To understand the mechanism of fluoride removal from the simulated zinc sulfate solution by the La(III)-modified zeolite,the adsorbent was characterized by XRD,SEM and EDS.The effects of absorbent dose and contact tim...To understand the mechanism of fluoride removal from the simulated zinc sulfate solution by the La(III)-modified zeolite,the adsorbent was characterized by XRD,SEM and EDS.The effects of absorbent dose and contact time,the adsorption isotherms and the sorption kinetics were investigated.The experimental results were compatible with the Langmuir isotherm model.The theoretical maximum adsorption capacities are 20.83 and 23.04 mg/g at 303 and 313 K,respectively.And the physisorption is revealed using the Temkin isotherm model and the D-R isotherm model.The sorption process is more suitable by the pseudo-second-order kinetic models.Thermodynamic parameters such as standard free energy change(ΔGΘ<0 kJ/mol),standard enthalpy change(ΔHΘ=8.28 kJ/mol)and standard entropy change(ΔSΘ=0.030 kJ/(mol?K))indicate the spontaneity of adsorption and endothermic physical sorption.Furthermore,the fluoride concentration in the industrial zinc sulfate solution decreases from 98.05 to 44.09 mg/L with the adsorbent dosage of 15 g/L.展开更多
The direct contact membrane distillation applied for fluoride removal from brackish groundwater was investigated. The self-prepared polyvinylidene fluoride membrane exhibited high rejection of inorganic salt solutes. ...The direct contact membrane distillation applied for fluoride removal from brackish groundwater was investigated. The self-prepared polyvinylidene fluoride membrane exhibited high rejection of inorganic salt solutes. The maximum permeate flux 35.6 kg/（m^2-hr） was obtained with the feed solution at 80℃ and the cold distillate water at 20℃. The feed concentration had no significant impact on the permeate flux and the rejection in fluoride. The precipitation of CaCO3 would clog the hollow fiber inlets and foul the membrane surface with increasing concentration factor when natural groundwater was used directly as the feed, which resulted in a rapid decline in the module efficiency. This phenomenon was diminished by acidification of the feed. The experimental results showed that the permeate flux and the quality of obtained distillate kept stable before concentration factor reached 5.0 with the acidified groundwater as feed. The membrane module efficiency began to decline gradually when the feed continued to be concentrated, which can be mainly attributed to the formation of CaF2 deposits on the membrane surface. In addition, a 300 hr continuous fluoride removal experiment of acidified groundwater was carried out with concentration factor at 4.0, the permeate flux kept stable and the permeate fluoride was not detected.展开更多
Lanthanum alginate bead is a new, highly active adsorbent. In the present study, we investigated its ad- sorption performance and its adsorption mechanism. The adsorption isotherm for fluoride onto lanthanum alginate ...Lanthanum alginate bead is a new, highly active adsorbent. In the present study, we investigated its ad- sorption performance and its adsorption mechanism. The adsorption isotherm for fluoride onto lanthanum alginate b ead fits the Langmuir model well, and the maximum adsorption capacity is 197.2 mg·g-1. X-ray diffraction shows the amorphous nature of lanthanum alginate bead, which allows for better accessibility to fluoride and thus better activity. Infrared spectra of lanthanum alginate bead before and after adsorption confirm its stable skeletal structure. Scanning electron microscopy shows that the dense surface structure of the adsorbent appear cracks after adsorption. T he adsorption mechanism of lanthanum alginate bead is considered as an ion exchange between F- and Cl- or OH-, as verified from the adsorbent and the solution by pH effect, energy dispersive X-ray, and ion chromatography.展开更多
Batch experiments were conducted to evaluate fluoride removal by Al,Fe,and Ti-based coagulants and adsorbents,as well as the effects of coexisting ions and formation of aluminum–fluoride complexes on fluoride removal...Batch experiments were conducted to evaluate fluoride removal by Al,Fe,and Ti-based coagulants and adsorbents,as well as the effects of coexisting ions and formation of aluminum–fluoride complexes on fluoride removal by co-precipitation with alum（Al_2（SO_4）_3·18H_2O）.Aluminum sulfate was more efficient than the other coagulants for fluoride removal in the pH range between 6 and 8.Nano-crystalline TiO_2 was more effective for fluoride removal than Al and Fe hydroxides in a pH range of 3–5.Coexisting anions in water decreased the removal of fluoride in the order：phosphate（2.5 mg/L） 〉 arsenate（0.1 mg/L） 〉 bicarbonate（200 mg/L） 〉sulfate（100 mg/L） = nitrate（100 mg/L） 〉 silicate（10 mg/L） at a pH of 6.0.The effect of silicate became more significant at pH 〉 7.0.Calcium and magnesium improved the removal of fluoride.Zeta-potential measurements determined that the adsorption of fluoride shifted the PZC of Al（OH）_3 precipitates from 8.9 to 8.4,indicating the chemical adsorption of fluoride at the surface.The presence of fluoride in solution significantly increased the soluble aluminum concentration at pH 〈 6.5.A Visual MINTEQ modeling study indicated that the increased aluminum solubility was caused by the formation of AlF^（2＋）,AlF^（＋2）,and AlF_3complexes.The AlF_x complexes decreased the removal of fluoride during co-precipitation with aluminum sulfate.展开更多
A series of novel adsorbents composed of cellulose(CL)with Ca/Al layered double hydroxide(CC_(x)A;where x represent the Ca/Al molar ratio)were prepared for the adsorption of antimony(Sb(V))and fluoride(F^(-))ions from...A series of novel adsorbents composed of cellulose(CL)with Ca/Al layered double hydroxide(CC_(x)A;where x represent the Ca/Al molar ratio)were prepared for the adsorption of antimony(Sb(V))and fluoride(F^(-))ions from aqueous solutions.The CC_(x)A was characterized by Fourier-transform infrared spectroscopy(FTIR),Brunauer–Emmett–Teller(BET),elemental analysis(CHNS/O),thermogravimetric analysis(TGA-DTA),zeta potential,X-ray photoelectron spectroscopy(XPS)and scanning electron microscopy with energy dispersive Xray spectroscopy(SEM-EDX)analysis.The effects of varying parameters such as dose,pH,contact time,temperature and initial concentration on the adsorption process were investigated.According to the obtained results,the adsorption processes were described by a pseudo-second-order kinetic model.Langmuir adsorption isotherm model provided the best fit for the experimental data and was used to describe isotherm constants.The maximum adsorption capacity was found to be 77.2 and 63.1 mg/g for Sb(V)and F^(-),respectively by CC_(3)A(experimental conditions:pH 5.5,time 60 min,dose 15 mg/10 mL,temperature 298 K).The CC_(3)A nanocomposite was able to reduce the Sb(V)and F^(-)ions concentration in synthetic solution to lower than 6μg/L and 1.5 mg/L,respectively,which are maximum contaminant levels of these elements in drinking water according to WHO guidelines.展开更多
Garlic peel,as the raw material,was modified by loading with zirconium(IV),exhibiting quite good uptaking behaviour for fluoride anion.The adsorption experiments were carried out in batch shaking vessels,and the proce...Garlic peel,as the raw material,was modified by loading with zirconium(IV),exhibiting quite good uptaking behaviour for fluoride anion.The adsorption experiments were carried out in batch shaking vessels,and the process was strongly dependent on the pH value.The adsorption fits Langmuir model well,and the maximum adsorption capacities at equilibrium pH 2 and 6 are evaluated to be 1.10 and 0.89 mol(fluoride)/kg of Zr-loaded garlic peel gel,respectively.The evaluation of effects of coexisting anions such as nitrate,sulfate and phosphate shows that nitrate and sulfate have no negative effect on the adsorption of fluoride,while phosphate has a little effect.Adsorption kinetics of fluoride is well described by pseudo-second-order rate equation,and the corresponding adsorption rate constant is calculated to be 3.25×10?3 g/(mg·min).展开更多
High fluoride groundwater occurs widely in China, presenting a quite serious environmental problem. Zeolite from Xinyang, China was tested as the fluoride removing adsorbent. Batch and column experiments on fluoride ...High fluoride groundwater occurs widely in China, presenting a quite serious environmental problem. Zeolite from Xinyang, China was tested as the fluoride removing adsorbent. Batch and column experiments on fluoride removal using modified zeolites treated with hydrochloric acid, sodium hydroxide, sodium chloride and ferric chloride, respectively show that 0.1 mol/L HCl modified zeolite can be used as an adsorbent for fluoride, with an adsorption capacity of 173.16 mg/kg.展开更多
2D carbon ribbon/Al_(2)O_(3) was synthesized with two-dimensional metal organic frameworks 2D-MOFs as precursors using the solvothermal and calcination methods.Batch experiments of adsorption parameters such as pH,liq...2D carbon ribbon/Al_(2)O_(3) was synthesized with two-dimensional metal organic frameworks 2D-MOFs as precursors using the solvothermal and calcination methods.Batch experiments of adsorption parameters such as pH,liquid/solid ratio,adsorption kinetics,adsorption thermodynamics,and anions competitions were investigated to understand the adsorptive behavior of fluoride on carbon ribbon/Al_(2)O_(3) and nitrogen-doped carbon ribbon/Al_(2)O_(3).The adsorption of fluoride on carbon ribbon/Al_(2)O_(3) could be described as the chemical and multilayer adsorption,while the adsorption of fluoride on nitrogen-doped carbon ribbon/Al_(2)O_(3) followed the chemical and monolayer adsorption phenomenon.The fluoride on nitrogen-doped carbon ribbon/Al_(2)O_(3) had a much faster adsorption rate of 3.1×10^(−7) m/s than carbon ribbon/Al_(2)O_(3),which was 1.2×10^(−7) m/s.The nitrogen-doping on carbon ribbon enhances structural defects and improves the adsorption performance of fluoride.Also,the diacetylene linkages(—C≡C—)and pyridinic-N were studied to understand their influences on removing fluoride.The result indicates that carbon ribbon and nitrogen-doped ribbon could serve as good adsorbents for removing fluoride.展开更多
The present study evaluated calcined Mg/Al layered double hydroxide(CLDH)availability for the removal of fluoride from local groundwaters.The Mg/Al layered double hydroxide(LDH)was synthesized by coprecipitation metho...The present study evaluated calcined Mg/Al layered double hydroxide(CLDH)availability for the removal of fluoride from local groundwaters.The Mg/Al layered double hydroxide(LDH)was synthesized by coprecipitation method and characterized by XRD,FT-IR and TGA-TDA analyses.Batch defluoridation experiments were performed under various conditions such as calcination,solution pH,contact time,temperature,material dosage and reuse.Experimental results indicate that fluoride removal strongly increased after calcination of the LDH up to 600℃.The maximum fluoride removal was obtained at solution pH of 6.85.Kinetics of fluoride removal followed the pseudo-second order kinetic model.The rise in solution temperature strongly enhances the removal efficiency.The adsorption mechanism involved surface adsorption,ion exchange interaction and original LDH structure reconstruction by rehydration of mixed metal oxides and concomitant intercalation of fluoride ions into the interlayer region.The optimum dosages required to meet the national standard for drinking water quality were found to be 0.29 and 0.8 g/L,respectively,for Bejaad and Settat goundwaters.A decrease in the fluoride uptake with increasing the number of regeneration cycles was observed.展开更多
Despite the development of various Lewis acidic nano-adsorbents for fluoride removal through innersphere coordination,strong competition for hydroxyl ions still hinders efficient water defluoridation.In addition,the c...Despite the development of various Lewis acidic nano-adsorbents for fluoride removal through innersphere coordination,strong competition for hydroxyl ions still hinders efficient water defluoridation.In addition,the critical issue of polysilicate scaling that results from the ubiquitous silicates must be addressed.To tackle these issues,an alternative approach to enhancing adsorption reactivity by modifying nano-adsorbents with dual Lewis and Bronsted acidity is proposed.The feasibility of this approach is demonstrated by growing zirconium phosphate(ZrP)inside a gel-type anion exchanger,N201,to produce nanocomposite ZrP@N201,in which the confined ZrP contained an otherwise metastable amorphous phase with Lewis acidic Zr^(4+) sites and Bronsted acidic monohydrogen phosphate groups(-O_(3)POH).Compared with the Lewis acidic nano-zirconium oxide analog(HZ0@N201),ZrP@N201 exhibited a greatly improved adsorption capacity(117.9 vs.52.3 mg/g-Zr)and mass transfer rate(3.56×10^(-6) vs.4.55×10^(-7) cm/s),while bulk ZrP produced a thermodynamically stableα-phase with Bronsted acidity that exhibited negligible adsorption capability toward fluoride.The enhanced defluoridation activity of ZrP@N201 is attributed to Bronsted acidity and the increased outer electron density of ZA+sites,as corroborated using XPS and solid-state NMR analysis.Moreover,Bronsted acidity strengthens the resistance of ZrP@N201 to silicate,allowing its full regeneration during cyclic defluoridation.Column tests demonstrated 3-10 times the amount of clean water from(waste)for ZrP@N201 as compared to both HZO@N201 and the widely used activated aluminum oxide.This study highlights the potential of developing nano-adsorbents with dual acidities for various environmental remediation applications.展开更多
基金Projects(51474238,51674301)supported by the National Natural Science Foundation of China
文摘To understand the mechanism of fluoride removal from the simulated zinc sulfate solution by the La(III)-modified zeolite,the adsorbent was characterized by XRD,SEM and EDS.The effects of absorbent dose and contact time,the adsorption isotherms and the sorption kinetics were investigated.The experimental results were compatible with the Langmuir isotherm model.The theoretical maximum adsorption capacities are 20.83 and 23.04 mg/g at 303 and 313 K,respectively.And the physisorption is revealed using the Temkin isotherm model and the D-R isotherm model.The sorption process is more suitable by the pseudo-second-order kinetic models.Thermodynamic parameters such as standard free energy change(ΔGΘ<0 kJ/mol),standard enthalpy change(ΔHΘ=8.28 kJ/mol)and standard entropy change(ΔSΘ=0.030 kJ/(mol?K))indicate the spontaneity of adsorption and endothermic physical sorption.Furthermore,the fluoride concentration in the industrial zinc sulfate solution decreases from 98.05 to 44.09 mg/L with the adsorbent dosage of 15 g/L.
基金supported by the High Technology Research and Development Program(863) of China(No.2009AA063901,2009AA062901)the National Natural Science Foundation of China(No. 20907066)
文摘The direct contact membrane distillation applied for fluoride removal from brackish groundwater was investigated. The self-prepared polyvinylidene fluoride membrane exhibited high rejection of inorganic salt solutes. The maximum permeate flux 35.6 kg/（m^2-hr） was obtained with the feed solution at 80℃ and the cold distillate water at 20℃. The feed concentration had no significant impact on the permeate flux and the rejection in fluoride. The precipitation of CaCO3 would clog the hollow fiber inlets and foul the membrane surface with increasing concentration factor when natural groundwater was used directly as the feed, which resulted in a rapid decline in the module efficiency. This phenomenon was diminished by acidification of the feed. The experimental results showed that the permeate flux and the quality of obtained distillate kept stable before concentration factor reached 5.0 with the acidified groundwater as feed. The membrane module efficiency began to decline gradually when the feed continued to be concentrated, which can be mainly attributed to the formation of CaF2 deposits on the membrane surface. In addition, a 300 hr continuous fluoride removal experiment of acidified groundwater was carried out with concentration factor at 4.0, the permeate flux kept stable and the permeate fluoride was not detected.
基金Supported by the Major National Science and Technology Special Project on Treatment and Control of Water Pollution(2009ZX07425-006)State Key Laboratory of Environmental Simulation and Pollution Control (09K04ESPCT)
文摘Lanthanum alginate bead is a new, highly active adsorbent. In the present study, we investigated its ad- sorption performance and its adsorption mechanism. The adsorption isotherm for fluoride onto lanthanum alginate b ead fits the Langmuir model well, and the maximum adsorption capacity is 197.2 mg·g-1. X-ray diffraction shows the amorphous nature of lanthanum alginate bead, which allows for better accessibility to fluoride and thus better activity. Infrared spectra of lanthanum alginate bead before and after adsorption confirm its stable skeletal structure. Scanning electron microscopy shows that the dense surface structure of the adsorbent appear cracks after adsorption. T he adsorption mechanism of lanthanum alginate bead is considered as an ion exchange between F- and Cl- or OH-, as verified from the adsorbent and the solution by pH effect, energy dispersive X-ray, and ion chromatography.
文摘Batch experiments were conducted to evaluate fluoride removal by Al,Fe,and Ti-based coagulants and adsorbents,as well as the effects of coexisting ions and formation of aluminum–fluoride complexes on fluoride removal by co-precipitation with alum（Al_2（SO_4）_3·18H_2O）.Aluminum sulfate was more efficient than the other coagulants for fluoride removal in the pH range between 6 and 8.Nano-crystalline TiO_2 was more effective for fluoride removal than Al and Fe hydroxides in a pH range of 3–5.Coexisting anions in water decreased the removal of fluoride in the order：phosphate（2.5 mg/L） 〉 arsenate（0.1 mg/L） 〉 bicarbonate（200 mg/L） 〉sulfate（100 mg/L） = nitrate（100 mg/L） 〉 silicate（10 mg/L） at a pH of 6.0.The effect of silicate became more significant at pH 〉 7.0.Calcium and magnesium improved the removal of fluoride.Zeta-potential measurements determined that the adsorption of fluoride shifted the PZC of Al（OH）_3 precipitates from 8.9 to 8.4,indicating the chemical adsorption of fluoride at the surface.The presence of fluoride in solution significantly increased the soluble aluminum concentration at pH 〈 6.5.A Visual MINTEQ modeling study indicated that the increased aluminum solubility was caused by the formation of AlF^（2＋）,AlF^（＋2）,and AlF_3complexes.The AlF_x complexes decreased the removal of fluoride during co-precipitation with aluminum sulfate.
文摘A series of novel adsorbents composed of cellulose(CL)with Ca/Al layered double hydroxide(CC_(x)A;where x represent the Ca/Al molar ratio)were prepared for the adsorption of antimony(Sb(V))and fluoride(F^(-))ions from aqueous solutions.The CC_(x)A was characterized by Fourier-transform infrared spectroscopy(FTIR),Brunauer–Emmett–Teller(BET),elemental analysis(CHNS/O),thermogravimetric analysis(TGA-DTA),zeta potential,X-ray photoelectron spectroscopy(XPS)and scanning electron microscopy with energy dispersive Xray spectroscopy(SEM-EDX)analysis.The effects of varying parameters such as dose,pH,contact time,temperature and initial concentration on the adsorption process were investigated.According to the obtained results,the adsorption processes were described by a pseudo-second-order kinetic model.Langmuir adsorption isotherm model provided the best fit for the experimental data and was used to describe isotherm constants.The maximum adsorption capacity was found to be 77.2 and 63.1 mg/g for Sb(V)and F^(-),respectively by CC_(3)A(experimental conditions:pH 5.5,time 60 min,dose 15 mg/10 mL,temperature 298 K).The CC_(3)A nanocomposite was able to reduce the Sb(V)and F^(-)ions concentration in synthetic solution to lower than 6μg/L and 1.5 mg/L,respectively,which are maximum contaminant levels of these elements in drinking water according to WHO guidelines.
基金Project(11140065) supported by Research Program for Returned Oversea Scholars of China
文摘Garlic peel,as the raw material,was modified by loading with zirconium(IV),exhibiting quite good uptaking behaviour for fluoride anion.The adsorption experiments were carried out in batch shaking vessels,and the process was strongly dependent on the pH value.The adsorption fits Langmuir model well,and the maximum adsorption capacities at equilibrium pH 2 and 6 are evaluated to be 1.10 and 0.89 mol(fluoride)/kg of Zr-loaded garlic peel gel,respectively.The evaluation of effects of coexisting anions such as nitrate,sulfate and phosphate shows that nitrate and sulfate have no negative effect on the adsorption of fluoride,while phosphate has a little effect.Adsorption kinetics of fluoride is well described by pseudo-second-order rate equation,and the corresponding adsorption rate constant is calculated to be 3.25×10?3 g/(mg·min).
基金This paperis supported by the National Natural Science Foundation of China( Nos.49772 15 8and4983 2 0 0 5)
文摘High fluoride groundwater occurs widely in China, presenting a quite serious environmental problem. Zeolite from Xinyang, China was tested as the fluoride removing adsorbent. Batch and column experiments on fluoride removal using modified zeolites treated with hydrochloric acid, sodium hydroxide, sodium chloride and ferric chloride, respectively show that 0.1 mol/L HCl modified zeolite can be used as an adsorbent for fluoride, with an adsorption capacity of 173.16 mg/kg.
基金the financial supports from the Key R&D Program of Hunan Province,China(No.2018SK2026)the National Key R&D Program of China(No.2018YFC1802204)the National Natural Science Foundation of China(No.51634010).
文摘2D carbon ribbon/Al_(2)O_(3) was synthesized with two-dimensional metal organic frameworks 2D-MOFs as precursors using the solvothermal and calcination methods.Batch experiments of adsorption parameters such as pH,liquid/solid ratio,adsorption kinetics,adsorption thermodynamics,and anions competitions were investigated to understand the adsorptive behavior of fluoride on carbon ribbon/Al_(2)O_(3) and nitrogen-doped carbon ribbon/Al_(2)O_(3).The adsorption of fluoride on carbon ribbon/Al_(2)O_(3) could be described as the chemical and multilayer adsorption,while the adsorption of fluoride on nitrogen-doped carbon ribbon/Al_(2)O_(3) followed the chemical and monolayer adsorption phenomenon.The fluoride on nitrogen-doped carbon ribbon/Al_(2)O_(3) had a much faster adsorption rate of 3.1×10^(−7) m/s than carbon ribbon/Al_(2)O_(3),which was 1.2×10^(−7) m/s.The nitrogen-doping on carbon ribbon enhances structural defects and improves the adsorption performance of fluoride.Also,the diacetylene linkages(—C≡C—)and pyridinic-N were studied to understand their influences on removing fluoride.The result indicates that carbon ribbon and nitrogen-doped ribbon could serve as good adsorbents for removing fluoride.
文摘The present study evaluated calcined Mg/Al layered double hydroxide(CLDH)availability for the removal of fluoride from local groundwaters.The Mg/Al layered double hydroxide(LDH)was synthesized by coprecipitation method and characterized by XRD,FT-IR and TGA-TDA analyses.Batch defluoridation experiments were performed under various conditions such as calcination,solution pH,contact time,temperature,material dosage and reuse.Experimental results indicate that fluoride removal strongly increased after calcination of the LDH up to 600℃.The maximum fluoride removal was obtained at solution pH of 6.85.Kinetics of fluoride removal followed the pseudo-second order kinetic model.The rise in solution temperature strongly enhances the removal efficiency.The adsorption mechanism involved surface adsorption,ion exchange interaction and original LDH structure reconstruction by rehydration of mixed metal oxides and concomitant intercalation of fluoride ions into the interlayer region.The optimum dosages required to meet the national standard for drinking water quality were found to be 0.29 and 0.8 g/L,respectively,for Bejaad and Settat goundwaters.A decrease in the fluoride uptake with increasing the number of regeneration cycles was observed.
基金We greatly appreciate the financial support from the National Key Research and Development Program of China(No.2022YFC3205300)the National Natural Science Foundation of China(No.22122604).
文摘Despite the development of various Lewis acidic nano-adsorbents for fluoride removal through innersphere coordination,strong competition for hydroxyl ions still hinders efficient water defluoridation.In addition,the critical issue of polysilicate scaling that results from the ubiquitous silicates must be addressed.To tackle these issues,an alternative approach to enhancing adsorption reactivity by modifying nano-adsorbents with dual Lewis and Bronsted acidity is proposed.The feasibility of this approach is demonstrated by growing zirconium phosphate(ZrP)inside a gel-type anion exchanger,N201,to produce nanocomposite ZrP@N201,in which the confined ZrP contained an otherwise metastable amorphous phase with Lewis acidic Zr^(4+) sites and Bronsted acidic monohydrogen phosphate groups(-O_(3)POH).Compared with the Lewis acidic nano-zirconium oxide analog(HZ0@N201),ZrP@N201 exhibited a greatly improved adsorption capacity(117.9 vs.52.3 mg/g-Zr)and mass transfer rate(3.56×10^(-6) vs.4.55×10^(-7) cm/s),while bulk ZrP produced a thermodynamically stableα-phase with Bronsted acidity that exhibited negligible adsorption capability toward fluoride.The enhanced defluoridation activity of ZrP@N201 is attributed to Bronsted acidity and the increased outer electron density of ZA+sites,as corroborated using XPS and solid-state NMR analysis.Moreover,Bronsted acidity strengthens the resistance of ZrP@N201 to silicate,allowing its full regeneration during cyclic defluoridation.Column tests demonstrated 3-10 times the amount of clean water from(waste)for ZrP@N201 as compared to both HZO@N201 and the widely used activated aluminum oxide.This study highlights the potential of developing nano-adsorbents with dual acidities for various environmental remediation applications.
