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Sarinho L, Carvalho P, Patoilo D, Ribeiro JP, Baião da Cruz J, Gaião J, Marques C, Nunes MI. Treatment of salt from hides curing stage by electrocoagulation for use in the pickling stage of the tanning industry. ENVIRONMENTAL RESEARCH 2023; 237:117095. [PMID: 37683784 DOI: 10.1016/j.envres.2023.117095] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 09/04/2023] [Accepted: 09/05/2023] [Indexed: 09/10/2023]
Abstract
The raw materials for the tanning industry, namely hides and skins, are preserved (curing stage) and carried with common salt, i.e., sodium chloride (NaCl). Proceeding to conversion into leather, pickling is a key stage of the tannery process, which entails high demand of water and salt. In this work, the salt-derived brine (SdB) generated from the curing of hides was treated by iron-driven electrocoagulation (EC), aiming at its later application in the pickling stage of the tanning industry, promoting a transition to zero waste emission policy. Focusing on reducing the brine's total organic carbon (TOC), central composite rotational design and response surface methodology were adopted to study the effect of electrolysis time (6.2-14.2 min) and current density (74-431 A·m-2) on the treatment of the SdB (≅ 7.5 % wt. NaCl). The quality of the treated brines was then assessed in pickling trials and compared with virgin brine. 68-83 % removal of TOC from the SdB were achieved under electrolysis time ranging 6.2-14.2 min and current density ranging 126-252 A·m-2. Under these operating ranges the quality of the wet-blue leathers was guaranteed. Lowest power consumption (0.44 kWh·m-3) was achieved under electrolysis time of 6 min and current density of 126 A·m-2, yielding 68 % removal of TOC. Moreover, the shrinkage temperature of the hides was improved with treated brine (103.5 °C-110.5 °C) compared to virgin brine (103.0 °C). The present study provides strong evidence that contaminated salt from the curing stage can be valorised within the tanning industry through electrocoagulation treatment and then used in another production stage, instead of being landfilled.
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Affiliation(s)
- Luana Sarinho
- CESAM - Centre for Environmental and Marine Studies, Department of Environment and Planning, University of Aveiro, 3810-193, Aveiro, Portugal; CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193, Aveiro, Portugal; DAO - Department of Environment and Planning, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Pedro Carvalho
- CICECO - Aveiro Institute of Materials, Department of Chemistry, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Diana Patoilo
- DAO - Department of Environment and Planning, University of Aveiro, 3810-193, Aveiro, Portugal
| | - João Peres Ribeiro
- CESAM - Centre for Environmental and Marine Studies, Department of Environment and Planning, University of Aveiro, 3810-193, Aveiro, Portugal; DAO - Department of Environment and Planning, University of Aveiro, 3810-193, Aveiro, Portugal
| | - José Baião da Cruz
- CTIC - Centro Tecnológico das Indústrias do Couro, Apartado 158, São Pedro, 2384-909, Alcanena, Portugal
| | - Joaquim Gaião
- CTIC - Centro Tecnológico das Indústrias do Couro, Apartado 158, São Pedro, 2384-909, Alcanena, Portugal
| | - Catarina Marques
- CESAM - Centre for Environmental and Marine Studies, Department of Environment and Planning, University of Aveiro, 3810-193, Aveiro, Portugal; DAO - Department of Environment and Planning, University of Aveiro, 3810-193, Aveiro, Portugal
| | - Maria Isabel Nunes
- CESAM - Centre for Environmental and Marine Studies, Department of Environment and Planning, University of Aveiro, 3810-193, Aveiro, Portugal; DAO - Department of Environment and Planning, University of Aveiro, 3810-193, Aveiro, Portugal.
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Wang Z, An X, Wang P, Du X, Hao X, Hao X, Ma X. Removal of high concentration of chloride ions by electrocoagulation using aluminium electrode. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:50567-50581. [PMID: 36795207 DOI: 10.1007/s11356-023-25792-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Accepted: 02/03/2023] [Indexed: 02/17/2023]
Abstract
Wastewater containing a high concentration of chloride ions (Cl- ions) generated in industrial production will corrode equipment and pipelines and cause environmental problems. At present, systematic research on Cl- removal by electrocoagulation is scarce. To study the Cl- removal mechanism, process parameters (current density and plate spacing), and the influence of coexisting ions on the removal of Cl- in electrocoagulation, we use aluminum (Al) as the sacrificial anode, combined with physical characterization and density functional theory (DFT) to study Cl- removal by electrocoagulation. The result showed that the use of electrocoagulation technology to remove Cl- can reduce the concentration of Cl- in an aqueous solution below 250 ppm, meeting the Cl- emission standard. The mechanism of Cl- removal is mainly co-precipitation and electrostatic adsorption by forming chlorine-containing metal hydroxyl complexes. The current density and plate spacing affect the Cl- removal effect and operation cost. As a coexisting cation, magnesium ion (Mg2+) promotes the removal of Cl-, while calcium ion (Ca2+) inhibits it. Fluoride ion (F-), sulfate (SO42-), and nitrate (NO3-) as coexisting anions affect the removal of Cl- ions through competitive reaction. This work provides a theoretical basis for the industrialization of Cl- removal by electrocoagulation.
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Affiliation(s)
- Zirui Wang
- Department of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, 030024, China
| | - Xiaowei An
- Department of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, 030024, China
| | - Peifen Wang
- Department of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, 030024, China
| | - Xiao Du
- Department of Chemical Engineering, Taiyuan University of Technology, Taiyuan, 030024, China
| | - Xiaogang Hao
- Department of Chemical Engineering, Taiyuan University of Technology, Taiyuan, 030024, China
| | - Xiaoqiong Hao
- Department of Petroleum and Chemical Engineering, Jiangsu Key Lab Advanced Catalytic Materials and Technology, Changzhou University, Changzhou, 213164, China
| | - Xuli Ma
- Department of Environmental Science and Engineering, Taiyuan University of Technology, Taiyuan, 030024, China.
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Qi S, Grossman AD, Ronen A, Bernstein R. Low-biofouling anaerobic electro-conductive membrane bioreactor: The role of pH changes in bacterial inactivation and biofouling mitigation. J Memb Sci 2022. [DOI: 10.1016/j.memsci.2022.120960] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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