introduced. FBA was prepared with the solid waste such as Enteromorpha prolifera, bentonite and fly ash. FBA-Fe/Ni was characterized via Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and the Brunauer–Emmett–Teller model and energy-dispersive spectrometry. The effects of various parameters on Cr(vi) and Pb(ii) removal by FBA-Fe/Ni, such as FBA-Fe/Ni dosage, pH of the solution, reaction temperature, Cr(vi) and Pb(ii) concentrations, co-existing ions and ionic strength were discussed. The possible removal mechanisms were proposed and the results indicated that there was a three-step reaction including the adsorption of Cr(vi) and Pb(ii) on the surface of FBA-Fe/Ni, the subsequent reduction and precipitation. The removal capacity of Cr(vi) and Pb(ii) by FBA-Fe/Ni was 25.07 mg g−1 and 164.19 mg g−1 at 303 K with an initial concentration of 1000 mg L−1 and FBA-Fe/Ni dosage of 0.20 g. In conclusion, this work demonstrated that FBA-Fe/Ni was a promising alternative material for Cr(vi) and Pb(ii) removal.In this study, Fe/Ni nanoparticles supported by a novel fly ash-based porous adsorbent (FBA-Fe/Ni) for Cr(vi) and Pb(ii) removal were investigated. 相似文献
10.
Swatantra Pratap Singh Karthik Rathinam Roni Kasher Christopher J. Arnusch 《RSC advances》2018,8(48):27027
Sericin, a protein waste product of the silk industry, was crosslinked with chitosan, and a chitosan–sericin conjugate (CS) was prepared, characterized and used to remove hexavalent chromium (Cr(vi)) ions and methyl orange (MO) dye from aqueous solutions. The CS was shown to effectively remove Cr(vi) ions and MO dye at maximum adsorption capacities (Langmuir) of 139 mg g−1 for Cr(vi) ions and 385 mg g−1 for MO dye. Moreover, the adsorption of both Cr(vi) ions and MO dye was highly pH dependent and varied under different experimental conditions. Cr(vi) ion and MO dye uptake by the CS was confirmed by attenuated total reflectance Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy (XPS) and energy dispersive spectrometry analysis. Additionally, XPS analysis of the Cr(vi)-loaded CS revealed that Cr(vi) was reduced to the less toxic Cr(iii). The CS was shown not only to be highly amenable to regeneration, but also to be able to effectively remove MO dye and Cr(vi) ions from a binary mixture.Sericin, a protein waste product of the silk industry, was crosslinked with chitosan, and a chitosan–sericin conjugate (CS) was prepared, characterized and used to remove hexavalent chromium (Cr(vi)) ions and methyl orange dye from aqueous solutions. 相似文献
11.
Shifeng Li Tingting You Yang Guo Shuhua Yao Shuyan Zang Min Xiao Zhigang Zhang Yanming Shen 《RSC advances》2019,9(22):12428
A one-step carbothermal synthesis and characterization of biochar-supported nanoscale zero-valent iron (nZVI/BC) was performed for the removal of hexavalent chromium (Cr(vi)) from aqueous solution. High dispersions of nanoscale zero-valent iron supported on biochar were successfully synthesized by the pyrolysis of an iron-impregnated biomass (corn stover) as the carbon and iron source under nitrogen atmosphere. The effects of the pyrolytic temperature on the Fe mineralogies formed on the biochar are discussed. In general, the effects of the treatment time, initial solution pH, and nZVI/BC dosage on the Cr(vi) removal are presented. The results showed high crystallinity and purity, and nZVI/BC was obtained at a pyrolytic temperature of 800 °C. The batch experimental results determined that the adsorption capacity of Cr(vi) decreases with the increase in the initial pH value from 4.0 to 10.0. The Cr(vi) adsorption kinetics data effectively followed a pseudo-second-order kinetics with a calculated rate constant of 0.0.3396 g mg−1 min−1. The calculated thermodynamic parameters, such as ΔG°, ΔH°, and ΔS°, were evaluated, and the results indicated that the Cr(vi) reduction on nZVI/BC was a spontaneous and endothermic process. The adsorption mechanism of Cr(vi) was investigated by XRD and XPS analyses and the results demonstrated that Cr(vi) was reduced to Cr(iii) and the oxidation of nZVI occurred during the reaction process. These results prove that nZVI/BC synthesized by a one-step carbothermal method can be considered as a potential candidate for the removal of Cr(vi) from aqueous solutions.A one-step carbothermal synthesis and characterization of biochar-supported nanoscale zero-valent iron (nZVI/BC) was performed for the removal of hexavalent chromium (Cr(vi)) from aqueous solution. 相似文献
12.
Weikang Liu Liang Yang Shihao Xu Yao Chen Bianhua Liu Zhong Li Changlong Jiang 《RSC advances》2018,8(27):15087
Hexavalent chromium Cr(vi), one of the most toxic contaminants, is released in the environment due to various anthropogenic activities. This study presents a novel sandwiched nanocomposite synthesized using graphene oxide (GO), manganese dioxide (MnO2) nanowires, iron oxide (Fe3O4) nanoparticles and polypyrrole (PPy) to remove hexavalent chromium ion Cr(vi) from water by an adsorption–reduction mechanism. In the sandwiched nanocomposites, GO provided enough surface area, functional groups, and hydrophilic surface for efficient absorption. Fe3O4 nanoparticles with excellent magnetic properties make it easy to separate and recover from water. Under acidic conditions, MnO2 nanowires act as both template and oxidant to initiate the polymerization of pyrrole monomers on its freshly activated surface to obtain GO/MnO2/Fe3O4/PPy (designated as GMFP) nanocomposite. GMFP could effectively adsorb Cr(vi) through electrostatic attraction, and the adsorbed Cr(vi) ions were partly reduced to trivalent chromium Cr(iii) (62%), resulting in the efficient adsorption and high removal of Cr(vi) from water. Hexavalent chromium adsorption by GMFP is strongly pH dependent and the adsorption kinetics followed the pseudo-second-order model. The Langmuir isothermal model described the adsorption isotherm data well and the maximum adsorption capacity was up to 374.53 mg g−1 at pH 2.0. These experimental results suggested that GMFP had great potential as an economic and efficient adsorbent of hexavalent chromium from wastewater, which has huge application potential.A sandwiched nanocomposite has been developed to remove hexavalent chromium ion Cr(vi) from water by an adsorption–reduction mechanism. 相似文献
13.
A bentonite supported amorphous aluminum (B–Al) nanocomposite was synthesized by the NaBH4 reduction method in an ethanol–water interfacial solution and characterized with SEM, TEM, XRD, FT-IR and XRF. Surface morphology and line scans obtained from TEM imaging suggest the successful synthesis of the nanocomposite while XRF data shows a drastic change in Al concentration in the synthesized nanocomposite with respect to raw bentonite. This synthesized nanocomposite was further utilized for the removal of hexavalent chromium (Cr(vi)) from aqueous solutions. The very high removal efficiency of the composite for Cr(vi) (i.e. 49.5 mg g−1) was revealed by the Langmuir sorption isotherm. More than 90% removal of Cr(vi) in just 5 minutes of interaction suggests very fast removal kinetics. Inner sphere complexation and coprecipitation of Cr(vi) can be concluded as major removal mechanisms. No influence of ionic strength suggests inner sphere complexation dominated in Cr(vi) uptake. pH of the solution didn''t influence the sorption much but comparatively the removal was higher under alkaline conditions (99.4%) than under acidic conditions (93.7%). The presence of humic acid and bicarbonate ions reduced the sorption significantly. The final product, Cr–Al(OH)3 results in precipitation by forming alum which indicates that clay supported amorphous aluminum nanocomposites can be considered as potential sorbents for toxic metal ions in the environment.Synthesis and application of bentonite supported amorphous aluminum nanocomposite as promising material for the removal of Cr(vi) from aqueous solutions. 相似文献
14.
The present investigation involves synthesis and characterization of MCM-41–AEAPTMS–Fe(iii)Cl using coordinated Fe(iii) on MCM-41–AEAPTMS for efficient removal of hazardous Cr(vi) ions from aqueous solution. The adsorbent MCM-41–AEAPTMS–Fe(iii)Cl was characterized using small-angle X-ray diffraction (SAX), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier-transform infrared (FT-IR) and Brunauer–Emmett–Teller (BET) surface analyzer techniques. The BET surface area was found to be 87.598 m2 g−1. The MCM-41–AEAPTMS–Fe(iii)Cl effectively adsorbs Cr(vi) with an adsorption capacity acquiring the maximum value of 84.9 mg g−1 at pH 3 at 298 K. The data followed pseudo-second-order kinetics and obeyed the Langmuir isotherm model. The thermodynamic data proved the exothermic and spontaneous nature of Cr(vi) ion adsorption on MCM-41–AEAPTMS–Fe(iii). Further, the higher value of ΔH° (−64.339 kJ mol−1) indicated that the adsorption was chemisorption in nature.The present investigation involves synthesis and characterization of MCM-41–AEAPTMS–Fe(iii)Cl using coordinated Fe(iii) on MCM-41–AEAPTMS for efficient removal of hazardous Cr(vi) ions from aqueous solution. 相似文献
15.
Liping Liang Yuanyuan Xue Gangliang Tian Qiaole Mao Zixuan Lou Qian Wu Qian Wang Juanshan Du Xu Meng 《RSC advances》2019,9(45):26136
The application of nano zero-valent iron (nZVI) in water environment was limited by its easily aggregation and potential biological toxicity. In this study, biochar embedded nZVI (BC-nZVI) was prepared by carbon-thermal reduction method, and the SEM-EDX mapping results showed that nZVI was successfully embedded on biochar. Meanwhile, BC-nZVI with the optimal Fe/C of 2/1 showed a similar Se(vi) removal efficiency to pure nZVI. Effects of pH, BC-nZVI loading, and initial Se(vi) concentration were studied. Se(vi) removal rates (at 30 min) by BC-nZVI at pH 4.0 and 5.0 were 98.2% and 95.9%, respectively. But Se(vi) removal rate (at 30 min) was sharply decreased to 25.8% at pH 6.0. With the increase of BC-nZVI loading from 0.5 g L−1 to 1 g L−1, Se(vi) removal rate (at 30 min) significantly increased from 25.5% to 95.9%. And the continuous increase of BC-nZVI loading to 2 g L−1 did not improve Se(vi) removal rate. Se(vi) less than 3 mg L−1 was completely removed by BC-nZVI in 30 min, but Se(vi) more than 6 mg L−1 only was removed about 25.9% at 30 min. Optimal parameters were pH 4.0, 2 g L−1 BC-nZVI, and 1.5 mg L−1 Se(vi). Variation of calculated amount, SOD activity, and protein content of Escherichia coli with nZVI and BC-nZVI indicated that nZVI and BC-nZVI both produced negative effects on the growth of E. coli. But the amount and SOD activity of E. coli with pure nZVI was lower than that with BC-nZVI. Moreover, E. coli with nZVI released more protein than that with BC-nZVI. So modified nZVI by biochar was less harmful to E. coli than nZVI.The application of nano zero-valent iron (nZVI) in water environment was limited by its easily aggregation and potential biological toxicity. 相似文献
16.
Shiqiu Zhang Haiqing Zhang Fang Liu Fan Yang Shengnan Zhou Kui Zheng Chunli Chu Le Liu Meiting Ju 《RSC advances》2019,9(54):31333
In order to remove hexavalent chromium (Cr(vi)) efficiently and simplify the adsorbent preparation process, we employed a single step method to prepare a new biochar supported manganese sulfide material. The nanoscale MnS particles were highly soldered on the biochar support surface, and this adsorbent displayed the effective removal of Cr(vi) (98.15 mg L−1) via synergistic effect between adsorption and reduction/precipitation under weak acid conditions (pH = 5.0–6.0). The adsorption kinetic data were described well by the pseudo second-order kinetic model, suggesting that the reaction process was a chemisorption process. The adsorption isotherm data were described well by the Redlich–Peterson model, further suggesting that this reaction was a hybrid chemical reaction-sorption process. In addition, the Dubinin–Radushkevich isotherm model with 8.28, 8.57, and 12.91 kJ mol−1 adsorption energy also suggests that it was a chemisorption process. The simple and eco-friendly preparation process, low-cost, and the high removal efficiency could make it a promising material for the purification of Cr(vi)-contaminated wastewater.In order to remove hexavalent chromium (Cr(vi)) efficiently and simplify the adsorbent preparation process, we employed a single step method to prepare a new biochar supported manganese sulfide material. 相似文献
17.
In the present work, leucoemeraldine-based hybrid porous polyanilines (LHPPs) have been synthesized by the Friedel–Crafts reaction of leucoemeraldine and octavinylsilsesquioxane (OVS) for Cr(vi) removal. The resulting LHPPs were characterized by Fourier transform infrared spectroscopy, powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy and N2 adsorption–desorption. The findings indiated that the LHPPs were amorphous, with apparent surface areas (SBET) in the range of 147 to 388 m2 g−1 and total volumes in the range of 0.13 to 0.44 cm3 g−1. Cr(vi) removal experiments displayed that the LHPPs exhibited highly efficient Cr(vi) removal performance. The maximum Cr(vi) removal capacity of LHPP-1 was 990.1 mg g−1 at 308 K and pH 1, which is higher than those of other reported polyaniline-based adsorbents. The adsorption process was a spontaneous, endothermic and chemical adsorption process. The adsorption behavior agreed well with Langmuir models and pseudo second-order equations. X-ray photoelectron spectroscopy and Fourier transformed infrared (FTIR) spectroscopy analysis revealed that the highly efficient Cr(vi) removal performance can be mainly attributed to the existence of numerous amine and imine groups on the surface of the LHPPs; these can function as adsorption active sites for Cr(vi) removal through electrostatic adsorption and reduction to Cr(iii) under acidic conditions. Moreover, the LHPPs exhibited excellent adsorption selectivity for Cr(vi) despite the presence of other metal ions (K+, Cu2+, Mn2+) and anions (NO3−, SO42−). Therefore, the LHPPs have potential applications for Cr(vi) removal in industrial wastewater.In the present work, leucoemeraldine-based hybrid porous polyanilines (LHPPs) have been synthesized by the Friedel–Crafts reaction of leucoemeraldine and octavinylsilsesquioxane (OVS) for Cr(vi) removal. 相似文献
18.
Reduced graphene oxide (rGO) supported Fe2O3 nanorod composites were prepared via a one-step hydrothermal method and further utilized for hexavalent chromium (Cr(vi)) removal from aqueous environments. The composite material exhibited an excellent removal efficiency for chromium (47.28 mg L−1), which was attributed to the electrostatic attraction and chemical reduction of chromium by the material. The removal mechanism was studied by SEM, BET, XPS, and FTIR. The results demonstrated that rGO was successfully modified by Fe2O3 nanorods (approximately 50 nm wide). Compared with graphene oxide (GO), the compound was much more easily separated from the solution after completing the removal. Furthermore, XPS characterization showed that Cr(vi) could also be reduced to low-toxicity Cr(iii) by hydroxyl groups. In the variables test, it was found that the removal process was pH-dependent. The results of the designed experiments for exploring the adsorption kinetics, isotherms and thermodynamics indicated that the removal process obeyed a pseudo-second-order kinetics model, Langmuir isotherm model and that it was a spontaneous exothermal process. This study provides the possibility of hydrothermal synthesis of Fe2O3/rGO for use as an excellent material to remove Cr(vi) from aqueous environments.Reduced graphene oxide (rGO) supported Fe2O3 nanorod composites were prepared via a one-step hydrothermal method and further utilized for hexavalent chromium (Cr(vi)) removal from aqueous environments. 相似文献
19.
Xiayuan Wu Chunrui Li Zuopeng Lv Xiaowei Zhou Zixuan Chen Honghua Jia Jun Zhou Xiaoyu Yong Ping Wei Yan Li 《RSC advances》2020,10(26):15107
Cr(vi) laden wastewaters generally comprise a range of multiple heavy metals such as Au(iii) and Cu(ii) with great toxicity. In the present study, cooperative cathode modification by biogenic Au nanoparticles (BioAu) reduced from aqueous Au(iii) and in situ Cu(ii) co-reduction were investigated for the first time to enhance Cr(vi) removal in microbial fuel cells (MFCs). With the co-existence of Cu(ii) in the catholyte, the MFC with carbon cloth modified with nanocomposites of multi-walled carbon nanotubes blended with BioAu (BioAu/MWCNT) obtained the highest Cr(vi) removal rate (4.07 ± 0.01 mg L−1 h−1) and power density (309.34 ± 17.65 mW m−2), which were 2.73 and 3.30 times as high as those for the control, respectively. The enhancements were caused by BioAu/MWCNT composites and deposited reduzates of Cu(ii) on the cathode surface, which increased the adsorption capacity, electronic conductivity and electrocatalytic activity of the cathode. This study provides an alternative approach for efficiently remediating co-contamination of multiple heavy metals and simultaneous bioenergy recovery.The cooperative cathode modification by BioAu from Au(iii) and in situ Cu(ii) co-reduction enhanced Cr(vi) removal and bioelectricity generation in MFCs. 相似文献
20.
6:2 fluorotelomer sulfonate (6:2 FtS) is being widely used as a mist suppressant in the chromate (Cr(vi)) plating process. As a result, it is often present alongside Cr(vi) in the chromate plating wastewater (CPW). While the removal of Cr(vi) from CPW has been studied for decades, little attention has been paid to the treatment of 6:2 FtS. In this study, the removal of Cr(vi) and 6:2 FtS by Ga2O3, In2O3, and TiO2 photocatalysts was investigated. In the Ga2O3/UVC system, over 95% of Cr(vi) was reduced into Cr(iii) after only 5 min. Simultaneously, 6:2 FtS was degraded into F− and several perfluorocarboxylates. The predominant reactive species responsible for the degradation of 6:2 FtS in the Ga2O3 system were identified to be hVB+ and O2˙−. In addition, it was observed that the presence of Cr(vi) helped accelerate the degradation of 6:2 FtS. This synergy between Cr(vi) and 6:2 FtS was attributable to the scavenging of eCB− by Cr(vi), which retarded the recombination of eCB− and hVB+. The In2O3/UVC system was also capable of removing Cr(vi) and 6:2 FtS, although at significantly slower rates. In contrast, poor removal of 6:2 FtS was achieved with the TiO2/UVC system, because Cr(iii) adsorbed on TiO2 and inhibited its reactivity. Based on the results of this study, it is proposed that CPW can be treated by a treatment train that consists of an oxidation–reduction step driven by Ga2O3/UVC, followed by a neutralization step that converts dissolved Cr(iii) into Cr(OH)3(S).6:2 fluorotelomer sulfonate (6:2 FtS) and chromate (Cr(vi)) in chromate plating wastewaters can be simultaneously removed by photocatalysis. 相似文献