Novel sorbents based on silica coated with polyethylenimine and crosslinked with poly(carboxylic acid): Preparation and characterization

Novel sorbents based on silica coated with polyethylenimine (SilPEI) and crosslinked with poly(carboxylic acid) were prepared and characterized. These sorbents are to be used for heavy metal decontamination of aqueous solutions and have to be prepared in easy and ecological ways. A part of the carboxylic moieties [from ethylenediaminetetraacetic acid (EDTA) or citric acid] reacts with some of the amine groups of polyethylenimine, initially coated onto the silica, whereas the other part remains free for further metal complexation. By changing various parameters (temperature, pH, presence or absence of an amide-forming agent), the conditions to prepare the best sorbent- that is, the sorbent exhibiting both a high capacity for metal complexation and good stability in an acidic medium (conditions for metal desorption or stripping)-were defined. The sorbent was prepared by a reaction of I g of SilPEI and 1 g of EDTA in water at 0degreesC, PH 6, during 10 h, using 0.5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride as a coupling agent. (C) 2003 Wiley Periodicals, Inc.