生物炭对废水中铜离子吸附的研究进展:改性方法与吸附机制

Copper Ion Removal from Wastewater by Biochar:Modification Method and Adsorption Mechanism

废水中的重金属铜离子(Cu(Ⅱ))会污染水体生态环境,并会通过食物链对人体健康造成潜在危害。生物炭可作为废水中Cu(Ⅱ)去除的有效吸附剂。然而,原状生物炭对Cu(Ⅱ)的吸附量有限,需要对生物炭进行定向改性以提升其去除效果。以废水中的Cu(Ⅱ)为对象,重点论述生物炭的改性方法和吸附机制。结果表明,生物炭的主要改性方法包括化学改性(酸、碱、高分子聚合物改性)、物理改性(球磨和气体活化)、金属改性(铁、锰改性)、矿物质改性和高分子聚合物改性等。改性方法对Cu(Ⅱ)去除效果的次序是:纳米羟基磷灰石改性>含氨基有机酸改性>锰改性>铁改性>碱改性。生物炭吸附Cu(Ⅱ)的主要机制包括孔隙扩散、静电作用、沉淀作用、配位作用、阳离子-π机制、离子交换和还原作用,具体的主导机制取决于生物炭的物化性质和溶液的性质。将来的研究方向包括:采取更为有效的改性方法提高对废水中痕量Cu(Ⅱ)的去除效果;利用先进的仪器和模型计算揭示微观机制;开展动态吸附柱或固定床试验。

Excessive copper ions in wastewater threaten the water ecological environment and cause potential harm to human health through the food chain.Biochar has been confirmed to be an effective adsorbent for Cu ion removal from wastewater.However,the adsorption capacity of the pristine biochar was limited.Modification can improve the adsorption amount of biochar.The modification method and adsorption mechanism of copper ions on biochars were summarized.The results showed that the main modification methods include chemical modification(acid and alkaline activation),physical modification(ball-milling and gas activation),metal modification(Fe and Mn),mineral modification,and high-molecular polymer modification.The order of removal effect of the modified methods on copper ions is as follows:nano-hydroxyapatite>amino-containing organic acid modification>manganese modification>iron modified>alkaline modification.The adsorption mechanisms of copper ion removal by biochar include pore-filling effect,electrostatic action,precipitation action,complexation,cation exchange,ion exchange and reduction.Specific dominant mechanisms highly depended on the physicochemical properties of biochar and experimental conditions.Future research should focus on precise modification methods to enhance the adsorption capacity of copper ions,reveal microscopic mechanisms through advanced instruments combined with theoretical calculations,and perform dynamic adsorption columns or fixed bed experiments.