Sustainable reuse of nickel converter slag as a heterogeneous electro-fenton catalyst for treating textile dyeing wastewater: Activity, mechanism and stability assessment
Graphical abstract
Introduction
The effluent generated by the textile dyeing industry is a complex mixture of recalcitrant molecules that can pose a severe risk to the ecological environment and human health (Didier de Vasconcelos et al., 2021). It causes aesthetic pollution, eutrophication and disturbances in aquatic life because of its weak light permeability and recalcitrance nature (Chen et al., 2021). If this continues, the quality of our water resources will deteriorate continuously (Ali et al., 2009). Thus, it is essential to ensure adequate treatment for effluents before they enter the environment (Eltaweil et al., 2021).
Various technologies, such as electrochemical process (Galal et al., 2021), photodegradation (Ali et al., 2018; Alothman et al., 2021), adsorption (Ali et al., 2019b; Fouda et al., 2022), membrane separation (Nasrollahi et al., 2019), and microbial degradation (Kashefi et al., 2019) have been used to remove these persistent contaminants. The electrochemical advanced oxidation processes (EAOPs) can realize rapid degradation and complete mineralization of organic pollutants through producing ROS, especially for dyes, herbicides and antibiotics (Oladipo et al., 2018). In EAOPs, the hetero-EF system combines the EF system, which produces H2O2 in situ, with the heterogeneous catalytic technology. Compared with the classic Fenton, it has many advantages, such as lower treatment cost, wider pH range and inhibition of iron sludge generation, so it has more potential for practical engineering applications (Rezgui et al., 2018). In recent years, many researchers have made remarkable progress in wastewater treatment using synthetic iron-based catalysts and natural iron-containing minerals as hetero-EF catalysts (Brillas and Martinez-Huitle, 2015). Natural minerals are generally preferred due to cost effects, complex synthesis routes and possible hazardous effects associated with synthetic iron-based catalysts (Abd El-Monaem et al., 2022; Ali et al., 2019a). Natural minerals are used as feedstock for steel and metallurgical industries (Ganiyu et al., 2020). Thus, it is of great practical significance for large-scale applications to prepare high-performance and stable catalysts with suitable feedstocks (Gomez et al., 2007).
Non-ferrous metals are irreplaceable raw materials to ensure low-carbon transformation and clean energy production, which leads to the global demand for non-ferrous metals rising continuously (Chen et al., 2022). With sustainable environmental development deeply rooted in people's minds, many countries and regions have promulgated new environmental protection policies and set strict environmental targets (Vorosmarty et al., 2021). The cleaning and recycling of by-products is the development trend of non-ferrous metallurgical industry.
NCS is a typical solid waste of non-ferrous metallurgy derived from nickel smelting process. Its tonnage is usually equivalent to concentrate or raw ore (Baghalha et al., 2006). Every year, NCS is dumped or stockpiled worldwide, which can potentially lead to undesirable environmental consequences (Piatak et al., 2015). In smelting non-ferrous metals, valuable metals (such as Co, Ni, Fe and Cu) exist in the slag in chemically dissolved form or as mechanically entrained metal or metal sulfide droplets. Therefore, NCS is also considered as an important renewable resource for valuable metals (Yang et al., 2014). Table S1 lists the research on NCS in recent years. NCS has not been effectively recycled yet. Most studies adopt traditional strategies to reduce the residual value of the process, such as optimizing input raw materials and adjusting process structure (Wang et al., 2018). The potential of these strategies to improve resource efficiency is limited (Vogl et al., 2021). Therefore, a new disposal solution is urgently needed to enhance the value of solid waste recycling of non-ferrous metallurgy. For example, developing the technology of recycling secondary resources is a promising choice. Using of NCS to prepare heterogeneous solid catalysts to degrade pollutants can help the non-ferrous metallurgical industry become more sustainable.
More and more studies have shown that catalysts' surface area and mechanical strength stability can be improved by supporting catalysts on the surface of clay minerals (Bo et al., 2021a). Laterite is a weathered shell containing siluminite rocks, which is ochreous red due to iron oxide (Khataee et al., 2015). It is abundant in the earth's crust. It can be found in many continents of the world, including Asia, Africa and Latin America (Sarkar et al., 2006). It is cheap, and its industrial value is low. In Xinjiang, it is only used for firing earthenware or sand filling in buildings, roads and another civil engineering. At present, several studies have investigated laterite as a solid catalyst for the Fenton-like process (Sangami and Manu, 2017), photo-Fenton process (Kamagate et al., 2018) and adsorption (Nguyen et al., 2022). Studies on the use of laterite as a catalyst support for wastewater degradation of in hetero-EF systems are minimal. In this work, laterite was used further to improve the stability of transition metals in NCS to reduce the risk of secondary pollution. Therefore, heterogeneous solid catalysts prepared from laterite and NCS are of great value in water treatment applications.
In this work, a typical methylene blue (MB) dye-containing wastewater was used as a model contaminant, and NLPC was synthesized using NCS and laterite for the processing of MB wastewater by the hetero-EF process. The main objectives are to investigate (i) the optimal preparation conditions for NLPC and the optimal reaction conditions of MB degradation by NLPC; (ii) the stability of NLPC and its ability to remove various pollutants in real water; (iii) the active species and degradation mechanisms in the system; and (iv) the degradation pathways of MB.
Section snippets
Chemicals and materials
NCS was obtained free of charge from Xinjiang Hami Zhongxin Mining Co., Ltd. Laterite was collected from the Aoitak Red Mountain in southwestern Xinjiang. The purity of all used chemical reagents is analytically pure at least, and used as received. Deionized water was used throughout this work. The information on other chemicals and materials was listed in supplementary data Text S1. The chemical structures of four target pollutants (MB, Rhodamine B (RhB), Sunset Yellow (SY) and Reactive black
Characterization of fresh and reused NLPC after 6th runs
The FTIR-spectra of NLPC with wavenumber of 4000-400 cm−1 was conducted. As shown in Fig. 2a, the conspicuous absorption peak at 2923 cm−1 was ascribed to the C–H bond stretching (Wu et al., 2022). The presence of hydroxyl on the catalyst surface led to bending vibration modes at 1115 and 794 cm−1, which belonged to the stretching vibration of the Fe–OH bond (Pelalak et al., 2020). The internal vibrations of the stretching, rocking and bending of the Al–O–Si bridge were responsible for the
Contributions to cleaner production
The waste of resources caused by solid waste puts enormous cost pressure on non-ferrous metallurgical companies. The pollution caused by huge amount of non-ferrous metallurgical solid waste is too large for environmental self-cleaning capability. Converting these solid wastes into building materials is a suitable disposal method. However, the availability of alkali activators and limited technical information are obstacles to their commercialization. The non-ferrous metallurgical solid waste
Conclusions
This work verified the feasibility of preparing an efficient hetero-EF catalyst from NCS to treat textile dyeing wastewater for the first time and provided a facile route for recycling and reusing NCS. The experimental results show that the NLPC has high catalytic activity and can degrade MB efficiently in a shorter time (30 min). The NLPC shows excellent stability and recyclability in different wastewater treatments. The impressive performance was attributed to the redox couples of surface ≡Co
CRediT authorship contribution statement
Lingke Miao: Conceptualization, Methodology, Software, Data curation, Writing – original draft. Junfeng Li: Supervision, Software, Validation, Writing – review & editing. Lijuan Yi: Visualization, Investigation, Writing – review & editing. Wenying Qu: Software, Validation, Writing – review & editing. Chengxiao Ma: Conceptualization, Methodology, Software. Xueting Feng: Data curation, Writing – original draft, Visualization, Investigation. Ying Xu: Visualization, Investigation. Ruining He:
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
Financial support from the National Natural Science Foundation of China (52260002), the Key Science and Technology Project in special issues of Bingtuan (2019DB007), the Special application science and technology project of the 7th division in Xinjiang Bingtuan (2021A03008) and the Special application science and technology project of the 1st division in Xinjiang Bingtuan (2022A007) are gratefully acknowledged.
References (94)
- et al.
Sustainable adsorptive removal of antibiotic residues by chitosan composites: an insight into current developments and future recommendations
Arab. J. Chem.
(2022) - et al.
Advances in carbon nanomaterials as lubricants modifiers
J. Mol. Liq.
(2019) - et al.
A comprehensive study on the electrocatalytic degradation, electrochemical behavior and degradation mechanism of malachite green using electrodeposited nanostructured β-PbO2 electrodes
Water Res.
(2018) - et al.
Effect of waste-based micro cellulose fiber as pore maker on characteristics of fired clay bricks
Construct. Build. Mater.
(2021) - et al.
Influence of dissolved organic matter and activated carbon pore characteristics on organic micropollutant desorption
Water Res.
(2018) - et al.
Decontamination of wastewaters containing synthetic organic dyes by electrochemical methods. An updated review
Appl. Catal. B Environ.
(2015) - et al.
Synergy between cobalt and nickel on NiCo2O4 nanosheets promotes peroxymonosulfate activation for efficient norfloxacin degradation
Appl. Catal. B Environ.
(2022) - et al.
Synchronous photosensitized degradation of methyl orange and methylene blue in water by visible-light irradiation
J. Mol. Liq.
(2021) - et al.
Spillovers and hedging effectiveness of non-ferrous metals and sub-sectoral clean energy stocks in time and frequency domain br
Energy Econ.
(2022) - et al.
OCNTs encapsulating Fe-Co PBA as efficient chainmail-like electrocatalyst for enhanced heterogeneous electro-Fenton reaction
Appl. Catal. B Environ.
(2020)