Excess reactive phosphorus(PO4)in waterways can lead to eutrophication.A low-cost approach to reducing PO4 levels in surface water was evaluated using the alum-based water treatment residual(Al-WTR)or Al-WTR augmented...Excess reactive phosphorus(PO4)in waterways can lead to eutrophication.A low-cost approach to reducing PO4 levels in surface water was evaluated using the alum-based water treatment residual(Al-WTR)or Al-WTR augmented with powdered activated carbon(PAC-WTR).Batch adsorption-desorption and continuous flow column experiments were performed to assess the specific adsorption capacities under various concentration and flow conditions.Both Al-WTR and PAC-WTR exhibited the ability to adsorb PO4.The overall,cumulative sorbed amount after a 28-d desorption step for Al-WTR was 33.93 mg/kg,significantly greater than the PAC-WTR value of 24.95 mg/kg(p<0.05).The continuous flow column experiments showed a theoretical PO4 uptake of 9.00 mg/g for Al-WTR and 7.14 mg/g for PAC-WTR over 720 h.When surface water was used,the Al-WTR and PAC-WTR columns removed 67.4%and 62.1%of the PO4,respectively.These results indicated that Al-WTR was more effective for in-field evaluation.展开更多
As safe byproducts of drinking water treatment processes,ferric and alum water treatment residuals（FARs） have the potential to be new phosphate（P） immobilization materials.In this study,batch experiments were cond...As safe byproducts of drinking water treatment processes,ferric and alum water treatment residuals（FARs） have the potential to be new phosphate（P） immobilization materials.In this study,batch experiments were conducted to investigate and compare the adsorption characteristics of three P species by FARs.The results showed that the kinetic processes of different P species＇ adsorption by FARs could be described by a pseudo second-order model.The ranking list of the initial adsorption rates with respect to different phosphates was pyrophosphate,phytate,orthophosphate,hexametaphosphate and glycerophosphate.Of the six models considered,the two-site Langmuir model most effectively described the adsorption characteristics of the various P species.Upon fitting the results,the maximum adsorption capacities were determined to be 40.24 mg/g for phytate,18.04 mg/g for pyrophosphate,17.14 mg/g for orthophosphate,15.86 mg/g for hexametaphosphate and 10.81 mg/g for glycerophosphate.In addition,the adsorption processes of the different P species were spontaneous endothermic processes and were favored at lower pH values.The pH dependency was found to be especially true for orthophosphate,where the adsorption capacity decreased by 1.22 mg/g with an increase in pH from 5 to 9.Fractionation of the adsorbed P species from the FARs demonstrated that Al-P and Fe-P were the dominating forms,constituting approximately 80%-90% of the total P fractions,which indicated that the adsorbed P species had a low leaching risk and could stably exist in the FARs.Therefore,the FARs could be effective in controlling pollution in water caused by different P species.展开更多
以给水处理厂废弃铁铝泥(ferric and alum water treatment residuals,FARs)为载体,考察了不同粒径FARs对砷(Ⅲ)的吸附效果.不同粒径FARs的有效铁铝含量、比表面积和孔体积分别为523.72～1 861.72 mmol.kg-1、28.15～265.59 m2.g-1和0.0...以给水处理厂废弃铁铝泥(ferric and alum water treatment residuals,FARs)为载体,考察了不同粒径FARs对砷(Ⅲ)的吸附效果.不同粒径FARs的有效铁铝含量、比表面积和孔体积分别为523.72～1 861.72 mmol.kg-1、28.15～265.59 m2.g-1和0.03～0.09 cm3.g-1,总有机质、富里酸、胡敏酸和胡敏素分别为46.97～91.58、0.02～32.27、22.27～34.09和10.76～34.22 mg.kg-1.SEM和XRD检测表明,不同粒径FARs均以无定形结构存在.批量实验结果表明,准一级和准二级动力学方程均能较好地反映FARs吸附砷(Ⅲ)的动力学过程.不同粒径FARs对砷(Ⅲ)的吸附量随着浓度的增加而增高,用Langmuir等温线方程拟合获得理论饱和吸附量在6.72～21.79 mg.g-1之间.pH值对FARs吸附砷(Ⅲ)的作用影响不大.砷(Ⅲ)吸附量大小与不同粒径FARs的理化性质的变化趋势基本一致,由相关性分析可得,有效铁铝含量和孔体积大小是影响FARs对砷(Ⅲ)吸附的主要因素.展开更多
探讨了酸活化和热活化方式对给水厂废弃铁铝泥(ferric and alum water treatment residuals,FARs)吸附磷能力的影响.结果表明,酸活化和热活化均能提高FARs的磷吸附能力,其中经2mol·L-1HCl酸活化的FARs(AH2.0-FARs)和300℃热活化的F...探讨了酸活化和热活化方式对给水厂废弃铁铝泥(ferric and alum water treatment residuals,FARs)吸附磷能力的影响.结果表明,酸活化和热活化均能提高FARs的磷吸附能力,其中经2mol·L-1HCl酸活化的FARs(AH2.0-FARs)和300℃热活化的FARs(H300-FARs)取得最好的磷吸附效果.结合SEM和XRD表征技术对活化机制分析得知,两种活化方式均会使FARs变得疏松、多孔,从而提高FARs对磷的吸附能力.Langmuir和Freundlich两种模型均可很好地反映活化前后FARs的等温吸附过程,FARs对磷的理论饱和吸附量由活化前的20.48mg·g-1分别增加到22.86mg·g-1(AH2.0-FARs)和29.66mg·g-1(H300-FARs).低pH值有利于FARs对磷的吸附.此外,解吸附实验结果表明活化后的FARs能够更好地固定磷.因此,活化后的FARs是一种相对更好的磷的吸附材料.展开更多
通过批量实验和柱状实验并结合磷的分级提取探究了给水处理厂废弃铁铝泥(ferric-alum water treatment re-siduals,FARs)吸附正磷酸盐的效果。批量实验结果表明,Langmuir和Freundlich方程均能较好地描述FARs对磷的等温吸附过程,且当pH从...通过批量实验和柱状实验并结合磷的分级提取探究了给水处理厂废弃铁铝泥(ferric-alum water treatment re-siduals,FARs)吸附正磷酸盐的效果。批量实验结果表明,Langmuir和Freundlich方程均能较好地描述FARs对磷的等温吸附过程,且当pH从5增至9时,FARs磷的饱和吸附量从41.68 mg/g减小到17.08 mg/g。pH越低,磷与FARs的结合能力越强。柱状实验结果表明,FARs具有显著的磷吸附能力,在运行的89 d里,磷的去除率保持在80%以上。出水pH与进水相比略有增加,但增加量不会对地表水体造成影响。磷的分级提取结果进一步说明,被吸附的磷主要以释磷风险小的铁铝结合态存在。综合实验结果表明,FARs可以作为高效磷吸附剂应用于地表水除磷。展开更多
通过批量实验探讨了给水厂废弃铁铝泥(Ferric and Alum Water Treatment Residuals,FARs)对Cd2+的吸附特征及影响因素.实验结果表明,在最初的6 h内,FARs对Cd2+的吸附量已经达到其平衡吸附量的90%,吸附较符合伪二级动力学模型(R2=0.99),...通过批量实验探讨了给水厂废弃铁铝泥(Ferric and Alum Water Treatment Residuals,FARs)对Cd2+的吸附特征及影响因素.实验结果表明,在最初的6 h内,FARs对Cd2+的吸附量已经达到其平衡吸附量的90%,吸附较符合伪二级动力学模型(R2=0.99),并且Langmuir(R2=0.99)和Freundlich(R2=0.90)方程均能较好地描述FARs对Cd2+的等温吸附过程,其Cd2+的饱和吸附量达35.39 mg·g-1.初始溶液p H由3.0增加到8.0时,FARs对Cd2+的吸附量缓慢增加,当p H升为9.0时,其对Cd2+去除率可达97%.FARs对Cd2+的吸附量随溶液体系离子强度的增加而减小.随着柠檬酸浓度的升高,FARs对Cd2+的吸附量显著降低,而水杨酸和酒石酸则微弱促进了对Cd2+的吸附.解吸实验证明,在p H为3.0时Cd2+的解吸率最高,但仅为11%左右.分级提取结果进一步表明,被吸附的Cd2+主要以酸溶态和残渣态存在.综合实验结果表明,FARs可以作为一种高效的吸附剂用于水体除镉.展开更多
基金This work was supported by Ohio EPA 319(Grant No.17(H)EPA-17)and the Ohio Water Development Authority(Grant No.80-17).
文摘Excess reactive phosphorus(PO4)in waterways can lead to eutrophication.A low-cost approach to reducing PO4 levels in surface water was evaluated using the alum-based water treatment residual(Al-WTR)or Al-WTR augmented with powdered activated carbon(PAC-WTR).Batch adsorption-desorption and continuous flow column experiments were performed to assess the specific adsorption capacities under various concentration and flow conditions.Both Al-WTR and PAC-WTR exhibited the ability to adsorb PO4.The overall,cumulative sorbed amount after a 28-d desorption step for Al-WTR was 33.93 mg/kg,significantly greater than the PAC-WTR value of 24.95 mg/kg(p<0.05).The continuous flow column experiments showed a theoretical PO4 uptake of 9.00 mg/g for Al-WTR and 7.14 mg/g for PAC-WTR over 720 h.When surface water was used,the Al-WTR and PAC-WTR columns removed 67.4%and 62.1%of the PO4,respectively.These results indicated that Al-WTR was more effective for in-field evaluation.
基金supported by the National Natural Science Foundation of China (No. 51278055,51179008)
文摘As safe byproducts of drinking water treatment processes,ferric and alum water treatment residuals（FARs） have the potential to be new phosphate（P） immobilization materials.In this study,batch experiments were conducted to investigate and compare the adsorption characteristics of three P species by FARs.The results showed that the kinetic processes of different P species＇ adsorption by FARs could be described by a pseudo second-order model.The ranking list of the initial adsorption rates with respect to different phosphates was pyrophosphate,phytate,orthophosphate,hexametaphosphate and glycerophosphate.Of the six models considered,the two-site Langmuir model most effectively described the adsorption characteristics of the various P species.Upon fitting the results,the maximum adsorption capacities were determined to be 40.24 mg/g for phytate,18.04 mg/g for pyrophosphate,17.14 mg/g for orthophosphate,15.86 mg/g for hexametaphosphate and 10.81 mg/g for glycerophosphate.In addition,the adsorption processes of the different P species were spontaneous endothermic processes and were favored at lower pH values.The pH dependency was found to be especially true for orthophosphate,where the adsorption capacity decreased by 1.22 mg/g with an increase in pH from 5 to 9.Fractionation of the adsorbed P species from the FARs demonstrated that Al-P and Fe-P were the dominating forms,constituting approximately 80%-90% of the total P fractions,which indicated that the adsorbed P species had a low leaching risk and could stably exist in the FARs.Therefore,the FARs could be effective in controlling pollution in water caused by different P species.
文摘探讨了酸活化和热活化方式对给水厂废弃铁铝泥(ferric and alum water treatment residuals,FARs)吸附磷能力的影响.结果表明,酸活化和热活化均能提高FARs的磷吸附能力,其中经2mol·L-1HCl酸活化的FARs(AH2.0-FARs)和300℃热活化的FARs(H300-FARs)取得最好的磷吸附效果.结合SEM和XRD表征技术对活化机制分析得知,两种活化方式均会使FARs变得疏松、多孔,从而提高FARs对磷的吸附能力.Langmuir和Freundlich两种模型均可很好地反映活化前后FARs的等温吸附过程,FARs对磷的理论饱和吸附量由活化前的20.48mg·g-1分别增加到22.86mg·g-1(AH2.0-FARs)和29.66mg·g-1(H300-FARs).低pH值有利于FARs对磷的吸附.此外,解吸附实验结果表明活化后的FARs能够更好地固定磷.因此,活化后的FARs是一种相对更好的磷的吸附材料.
