煤基腐殖酸吸附Cu^(2+)特征的影响因素

Adsorption Characteristics of Cu(Ⅱ)on Weathered Coal-based Humic Acid and Its Influencing Factors

为有效发挥煤基腐殖酸在缓解农田Cu2+污染和提升作物Cu2+生物有效性等方面的作用,采用新疆风化煤所提取的腐殖酸(煤基HA)作为吸附剂,应用批量平衡法研究pH、共存阳离子、温度和接触时间等因素影响下,煤基HA对Cu2+离子的吸附特征。结果表明:pH是影响煤基HA吸附Cu2+的最主要因素,pH值3~6时Cu2+吸附率急剧增加,增长曲线整体呈"S"形。共存Na+浓度增加(0~1.0mol/L),Cu2+在煤基HA上的吸附受抑制。298K和318K温度影响下的2条吸附等温曲线存在共性,均表现为先增加后趋于平衡的特点,其中,Langmuir方程对其规律的描述最为贴切。温度(298~318K)和初始Cu2+浓度(0~1 000mg/L)均与Cu2+的吸附数量呈正相关,自发、吸热及混乱度增加是该热力学吸附过程的三大特点。煤基HA对Cu2+的动力学吸附可大致分为快速提升和缓速平衡2个阶段,Elovich和双常数方程能很好描述该过程。温度有利于反应速率的提升,但其未能对吸附后表面结构的有序度产生影响。

To explore the effects of the humic acid extracted from a weathered coal of Xinjiang province（coal-based HA,a superior adsorbent）on alleviating the degree of contamination of Cu2＋in a farmland and improving its biological effectiveness,the batch experiments were performed to study the effects of influencing factors（pH,co-existing cation,temperature,and contact time）on the characteristics of Cu2＋sorption on the coal-based HA.The results were shown that：pH was the most prominent influencing factor of Cu2＋adsorbed on the coal-based HA.In the range of pH 3~6,the adsorption rate of Cu2＋had a rapid increase,however,the whole growth curve was regarded as S-type.With the concentration of co-existing Na＋（0~1.0mol/L）increasing,the sorption of Cu2＋on the coal-based HA was inhibited.Two sorption isotherms,happened under the two temperatures（298Kand 318K）,had a common feature that increasing first and then reaching an equilibrium state.In the process,the description of Langmuir model was the most appropriate.The temperature（298~318K）and initial Cu2＋concentrations（0~1 000mg/L）were positively correlated with the adsorption amount of Cu2＋.The thermodynamics adsorption of Cu2＋on the coal-based HA was a spontaneous,endothermal and increasing confused process.The kinetics of coal-based HA adsorbing Cu2＋could be divided into rapid and slow reaction stages.Both the equations,Elovich and double constant,had some great advantages on describing the process.The temperature was conducive to enhance the reaction rate,but it had no impact on the degree of order of surface outside the coal-based HA.