College of Civil Engineering, Zhejiang Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology, Zhejiang University of Technology, Hangzhou, 310023, China; Mizuda Group Co. LTD, Huzhou, 313000, China.
College of Civil Engineering, Zhejiang Key Laboratory of Civil Engineering Structures & Disaster Prevention and Mitigation Technology, Zhejiang University of Technology, Hangzhou, 310023, China.
Environ Pollut. 2024 Mar 1;344:123305. doi: 10.1016/j.envpol.2024.123305. Epub 2024 Jan 7.
Iron sludge, produced during the drinking water treatment process, can be recycled as potential iron resource to create environmental functional material. In this study, sulfur-iron composites derived from iron sludge (S-Fe composites) was synthesized through sulfidation and carbonization, and used for the tetracycline (TC) removal under aerobic and anoxic conditions. The reactivities of these as-prepared products were strongly depended on pyrolysis temperatures. In particular, sulfidated nanoscale zero-valent iron loaded on carbon (S-nFe@CIS) carbonized at 800 °C exhibited the highest TC removal efficiency with 86.6% within 30 min at circumneutral pH compared with other S-Fe composites. The crystalline structure of α-Fe, FeS and S as main active sites in S-nFe@CIS promoted the degradation of TC. Moreover, the Fe/S molar ratios significantly affected the TC removal rates, which reached the best value as the optimal S/Fe of 0.27. The results illustrated that the optimized extent of sulfidation could facilitate electron transfer from nFe towards contaminants and accelerate Fe(III)/Fe(II) cycle in reaction system compared to bared nFe@CIS. We revealed that removal of TC by S-nFe@CIS in the presence of dissolved oxygen (DO) is mainly attributed to oxidation, adsorption and reduction pathways. Their contribution to TC removal were 31.6%, 25.2% and 28.8%, respectively. Furthermore, this adsorption-oxygenation with the formation of S-nFe@CIS-TC* complexes was a surface-mediated process, in which DO was transformed by the structural FeS on complex surface to •OH with the generation of HO intermediate. The intermediates of TC and toxicity analysis indicate that less toxicity products generated through degradation process. This study provides a new reclamation of iron sludge and offers a new insight into the TC removal by S-nFe@CIS under aerobic conditions.
铁泥是饮用水处理过程中产生的，可以回收作为潜在的铁资源，用于制备环境功能材料。本研究采用硫化碳化法制备了铁泥基硫铁复合材料（S-Fe 复合材料），并考察了其在好氧和缺氧条件下对四环素（TC）的去除性能。结果表明，所制备的复合材料的反应活性强烈依赖于热解温度。特别是，在 800°C 下热解制备的负载在碳上的硫化纳米零价铁（S-nFe@CIS）在近中性 pH 条件下，对 TC 的去除效率最高，在 30 min 内达到 86.6%，优于其他 S-Fe 复合材料。S-nFe@CIS 中的主要活性位 α-Fe、FeS 和 S 的晶体结构促进了 TC 的降解。此外，Fe/S 摩尔比对 TC 的去除速率有显著影响，当 S/Fe 比为 0.27 时达到最佳值。结果表明，优化的硫化程度可以促进 nFe 向污染物转移电子，并加速反应体系中 Fe(III)/Fe(II)循环。与裸露的 nFe@CIS 相比，S-nFe@CIS 中优化的硫化程度更有利于电子从 nFe 向污染物转移，从而加速 Fe(III)/Fe(II)循环。我们揭示了在有氧条件下，S-nFe@CIS 去除 TC 主要归因于氧化、吸附和还原途径。它们对 TC 去除的贡献分别为 31.6%、25.2%和 28.8%。此外，这种吸附-氧化作用伴随着 S-nFe@CIS-TC*复合物的形成，是一个表面介导的过程，其中 DO 在复合物表面的结构 FeS 作用下转化为 •OH，并生成 HO 中间体。TC 的中间产物和毒性分析表明，降解过程生成的毒性产物较少。本研究为铁泥的再利用提供了新途径，并为 S-nFe@CIS 在好氧条件下去除 TC 提供了新的见解。
