Removal of chemical oxygen demand from thin-film transistor liquid-crystal display wastewater using chitosan-coated bentonite: Isotherm, kinetics and optimization studies

doi:10.1016/j.jclepro.2017.12.052

CNU IR > College of Sustainable Environment and Recreation > Dept. of Environmental Resources Management > Periodical Articles > Item 310902800/32186

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Title:	Removal of chemical oxygen demand from thin-film transistor liquid-crystal display wastewater using chitosan-coated bentonite: Isotherm, kinetics and optimization studies
Authors:	Ligaray, Mayzonee Futalan, Cybelle M. de Luna, Mark Daniel Wan, Meng-Wei
Contributors:	Ulsan Natl Inst Sci & Technol, Sch Urban & Environm Engn Natl Res Ctr Disaster Free & Safe Ocean City Univ Philippines, Dept Chem Engn Chia Nan Univ Pharm & Sci, Dept Environm Resources Management
Keywords:	Central composite design Chitosan-coated bentonite Chemical oxygen demand Optimization TFT-LCD wastewater Thermodynamics
Date:	2018-02-20
Issue Date:	2019-11-15 15:44:13 (UTC+8)
Publisher:	ELSEVIER SCI LTD
Abstract:	In this study, real thin-film transistor liquid-crystal display wastewater with an initial chemical oxygen demand (COD) concentration of 1348.00 ppm was treated using chitosan-coated bentonite (CCB). Characterization analysis of the CCB adsorbent was performed using Brunauer-Emmett-Teller surface area analysis, scanning electron microscopy, and Fourier-transform infrared spectrometer. The effect of parameters such as contact time, CCB dosage, pH and temperature on the COD removal was examined. Results show that increasing the contact time and CCB dosage increases COD removal efficiency while no considerable change was observed in removal efficiency with varying temperature and pH. Adsorption experiments showed that the removal of COD using CCB best fits the Langmuir isotherm (R-2 >= 0.9821) while kinetic data was best described by the pseudo-second order equation (R-2 >= 0.9980), which implies that chemisorption is the rate-determining step. Thermodynamic studies revealed that adsorption of COD onto CCB was spontaneous, exothermic (Delta H degrees = 5.95 kJ/mol) and decreased randomness in the system (Delta S degrees = -0.88 J/mol.K). Optimization studies using response surface methodology with central composite design was performed to determine the operating parameters that would yield the maximum COD removal. It was determined that the optimum conditions of 2032 h, 0.8 g CCB, pH 4.0, and 30 degrees C would yield a maximum removal of COD of 73.34%. (C) 2017 Elsevier Ltd. All rights reserved.
???metadata.dc.relation.uri???:	http://dx.doi.org/10.1016/j.jclepro.2017.12.052
Relation:	Journal of Cleaner Production, v.175, pp.145-154
Appears in Collections:	[Dept. of Environmental Resources Management] Periodical Articles

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