A comparison for the removal of two different textile dyes by raw Helianthus annuus L. seed shells

Abstract

A detailed study was carried out to compare the removal of Reactive Blue 221 and Red X-5GN dyes using raw Helianthus Annuus L. seed shell as a natural adsorbent. There is no study in the literature for comparing the treatment of these anionic and cationic dyes using the current seed shell in raw form. Bringing a natural waste to the economy that can compete with adsorbents such as activated carbon commercially used in dye removal, will offer important advantages. The variation of initial pH value, shell dosage, contact time and, initial dye concentration was investigated. Reactive Blue 221 was successfully removed at pH 2 with a treatment efficiency of above 90%, while Red X-5GN was treated at pH 4 with a removal efficiency of 97%. Appropriate adsorbent dosages were 4 and 10 g/L for Reactive Blue 221 and Red X-5GN, respectively. Adsorption data of two dyes fitted very well to the pseudo-second-order reaction model with R-2 values of 0.979-0.999. The data were best repreŞented by the Langmuir model for Reactive Blue 221 with an R-2 of 0.986. Freundlich isotherm was the most suited model for adsorption of Red X-5GN dye with an R-2 of 0.996. The maximum uptake capacities were found to be 27.40 mg/g for Red X-5GN and 30.58 mg/g for Reactive Blue 221. The results showed that the conditions of adsorption for each dye can be significantly different. Besides, the potential of this seed shell as an eco-friendly and low-cost adsorbent was exhibited with perfect treatment results. [GRAPHICS]