基于煤基电极的电吸附处理氰化废水技术及其应用基础研究

The high efficiency, low cost treatment and comprehensive utilization of cyanide and valuable metal ions in cyanide wastewater are the key links to save energy, reduce consumption, tap potentiality and increase profit in gold industry. The characteristics of the surface structure of the coal based electrode materials, the directional migration, adsorption and desorption behavior of ions in the wastewater system under electric field and the technical parameters and the influence rules of the dynamic continuity experiment process will be mainly studied on the basis of the process and technical characteristics of treating cyanide wastewater by adsorption with coal-based electrode as the anode and cathode by theoretical analysis and experimental research. The ionic form, chemistry and electrochemical reaction characteristics of cyanide wastewater system will be analyzed as well. The purpose of the present project is to obtain the structure-activity relationship and control methods among the surface structure of the coal-based electrode materials and its adsorption properties, electrochemical properties. The mechanism of the matching adsorption and catalytic oxidation of the ions in the wastewater under electric field can be revealed. The mechanism of mutual promotion between ion adsorption, anodic oxidation and enrichment and sedimentation and electro adsorption reaction in the process of treating cyanide wastewater by adsorption with electrode can be determined further. Finally a theoretical model and control method for treating cyanide wastewater by adsorption with electrode can be formed. This can supply a new approach for the comprehensive treatment of cyanide and heavy metal ions in wastewater. This is of great significance to the resource and harmless treatment of cyanide wastewater as well.

氰化废水中氰化物与有价金属离子的高效、低成本处理与综合利用是目前黄金行业节能降耗、挖潜增效的关键环节。本课题采用理论分析与实验研究相结合的方法，基于以煤基材料为阴阳极的电吸附处理氰化废水工艺及技术特征，在解析氰化废水体系中离子形态、化学及电化学反应特性的基础上，重点研究了煤基电极材料表面结构特性、电场作用下废水体系中离子的定向迁移、吸附解吸行为，以及动态连续性实验过程的技术参数及影响规律，旨在探明煤基电极材料表面结构与其吸附性能、电化学性能之间的构效关系与调控方法，揭示电场作用下废水中各离子在阳极表面的匹配吸附与催化氧化规律，进一步确定电吸附处理氰化废水过程中离子吸附、阳极氧化与富集沉淀作用间的互促增效机制及电吸附反应机理。最终形成电吸附处理氰化废水的技术调控理论模型和控制方法，为废水中氰化物及重金属离子的综合处理开创了一条新途径，对含氰废水的资源化、无害化处理具有重要的指导意义。

以陕北低变质粉煤、液化残渣为原料，采用成型热解活化工艺可制备出吸附性能与电化学性能优良的煤基电极材料，以此为阴阳极可电吸附处理氰化提金废水。研究成果对黄金冶炼及低变质煤清洁转化领域节能降耗与生态环境保护具有一定的科学价值和现实意义。DCLR添加比例20%，成型压力6MPa，热解时间90min，终温800℃，KOH添加量15mol/L时，煤基电极材料比表面积可达到412m2/g，碘吸附值782.32mg/g，微孔率为84.04%。700~800℃热分解形成的K蒸汽对煤基质的腐蚀与插层作用是微孔形成的主要原因。低变质煤与液化残渣共热解过程存在明显的供氢作用与协同效应，二者既是氢的传递者，也是氢的供体，焦油中的芳香烃和酚类物质在供氢作用以及催化作用下发生加氢裂解，使得焦油中轻质组分含量增加，芳香烃和酚含量降低，烷烃含量上升。.电吸附动力学及热力学研究表明，游离氰、硫氰根、锌氰、铜氰及铁氰络合离子的电吸附过程符合准二级动力学模型，主要受扩散步骤控制。电吸附过程均遵循Langmuir模型，属于单分子层吸附，反应过程主要以偶极间力和配位基交换作用为主。含氰废水中C≡N结构具有良好的传输电子功能，C端和N端都具有良好的配位能力，易于连接过渡金属形成扩展结构，电场作用下，金属氰络合离子在电极双电层部位局部浓缩，彼此之间易产生桥联作用生成络合沉淀。采用一阴两阳电极体系处理氰化废水，CNT、Cu、Zn、CN-、SCN-的去除率分别为97.03%、95.79%、99.82%、99.42%、94.19%，处理后废水可100%返回循环利用。电吸附过程是离子定向迁移、吸附与电吸附、富集沉淀三者共同作用的结果，电场作用下溶液中金属氰络合离子、游离氰及硫氰根等定向迁移，在阳极表面吸附的同时溶液中会产生以CuSCN、Zn2Fe(CN)6为主的絮状沉淀，达到去除氰化物的目的。