Use of Biopolymeric Membranes for Adsorption of Paraquat Herbicide from Water

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The use of membranes prepared with alginate and chitosan to adsorb paraquat aqueous solution was evaluated as a potential alternative technique for remediation of contaminated water. Production of bilayer membranes was based on the electrostatic interaction between alginate (a polyanion) and chitosan (a polycation). Herbicide adsorption experiments were performed using three different membranes, consisting of pure alginate, pure chitosan, and a chitosan/alginate bilayer. Adsorption was characterized using the Langmuir and Freundlich isotherm models, as well as by applying pseudo-first order and pseudo-second order kinetic models. The potential use of the membranes in environmental applications was evaluated using water collected from the Sorocabinha River in So Paulo State, Brazil. The results indicated that interactions between the membranes and the herbicide were strongly related to the type of biopolymer and the physical-chemical characteristics of the herbicide.223630933104Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação para o Desenvolvimento da UNESP (FUNDUNESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Chitosan and alginate biopolymer membranes for remediation of contaminated water with herbicides

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)This study investigated the adsorption behavior of the herbicides diquat, difenzoquat and clomazone on biopolymer membranes prepared with alginate and chitosan (pristine and multi-layer model) for contaminated water remediation applications. Herbicides, at concentrations ranging from 5 mu M to 200 mu M, were adsorbed in either pure alginate, pure chitosan or a bilayer membrane composed of chitosan/alginate. No adsorption of clomazone was observed on any of the membranes, probably due to lack of electrostatic interactions between the herbicide and the membranes. Diquat and difenzoquat were only adsorbed on the alginate and chitosan/alginate membranes, indicating that this adsorption takes place in the alginate layer. At a concentration of 50 mu M, diquat adsorption reaches ca. 95% after 120 min on both the alginate and chitosan/alginate membranes. The adsorption of difenzoquat, at the same concentration, reaches ca. 62% after 120 min on pure alginate membranes and ca. 12% on chitosan/ alginate bilayer membranes. The adsorption isotherms for diquat and difenzoquat were further evaluated using the isotherm models proposed by Langmuir and by Freundlich, where the latter represented the best-fit model. Results indicate that adsorption occurs via coulombic interactions between the herbicides and alginate and is strongly related to the electrostatic charge, partition coefficients and dissociation constants of the herbicides. Biopolymer based membranes present novel systems for the removal of herbicides from contaminated water sources and hold great promise in the field of environmental science and engineering. (C) 2013 Elsevier Ltd. All rights reserved.131222227Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação para o Desenvolvimento da UNESP (FUNDUNESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Paraquat-loaded alginate/chitosan nanoparticles: Preparation, characterization and soil sorption studies

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Agrochemicals are amongst the contaminants most widely encountered in surface and subterranean hydrological systems. They comprise a variety of molecules, with properties that confer differing degrees of persistence and mobility in the environment, as well as different toxic, carcinogenic, mutagenic and teratogenic potentials, which can affect non-target organisms including man. In this work, alginate/chitosan nanoparticles were prepared as a carrier system for the herbicide paraquat. The preparation and physicochemical characterization of the nanoparticles was followed by evaluation of zeta potential, pH, size and polydispersion. The techniques employed included transmission electron microscopy, differential scanning calorimetry and Fourier transform infrared spectroscopy. The formulation presented a size distribution of 635 +/- 12 nm, polydispersion of 0.518, zeta potential of -22.8 +/- 2.3 mV and association efficiency of 74.2%. There were significant differences between the release profiles of free paraquat and the herbicide associated with the alginate/chitosan nanoparticles. Tests showed that soil sorption of paraquat, either free or associated with the nanoparticles. was dependent on the quantity of organic matter present. The results presented in this work show that association of paraquat with alginate/chitosan nanoparticles alters the release profile of the herbicide, as well as its interaction with the soil, indicating that this system could be an effective means of reducing negative impacts caused by paraquat. (C) 2011 Elsevier B.V. All rights reserved.19041699366374Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação para o Desenvolvimento da UNESP (FUNDUNESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq