生物炭内源磷和外源磷的释放及对铅的吸附

Release of Inherent-P and Laden-P from Biochar and Adsorption on Lead

摘要: 文章以小麦秸秆制备不同磷含量的改性生物炭，探究其对重金属Pb²⁺的吸附机理与磷释放特征之间的关系。利用元素分析、XPS对生物炭的元素组成和官能团结构进行分析；探究固液比、电解质强度和有机酸对磷释放的影响。结果表明：四种生物炭P含量在2.53 mg∙g⁻¹~10.82 mg∙g⁻¹范围，且制备的生物炭均为碱性(pH > 9)。生物炭的磷素累积释放表明生物炭内源磷的释放是持续渐进的过程。固液比、电解质强度、有机酸等环境因素对生物炭中磷的释放特征产生一定影响。溶液pH升高能够促进生物炭对重金属Pb的吸附，当溶液pH从3升至6时，生物炭对Pb的吸附效率由(6.49%~13.28%)提升至(92.26%~99.47%)。为磷酸盐改性生物炭用作缓释磷肥和重金属钝化剂提供理论依据。

Abstract: Modified biochar with different phosphorus contents was prepared from wheat straw to explore the relationship between the adsorption mechanism of heavy metal Pb²⁺ and the characteristics of phosphorus release. Elemental composition and functional group structure of biochar were ana-lyzed by elemental analysis and XPS. The effects of solid-liquid ratio, electrolyte strength and or-ganic acids on phosphorus release were investigated. The results showed that the P content of the four biochars ranged from 2.53 mg•g⁻¹ to 10.82 mg•g⁻¹, and all the biochars prepared were alkaline (pH > 9). The cumulative phosphorus release process of biochar indicates that the endogenous phosphorus release of biochar is a continuous and gradual process. The solid-liquid ratio, electrolyte strength, organic acids and other environmental factors have certain effects on the re-lease characteristics of phosphorus from biochars. When the pH of solution increases from 3 to 6, the adsorption efficiency of Pb by biochar increases from (6.49%~13.28%) to (92.26%~99.47%). It provides theoretical basis for phosphate modified biochar to be used as slow release phosphate fertilizer and heavy metal passivator.