Adsorption and photocatalysis kinetics of herbicide onto titanium oxide and powdered activated carbon

Abstract

The adsorption and photocatalysis kinetics of metsulfuron-methyl (MM) onto titanium oxide (TiO 2) and powdered activated carbon (PAC) were studied at varying adsorbent amount and MM concentration. The overall mass transfer in adsorption was estimated from concentration decay curves obtained in the batch adsorber. The maximum adsorption capacity decreased with increasing adsorbent amount in TiO 2 adsorption. The adsorption isotherms of MM could be plotted using the Langmuir isotherm model with a reasonable degree of accuracy having higher 2 r values rather than Freundlich isotherm model. Linear driving force approximation (LDFA) kinetic equation with Langmuir adsorption isotherm model was successfully applied to predict the adsorption kinetics data in various concentrations of MM in photobatch reactor. The estimated mass transfer coefficient was used to be 3.0×10-5 , 5.5×10-5 , 9.1×10-5 m/s in PAC adsorption and 2.0×10-5 , 1.1×10-5 , 9.0×10-6 m/s in TiO 2 adsorption for a different MM concentration of 20, 50 and 70 mg/L, respectively. Photocatalysis kinetics was same with TiO 2 of 0.2 g/L regardless of TiO 2 amounts and the MM degradation kinetics was enhanced by TiO 2 catalysis rather than only UV-light degradation. Among the photocatalysis kinetics model with first-order, second-order and Langmuir-Hinshelwood (L-H) model, a second-order kinetic model was found to well present the experimental data of MM by TiO 2 catalyst for the range of various TiO 2 amounts and MM concentration studied.

Determination of the photocatalytic activity of TiO2 with high adsorption capacity

“…Photocatalysis is a surface phenomenon, a critical step in intervening in the effectiveness of photodegradation is adsorption of pollutants on the photocatalyst surface. Many studies measured the adsorption and the kinetics of photodegradation M. Janus (&) Á E. Kusiak-Nejman Á A. W. Morawski West Pomeranian University of Technology, Institute of Chemical and Environmental Engineering, Pułaskiego 10, 70-322 Szczecin, Poland e-mail: mjanus@zut.edu.pl of different compounds on TiO 2 photocatalyst, such as potassium hydrogenphtalate [1], metsulfuron-methyl [2], phenol and Methylene Blue [3,4], 2-chlorophenol [5], thionine, Eosin-Y, Rhodamine B [6], Reactive Black [4,7], volatile organic compounds (VOCs) [8].…”

Adsorption and visible light-driven photocatalytic degradation of Rhodamine B in aqueous solutions by Ag@AgBr/SBA-15

“…As shown in Fig.S4 (b), when the 50Ag@AgBr/SBA-15 dosage increased from 0.1 to 0.4 g/L, the rate constant increased almost linearly, from 1.62E -4 min -1 to 13.8E -4 min -1 , which can be ascribed to the increased numbers of photons adsorbed, active sites and RhB molecules adsorbed. Kim [50] has investigated the photocatalysis kinetics of herbicide onto TiO 2 and powdered activated carbon, and found that a second-order kinetic model fitted the data well. His result is accordance with ours.…”

Comparison of azo dye AR88 degradation efficiency using various oxidant systems

“…Hydroxyl radical is an extraordinarily reactive species which can attack most parts of the organic molecules at a rapid rate [8]. Many researchers have used AOPs for photocatalysis, sonolysis, Fenton and modified Fenton reactions, ozonation, and UV/H 2 O 2 for the degradation of azo dyes [9][10][11][12][13]. Matilainen and Sillanpää [14] provided a thorough review of published oxidation and AOPs studies that have been conducted on both industrial and synthetic wastewaters.…”