锌改性污泥生物炭/聚乙烯醇小球对水中磷的去除

Removal of phosphate by zinc modified sludge biochar/polyvinyl alcohol beads

摘要:

为了实现市政污泥的减量化、无害化及资源化，以市政污泥制备的生物炭（MSBC）为骨架，经负载纳米零价锌（nZVZ），再与聚乙烯醇（PVA）复合，最后用钙离子作为交联剂，制备nZVZ-MSBC/PVA小球，将其用于吸附水中的磷。利用SEM、BET、FTIR和XPS对nZVZ-MSBC/PVA小球的微观形貌、结构组成进行表征，考察m(nZVZ-MSBC)∶m(PVA)对nZVZ-MSBC/PVA小球磷吸附性能的影响，探究其吸附过程的动力学和热力学特性，推测其吸附机理。结果表明，以m(nZVZ-MSBC)∶m(PVA)＝1∶1制备的nZVZ-MSBC/PVA小球〔nZ-C/PVA(1∶1)〕对pH＝5的磷离子溶液具有最佳的磷吸附性能，其呈现为三维多孔结构；nZ-C/PVA(1∶1)对磷的吸附是一个吸热过程，符合伪二级动力学模型和Langmuir模型，吸附量在318 K下最大可达274.30 mg/g，单层化学吸附在吸附过程中占主导地位；吸附机理包括静电相互作用、氢键连接、表面沉积及络合作用等。

Abstract:

To realize the reduction, harmlessness and recycling of the municipal sludge, nZVZ-MSBC/PVA gel bead was prepared by skeletal deposition of nano-zero-valent zinc (nZVZ) into municipal sludge biochar (MSBC) followed recombining with polyvinyl alcohol (PVA) using Ca2+ as cross-linking agent. And it was used to adsorb phosphate from water. It could not only efficiently adsorb phosphate, but also facilitate post-adsorption separation from water. The micromorphology and structural composition the nZVZ-MSBC/PVA beads were characterized using SEM, BET, FTIR, and XPS. The influence of m(nZVZ-MSBC)∶m(PVA) for phosphate adsorption performance of nZVZ-MSBC/PVA beads was investigated. The kinetics and thermodynamic properties were explored. In addition, the adsorption mechanism was speculated. The results showed that nZVZ-MSBC/PVA beads [nZ-C/PVA(1∶1)] prepared with m(nZVZ-MSBC)∶m(PVA)＝1∶1 exhibited the optimal phosphate adsorption performance for phosphate solution at pH=5. And the beads presented three-dimensional porous structure. The adsorption of phosphate by nZ-C/PVA(1∶1) beads was an endothermic process. And it was fitted Pseudo-second-order dynamics and Langmuir models. The maximum adsorption amount could reach 274.30 mg/g at 318 K. The adsorption process was dominated by monolayer chemisorption. The adsorption mechanism included electrostatic interaction, hydrogen bonding, surface deposition, complexation and so on.