摘要
用改性天然磷灰石处理低浓度含Cr(Ⅵ)废水,考察反应时间、改性天然磷灰石用量、反应温度和初始pH对Cr(Ⅵ)去除的影响,研究了Cr(Ⅵ)去除的动力学及热力学,分析了反应机理。结果表明:(1)在改性天然磷灰石用量为10g/L、Cr(Ⅵ)初始质量浓度为10.000mg/L、初始pH为2.0、反应温度为283.15K、反应时间为90min的条件下,Cr(Ⅵ)去除率为99.38%,Cr(Ⅵ)残余质量浓度为0.062mg/L,低于《地表水环境质量标准》(GB 3838—2002)中Ⅴ类标准限值(0.1mg/L)。(2)改性天然磷灰石去除Cr(Ⅵ)的反应符合一级反应动力学模型,是放热反应,反应温度低于410.83K时反应能自发进行。作用机理主要是以络阴离子形式存在的Cr(Ⅵ)自发吸附在磷灰石溶解形成的带正电荷表面,然后与溶解的Ca2+反应,形成铬酸钙沉积在固体表面,实现相转移。
The low concentration Cr（Ⅵ） containing waste water was treated using modified natural apatite as treating agent. The effect of reaction time,modified natural apatite dosage,reaction temperature and initial pH on the removal of Cr（Ⅵ） was investigated. The kinetics and thermodynamics of the reaction between the treating agent and Cr（Ⅵ） was investigated. And mechanism was analyzed. The result indicated that.. （1） with the optimum condition of the modified natural apatite dosage 10 g/L,initial pH 2.0, reaction temperature 283.15 K,initial Cr（Ⅵ ） mass concentration 10.000 mg/L and reaction time 90 min,the Cr（ Ⅵ ） removal rate was 99.38% ,and the Cr（ Ⅵ ） mass concentration of the treated waste water was 0.062 mg/L,which was lower than standard limits of class V of ＂Surface water environmental quality stand＂ （GB 3838-2002） （0.1 mg/L）. （2） The reaction was exothermic reaction and accord with the first reaction kinetics equation. When the reaction temperature was lower than 410.83 K, the reaction was spontaneous. Complex anion of Cr（Ⅵ） was spontaneously adsorbed on the surface formed by the dissolution of apatite with positively charged,and it reacted with Ca2＋ that dissolved into the water. The calcium chromate was generated and it deposited in the solid surface.
出处
《环境污染与防治》
CAS
CSCD
北大核心
2017年第10期1097-1100,共4页
Environmental Pollution & Control
基金
国家科技支撑计划项目(No.2012BAC02B04)
