Síntese e caracterização de polímeros à base de ácido metacrílico com potencial para remoção de metais de soluções aquosas

Abstract

New methods for heavy metal removal from aqueous solutions are necessary, particularly for regions where mining and other activities involving such toxicants are typical. The use of membrane-based methods in combination with polymers able to bind ions is a very efficient and easy way to remove toxic and undesirable ions from aqueous solutions. Herein, a new method for ion removal is presented. Solutions of different polymers based on polymethacrylic acid (PMAA) were entrapped in a dialysis sack, so that only the small ions can flow through the membrane and bind to the polymer inside. The polymers were synthesized by free radical polymerization (FRP) and the controlled radical polymerization method, RAFT. FRP and RAFT PMAA homopolymers were tested in removal assays as well as a PMAAM-methacrylamide copolymer. All materials were able to remove Cu(II) and Cd(II) from buffered aqueous solution (pH=5.7). The best result, obtained with PMAA-CRP, reached 94.8 mg of Cu(II) and 134.1mg of Cd(II) bound per gram of polymer. The better result for the FRP polymer may be due to its higher molar mass, although more studies are necessary to confirm that. The copolymer showed the lowest binding due most probably to its reduced negative density on the chain. The binding process is described as due to ion exchange, since the PMAA is considered a condensed polymer at the conditions studied. Because is a passive method, the removal system developed is, in principle, more convenient and energy efficient than other alternatives to be used in real conditions.