Comparison of gel anion exchangers of various basicity in direct dye removal from aqueous solutions and wastewaters

The goal of this paper is to study the effectiveness of the weakly (Amberlite IRA 67) and strongly (Amberlite IRA 458) basic gel anion exchangers of polyacrylic matrix in Direct Red 75 (DR75) removal from aqueous solutions and wastewaters. The monolayer sorption capacities Q0 determined from the Langmuir isotherm model for the weakly and strongly basic anion exchangers were found to be 994.9 and 430.8 mg/g, respectively. For comparison, a low cost sorbent prepared from orange peels exhibited low affinity for the dye, Q0 equals 74.1 mg/g. The presence of inorganic salts such as NaCl, Na2CO3 and Na2SO4 as well as the non-ionic surfactant exhibited only minor effects on the dye sorption. The uptake of DR75 was remarkedly reduced in the presence of the cationic surfactant. The sorption of DR75 on the anion exchangers was pH independent. The kinetics fitted the pseudo-second order rate expression. With the decreasing particle sizes of anion exchangers, the increase in dye loading was observed. Almost 60% of dye can be desorbed from Amberlite IRA 67 using 1 M NaOH in 40% methanol.

The goal of this paper is to study the effectiveness of the weakly (Amberlite IRA 67) and strongly (Amberlite IRA 458) basic gel anion exchangers of polyacrylic matrix in Direct Red 75 (DR75) removal from aqueous solutions and wastewaters. The monolayer sorption capacities Q0 determined from the Langmuir isotherm model for the weakly and strongly basic anion exchangers were found to be 994.9 and 430.8 mg/g, respectively. For comparison, a low cost sorbent prepared from orange peels exhibited low affinity for the dye, Q0 equals 74.1 mg/g. The presence of inorganic salts such as NaCl, Na2CO3 and Na2SO4 as well as the non-ionic surfactant exhibited only minor effects on the dye sorption. The uptake of DR75 was remarkedly reduced in the presence of the cationic surfactant. The sorption of DR75 on the anion exchangers was pH independent. The kinetics fitted the pseudo-second order rate expression. Decreasing particle sizes of anion exchangers, the increase of dye loading was observed. Almost 60% of dye can be desorbed from Amberlite IRA 67 using 1 M NaOH in 40% methanol.Figure optionsDownload as PowerPoint slideHighlights
► Effective sorption of Direct Red 75 on weakly basic anion exchanger Amberlite IRA 67.
► Na2SO4, Na2CO3, NaCl and non-ionic surfactant do not influence sorption of dye.
► Cationic surfactant significantly reduced sorption of direct dye.
► Effective regeneration by means of 1 M NaOH in methanol.