Removal of microcystin-LR from water by polymers based on N-vinylformamide structure

Abstract

The work describes the results of experiments aimed at developing a new method using synthetic polymers to remove microcystins from water. Three hydrophilic polymers were synthesized based on a N-vinylformamide (NVF) structure cross-linked with divinylbenzene (DVB): p(NVF-co-DVB), p(VAm-co-DVB), and, after reaction with glutaraldehyde (GA), p(VAm-co-DVB)GA. The physicochemical characteristics of the resulting polymers were determined by measuring element content, specific surface area, total pore volume and the positive zeta potential of the surface. All the tested polymers showed more than 99.5% adsorption of microcystin-LR (MC-LR) in aqueous solution during 15 min of incubation. Desorption of MC-LR from the complexes formed with polymers depended on the type of polymer and the solvent and ranged from 0 to 22.8%. The yield from application of a field of acoustic waves to methanol solution freed from the MC-LR–p(NVF-co-DVB) complex was 25.1% MC-LR. These results suggest the occurrence of strong bonds in the complex, bonds formed through physical interaction between the negative resultant charge of the MC-LR molecule and the positive charge of the polymer surface. The MC-LR adsorption capacity of the polymer depended on the dose of the toxin: 99.5% at a MC-LR: polymer ratio of 1:1,000 (w/w) and 98.6% at a 1:100 ratio.