【摘要】 针对高效低廉的吸附材料——WTR(water treatment residuals,给水厂残泥)因颗粒细小在水处理工艺中难以应用的问题,利用免烧法制备出WTR陶粒,研究其对Pb和Cd的吸附特征.批量吸附试验结果表明,准二级动力学模型和Langmuir等温吸附模型能较好地描述WTR免烧陶粒对Pb和Cd的吸附动力学(R~2>0. 995 8)与等温吸附过程(R~2>0. 994 8).在溶液pH为5、恒温25℃、振荡24 h下,Langmuir等温吸附模型计算得到的WTR免烧陶粒对Pb和Cd的最大吸附容量分别为13. 97和18. 60 mg/g.单因素条件试验结果表明,WTR免烧陶粒对Pb和Cd的吸附量均随溶液初始pH的升高而增加,当pH由3升至9时,WTR免烧陶粒对Pb和Cd的吸附量分别增加了1. 44和0. 95倍;离子强度的增加不利于WTR免烧陶粒对Pb和Cd的吸附.批量等温解吸试验结果表明,在pH为4～8的溶液中,Pb和Cd较难从WTR免烧陶粒中解吸出来,解吸率均在3. 5%以内;当溶液pH为3时,Pb和Cd的解吸率分别高达65. 88%和45. 01%. BCR分级提取结果表明,Pb和Cd均主要以酸提取态形式(占比在68. 18%以上)存在于WTR免烧陶粒中;同时,随着初始吸附量的增加,酸提取态比例显著减少,而还原态和残渣态比例显著增加.研究显示,WTR免烧陶粒对Pb和Cd具有较强的吸附能力,可作为一种高效的重金属吸附材料应用于水处理工艺中.更多还原

【Abstract】 Reusing drinking water treatment residuals (WTR) as an efficient adsorbing material in wastewater treatment encountered many problems due to the fine particles of WTR. In order to solve the WTR application problems,WTR ceramsite was prepared by non-burning method,and the adsorption characteristics of Pb and Cd by WTR unburned ceramsite were investigated in this study. The results of batch adsorption experiments showed that the kinetics and isothermal processes of Pb/Cd adsorption to WTR unburned ceramsite were well described by the pseudo-second-order model (R~2> 0. 9958) and the Langmuir model (R~2> 0. 9948),respectively. The maximum adsorption capacities under laboratory conditions (solution pH = 5,constant temperature 25 ℃,vibrating time 24 h) estimated by the Langmuir model was 13. 97 mg/g for Pb and 18. 60 mg/g for Cd. The results of the single-factor experiments exhibited that the adsorption quantities of Pb and Cd on WTR unburned ceramsite increased with the increasing initial solution pH. Specifically,as the pH raised from3 to 9,the adsorption quantities of Pb and Cd increased by 1. 44 and 0. 95 times,respectively. The increase of solution ionic strength is not favourable for Pb and Cd by WTR unburned ceramsite. Results of the isothermal desorption experiment demonstrated that the desorption of Pb and Cd by WTR unburned ceramsite was lower than 3. 5% in the initial solution pH range of 4-8; and the desorption rate of Pb and Cd reached up to 65. 88% and 45. 01%,respectively,at the acidic solution condition with pH of 3. BCR fractional extraction indicated that Pb and Cd were mainly present in the acid-soluble form accounting for more than 68. 18% of the total Pb and Cd. Moreover,as the adsorption increased,the proportion of the acid-soluble form significantly decreased,and instead the proportion of residual form increased. From the above results,it can be concluded that WTR unburned ceramsite has strong adsorption capacity for both Pb and Cd,and it can be used as a highly efficient heavy metal adsorption material in wastewater treatment.更多还原