碱性钙基膨润土对亚甲基蓝和刚果红的吸附去除

Adsorption of Methylene blue and Congo red on alkaline Ca-bentonite

摘要:

本论文研究了碱性钙基膨润土(ACB)对水体中的亚甲基蓝(MB)和刚果红(CR) 染料的吸附性能，考察了吸附剂用量、吸附时间及温度、pH值及盐等因素对吸附效果的影响，同时进行了两种染料在碱性钙基膨润土上的吸附等温模型、吸附动力学模型研究。研究结果表明，ACB对MB、CR的脱色率随着吸附剂用量的增加而增加，在实验条件下，50 mg/L MB和100 mg/L CR的最佳吸附剂浓度分别为1.0 g/L和2.0 g/L；升高温度可以加快吸附速率，但对最终的脱色率影响很小；50 mg/L MB的吸附平衡时间在60 min左右，100 mg/L CR的吸附平衡时间在120 min左右；在pH值3-12范围内，ACB对MB的脱色率都稳定在99%左右，而适宜ACB吸附CR的pH范围为3-7,对CR的脱色率保持在90%左右； NaCl的加入对MB的吸附效果影响很小，对CR的吸附则有很强的抑制作用；ACB对MB的吸附同时符合Langmuir和Freundlich模型，而ACB对CR的吸附则更符合Langmuir模型；ACB对两种染料的吸附过程均符合准二级动力学模型，颗粒内扩散模型的拟合结果说明吸附过程存在颗粒内扩散作用。

Abstract:

Alkaline Ca-bentonite (ACB) was investigated to remove Methylene blue (MB) and Congo red (CR) from aqueous solution as a function of adsorbent dosage, contact time and temperature, initial pH and salt. The adsorption isotherms and adsorption kinetics of the two dyes on ACB were also studied. The main results are as follows: MB and CR removal by ACB increased with the increase of adsorbent dosage. Under experimental conditions, the optimum adsorbent dosage for 50 mg/L MB and 100 mg/L CR were 1.0 g/L and 2.0 g/L, respectively; The elevated adsorption temperature contributed to accelerate the adsorption rate of MB and CR on ACB, but it had little impact on the final decolorizing rate of MB and CR；For 50 mg/L MB and 100 mg/L CR with the optimum adsorbent dosage of ACB, the adsorption equilibrium time were 60 min and 120 min, respectively. The decolorizing rate of MB by ACB remained about 99% when the initial pH increased from 3 to 12, and that of CR by ACB remained about 90% within the optimum pH range 3-7.The addition of NaCl had little effect on MB adsorption but suppressed CR adsorption obviously. MB adsorption on ACB followed both the Langmuir model and the Freundlich model, but CR adsorption on ACB followed the Langmuir model better.The adsorption process of MB and CR can be better described by the pseudo-second-order model than the pseudo-first-order model. The intraparticle diffusion model studies indicated there was pore-filling by diffusing during the adsorption process.