絮凝-电解氧化联合处理氰化提金废水

采用絮凝-电解氧化联合技术处理氰化废水，主要研究了聚硅酸铝铁 (PSAF) 添加量、絮凝时间、pH、电压、电解时间、极板间距对总氰(CN_T)、游离氰(CN⁻)、Cu、Zn离子去除率的影响，并对其反应机制做了分析。研究表明，当PSAF添加量为2 g·L⁻¹，絮凝时间为30 min，pH为9条件下，CN_T、CN⁻、Zn、Cu离子的去除率分别可达42.97%、100%、84.40%、34.88%。Zn(CN)₄²⁻、Cu(CN)₃²⁻、CN⁻的吸附量分别为567.88、89.76、439.74 mg·L⁻¹。以钛板为阴极，石墨板为阳极，采用一阴两阳体系对絮凝后液进行电解氧化实验，在电压为3 V、电解时间为2 h、极板间距为10 mm条件下，CN_T、CN⁻、Zn、Cu离子的去除率可达91.70%、100%、99.15%、94.49%。絮凝过程中Zn(CN)₄²⁻、Cu(CN)₃²⁻、CN⁻的去除是由电荷中和和化学吸附共同作用的，其中电荷中和起主要作用。Zn(CN)₄²⁻、Cu(CN)₃²⁻、CN^-的化学吸附主要归因于其与PSAF水解产生的羟基阳离子发生交换反应。XRD分析表明，加入酸性絮凝剂PSAF的瞬间，部分Zn(CN)₄^2-反应为Zn(CN)₂沉淀。电解氧化过程中Zn(CN)₄²⁻、Cu(CN)₃²⁻破络释放的氰根会被阳极表面产生的O₂、·OH完全氧化为N₂和CO₂，Zn、Cu离子在阴极板电沉积而被去除。

Cyanidation gold extraction wastewater treatment by combined flocculation-electrolysis oxidation

In this study, the flocculation-electrolysis technology was used to treat the high-concentration cyanidation gold extraction wastewater. The effects of polyaluminum ferric silicate (PSAF) addition, flocculation time, pH, voltage, electrolysis time and electrode distance on the removal rates of total cyanide (CNT), free cyanide (CN−), Cu ions and Zn ions were mainly studied, and the reaction mechanism was also identified. The results showed that when PSAF dosage was 2 g·L−1, the flocculation time was 30 min and pH was 9, the removal rates of CNT, CN−, Zn, and Cu ions in wastewater could reach 42.97%, 100%, 84.40% and 34.88%, respectively. The adsorption capacities of Zn(CN)42−, Cu(CN)32−, and CN− were 567.88 mg·L−1、89.76 mg·L−1、439.74 mg·L−1, respectively. The electrolytic oxidation experiments of the flocculated liquid were conducted by using a graphite plate-cathode and two titanium plate-anode system. At the voltage of 3 V, electrolysis time of 2 h and electrode distance of 10 mm, the removal rates of CNT, CN−, Zn and Cu ions in the wastewater were 91.70%、100%、99.15% and 94.49%, respectively. Zeta potential and FTIR analysis showed that the removal of Zn(CN)42−, Cu(CN)32−, CN− during the flocculation process was a combination of charge neutralization and chemisorption, of which charge neutralization played a major role. The chemisorption of Zn(CN)42−, Cu(CN)32−, and CN− was mainly attributed to the exchange reaction with the positively charged hydroxyl cations produced by PSAF hydrolysis. XRD analysis showed that a part of Zn(CN)42− reacted as Zn(CN)2 precipitate at the moment of acidic flocculant PSAF dosing. During the electrolytic oxidation process, the cyanogen released by Zn(CN)42− and Cu(CN)32− breaking could be completely oxidized to N2 and CO2 by O2, ·OH generated on the anode surface, and Zn and Cu ions were removed by the electrodeposition on the cathode plate.