水浮莲干体对甲基橙的吸附研究

Adsorption of Methyl Orange Dye (MO) on Dried Pistia stratiotes

研究了水浮莲干体对模拟染料废水中甲基橙(MO)的吸附行为,考察吸附时间、溶液初始pH值、水浮莲干体用量和MO初始质量浓度等因素对MO吸附的影响。结果表明,在MO溶液初始pH值为5.5、初始质量浓度为25 mg·L-1条件下,添加12.5 g·L-1粒径为0.250～0.425 mm的水浮莲干体,于25℃条件下以120 r·min-1振荡吸附90 min后,MO吸附率可达72.1%。酸性环境有利于MO吸附;一定范围内,水浮莲干体用量的增加以及MO初始浓度的升高都会导致吸附率升高。水浮莲干体对MO的吸附过程更符合Freundlich吸附等温方程,Lagergren准二级动力学方程更适合模拟其吸附动力学行为。随温度升高,MO平衡吸附量呈减少趋势。水浮莲干体及浸出液中Cr、Ni、Cu、As、Cd和Pb含量远低于GB 5085.3—2007《危险废物鉴别标准浸出毒性鉴别》中的限量值,因此将水浮莲干体作为新型吸附剂应用于染料废水处理,不会导致二次污染。

Adsorption of methyl orange dye （MO） on dried Pistia stratiotes in simulated wastewater was investigated in an experiment,to explore effects of factors,such as adsorption duration,initial pH of the solution,dosage of dried Pistia stratiotes and initial MO concentration on the adsorption.Results show that when the wastewater was 5.5 in initial pH,and 25 mg · L-1 in initial MO concentration,by adding 12.5 g-L-1 of dried Pistia stratiotes with O.250-0.425 mm in particle size,and then the solution was shaken on a vibrator at 120 r · min-1 for 90 min under the room temperature （25 ℃）,up to 72.1％ of the MO in the wastewater could be removed.It was found that lower pH was conducive to MO adsorption; within a certain range,adsorption rate increased with dosage of the adsorbent dosage and initial concentration of MO in the solution.The adsorption data show that the process of the adsorption fitted the Freundlich adsorption isothermal equation quite well and dynamic behavior of the adsorption did the Lagergren pseudo-second-order kinetics equation well.With rising temperature,MO equilibrium adsorption capacity decreased.Analysis of the Pistia stratiotes and its extractant shows that chromium,nickel,copper,arsenic,cadmium and lead contents therein were far below the limit set in GB 5085.3-2007 （Identification Standards for Hazardous Wastes-Identification for Extraction Toxicity）.Therefore,dried Pistia stratiotes can be used as a new type of adsorbent in dyeing wastewater treatment without risk of secondary pollution.