ABSTRACT
The affinity of some agricultural wastes, e.g. sunflower stalks, cotton stalks and rice straw toward metal ions uptake is investigated. The effect of chemical modifications, e.g. phosphorylation, sulfonation and phosphosulfonation of these wastes on their efficiency as cation exchangers is also studied. Different variables which affect these chemical modifications, e.g. particle size of residues, quantity of pyridine in reaction medium and percent of chlorosulfonic in the used acid for chemical modification are also evaluated. The prepared cation exchanger from phosphosulfonated of alkali treated sunflower stalks [particle size 125micro m] in presence of pyridine [30 ml] and acids mixture [30% cholorosulfonic acid and 70% phosphorus oxychloride] has the highest efficiency towards metal ions uptake. Modified and nonmodified sunflower stalks have higher efficiency toward metal ions uptake than cotton stalks and rice straw. Infrared spectra of sunflower phosphorylated, sulfonated and phosphosulfonated sunflower stalks are also investigated. New bands at 1200 and 965 cm[-1] and at 1400 cm[-1] are characteristic to C-O-P and C-O-S, respectively. The fragments that obtained from mass spectra are characteristic of six carbon sugar mono ester which produces copious hydroxymethyl furfural group