Removal of metaldehyde pesticide from aquatic media using modified cellulose obtained from Populus nigra plant, as potential adsorbent

Abstract

Abstract In this study modified cellulose based adsorbent was prepared from Populus nigra plant, and used for elimination of metaldehyde (herbicide) from model waste water. The adsorbent was characterized through analytical technique such as FTIR, SEM, EDX and XRD for structural adsorption related parameters. The results of SEM showed the suitability of the material to be used as adsorbent and FTIR showed successful crosslinking of polyvinyl alcohol into cellulose structure. In order to get maximum reclamation benefits from adsorbent it was subjected to a number of tests evaluating the effect of metaldehyde concentration, sorbent dose, contact time, initial pH of solution and temperature. The maximum removal of 70 % was achieved under conditions of 80 mg/L metaldehyde concentration, 60 min contact time, pH of 8, 0.08 g sorbent dosage, and room temperature (25 °C). The Langmuir isotherm model with correlation coefficients of 0.9855 and maximum adsorption capacity recorded was 8.32 mg/g, while excellent agreement was shown by kinetic data with pseudo second order kinetic model with R 2 = 0.9876. Thermodynamic study indicated enthalpy change (ΔH° = −129 kJ/mol) to be negative, entropy change (ΔS° = 161.7 j/mol) positive, and the Gibbs free energy (ΔG) as negative showing that the process to be exothermic and feasible/spontaneous with an increase of randomness at solid liquid interface. The finding indicated that modified cellulose could be used as an efficient adsorbent for removal of metaldehyde from model waste water. However, further validation with other pollutants will be helpful in checking reproducibility of the present findings.