Department of Environmental Engineering, China Jiliang University, Hangzhou 310018, Zhejiang Province, China.
China Huadong Engineering Corporation Limited, Hangzhou 311122, Zhejiang Province, China.
Environ Pollut. 2022 Jan 15;293:118521. doi: 10.1016/j.envpol.2021.118521. Epub 2021 Nov 15.
Biochar modification by metals and metal oxides is considered a practical approach for enhancing the adsorption capacity of anionic compounds such as phosphate (P). This study obtained paper mill sludge (PMS) biochar (PMSB) via a one-step process by pyrolyzing PMS waste containing ferric salt to remove anionic P from water. The ferric salt in the sludge was transformed into ferric oxide and zero-valent-iron (Fe) in N atmosphere at pyrolysis temperatures ranging from 300 to 800 °C. The maximum adsorption (Q) of the PMSBs for P ranged from 9.75 to 25.19 mg P/g. Adsorption is a spontaneous and endothermic process, which implies chemisorption. PMSB obtained at 800 °C (PMSB800) exhibited the best performance for P removal. Fe in PMSB800 plays a vital role in P removal via adsorption and coprecipitation, such as forming the ≡Fe-O-P ternary complex. Furthermore, the possible chemical precipitation of P by CaO decomposed from calcite (CaCO; an additive of paper production that remains in PMS) may also contribute to the removal of P by PMSB800. Moreover, PMSBs can be easily separated magnetically from water after application and adsorption. This study achieved a waste-to-wealth strategy by turning waste PMS into a metal/metal oxide-embedded biochar with excellent P removal capability and simple magnetic separation properties via a one-step pyrolysis process.
生物炭通过金属和金属氧化物的改性被认为是增强阴离子化合物（如磷酸盐（P））吸附能力的一种实用方法。本研究通过一步热解含铁盐的造纸厂污泥（PMS）废物来获得纸厂污泥生物炭（PMSB），以去除水中的阴离子 P。污泥中的铁盐在 N 气氛下于 300 至 800°C 的热解温度下转化为氧化铁和零价铁（Fe）。PMSB 对 P 的最大吸附量（Q）范围为 9.75 至 25.19mg P/g。吸附是一种自发和吸热的过程，表明是化学吸附。在 800°C 下获得的 PMSB（PMSB800）对 P 的去除表现出最佳性能。PMSB800 中的 Fe 通过吸附和共沉淀在 P 的去除中起着至关重要的作用，例如形成 ≡Fe-O-P 三元配合物。此外，碳酸钙（CaCO；造纸生产的添加剂，残留在 PMS 中）分解产生的 CaO 可能会通过化学沉淀来去除 P，这也可能有助于 PMSB800 去除 P。此外，PMSB 在应用和吸附后可以通过磁场很容易地从水中分离出来。本研究通过一步热解过程，将废物 PMS 转化为具有优异的 P 去除能力和简单的磁性分离性能的金属/金属氧化物嵌入生物炭，实现了废物变宝的策略。
