赤泥/煤基铁炭材料的制备及其脱除废水Cr(Ⅵ)的性能

Preparation of red mud/coal based material and its performance to remove Cr(Ⅵ) in waste water

以脱钠赤泥、粉状褐煤为原料,羧甲基纤维素钠为黏结剂,采用碳热还原法制备了可替代商业铁炭微电解填料的廉价铁炭材料,用于去除废水中的Cr(Ⅵ)。考察了不同的制备参数(炭化温度、炭化时间、赤泥/煤质量比)和吸附条件(溶液pH、浓度),以提升Cr(Ⅵ)去除效果。结果表明质量比(赤泥/煤)为1/3、800℃炭化1h的赤泥/煤基铁炭材料,可达到最大Cr(Ⅵ)吸附量(4.03 mg·g^(-1))、最低铁溶出量(<0.19 mg·g^(-1))和最大比吸附量(12.97 mg·g^(-1),由Langmuir吸附等温线模型算出)。赤泥/煤基铁炭材料对Cr(Ⅵ)的吸附等温线符合Freundlich方程,其吸附动力学可用准一级或准二级动力学方程来描述。多种表征(XRD、XRF、BET和SEM等)结果进一步表明赤泥/煤基铁炭材料比商业铁炭填料具有更高的铁还原度、更大的比表面积和孔容以及更好的颗粒分散度,使其具有更好的Cr(Ⅵ)的去除效果。

As the cheap substitution of commercial iron carbon microelectrolyte filler to remove Cr（Ⅵ） in waste water, the red mud/coal based material was prepared from the mixtures of red mud, pulverized lignite and sodium carboxymethyl cellulose via a carbothermal method. The different preparation parameters （carbonization temperature, carbonization time, mass ratio of red mud/coal） and adsorption conditions （solution pH, concentration） were investigated to improve the removal efficiency of Cr（Ⅵ）. The results demonstrated that the red mud/coal based material carbonizated at 800℃ for 1 h with the mass ratio （red mud/coal） of 1/3 can reach the highest Cr（Ⅵ） removal capacity （4.03 mg·g^-1）, the lowest Fe dissolution ratio （〈 0.19 mg·g^-1） and the maximum adsorption capacity （12.97 mg·g^-1, according to the Langmuir adsorption isotherm models）. The adsorption isotherm of Cr（Ⅵ） on the red mud/coal based material was well consistent with Freundlich equation model, and its adsorption kinetics can be described by the pseudo-first-order or pseudo-second-order equation. The multiple characterization methods （XRD, XRF, BET, and SEM） further revealed that the red mud/coal based material had higher reduction degree of Fe element, bigger BET area and volume and better particle dispersion than the commercial iron carbon microelectrolyte filler, which accounted for its excellent removal efficiency of Cr（Ⅵ）.