title: Removal of glyphosate herbicide from water using biopolymer membranes.
abstract: Enormous amounts of pesticides are manufactured and used worldwide, some of which reach soils and aquatic systems. Glyphosate is a non-selective herbicide that is effective against all types of weeds and has been used for many years. It can therefore be found as a contaminant in water, and procedures are required for its removal. This work investigates the use of biopolymeric membranes prepared with chitosan (CS), alginate (AG), and a chitosan/alginate combination (CS/AG) for the adsorption of glyphosate present in water samples. The adsorption of glyphosate by the different membranes was investigated using the pseudo-first order and pseudo-second order kinetic models, as well as the Langmuir and Freundlich isotherm models. The membranes were characterized regarding membrane solubility, swelling, mechanical, chemical and morphological properties. The results of kinetics experiments showed that adsorption equilibrium was reached within 4 h and that the CS membrane presented the best adsorption (10.88 mg of glyphosate/g of membrane), followed by the CS/AG bilayer (8.70 mg of glyphosate/g of membrane). The AG membrane did not show any adsorption capacity for this herbicide. The pseudo-second order model provided good fits to the glyphosate adsorption data on CS and CS/AG membranes, with high correlation coefficient values. Glyphosate adsorption by the membranes could be fitted by the Freundlich isotherm model. There was a high affinity between glyphosate and the CS membrane and moderate affinity in the case of the CS/AG membrane. Physico-chemical characterization of the membranes showed low values of solubility in water, indicating that the membranes are stable and not soluble in water. The SEM and AFM analysis showed evidence of the presence of glyphosate on CS membranes and on chitosan face on CS/AG membranes. The results showed that the glyphosate herbicide can be adsorbed by chitosan membranes and the proposed membrane-based methodology was successfully used to treat a water sample contaminated with glyphosate. Biopolymer membranes therefore potentially offer a versatile method to eliminate agricultural chemicals from water supplies.
authors.affiliation: Departamento de Engenharia Ambiental, Universidade Estadual Paulista - UNESP, Avenida Três de Março, n° 511, CEP 18087-180 Sorocaba, SP, Brazil.
authors.forename: Rafael T A
authors.initials: RT
authors.lastname: Carneiro
authors.affiliation: Departamento de Engenharia de Materiais e Bioprocessos, Faculdade de Engenharia Química, Universidade Estadual de Campinas - UNICAMP, Campinas, SP, Brazil.
authors.forename: Thiago B
authors.initials: TB
authors.lastname: Taketa
authors.affiliation: Departamento de Engenharia de Materiais e Bioprocessos, Faculdade de Engenharia Química, Universidade Estadual de Campinas - UNICAMP, Campinas, SP, Brazil.
authors.forename: Reginaldo J
authors.initials: RJ
authors.lastname: Gomes Neto
authors.affiliation: Departamento de Engenharia Ambiental, Universidade Estadual Paulista - UNESP, Avenida Três de Março, n° 511, CEP 18087-180 Sorocaba, SP, Brazil.
authors.forename: Jhones L
authors.initials: JL
authors.lastname: Oliveira
authors.affiliation: Departamento de Engenharia Ambiental, Universidade Estadual Paulista - UNESP, Avenida Três de Março, n° 511, CEP 18087-180 Sorocaba, SP, Brazil; Departamento de Bioquímica, Instituto de Biologia, Universidade Estadual de Campinas - UNICAMP, Campinas, SP, Brazil.
authors.forename: Estefânia V R
authors.initials: EV
authors.lastname: Campos
authors.affiliation: Departamento de Engenharia de Materiais e Bioprocessos, Faculdade de Engenharia Química, Universidade Estadual de Campinas - UNICAMP, Campinas, SP, Brazil; Departamento de Ciências Exatas e da Terra, Universidade Federal de São Paulo - UNIFESP, Diadema, SP, Brazil.
authors.forename: Mariana A
authors.initials: MA
authors.lastname: de Moraes
authors.affiliation: Departamento de Bioquímica, Instituto de Biologia, Universidade Estadual de Campinas - UNICAMP, Campinas, SP, Brazil.
authors.forename: Camila M G
authors.initials: CM
authors.lastname: da Silva
authors.affiliation: Departamento de Engenharia de Materiais e Bioprocessos, Faculdade de Engenharia Química, Universidade Estadual de Campinas - UNICAMP, Campinas, SP, Brazil.
authors.forename: Marisa M
authors.initials: MM
authors.lastname: Beppu
authors.affiliation: Departamento de Engenharia Ambiental, Universidade Estadual Paulista - UNESP, Avenida Três de Março, n° 511, CEP 18087-180 Sorocaba, SP, Brazil. Electronic address: leonardo@sorocaba.unesp.br.
authors.forename: Leonardo F
authors.initials: LF
authors.lastname: Fraceto
mesh_terms: D000327:Adsorption; D000464:Alginates; D001704:Biopolymers; D048271:Chitosan / Q000737:chemistry; D020723:Glucuronic Acid; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry; D006540:Herbicides / Q000737:chemistry*; D006603:Hexuronic Acids; D007700:Kinetics; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D000097797:Glyphosate
chemical_list: D000464:Alginates; D001704:Biopolymers; D048271:Chitosan; D020723:Glucuronic Acid; D005998:Glycine; D006540:Herbicides; D006603:Hexuronic Acids; D014867:Water; D014874:Water Pollutants, Chemical; D000097797:Glyphosate
keywords: Alginate; Chitosan; Glyphosate; Membranes; Sorption; Water contamination