Preparation of new polymeric sorbents for removal of organic wastes

The environmental protection becomes a difficult task while many industries produce wastes that cause serious pollution. In the textile industry, large quantities of aqueous wastes and dye effluents are discharged from the dyeing process with strong persistent color. Most of these dye wastes are toxic and may be carcinogenic, and this poses a serious hazard to aquatic living organisms. As a result, the removal of dyestuffs from effluents becomes important, and many governments have established environmental restrictions with regard to the quality of colored effluents and have forced dye-using industries to decolorize their effluents before discharging. In this study, poly(styrene) based quaternary ammonium carboxlate based resins were prepared to remove acidic and basic dyes from aqueous solutions. In this study, a beaded polymer with quaternary amine functions were prepared in two steps, starting from poly(vinyl benzyl chloride-co-ethylene glycol dimethacrylate) based beads, according to the synthetic protocol; modification of ethyl piperazine and imidazole quaternization of chloroacetic acid, respectively. Poly (vinyl imidazole) grafted onto PVBC resin was prepared by using reverse ATRP technique. The grafting degree of the resin was found about 59% after 72 h. Therefore, core-shell type polymeric sorbent was obtained for removal of acidic dyes from water. Linear polymers grafted onto crosslinked polymer resin particles offer numerous potential applications due to the combination of the non-solubility resin and the flexibility of the graft polymer side-chains as the functional group carrier. The flexible side-chains can provide pseudo-homogeneous reaction conditions and better accessibility of the involved functional groups. The atom transfer radical polymerization (ATRP) technique, for instance, provides chain growing mostly on the solid surface if the initiator function is covalently bound to the surface. Dye sorption and desorption experiments were investigated under various operating conditions. Phenols are generally considered as one of the important organic pollutants discharged into the environment causing unpleasant taste and odor of drinking water. Three mechanisms of phenolic compounds adsorption is postulated namely, π-π dispersion interaction, electron-donor acceptor complex formation and hydrogen bond formation. This methodology was used to prepare new polymeric sorbents for phenol removal. Ethyl piperazine and imidazole modified PVBC beads were quaternized with chloroacetamide. The resulting polymer resins, which had a total nitrogen content of about 4.50 mmol/g, was effective in extracting phenol from aqueous solutions. The phenol sorption capacity was around 0.208 g phenol/g resin in non-buffered conditions. Another sorbent was prepared starting from the reaction of PVBC beads with N,N-dimethylethylenediamine. The resulting beads were quaternized with chloroacetamide to obtain quaternary amide containing sorbent. The phenol sorption capacity was around 0.220 g phenol / g resin in non-buffered conditions. The adsorption conditions (initial phenol concentration and pH) were varied to evaluate mechanism of adsorption of phenol on the prepared resins. These resins are also able to remove phenol completely even from highly diluted aqueous phenol solutions. Atrazine is another important organic pollutant. Many techniques have been researched and developed for removal of hazardous agricultural chemicals that migrate to the environment, including photocatalytic degradation, biological repair, sorption, etc. Sorption is recognized as one of the most applicable technologies for contamination removal. Regarding that adsorption on solid substrates, such as activated carbon, biosorbents or clay, are widely used method for removing atrazine from waters. In this study, poly (2-acrylamido-2-methylpropane sulfonic acid) (AMPS) grafted onto crosslinked PVBC resin by ATRP polymerization technique for removal of atrazine from water. Atrazine is a basic compound. Therefore, acidic type of sorbents can be used to remove atrazine. Atrazine sorption capacities of the polymeric sorbent was determined depending on different waste concentration and pH. Trace contaminants of atrazine removal experiments were also investigated and different kinetic models were applied. Prepared sorbents were characterized by using analytical and spectroscopic techniques to determine functional groups. Morphological characterization of core-shell type resins were studied with scanning electron microscope (SEM).