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Degradation of metaldehyde in water by nanoparticle catalysts and powdered activated carbon

Author:
Li, Zhuojun, Kim, Jong Kyu, Chaudhari, Vrushali, Mayadevi, Suseeladevi, Campos, Luiza C.
Source:
Environmental science and pollution research international 2017 v.24 no.21 pp. 17861-17873
ISSN:
0944-1344
Subject:
activated carbon, adsorption, aqueous solutions, catalysts, drinking water, equations, metaldehyde, models, nanoparticles, oxidation, pesticides, photocatalysis, sorption isotherms, titanium dioxide, ultraviolet radiation, United Kingdom
Abstract:
Metaldehyde, an organic pesticide widely used in the UK, has been detected in drinking water in the UK with a low concentration (<1 μg L⁻¹) which is still above the European and UK standard requirements. This paper investigates the efficiency of four materials: powdered activated carbon (PAC) and carbon-doped titanium dioxide nanocatalyst with different concentrations of carbon (C-1.5, C-40, and C-80) for metaldehyde removal from aqueous solutions by adsorption and oxidation via photocatalysis. PAC was found to be the most effective material which showed almost over 90% removal. Adsorption data were well fitted to the Langmuir isotherm model, giving a q ₘ (maximum/saturation adsorption capacity) value of 32.258 mg g⁻¹ and a K L (Langmuir constant) value of 2.013 L mg⁻¹. In terms of kinetic study, adsorption of metaldehyde by PAC fitted well with a pseudo-second-order equation, giving the adsorption rate constant k ₂ value of 0.023 g mg⁻¹ min⁻¹, implying rapid adsorption. The nanocatalysts were much less effective in oxidising metaldehyde than PAC with the same metaldehyde concentration and 0.2 g L⁻¹ loading concentration of materials under UV light; the maximum removal achieved by carbon-doped titanium dioxide (C-1.5) nanocatalyst was around 15% for a 7.5 ppm metaldehyde solution. Graphical abstract ᅟ
Agid:
5762727