核桃壳吸附去除水中罗丹明B的响应曲面优化及机理

Optimization and Mechanism of Response Surface Methodology for Adsorption of Rhodamine-B Dye by Walnut Shell

以废弃核桃壳为原料,制备低成本吸附剂,用于吸附废水中的染料罗丹明-B。采用响应曲面法研究pH、吸附剂投加量、初始染料浓度和接触时间对核桃壳吸附罗丹明B的影响,并对试验条件进行优化。研究结果表明,pH对核桃壳吸附罗丹明B的吸附容量影响显著,且当pH值为3.50,吸附剂投加量为0.05 g,初始染料浓度为175 mg/L,接触时间为80 min时,核桃壳对罗丹明B的吸附效果最好。相较于Freundlich模型,Langmuir模型更适合模拟核桃壳对罗丹明B的吸附。核桃壳对罗丹明B的吸附过程符合准二级动力学,且热力学计算表明该吸附过程是一个自发的吸热过程。红外光谱结果表明核桃壳上的-OH、-NH等官能团是罗丹明B的主要结合位点。研究结果表明核桃壳是一种具有潜力的吸附剂,可以有效去除废水中的罗丹明B染料。

A low cost adsorbent of walnut shell obtained from agricultural wastes was used to absorb dye rhodamine-B from aqueous solution. Response surface methodology (RSM) had been explored to study the influences of pH, adsorbent dosage, initial dye concentration and contact time on rhodamine-B adsorption and optimize the experimental conditions. The results indicated that pH has the significant effect on the adsorption process, and the optimal condition was pH value of 3.50, adsorbent dosage of 0.05 g, initial dye concentration of 175 mg/L, and contact time of 80 min. The Langmuir isotherm model was more applicable for describing the adsorption than Freundlich isotherm model. The kinetic study indicated that the experimental data were well fitted by the pseudo-second-order model, and thermodynamic study demonstrated that the adsorption was a spontaneous and endothermic process. The FTIR analysis indicated the functional groups of -OH,-NH on the walnut shell were the active binding sites for rhodamine B adsorption. The results revealed that WNS was a promising adsorbent to remove rhodamine B dye from wastewater.