除铁除锰水厂反冲洗泥吸附除砷

Arsenic adsorption behaviors of backwash sludge from waterworks for iron and manganese removal

摘要:

除铁除锰水厂生物滤池反冲洗过程产生大量富含铁锰氧化物的污泥，直接排放会对环境造成污染，为此，采用XRD和TEM对预处理后的反冲洗泥进行表征，并通过静态吸附试验研究其吸附除砷特性和相关机制.结果表明：铁锰氧化物反冲洗泥为无定型结构，粒径小且比表面积大.Langmuir等温方程更符合铁锰氧化物反冲洗泥对As(Ⅴ)吸附特性(R²>0.99)，As(Ⅲ)吸附行为不能由单一模型模拟.25 ℃时As(Ⅲ)和As(Ⅴ)最大吸附容量分别为36.53和40.37 mg/g，温度越高吸附容量越大.准二级动力学能较好地反映铁锰氧化物反冲洗泥对As(Ⅲ)和As(Ⅴ)的等温吸附动力学(R²>0.99)，随着pH升高对As(Ⅴ)的吸附量逐渐降低，As(Ⅲ)吸附量降低、升高再降低.H₂PO₄^-与SiO₃^2-能显著抑制砷的吸附，其他离子对吸附过程影响不大.

Abstract:

In the process of bio-filter backwash for biological iron and manganese removal from groundwater, a large quantity of sludge rich in iron and manganese oxides was produced, and was trying to be used as an arsenic removal adsorbent to avoid pollution caused by its direct emission. The sludge was characterized after pretreatment using XRD and TEM, and its adsorption properties and related mechanism were studied through the static adsorption experiments. The results show that the sludge of iron and manganese oxides is non-setting structure with small particle size and large specific surface area. The Langmuir isotherm equation is more in line with the adsorption characteristics of As(Ⅴ) (R²>0.99), and As (Ⅲ) adsorption behavior cannot be simulated by a single model. The maximum adsorption capacity for As (Ⅲ) and As(Ⅴ) is 36.53 mg/g and 40.37 mg/g respectively, and the adsorption capacity increases with the increase of the temperature. The adsorption of As (Ⅲ) and As(Ⅴ) conforms to the pseudo-second order kinetic model with R² more than 0.99, and As(Ⅴ) adsorption capacity decreases gradually with the increase of pH, while As (Ⅲ) adsorption capacity experiences a process of decrease and increase and then decrease. H₂PO₄^- and SiO₃^2-has significant inhibition on arsenic adsorption and other ions have little effect on the adsorption process.