Preparation of graphene oxide/organo-modified bentonite composites and their adsorption on Cd(Ⅱ)
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摘要: 以氧化石墨烯(GO)、膨润土(Bent)、十六烷基三甲基溴化铵(CTAB)为原料,合成了GO/有机改性Bent (OM-Bent)复合材料,用其处理浓度为10 mg·L-1的含Cd (Ⅱ)废水。研究了GO/OM-Bent复合材料中GO含量、pH、GO/OM-Bent复合材料投加量、反应时间、Cd (Ⅱ)初始浓度及共存离子对GO/OM-Bent复合材料吸附Cd (Ⅱ)的影响。结果表明:在pH值为6、GO质量分数为30wt%、GO/OM-Bent复合材料投加量为200 mg·L-1时,GO/OM-Bent复合材料吸附Cd (Ⅱ)效果最佳,120 min即达到平衡,较同等条件下OM-Bent和GO单独作用时Cd (Ⅱ)吸附量分别高12.01 mg·g-1和5.39 mg·g-1;准二级动力学模型能很好地描述其吸附过程,吸附等温线符合Langmuir模型,温度为303 K时,GO/OM-Bent复合材料对Cd (Ⅱ)的最大吸附量为133.33 mg·g-1。解吸实验结果表明,经5次吸附-解吸循环实验后,Cd (Ⅱ)的吸附率仍高达83.5%,说明GO/OM-Bent复合材料具有很好的循环再生性能。Abstract: Graphene oxide/organo-modified bentonite(GO/OM-Bent) composites were prepared by the synthesis of GO, Bent and cetyltrimethyl ammonium bromide (CTAB), then the composites were used to treat Cd(Ⅱ)-containing wastewater at a concentration of 10 mg·L-1. The effects of GO content in GO/OM-Bent composite, pH value, GO/OM-Bent composite dosage, reaction time, initial concentration of cadmium and coexisting ions on adsorption of Cd(Ⅱ) by GO/OM-Bent composite were investigated by batch test. The adsorption results of GO/OM-Bent composites are balanced at 120 min with the best effect on Cd(Ⅱ) adsorption under the optimal condition:the pH value is 6, the mass fraction of GO is 30wt%, the GO/OM-Bent composite dosage is 200 mg·L-1; Under the same conditions, the adsorption capacity of GO/OM-Bent composite is 12.01 mg·g-1 and 5.39 mg·g-1 higher than that of OM-Bent and GO, respectively; the pseudo-second-order kinetics model can well describe the adsorption process and the adsorption isotherm conforms to the Langmuir model. At 303 K, the maximum adsorption capacity of GO/OM-Bent composite on Cd(Ⅱ) could be reached 133.33 mg·g-1. The results of desorption test shows that the adsorption efficiency of Cd(Ⅱ) remains as high as 83.5% after 5 cycles of adsorption-desorption, indicating that GO/OM-Bent composite has good cyclic regeneration performance.
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Key words:
- graphene oxide /
- organo-modified bentonite /
- adsorption /
- desorption /
- Cd (Ⅱ) /
- coexisting ion
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