Application of rice husk nanosorbents containing 2,4-dichlorophenoxyacetic acid herbicide to control weeds and reduce leaching from soil

In the present study, the adsorptive behaviour of 2,4-D on to nanosized rice husk was evaluated for its effective usage as herbicide carrier. The rice husk waste which is known to cause serious environmental problem, was reduced to nanosize (n-RH) via a mechanical method and was loaded with 2,4-D to serve the purpose. The resulting nanosized rice husk was characterized before and after 2,4-D sorption by scanning electron microscopy (SEM), Fourier transform infrared analysis (FT-IR), dynamic light scattering (DLS) and zeta potential analyser. A series of sorption experiments were conducted for optimizing the n-RH to 2,4-D loading concentration where the weight ratio of 1:0.10 and contact time of 90 min was optimised. The mechanism of 2,4-D sorption onto the n-RH carrier was evaluated using isotherm and kinetic models and was found to be a monolayer mode of sorption following chemisorption process. The sustained release and reduced leaching property of the DnRH nanoformulation was also checked and was found to exhibit better herbicidal activity against the tested target plant (Brassica sp.) compared with that of the commercial 2,4-D, along with increased sustained release of 2,4-D in both water and soil. Based on the environmental friendliness of the carrier, sustained release and enhanced herbicidal activity, the current nanoformulation could be a boon for effective herbicide usage with reduced consumption rate. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.