title: Kinetics, thermodynamics and mechanistic studies of carbofuran removal using biochars from tea waste and rice husks.
abstract: This study reports the thermodynamic application and non-linear kinetic models in order to postulate the mechanisms and compare the carbofuran adsorption behavior onto rice husk and tea waste derived biochars. Locally available rice husk and infused tea waste biochars were produced at 700 °C. Biochars were characterized by using proximate, ultimate and surface characterization methods. Batch experiments were conducted at 25, 35, and 45 °C for a series of carbofuran solutions ranging from 5 to 100 mg L(-1) with a biochar dose of 1 g L(-1) at pH 5.0 with acetate buffer. Molar O/C ratios indicated that rice husk biochar (RHBC700) is more hydrophilic than tea waste biochar (TWBC700). Negative ΔG (Gibbs free energy change) values indicated the feasibility of carbofuran adsorption on biochar. Increasing ΔG values with the rise in temperature indicated high favorability at higher temperatures for both RHBC and TWBC. Enthalpy values suggested the involvement of physisorption type interactions. Kinetic data modeling exhibited contribution of both physisorption, via pore diffusion, π*-π electron donor-acceptor interaction, H-bonding, and van der Waals dispersion forces and chemisorption via chemical bonding with phenolic, and amine groups. Equilibrium adsorption capacities of RHBC and TWBC determined by pseudo second order kinetic model were 25.2 and 10.2 mg g(-1), respectively.
authors.affiliation: Chemical and Environmental Systems Modeling Research Group, National Institute of Fundamental Studies, Kandy, Sri Lanka. Electronic address: meththikavithanage@gmail.com.
authors.forename: Meththika
authors.initials: M
authors.lastname: Vithanage
authors.affiliation: Chemical and Environmental Systems Modeling Research Group, National Institute of Fundamental Studies, Kandy, Sri Lanka.
authors.forename: S S
authors.initials: SS
authors.lastname: Mayakaduwa
authors.affiliation: Chemical and Environmental Systems Modeling Research Group, National Institute of Fundamental Studies, Kandy, Sri Lanka.
authors.forename: Indika
authors.initials: I
authors.lastname: Herath
authors.affiliation: Korea Biochar Research Center & Department of Biological Environment, Kangwon National University, Chuncheon 200-701, Republic of Korea.
authors.forename: Yong Sik
authors.initials: YS
authors.lastname: Ok
authors.affiliation: School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Dinesh
authors.initials: D
authors.lastname: Mohan
mesh_terms: D000327:Adsorption; D028241:Camellia sinensis / Q000737:chemistry*; D002235:Carbofuran / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D007700:Kinetics; D012275:Oryza / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D014866:Waste Products / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D014866:Waste Products; D014874:Water Pollutants, Chemical; C540010:biochar; D002606:Charcoal; D002235:Carbofuran
keywords: Chemisorption; Enthalpy; Entropy; Pesticide; Physisorption