In-situ formation of green rust during Fe(II) coagulation: dual reductive and adsorptive pathways for dyeing wastewater treatment

IF 11.4 1区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL

Water Research Pub Date : 2025-07-06 DOI:10.1016/j.watres.2025.124174

Xian Zhao, Jia-Yi Wang, Yu-Qian Wang, Chen-Hao Cui, Xin Yan, Wei Dai, An-Ran Zhang, Zhen-Ying Zhang, Ding-Ding Tang, Yan Zhou, Qiong Qin, Ji-Wei Pang, Lu-Yan Zhang, Nan-Qi Ren, Jie Ding, Shan-Shan Yang

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Abstract

Green rust (GR), a reductive iron-based mineral pivotal in soil and groundwater remediation, remains unexplored for wastewater treatment. This study reveals that high-pH-Fe(II) coagulation enables in-situ generation of stabilized GR, thereby enhancing the coagulation efficiency (> 90% removal for diverse dyes). The formation mechanism includes three sequential stages: Initially, alkaline conditions facilitate abundant Fe(OH)₂; Subsequently, partial oxidation of Fe(II) by oxidants produces anoxic zones, where Fe(II)/Fe(III) co-precipitation initiates GR crystallization; Simultaneously, multivalent anions intercalate into GR interlayers, further enhancing GR stability through strong electrostatic interactions. GR-enhanced-Fe(II) coagulation demonstrates dual dyes removal mechanisms: direct reductive degradation of electrophilic moieties (e.g., azo bond) and adsorption-coprecipitation of macromolecules. Based on the mechanism insights, it is found that GR-enhanced-Fe(II) coagulation achieves unparalleled removal of both anionic and cationic dyes (nearly 100% decolorization for 50 mg/L dye solutions) under anoxic conditions. HPLC-MS and DFT confirm GR-driven reductive cleavage of Reactive Red 2 into low-molecular-weight byproducts. Pilot and full-scale trials at a dyeing wastewater treatment plant concluded that GR-enhanced-Fe(II) coagulation achieves 53.5% COD removal, outperforming conventional Fe(II) processes (46.5%) under actual hydraulic and pollutant load fluctuations. This work expands coagulation theory and offers a cost-effective strategy for wastewater treatment, adaptable to diverse effluents while retaining operational simplicity.

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铁（II）混凝过程中绿锈的原位形成：染色废水处理的双重还原和吸附途径

绿锈（GR）是一种在土壤和地下水修复中起关键作用的还原性铁基矿物，目前尚未被用于废水处理。本研究表明，高ph - fe （II）混凝可以原位生成稳定GR，从而提高混凝效率(>；对各种染料去除率达90%)。形成机制包括三个连续的阶段：最初，碱性条件有利于丰富的Fe(OH)2；随后，Fe（II）被氧化剂部分氧化产生缺氧区，其中Fe(II)/Fe（III）共沉淀引发GR结晶；同时，多价阴离子嵌入GR中间层，通过强静电相互作用进一步增强GR的稳定性。gr增强- fe （II）混凝显示了双重染料去除机制：亲电基团（如偶氮键）的直接还原降解和大分子的吸附-共沉淀。基于对机理的了解，我们发现在缺氧条件下，gr增强- fe （II）混凝对阴离子和阳离子染料的去除率都达到了无与伦比的水平（50 mg/L染料溶液的脱色率接近100%）。HPLC-MS和DFT证实了gr驱动的活性红2还原裂解成低分子量副产物。在一家印染废水处理厂进行的中试和全面试验得出结论，在实际水力和污染物负荷波动下，gr -强化铁（II）混凝法的COD去除率为53.5%，优于传统的铁（II）工艺（46.5%）。这项工作扩展了混凝理论，并为废水处理提供了一种具有成本效益的策略，适用于各种废水，同时保持操作简单性。

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来源期刊

Water Research 环境科学-工程：环境

CiteScore

20.80

自引率

9.40%

发文量

1307

审稿时长

38 days

期刊介绍： Water Research, along with its open access companion journal Water Research X, serves as a platform for publishing original research papers covering various aspects of the science and technology related to the anthropogenic water cycle, water quality, and its management worldwide. The audience targeted by the journal comprises biologists, chemical engineers, chemists, civil engineers, environmental engineers, limnologists, and microbiologists. The scope of the journal include: •Treatment processes for water and wastewaters (municipal, agricultural, industrial, and on-site treatment), including resource recovery and residuals management; •Urban hydrology including sewer systems, stormwater management, and green infrastructure; •Drinking water treatment and distribution; •Potable and non-potable water reuse; •Sanitation, public health, and risk assessment; •Anaerobic digestion, solid and hazardous waste management, including source characterization and the effects and control of leachates and gaseous emissions; •Contaminants (chemical, microbial, anthropogenic particles such as nanoparticles or microplastics) and related water quality sensing, monitoring, fate, and assessment; •Anthropogenic impacts on inland, tidal, coastal and urban waters, focusing on surface and ground waters, and point and non-point sources of pollution; •Environmental restoration, linked to surface water, groundwater and groundwater remediation; •Analysis of the interfaces between sediments and water, and between water and atmosphere, focusing specifically on anthropogenic impacts; •Mathematical modelling, systems analysis, machine learning, and beneficial use of big data related to the anthropogenic water cycle; •Socio-economic, policy, and regulations studies.