A new base-aluminum-chloride-loaded fiber[PET-AA-NN-Al_2（OH）_nCl_（6-n）]was prepared with polyethylene glycol terephthalate （PET） as adsorbent for fast removal of arsenic（Ⅴ） from water.This new fibrous adsorbe...A new base-aluminum-chloride-loaded fiber[PET-AA-NN-Al_2（OH）_nCl_（6-n）]was prepared with polyethylene glycol terephthalate （PET） as adsorbent for fast removal of arsenic（Ⅴ） from water.This new fibrous adsorbent was characterized by using SEM and C NMR spectroscopy.Adsorption kinetic curve indicated that this new fibrous adsorbent could fast remove arsenic（Ⅴ） from water, and adsorption isotherm also indicated that PET-AA-NN-A1_2（OH）_nC1_（6-n） had high equilibrium adsorption capacity for arsenic（Ⅴ）.展开更多
A highly selective ligand exchange type adsorbent was developed for the removal of trace arsenic（V） （As（V）） and phosphate from water. This adsorbent was prepared by loading zirconium（IV） on monophosphonic acid...A highly selective ligand exchange type adsorbent was developed for the removal of trace arsenic（V） （As（V）） and phosphate from water. This adsorbent was prepared by loading zirconium（IV） on monophosphonic acid resin. This adsorbent was able to remove toxic anions efficiently at wide pH ranges. However, low pH was preferable for maximum breakthrough capacity in an adsorption operation. The effiect of a large amount of competing anions such as chloride, bicarbonate, and sulfate on the adsorption systems of As（V） and phosphate anions was investigated. The experimental findings revealed that the As（V） and phosphate uptakes were not affiected by these competing anions despite the enhancement of the breakthrough points and total adsorption. Phosphate anion was slightly preferable than As（V） in their competitive adsorption by the adsorbent. The adsorbed As（V） and phosphate on the Zr（IV）-loaded resin were quantitatively eluted with 0.1 mol/L sodium hydroxide solution, and the adsorbent was regenerated by 0.5 mol/L sulfuric acid. During several cycles of adsorption-elution-regeneration operations, no Zr（IV） was detected in the column efiuents. Therefore, the Zr（IV）- loaded monophosphonic acid resin is an efiective ligand exchange adsorbent for removing trace concentrations of As（V） and phosphate from water.展开更多
In the H2SO4 medium and in the presence of dodecylbenzene sulfonic acid sodiumsalt (DBS), dimethyl yellow (R) could emit strong and stable solid substrate room temperature phosphorescence (RTP) on filter paper. And Na...In the H2SO4 medium and in the presence of dodecylbenzene sulfonic acid sodiumsalt (DBS), dimethyl yellow (R) could emit strong and stable solid substrate room temperature phosphorescence (RTP) on filter paper. And NaIO4 could oxidize R to cause the RTP quenching. Arsenic(V) could catalyze the reaction of NaIO4 oxidizing R, which caused the RTP sharply quenching. The reducing value of phosphorescence intensity (ΔIp) for the system with DBS is 3.3 times higher than that without DBS. Moreover, the ΔIp is proportional to the concentration of As(V). Based on the facts above, a new RTP quenching method for the determination of trace As(V) has been established.展开更多
Nanostructured ZnFe2O4 was synthesized by the heat treatment of a mechanically activated mixture of ZnO/α-Fe2O3.X-ray diffraction(XRD)and differential thermal analysis(DTA)results demonstrated that,after 5 h of the m...Nanostructured ZnFe2O4 was synthesized by the heat treatment of a mechanically activated mixture of ZnO/α-Fe2O3.X-ray diffraction(XRD)and differential thermal analysis(DTA)results demonstrated that,after 5 h of the mechanical activation of the mixture,ZnFe2O4 was formed by heat treatment at 750°C for 2 h.To improve the characteristics of ZnFe2O4 for adsorption applications,the chemical activation process was performed.The 2 h chemical activation with 1 mol·L?1 HNO3 and co-precipitation of 52%?57%dissolved ZnFe2O4 led to an increase in the saturated magnetization from 2.0 to 7.5 emu·g?1 and in the specific surface area from 5 to 198 m2·g?1.In addition,the observed particle size reduction of chemically activated ZnFe2O4 in field emission scanning electron microscopy(FESEM)micrographs was in agreement with the specific surface area increase.These improvements in ZnFe2O4 characteristics considerably affected the adsorption performance of this adsorbent.Adsorption results revealed that mechano-thermally synthesized ZnFe2O4 had the maximum arsenic adsorption of 38%with the adsorption capacity of 0.995 mg·g?1 in a 130 mg·L?1 solution of As(V)after 30 min of agitation.However,chemically activated ZnFe2O4 showed the maximum arsenic adsorption of approximately 99%with the adsorption capacity of 21.460 mg·g?1 under the same conditions.These results showed that the weak adsorption performance of mechano-thermally synthesized ZnFe2O4 was improved by the chemical activation process.展开更多
In the “Laguna” region of Coahuila state, Mexico like other places in the world, the groundwater needs to be treated to meet the quality required for human consumption. The study had probed that a Mexican fly ash ca...In the “Laguna” region of Coahuila state, Mexico like other places in the world, the groundwater needs to be treated to meet the quality required for human consumption. The study had probed that a Mexican fly ash can be used as a raw material to obtain effective low cost adsorbents for drinking water treatment, as well evaluated the effects of pH, ion coexistence, dose, arsenic (As) concentration and temperature on the As(V) uptake by using P and W modified zeolites (PMOD and WMOD) obtained from a Mexican fly ash. The As(V) adsorption capacity of the WMOD zeolite was not affected by pH and As(V) concentrations in aqueous solution was achieved 0.01 mg/L in the studied pH range;however, the As(V) removal by using PMOD zeolite decreased at high pH values. Carbonate concentration had a negative effect on the As(V) uptake of both zeolites but this effect was higher for the PMOD zeolite. The maximum adsorption capacities (Qmax) were 76.11 and 44.44 mg of As(V)/g of zeolite for the WMOD and the PMOD zeolites, respectively. The adsorption process was endothermic, spontaneous and occurred by chemical exchange. The experimental data were best interpreted by a pseudo-second order kinetic model. The WMOD zeolite showed a higher adsorption capacity and rate than the PMOD even at the highest evaluated As(V) concentration. The adsorption capacity of the regenerated WMOD zeolite was similar to the original zeolite. Because of the high As(V) adsorption capacity, chemical stability and regenerability, the WMOD zeolite is potentially useful as low-cost adsorbent for As(V) removal from aqueous effluents.展开更多
Despite scarce studies have analyzed the relative growth inhibition of As (III) and As (V) to diatom, clear pattern of interspecies difference have been shown, identifying cell size as a key property determining the s...Despite scarce studies have analyzed the relative growth inhibition of As (III) and As (V) to diatom, clear pattern of interspecies difference have been shown, identifying cell size as a key property determining the sensitivity of diatom to As. Evidence from cultures suggests that cell size is a key factor in determining the extent of arsenic (III) & (V) stress of diatom, with relatively lesser effects of As (V) than As (III) on small cells. Cent percent growth inhibition was observed for large size group (Coscinodiscus radiatus, Surirella, Amphipleura, Thalassiothrix, Cyclotella and Thalassiosira decipiens) relative to smaller size group (Skeletonema cf. costatum, Navicula rhombica, Amphora hyaline, Nitzschia longissima except Thalassisira. Interspecies differences in As tolerance by diatom in the mangrove ecosystem indicates cell size could be only one factor contributing to these differences. The results show that 81.7% of total arsenic was uptaken from culture media originally amended with arsenic. Looking to the extreme tolerance and arsenic removal efficiency, application of the species with smaller cell size relative to the other tested diatom for bioremediation purpose can be envisaged.展开更多
基金support provided by the National Science Funds for Young Scientists(No.51008152)
文摘A new base-aluminum-chloride-loaded fiber[PET-AA-NN-Al_2（OH）_nCl_（6-n）]was prepared with polyethylene glycol terephthalate （PET） as adsorbent for fast removal of arsenic（Ⅴ） from water.This new fibrous adsorbent was characterized by using SEM and C NMR spectroscopy.Adsorption kinetic curve indicated that this new fibrous adsorbent could fast remove arsenic（Ⅴ） from water, and adsorption isotherm also indicated that PET-AA-NN-A1_2（OH）_nC1_（6-n） had high equilibrium adsorption capacity for arsenic（Ⅴ）.
文摘A highly selective ligand exchange type adsorbent was developed for the removal of trace arsenic（V） （As（V）） and phosphate from water. This adsorbent was prepared by loading zirconium（IV） on monophosphonic acid resin. This adsorbent was able to remove toxic anions efficiently at wide pH ranges. However, low pH was preferable for maximum breakthrough capacity in an adsorption operation. The effiect of a large amount of competing anions such as chloride, bicarbonate, and sulfate on the adsorption systems of As（V） and phosphate anions was investigated. The experimental findings revealed that the As（V） and phosphate uptakes were not affiected by these competing anions despite the enhancement of the breakthrough points and total adsorption. Phosphate anion was slightly preferable than As（V） in their competitive adsorption by the adsorbent. The adsorbed As（V） and phosphate on the Zr（IV）-loaded resin were quantitatively eluted with 0.1 mol/L sodium hydroxide solution, and the adsorbent was regenerated by 0.5 mol/L sulfuric acid. During several cycles of adsorption-elution-regeneration operations, no Zr（IV） was detected in the column efiuents. Therefore, the Zr（IV）- loaded monophosphonic acid resin is an efiective ligand exchange adsorbent for removing trace concentrations of As（V） and phosphate from water.
文摘In the H2SO4 medium and in the presence of dodecylbenzene sulfonic acid sodiumsalt (DBS), dimethyl yellow (R) could emit strong and stable solid substrate room temperature phosphorescence (RTP) on filter paper. And NaIO4 could oxidize R to cause the RTP quenching. Arsenic(V) could catalyze the reaction of NaIO4 oxidizing R, which caused the RTP sharply quenching. The reducing value of phosphorescence intensity (ΔIp) for the system with DBS is 3.3 times higher than that without DBS. Moreover, the ΔIp is proportional to the concentration of As(V). Based on the facts above, a new RTP quenching method for the determination of trace As(V) has been established.
文摘Nanostructured ZnFe2O4 was synthesized by the heat treatment of a mechanically activated mixture of ZnO/α-Fe2O3.X-ray diffraction(XRD)and differential thermal analysis(DTA)results demonstrated that,after 5 h of the mechanical activation of the mixture,ZnFe2O4 was formed by heat treatment at 750°C for 2 h.To improve the characteristics of ZnFe2O4 for adsorption applications,the chemical activation process was performed.The 2 h chemical activation with 1 mol·L?1 HNO3 and co-precipitation of 52%?57%dissolved ZnFe2O4 led to an increase in the saturated magnetization from 2.0 to 7.5 emu·g?1 and in the specific surface area from 5 to 198 m2·g?1.In addition,the observed particle size reduction of chemically activated ZnFe2O4 in field emission scanning electron microscopy(FESEM)micrographs was in agreement with the specific surface area increase.These improvements in ZnFe2O4 characteristics considerably affected the adsorption performance of this adsorbent.Adsorption results revealed that mechano-thermally synthesized ZnFe2O4 had the maximum arsenic adsorption of 38%with the adsorption capacity of 0.995 mg·g?1 in a 130 mg·L?1 solution of As(V)after 30 min of agitation.However,chemically activated ZnFe2O4 showed the maximum arsenic adsorption of approximately 99%with the adsorption capacity of 21.460 mg·g?1 under the same conditions.These results showed that the weak adsorption performance of mechano-thermally synthesized ZnFe2O4 was improved by the chemical activation process.
文摘In the “Laguna” region of Coahuila state, Mexico like other places in the world, the groundwater needs to be treated to meet the quality required for human consumption. The study had probed that a Mexican fly ash can be used as a raw material to obtain effective low cost adsorbents for drinking water treatment, as well evaluated the effects of pH, ion coexistence, dose, arsenic (As) concentration and temperature on the As(V) uptake by using P and W modified zeolites (PMOD and WMOD) obtained from a Mexican fly ash. The As(V) adsorption capacity of the WMOD zeolite was not affected by pH and As(V) concentrations in aqueous solution was achieved 0.01 mg/L in the studied pH range;however, the As(V) removal by using PMOD zeolite decreased at high pH values. Carbonate concentration had a negative effect on the As(V) uptake of both zeolites but this effect was higher for the PMOD zeolite. The maximum adsorption capacities (Qmax) were 76.11 and 44.44 mg of As(V)/g of zeolite for the WMOD and the PMOD zeolites, respectively. The adsorption process was endothermic, spontaneous and occurred by chemical exchange. The experimental data were best interpreted by a pseudo-second order kinetic model. The WMOD zeolite showed a higher adsorption capacity and rate than the PMOD even at the highest evaluated As(V) concentration. The adsorption capacity of the regenerated WMOD zeolite was similar to the original zeolite. Because of the high As(V) adsorption capacity, chemical stability and regenerability, the WMOD zeolite is potentially useful as low-cost adsorbent for As(V) removal from aqueous effluents.
文摘Despite scarce studies have analyzed the relative growth inhibition of As (III) and As (V) to diatom, clear pattern of interspecies difference have been shown, identifying cell size as a key property determining the sensitivity of diatom to As. Evidence from cultures suggests that cell size is a key factor in determining the extent of arsenic (III) & (V) stress of diatom, with relatively lesser effects of As (V) than As (III) on small cells. Cent percent growth inhibition was observed for large size group (Coscinodiscus radiatus, Surirella, Amphipleura, Thalassiothrix, Cyclotella and Thalassiosira decipiens) relative to smaller size group (Skeletonema cf. costatum, Navicula rhombica, Amphora hyaline, Nitzschia longissima except Thalassisira. Interspecies differences in As tolerance by diatom in the mangrove ecosystem indicates cell size could be only one factor contributing to these differences. The results show that 81.7% of total arsenic was uptaken from culture media originally amended with arsenic. Looking to the extreme tolerance and arsenic removal efficiency, application of the species with smaller cell size relative to the other tested diatom for bioremediation purpose can be envisaged.
