芒果核壳炭的制备及对水中Cr^6＋的吸附

Adsorption of Cr^(6+) from aqueous solutions by modified mango shell

以芒果核壳为原料通过H3PO4活化制备了新型的吸附剂H3PO4-C。考察了影响该吸附剂对水体中Cr(VI)的去除效果的因素,并研究了吸附动力学特征和吸附过程控制机理。结果表明,芒果壳生物质炭对Cr(VI)具有良好的吸附能力,在25℃下,较佳的吸附条件为:当投加量为3 g·L^(-1),Cr(VI)初始浓度为50 mg·L^(-1),溶液p H值为3时,吸附5h,去除率为93.8%。准一级、准二级动力学模型用来拟合吸附过程,结果表明,准二级动力学符合该吸附过程,吸附速率常数为0.001 3 g·(mg·min)-1。用Langmuir和Freundlich模型描述吸附等温过程,结果说明,该吸附过程服从Langmuir吸附,饱和吸附量为28.571 mg·g-1,内扩散为该吸附过程的限速步骤,内扩散系数D=4.21×10-9cm2·s-1。

Mango shell was modified with H_3PO_4 to prepare a novel adsorbent. The effects of certain parameters on the removal rate and kinetic characteristics,as well as the mechanism governing the adsorption process,were investigated. The results showed that the maximum Cr6 ＋removal rate was 93. 8% under the following conditions： temperature of 25 ℃,Cr6 ＋initial concentration of 50 mg·L^-1,adsorption time of 5 h,p H of 3,adsorbent dosage of 3 g ·L^-1. The adsorption process was fitted to kinetic models,including first-order and pseudo-second-order equations. The process followed pseudo-second-order kinetics with an adsorption rate constant of 0. 001 3 g·（ mg·min）- 1. Langmuir and Freundlich models were used to describe the adsorption equilibrium data. The results indicated that the Langmuir model provided a more acceptable fit to the experimental data than the Freundlich equation. The maximum Cr6 ＋uptake was Qm= 28. 571 mg·g- 1. The inner diffusion was the key step in this adsorption system,and the inner diffusion coefficient was D = 4. 21 × 10- 9cm2·s- 1.