竹炭负载氧化锌对Cr(Ⅵ)的吸附性能和机理

Adsorption Capacity and Mechanism of ZnO Loading Bamboo Biochar for Cr(Ⅵ)

本文以竹制生物炭为原材料,通过共沉淀法负载氧化锌制备锌改性生物炭(ZnBC)。通过批量实验探究ZnBC对废水中Cr(Ⅵ)的吸附性能,采用SEM、XRD、FTIR和XPS等分析方法对吸附Cr(Ⅵ)前后的ZnBC进行表征。实验结果表明,在pH=7、反应时间720 min、反应温度298 K时,ZnBC对Cr(Ⅵ)的吸附效果最好。Cr(Ⅵ)的吸附结果符合拟二级(PSO)和Langmuir模型理论,表明吸附类型为化学吸附和单分子层吸附;通过Langmuir模型拟合得出的饱和吸附量为106.383 mg/g。共存离子实验表明,ZnBC对Cr(Ⅵ)有较好的选择吸附性。ZnBC对Cr(Ⅵ)的吸附机理主要包括光催化还原、官能团络合、阳离子-π以及沉淀作用。研究表明,ZnBC作为去除水溶液中Cr(Ⅵ)的吸附剂具有较大的应用潜力。

Zn-modified biochar(ZnBC)was prepared from bamboo biochar by co-precipitation loading ZnO.The adsorption performance of ZnBC for Cr(Ⅵ)in wastewater was investigated by batch experiments.The ZnBC before and after adsorption was characterized by SEM,XRD,FTIR and XPS.The experimental results show that the adsorption of Cr(Ⅵ)by ZnBC is the best at pH=7,reaction time 720 min and reaction temperature 298 K.The adsorption results of Cr(Ⅵ)conform to the pseudo-second-order(PSO)and Langmuir model theory,indicating that the adsorption types are chemical adsorption and monolayer adsorption.The saturated adsorption capacity fitted by Langmuir model is 106.383 mg/g.The coexisting ion experiments show that ZnBC has good selective adsorption for Cr(Ⅵ).The adsorption mechanism of Cr(Ⅵ)by ZnBC mainly includes photocatalytic reduction,functional group complexation,cation-πand precipitation.The results show that ZnBC has great application potential as adsorbent for removing Cr(Ⅵ)from aqueous solution.