Use of Biopolymeric Membranes for Adsorption of Paraquat Herbicide from Water Daniela Sgarbi Cocenza & Mariana A. de Moraes & Marisa M. Beppu & Leonardo Fernandes Fraceto Received: 30 September 2011 / Accepted: 18 January 2012 / Published online: 4 February 2012 # Springer Science+Business Media B.V. 2012 Abstract The use of membranes prepared with algi- nate and chitosan to adsorb paraquat aqueous solution was evaluated as a potential alternative technique for remediation of contaminated water. Production of bi- layer membranes was based on the electrostatic inter- action 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 mem- branes in environmental applications was evaluated using water collected from the Sorocabinha River in São 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. Keywords Herbicides . Water contamination . Adsorption . Membranes . Natural polymers 1 Introduction The modernization of agriculture that began in the 1960s has increased productivity, although many of the chemicals used nowadays can be harmful to humans and the environment (Recena et al. 2006). Pesticides and herbicides have become ubiquitous in modern ag- riculture (Lezcano et al. 2002), and Brazil is the third largest consumer of these chemicals. Contamination of water by agrochemicals is a widespread problem, af- fecting supplies of potable water and requiring expen- sive water treatment (Foster et al. 1991). Paraquat, 1-1′-dimethyl-4,4′-bipiridyl (Fig. 1), a biquaternary ammonium compound, is a nonselective contact herbicide that is normally synthesized as dichloride salt. It was introduced in the 1960s, and today (together with glyphosate), it is one of the most common herbicides worldwide. It is used in over 100 countries in plantations of tobacco, rice, coffee, sugar cane, beans, apples, soy, grapes, and other crops (Recena et al. 2006; USEPA 2010). It is also employed to control weeds and grasses in fields prior to pasture renovation and as a defoliant in cotton plantations (Núnez et al. 2002; Prade et al. 1998). Water Air Soil Pollut (2012) 223:3093–3104 DOI 10.1007/s11270-012-1092-x D. S. Cocenza : L. F. Fraceto (*) Department of Environmental Engineering, São Paulo State University (UNESP), Avenida Três de Março, nº 511, CEP 18087-180 Sorocaba, São Paulo, Brazil e-mail: leonardo@sorocaba.unesp.br M. A. de Moraes : M. M. Beppu School of Chemical Engineering, University of Campinas (UNICAMP), Avenida Albert Einstein, 500, CEP 13083-852 Campinas, São Paulo, Brazil