|Title:||Caustic recovery from green liquor of agro-based paper mills using electrolysis|
Sujit Kumar K.
|Published in:||Separation and Purification Technology|
|Abstract:||In the chemical recovery section of pulp and paper mills, the cooking liquor (white liquor, mainly caustic, NaOH) is regenerated by addition of fresh lime (CaO) in green liquor solution (rich in sodium carbonate, Na2CO3), where calcium carbonate (CaCO3) get precipitated leaving NaOH in solution (causticizing process). Subsequently, CaO is regenerated from precipitated CaCO3 following washing/drying/calcination steps which are highly energy intensive and environmentally unsafe. The current investigation reports conversion of green liquor to caustic solution using electrolysis through a cation exchange membrane (CEM) placed between two electrodes. Process parameters e.g. current density, feed concentration, flow velocity, flow promoter, electrode-membrane spacing, role of gravity flow were systematically investigated to find optimum values. Process optimization was performed with Na2CO3 (highest constituent of green liquor) solution to avoid complexity, which were then extended to complex salt mixtures of green liquors (synthetic/ industrial sample). Performance analysis of any batch was carried out based on moles of NaOH produced and associated current efficiency and energy consumption observed. With 600 A·m−2 current density, 1.93 mol·L−1 of NaOH could be produced in 6 h of electrolysis through a cell of 66 × 10−4 m2 of CEM, where flow rates of both feed and catholyte streams were counter current and fixed at 3.472 × 10−3 m·s−1. © 2021 Elsevier B.V.|
|Citation:||Separation and Purification Technology, 262|
|Author Scopus IDs:||57203902684|
|Author Affiliations:||Mandal, P., Department of Polymer and Process Engineering, Indian Institute of Technology Roorkee, India|
Bhuvanesh, E., Department of Polymer and Process Engineering, Indian Institute of Technology Roorkee, India
Goel, P., Department of Polymer and Process Engineering, Indian Institute of Technology Roorkee, India
Sujit Kumar, K., Department of Polymer and Process Engineering, Indian Institute of Technology Roorkee, India
Chattopadhyay, S., Department of Polymer and Process Engineering, Indian Institute of Technology Roorkee, India
|Funding Details:||Financial support to execute the synthesis and the experimental work is gratefully acknowledged to Indian Institute of Technology Roorkee (No. IITR/SRIC/244/FIG-Sch-A), India, Imprint project (IMP/2018/000282 dated 08.01.2019) from Science and Engineering Research Board (SERB), Department of Science and Technology (DST), India and Uchchatar Avishkar Yojana (UAY) project (ICSR/UAY/2016/SN dated 04.01.2017) from Ministry of Human Resource Development (MHRD), Department of Science and Technology (DST), M/s Permionics Membrane. Pvt. Ltd. India. An Indian patent ?Electro-membrane processes to recover caustic from green liquor of agro-based paper mills? filed with allotted application no. 202011047687 dated 02th November, 2020. We are extremely thankful to Prof. Vivek Kumar, Center for Rural Development and Technology, Indian Institute of Technology, Delhi, Prof. S. P. Singh, Department of Paper Technology, Indian Institute of Technology Roorkee and Prof. S. Sridhar Sr. Principal Scientist, Center for Scientific and Industrial Research- Indian Institute of Chemical Technology, Hyderabad for their innovative ideas, expert opinions and sparing time for technical discussion during execution of the research work. ICSR/UAY/2016/SN dated 04.01.2017; Department of Science and Technology, Ministry of Science and Technology, India, डीएसटी; Science and Engineering Research Board, SERB; Indian Institute of Technology Roorkee, IITR: 08.01.2019, IITR/SRIC/244/FIG-Sch-A, IMP/2018/000282; Ministry of Human Resource Development, MHRD: 202011047687; Indian Institute of Technology Delhi, IIITD|
|Corresponding Author:||Chattopadhyay, S.; Department of Polymer and Process Engineering, India; email: email@example.com|
|Appears in Collections:||Journal Publications [PE]|
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