铁酸镍基水热炭协同次氯酸根氧化去除废水中铊

Removal of Tl from wastewater by nickel ferrite-based hydrothermal carbon coupled with hypochlorite oxidation

以铁酸镍和葡萄糖为原料构建炭包裹的磁性水热炭(NiFe_2O_4@C)作为可重复利用的高效吸附剂,并催化次氯酸根协同氧化以去除废水中的铊。考察了初始pH、混凝pH、反应温度、共存物和氧化剂投加量等因素对除铊的影响,结合X射线粉末衍射仪(XRD)、X射线光电子能谱(XPS)和电子自旋共振光谱仪(ESR)等表征手段探究了其除铊机理。在铊初始浓度20 mg/L、初始pH 10、吸附剂投加量0.5 g/L、次氯酸钠投量10 mmol/L时,铊去除率达到99%以上。Ca^(2+)、Mg^(2+)、EDTA、DPTA抑制除铊。吸附过程更适合拟一级动力学模型,等温吸附更适用于Langmuir和Temkin方程描述,最大铊吸附量达989 mg/g。NiFe_2O_4@C对Tl(I)的去除机理主要为氧化沉淀和表面羟基络合。材料再生实验表明NiFe2O4@C有很好的脱附与再生能力。本研究为废水除铊提供了一定的理论和技术参考依据。

In this study,carbon-coated magnetic hydrothermal carbon(NiFe2O4@C)was constructed from nickel ferrite and glucose as a reusable high-efficiency adsorbent,and the hypochlorite was catalyzed by oxidation to remove strontium from wastewater.The effects of initial pH,coagulation pH,reaction temperature,co-existing substance and hypochlorite dosage on thallium removal were examined,and mechanism on thallium removal was investigated by X-ray powder diffractometry(XRD),X-ray photoelectron spectroscopy(XPS)and electron spin resonance spectroscopy(ESR).When the initial concentration of thallium was 20 mg/L,the initial pH was 10,the adsorbent dosage was 0.5 g/L,and the sodium hypochlorite dosage was 10 mmol/L,the thallium removal efficiency reached more than 99%.Ca^2+,Mg^2+,EDTA,and DPTA can inhibit thallium removal.The adsorption process is more suitable for the pseudo-first order kinetic model,and isothermal adsorption is more suitable for the description of Langmuir and Temkin equation.The saturated adsorption capacity is high up to 989 mg/g.The removal mechanism of Tl(I)by NiFe2O4@C was mainly surface hydroxyl complexation and oxidation precipitation.Material regeneration experiments show that NiFe2O4@C has a good ability of desorption and regeneration.This study provides a theoretical and technical reference for thallium removal in wastewater.