A1-Fe (hydr)oxides with different A1/Fe molar ratios (4:1, 1:1, 1:4, 0:1) were prepared using a co- precipitation method and were then employed for simultaneous removal of arsenate and fluoride. The 4A1 : Fe ...A1-Fe (hydr)oxides with different A1/Fe molar ratios (4:1, 1:1, 1:4, 0:1) were prepared using a co- precipitation method and were then employed for simultaneous removal of arsenate and fluoride. The 4A1 : Fe was superior to other adsorbents for removal of arsenate and fluoride in the pH range of 5.0-9.0. The adsorption capacity of the A1-Fe (hydr)oxides for arsenate and fluoride at pH 6.50.3 increased with increasing A1 content in the adsorbents. The linear relationship between the amount of OH released from the adsorbent and the amount of arsenate or fluoride adsorbent by 4A1 : Fe indicated that the adsorption of arsenate and fluoride by A1- Fe (hydr)oxides was realized primarily through quantita- tive ligand exchange. Moreover, there was a very good correlation between the surface hydroxyl group densities of A1-Fe (hydr)oxides and their adsorption capacities for arsenate or fluoride. The highest adsorption capacity for arsenate and fluoride by 4A1 : Fe is mainly ascribed to its highest surface hydroxyl group density besides its largest pHpzc. The dosage of adsorbent necessary to remove arsenate and fluoride to meet the drinking water standard was mainly determined by the presence of fluoride since fluoride was generally present in groundwater at much higher concentration than arsenate.展开更多
Diphenylarsinic acid(DPAA)is a phenyl arsenic compound derived from chemical warfare weapons.Macroscopic and microscopic work on DPAA sorption will provide useful information in predicting the partitioning and mobilit...Diphenylarsinic acid(DPAA)is a phenyl arsenic compound derived from chemical warfare weapons.Macroscopic and microscopic work on DPAA sorption will provide useful information in predicting the partitioning and mobility of DPAA in the soil-water environment.Here,batch experiments and extended X-ray absorption fine structure(EXAFS)spectroscopy were used to investigate the sorption mechanisms of DPAA.The DPAA sorption data from 11 soil types was found to fit the Freundlich equation,and the sorption capacity,Kf,was significantly and positively correlated with oxalateextractable Fe2o3.The Kf values of eight of the 11 untreated soils(1.51113.04)significantly decreased upon removal of amorphous metal(hydr)oxides(0.51-13.37).When both amorphous and crystalline metal(hydr)oxides were removed from the untreated soils,the values either decreased or slightly increased(0.65-3.09).Subsequent removal of soil organic matter from these amorphous and crystalline metal(hydr)oxide-depleted samples led to ftirther decreases in A^f to 0.021.38,with only one exception(Sulfic Aquic-Orthic Halosols).These findings strongly suggest that ligand exchange reactions with amorphous metal(hydr)oxides contribute most to DPAA sorption on soils.EXAFS data provide further evidence that DPAA primarily formed bidentate binuclear(~C)and monodentate mononuclear(1 V)coring-sharing complexes with As-Fe distances of 3.34 and 3.66 A,respectively,on Fe(hydr)oxides.Comparison of these results with earlier studies suggests that 2C and 1 F complexes of DPAA may be favored under low and high surface coverages,respectively,with the formation of 1 V bonds possibly conserving the sorption sites or decreasing the steric hindrance derived from phenyl substituents.展开更多
为克服活性炭磷吸附能力有限的问题,使用ZnCl_2、十六烷基三甲基氯化铵(CTAC)和Fe/Al(氢)氧化物纳米颗粒分别研究了物理结构法、表面活性剂法和载体法3种表面修饰方法对活性炭磷吸附能力的影响。实验发现,载体法为3种方法中最好的修饰...为克服活性炭磷吸附能力有限的问题,使用ZnCl_2、十六烷基三甲基氯化铵(CTAC)和Fe/Al(氢)氧化物纳米颗粒分别研究了物理结构法、表面活性剂法和载体法3种表面修饰方法对活性炭磷吸附能力的影响。实验发现,载体法为3种方法中最好的修饰方法。对载体法制备吸附剂的材料用量的比较发现,在Fe(Ⅲ)和Al(Ⅲ)摩尔比为9:1的条件下,把1.5 g活性炭加入到总浓度为1 mol·L^(-1)的200 m L Fe(Ⅲ)和Al(Ⅲ)混合溶液中,形成的纳米Fe/Al(氢)氧化物能够较好地利用活性炭表面,该复合材料1.5AC-Fe/Al在磷平衡浓度约为50 mg·L^(-1)时吸附量达到29.3 mg·g^(-1)。该材料表征结果表明,纳米Fe/Al(氢)氧化物颗粒被成功负载在活性炭表面。在酸性条件下,复合材料表面的—H^+和—OH_2^+所引起的静电吸附和配位交换是促进吸附带负电磷酸根离子的原因。展开更多
文摘A1-Fe (hydr)oxides with different A1/Fe molar ratios (4:1, 1:1, 1:4, 0:1) were prepared using a co- precipitation method and were then employed for simultaneous removal of arsenate and fluoride. The 4A1 : Fe was superior to other adsorbents for removal of arsenate and fluoride in the pH range of 5.0-9.0. The adsorption capacity of the A1-Fe (hydr)oxides for arsenate and fluoride at pH 6.50.3 increased with increasing A1 content in the adsorbents. The linear relationship between the amount of OH released from the adsorbent and the amount of arsenate or fluoride adsorbent by 4A1 : Fe indicated that the adsorption of arsenate and fluoride by A1- Fe (hydr)oxides was realized primarily through quantita- tive ligand exchange. Moreover, there was a very good correlation between the surface hydroxyl group densities of A1-Fe (hydr)oxides and their adsorption capacities for arsenate or fluoride. The highest adsorption capacity for arsenate and fluoride by 4A1 : Fe is mainly ascribed to its highest surface hydroxyl group density besides its largest pHpzc. The dosage of adsorbent necessary to remove arsenate and fluoride to meet the drinking water standard was mainly determined by the presence of fluoride since fluoride was generally present in groundwater at much higher concentration than arsenate.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.41807117 and 41230858)the Cultivation Project on Excellent Undergraduates'Thesis(design,create)of Anhui Normal University(No.pyjh2018487)the Innovation and Entrepreneurship Training Project for College Students(No.201910370072)。
文摘Diphenylarsinic acid(DPAA)is a phenyl arsenic compound derived from chemical warfare weapons.Macroscopic and microscopic work on DPAA sorption will provide useful information in predicting the partitioning and mobility of DPAA in the soil-water environment.Here,batch experiments and extended X-ray absorption fine structure(EXAFS)spectroscopy were used to investigate the sorption mechanisms of DPAA.The DPAA sorption data from 11 soil types was found to fit the Freundlich equation,and the sorption capacity,Kf,was significantly and positively correlated with oxalateextractable Fe2o3.The Kf values of eight of the 11 untreated soils(1.51113.04)significantly decreased upon removal of amorphous metal(hydr)oxides(0.51-13.37).When both amorphous and crystalline metal(hydr)oxides were removed from the untreated soils,the values either decreased or slightly increased(0.65-3.09).Subsequent removal of soil organic matter from these amorphous and crystalline metal(hydr)oxide-depleted samples led to ftirther decreases in A^f to 0.021.38,with only one exception(Sulfic Aquic-Orthic Halosols).These findings strongly suggest that ligand exchange reactions with amorphous metal(hydr)oxides contribute most to DPAA sorption on soils.EXAFS data provide further evidence that DPAA primarily formed bidentate binuclear(~C)and monodentate mononuclear(1 V)coring-sharing complexes with As-Fe distances of 3.34 and 3.66 A,respectively,on Fe(hydr)oxides.Comparison of these results with earlier studies suggests that 2C and 1 F complexes of DPAA may be favored under low and high surface coverages,respectively,with the formation of 1 V bonds possibly conserving the sorption sites or decreasing the steric hindrance derived from phenyl substituents.
文摘为克服活性炭磷吸附能力有限的问题,使用ZnCl_2、十六烷基三甲基氯化铵(CTAC)和Fe/Al(氢)氧化物纳米颗粒分别研究了物理结构法、表面活性剂法和载体法3种表面修饰方法对活性炭磷吸附能力的影响。实验发现,载体法为3种方法中最好的修饰方法。对载体法制备吸附剂的材料用量的比较发现,在Fe(Ⅲ)和Al(Ⅲ)摩尔比为9:1的条件下,把1.5 g活性炭加入到总浓度为1 mol·L^(-1)的200 m L Fe(Ⅲ)和Al(Ⅲ)混合溶液中,形成的纳米Fe/Al(氢)氧化物能够较好地利用活性炭表面,该复合材料1.5AC-Fe/Al在磷平衡浓度约为50 mg·L^(-1)时吸附量达到29.3 mg·g^(-1)。该材料表征结果表明,纳米Fe/Al(氢)氧化物颗粒被成功负载在活性炭表面。在酸性条件下,复合材料表面的—H^+和—OH_2^+所引起的静电吸附和配位交换是促进吸附带负电磷酸根离子的原因。