榴莲壳和不同炭材料对低汞溶液的吸附动力学

赵子科; 陈春亮; 柯盛; 赵利容; 张际标; 李剑

doi:10.15898/j.cnki.11-2131/td.202106010069

榴莲壳和不同炭材料对低汞溶液的吸附动力学

Adsorption Kinetics of Low Mercury Solution with Durian Shell and Activated Carbon

摘要

摘要: 含Hg（Ⅱ）废水直接排放会对环境产生危害，目前多采用活性炭去除，而活性炭制作需要高温热解和活化，导致其使用成本较高。近年来，果皮、果渣、炉渣等废弃物也被尝试应用于直接去除水溶液中的重金属离子。本文采用榴莲壳、椰壳活性炭和活性炭纤维在不同条件下对低浓度Hg（Ⅱ）溶液进行吸附，使用原子荧光光谱法对吸附溶液中剩余的Hg（Ⅱ）含量进行测定，着重对榴莲壳的吸附机理进行探索。实验结果揭示，Hg（Ⅱ）在Lagergren准二级动力学模型下，三种材料最大吸附量（Q_m）比较结果为：活性炭纤维（5.61μg/g）>榴莲壳（1.68μg/g）>椰壳活性炭（0.96μg/g）。吸附试验和热力学方程得出三种材料对Hg（Ⅱ）的吸附均是自发进行的（ΔG < 0）；椰壳活性炭对Hg（Ⅱ）的吸附以物理吸附为主（ΔH>0）；榴莲壳吸附为吸热过程（ΔH < 0），吸附体系升温可提高榴莲壳吸附Hg（Ⅱ）的速率和吸附容量。本研究表明来源广泛的榴莲壳可以作为吸附剂处理含Hg（Ⅱ）的废水，达到以废治废的目的。

Abstract:
BACKGROUNDThe direct discharge of Hg(Ⅱ) is harmful to the environment. At present, activated carbon is used to remove it, but the production of activated carbon through high-temperature pyrolysis and activation is very expensive.
OBJECTIVESTo investigate the adsorption difference and mechanism on low-concentration Hg(Ⅱ) for durian shell, coconut shell activated carbon and activated carbon fiber under different conditions.
METHODSThe remaining Hg(Ⅱ) in the adsorption solution was determined by atomic fluorescence spectrometry. The adsorb kinetic parameters of different adsorbents were determined by Lagergren pseudo-second-order kinetic model.
RESULTSIn the Lagergren pseudo-second-order kinetic model, the maximum adsorption capacity (Q_M) of the three materials was as follows: activated carbon fiber (5.61μg/g)>durian shell (1.68μg/g)>coconut shell activated carbon (0.96μg/g). The adsorption test and thermodynamic equation showed that the adsorption of Hg(Ⅱ) by the three materials was spontaneous (ΔG < 0). The adsorption of Hg(Ⅱ) by coconut shell activated carbon was mainly physical adsorption (ΔH>0), while the adsorption of durian shell was an endothermic process (ΔH < 0). Due to the increase of temperature, the adsorption rate and adsorption capacity were improved.
CONCLUSIONSDurian shell from a wide range of sources can be used as an effective adsorbent to treat wastewater containing Hg(Ⅱ).

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