矿物-有机-磷复合材料对灌溉水中重金属去除及矿质养分补充
- Removal of heavy metals and supplementation of mineral nutrients in irrigation water by mineral-organic-phosphorus composites
- 基金项目：国家自然科学基金重点项目(52230006)；国家自然科学(42007123)；广西科技基地与人才专项项目(Guike AD19245181)；广西壮族自治区自然科学(2020GXNSFBA159026)；广东省基础与应用基础研究(2019A1515110753)；广西环境污染控制理论与技术重点实验室科研经费(1801K005)；桂林理工大学(GLUTQD2017139)
- 摘要：灌溉水和农田土壤中的Pb2+和Cd2+复合污染以及必需矿质养分的缺乏对农产品安全和质量构成威胁。为应对这些问题,采用钾长石、褐煤腐植酸和磷酸二氢钾为主要原料,通过球磨、热活化和水热合成,创新和经济地制备了矿物-有机-磷复合材料(M-HA-P)。研究了在单一和复合污染体系中重金属去除和矿质养分释放的同步机制。在25 ℃下,M-HA-P在单一吸附条件下对Pb2+和Cd2+的吸附容量分别高达709和133 mg.g?1。而在复合吸附中,Pb2+和Cd2+在M-HA-P表面的协同作用增强了官能团的络合能力,进一步提升了吸附效率。pH≥3时,Pb2+/Cd2+在M-HA-P上的解吸极具挑战性；而pH≤0.5时,M-HA-P和Pb2+/Cd2+可回收利用。单一吸附Pb2+后,主要形成Pb2P2O7、PbHPO4、PbAl2O4、Pb3SiO5、Pb4SiO6等稳定性化合物；而吸附Cd2+后,主要生成Cd(H2PO4)2、CdP4O11、Cd2P4O12和Cd3Al2Si3O12等。复合吸附后,主要生成PbHPO4、Pb10(PO4)6(OH)2、Pb3(PO4)2、Pb5SiO7、Cd4P8O24.12H2O、Cd5H2(PO4)4.4H2O和CdSiO3等难溶性化合物。M-HA-P的高效去除重金属主要依赖几个关键过程：与氢氧化物、磷酸盐、硅酸盐、铝酸盐和硅铝酸盐等形成的沉淀；表面官能团(羟基、羧基和醚键)的络合；以及π-Pb2+/π-Cd2+相互作用、静电吸引和离子交换的作用。在实际灌溉水中,M-HA-P在10 min内对Pb2+和Cd2+的去除率分别高达90.1 %和82.4 %,并在60 min内K+、Si4+和Mg2+的浓度分别显著增加了597 %、8.05 %和708 %。M-HA-P展现出作为经济且可持续解决方案的巨大潜力,适用于处理灌溉水中的重金属污染和养分缺乏问题,促进了钾长石和褐煤腐植酸在环境和农业修复中的应用。
- Abstract：The combined pollution of Pb2+ and Cd2+ in irrigation water and agricultural soil, along with the deficiency of essential mineral nutrients, poses a threat to the safety and quality of agricultural products. To address these issues, an innovative and economical mineral-organic-phosphorus composite material (M-HA-P) was prepared using potassium feldspar, lignite humic acid, and monopotassium phosphate as the primary raw materials, through ball milling, thermal activation, and hydrothermal synthesis. The simultaneous mechanisms of heavy metal removal and mineral nutrient release in both single and combined pollution systems were investigated. Under single adsorption conditions at 25 ℃, M-HA-P exhibited high adsorption capacities of up to 709 mg.g?1 for Pb2+ and 133 mg.g?1 for Cd2+, respectively. In combined adsorption, the synergistic effect of Pb2+ and Cd2+ on the M-HA-P surface enhances the complexation capability of functional groups, further boosting the adsorption efficiency. Desorption of Pb2+/Cd2+ from M-HA-P is highly challenging at pH ≥ 3, whereas M-HA-P and Pb2+/Cd2+ are recoverable at pH ≤ 0.5. After single adsorption of Pb2+, stable compounds such as Pb2P2O7, PbHPO4, PbAl2O4, Pb3SiO5, and Pb4SiO6 are primarily formed. For Cd2+ adsorption, the main products are Cd(H2PO4)2, CdP4O11, Cd2P4O12, and Cd3Al2Si3O12. In combined adsorption, insoluble compounds including PbHPO4, Pb10(PO4)6(OH)2, Pb3(PO4)2, Pb5SiO7, Cd4P8O24.12H2O, Cd5H2(PO4)4.4H2O, and CdSiO3 are predominantly generated. The efficient removal of heavy metals by M-HA-P relies on several key processes: precipitation with hydroxides, phosphates, silicates, and aluminates; complexation with surface functional groups (hydroxyl, carboxyl, and ether groups); π-Pb2+/π-Cd2+ interactions; electrostatic attraction; and ion exchange. In actual irrigation water, M-HA-P achieved removal rates of up to 90.1 % for Pb2+ and 82.4 % for Cd2+ within 10 min, and significantly increased K+, Si4+, and Mg2+ concentrations by 597 %, 8.05 %, and 708 %, respectively, within 60 min. M-HA-P demonstrates significant potential as an economical and sustainable solution for addressing heavy metal pollution and nutrient deficiency in irrigation water, promoting the application of potassium feldspar and lignite humic acid in environmental and agricultural remediation.
