Spent caustic wastewater treatment using direct contact membrane distillation with electroblown styrene-acrylonitrile me
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ORIGINAL PAPER
Spent caustic wastewater treatment using direct contact membrane distillation with electroblown styrene‑acrylonitrile membrane A. S. Niknejad1 · S. Bazgir1,2 · M. Ardjmand3 · M. M. A. Shirazi4,5 Received: 20 June 2020 / Revised: 13 September 2020 / Accepted: 30 September 2020 © Islamic Azad University (IAU) 2020
Abstract Spent caustic is classified as a highly polluted and high-risk hazardous wastewater, which severely threatens the environment. In this work, a novel approach was proposed to treat the neutralized spent caustic wastewater using an electroblown nanofibrous styrene-acrylonitrile (SAN) membrane for direct contact membrane distillation (DCMD). The obtained results revealed that the permeate flux of the SAN membrane was lower compared to the commercial polytetrafluoroethylene (PTFE) membrane owing to the thicker structure. The higher surface hydrophobicity of the SAN membrane limited the intrusion of the feed water into the membrane pores. Therefore, extremely pure permeate water was produced. Stable permeate flux (12.03 kg/m2 h) and rejection factor (99.98%) were achieved for the hot-pressed SAN membrane during 96 h continuous DCMD test. Water contact angle of ˃ 90° was remained for both PTFE and SAN membranes, showing that DCMD performance was considerable even after 96 h operation. Besides, the chemical oxygen demand and sulfide removal factor for the fabricated membrane were 99.2 and 99.99%, respectively. Overall, the neutralization followed by the DCMD process can be considered as a proper alternative for treating the spent caustic wastewater. Keywords Direct contact membrane distillation (DCMD) · Styrene-acrylonitrile (SAN) · COD removal · Electroblowing · Neutralized spent caustic Abbreviations A Effective membrane area AOPs Advanced oxidation BOD Biological oxygen demand C Concentration COD Chemical oxygen demand CTAB Cetyltrimethylammonium bromide DCMD Direct contact membrane distillation
Editorial responsibility: Samareh Mirkia. * S. Bazgir [email protected] 1
Nanopolymer Research Laboratory (NPRL), Science and Research Branch, Islamic Azad University, Tehran, Iran
2
Department of Polymer Engineering, Petroleum and Chemical Engineering Faculty, Science and Research Branch, Islamic Azad University, Tehran, Iran
3
Department of Chemical Engineering, South Tehran Branch, Islamic Azad University, Tehran, Iran
4
Chemical Engineering Department, Faculty of Engineering, University of Kashan, Kashan, Iran
5
Membrane Industry Development Institute, Tehran, Iran
DMF Dimethylformamide EC Electrical conductivity FD Permeate flux decline IPA Isopropyl alcohol J Permeate flux LEP Liquid entry pressure of water LPG Liquefied petroleum gas m Permeate weight MD Membrane distillation NSC Neutralized spent caustic PP Polypropylene PTFE Polytetrafluoroethylene r Mean pore size R (%) Dilute rejection factor S-2 Neat nanofibrous membrane SAN Styrene-acrylonitrile SC Spent caustic SEM Scanning electron microscope SP-2 Hot-pressed nanofibrous membrane
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