Chemically modified sunflower stalks as adsorbents for color removal from textile wastewater

Abstract

Quaternary ammonium groups were chemically grafted onto sunflower stalks in order to improve their adsorption performance to anionic species in wastewater. The chemically modified sunflower stalks were evaluated as adsorbents for two basic dyes (Methylene Blue and Basic Red 9) and two direct dyes (Congo Red and Direct Blue 71) in aqueous solutions by using equilibrium isotherms and kinetic adsorption. Before the modification, sunflower stalks exhibited relatively low adsorption to the direct dyes but very high adsorption to the basic dyes. The modified sunflower stalks showed increased adsorption to the anionic dyes, but slightly reduced adsorption to the cationic dyes, due to the existence of quaternary ammonium ions on the surface of the residues. The maximum adsorption capacities of two direct dyes on the modified sunflower stalks are 191.0 and 216.0 mg g for Congo Red and Direct Blue 71 at 50°C, respectively, which were at least four times higher than that of the unmodified residues. The adsorption rates of two direct dyestuffs are much higher on the modified residues than on the unmodified ones. Within 30 min, about 80% of direct dyes were removed from the solutions by the residues.

Application of low-cost adsorbents for dye removal – A review

“…The coulombic forces between dye species and negatively charged cellulose in water are the major interactions which affect the adsorption of dyes on the materials. Shi et al (1999) improved the adsorption capacity of sunflower stalks by chemically grafting quaternary ammonium groups on them. The modified sunflower stalks exhibited increased adsorption capacity for anionic dyes due to the existence of quaternary ammonium ions on the surface of the residues.…”

Characteristics and adsorption capacities of low-cost sorbents for wastewater treatment: A review

“…The application of soy meal hull (SMH) for the removal of direct and acid dyes from aqueous solutions was investigated by Arami et al [64]. Shi et al [83] improved the adsorption capacity of sunflower stalks by chemically grafting A C C E P T E D M A N U S C R I P T…”

Radiation-induced grafting of cellulose for adsorption of hazardous water pollutants: A review

“…Shi et al (1999) improved the adsorption capacity of sunflower stalks by chemically grafting quaternary ammonium groups on them. The maximum adsorption capacities on modified sunflower stalks were found to be 191.0 and 216.0 mg g À 1 for Congo red and direct blue dyes.…”