摘要
通过人工合成的方法制得腐殖酸改性针铁矿(HA-α-FeOOH),考察了吸附时间、吸附剂用量、U(Ⅵ)初始浓度和pH值等因素对吸附U(Ⅵ)过程的影响.同时,利用傅里叶红外光谱(FTIR)、扫描电镜(SEM)和X射线能谱(EDS)分析了其对U(Ⅵ)的吸附机理.试验结果表明,在25℃、pH为4的条件下,腐殖酸改性针铁矿作用4 h对5 mg·L-1的含铀废水的去除率几乎达到100%.Freundlich等温吸附模型、准二级动力学模型对吸附过程的拟合效果较好,主要吸附模式为多层吸附;改性针铁矿对U(Ⅵ)的吸附是自发的吸热反应.SEM-EDS和FIIR分析结果表明,改性针铁矿吸附U(Ⅵ)的机理主要表现为内层络合作用及离子交换,与U(Ⅵ)作用的基团主要是羟基、酚羟基和羧基.
The goethite modified with humic acid( HA-α-FeOOH) was developed as an artificial absorbent for the removal of uranium( Ⅵ) ions from uranium-contained wastewater. To investigate the effects of experimental parameters on adsorption behavior,a batch of experiments were performed by changing solution pH,HA-α-FeOOH dosage,initial concentration of U( Ⅵ) ions and contact time. The adsorption characteristics of U( Ⅵ) by HA-α-FeOOH were analyzed by FT-IR,SEM and EDX. It is shown that the removal rate of 5 mg·L-1U( Ⅵ) wastewater by HA-α-FeOOH almost reaches 100%under the condition of pH 4,25 ℃ and contact time for 4 hours. The experimental data fitted well with Freundlich isotherm model,indicating that the adsorption was multilayer adsorption model. The adsorption process could be described by pseudo-second-order kinetic model. Thermodynamic parameters such as Gibbs free energy change,enthalpy change and entropy change were calculated,and the results showed that the adsorption of U( Ⅵ) onto HA-α-FeOOH was feasible,spontaneous and endothermic in nature. FTIR and SEM-EDS results showed that the adsorption mainly involves internal complexation and ion exchange,and the main binding sites with U( Ⅵ) are hydroxy,phenolic hydroxyl and carboxyl.
出处
《环境科学学报》
CAS
CSCD
北大核心
2014年第9期2271-2278,共8页
Acta Scientiae Circumstantiae
基金
国家自然科学基金(No.11175081)
湖南省科技计划重点项目(No.2011SK2015)
湖南省高校创新平台项目(No.13K085
13K086)
湖南省自然科学基金项目(No.13JJ3078)~~
