摘要
采用高温液相生长法制得g-C_3N_4薄膜电极并作为光阳极,以石墨毡作为阴极,建立了光电催化系统.通过对比光电催化体系、K_2S_2O_8体系以及外加K_2S_2O_8到光电催化体系,发现在光电催化系统下外加K_2S_2O_8可以有效地提高光电催化降解Cu(CN)_3^(2-)的效率,并实现了Cu在阴极上的有效回收.探究了K_2S_2O_8投加量对CN-降解率和Cu回收率的影响,发现当K_2S_2O_8浓度为1 mmol·L^(-1),偏压为1.0 V时,CN-的去除率和Cu回收率分别达到86.23%和82.11%.通过SEM、EDS和XPS分析阴阳极表面形貌,发现部分Cu+被氧化以CuO的形式存在于沉淀和阳极表面,大部分铜离子通过电化学还原作用以单质铜的形式沉积于阴极表面,铜离子有效地从体系中去除.电子顺磁共振及淬灭实验分析表明,CN-的氧化去除是硫酸根自由基(SO·-4)氧化和非自由基氧化共同作用.
Oxidation of Cu-cyanides by a photoelectrocatalytic method was enhanced by adding peroxydisulfate（PS）.In the photoelectrocatalytic system（PEC）,graphitic carbon nitride（g-C_3N_4） thin films prepared by a liquid-based reaction and graphitic carbon felt（GCF） were used as the photoanode and cathode,respectively.First,various processes,including PEC,PS oxidation,and PEC with PS addition（PEC/PS）,were compared for Cu-cyanide removal.The addition of PS improved greatly the photoelectrocatalytic efficiency for the oxidation of CN-and the recovery of Cu on the cathode.The effect of the amount of K_2S_2O_8 was investigated in detail.The removal efficiency of CN-and Cu recovery can reach up to 86.23% and 82.11%,respectively,with 1 mmol·L^-1 K_2S_2O_8 at 1.0 V bias potential.Combined with the SEM,EDS,and XPS analysis of the electrode surface,it was concluded that the free Cu＋was oxidized and existed in the precipitation and photoanode in the form of Cu O.Conversely,the liberated Cu~＋/Cu^（2＋） ions were electrochemically reduced to elemental Cu on the surface of the graphitic carbon felt cathode.As a result,metal Cu was recovered from the wastewater of the copper cyanide complexes.Electron spin resonance and radical quenching experiment analysis showed that the oxidation of CN-is assigned to sulfate radical oxidation and non-radical oxidation processes.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2018年第1期145-151,共7页
Environmental Science
基金
国家自然科学基金优秀青年基金项目(51222802)
