Raphanus caudatus biomass powder as potential adsorbent for the removal of crystal violet and Rhodamine B dye from wastewater

Abstract

Abstract In this work, Raphanus caudatus (radish pod) leaves biomass was used as an adsorbent for the removal of crystal violet (CV) and Rhodamine B (RhB) dye from water medium. Adsorption process was performed by changing different adsorption factors such as adsorbent dose, agitation time, adsorbate concentration, pH and temperature to get maximum removal of dyes. It was observed that R. caudatus leaves biomass showed 48.7 and 19.0 mg/g value of adsorption capacity for CV and RhB dyes, respectively. High adsorption capacity value for CV was observed due to its less complex structure and small sized molecules as compared to the RhB dye molecules. Dyes removal process followed pseudo second order with the values of regression factor (R 2) found as 0.999 and 0.998 for CV and RhB, respectively. Values of R 2 were found as 0.999 and 0.998 for the removal of CV and RhB respectively while following the Langmuir adsorption isotherm model. It illustrates the single layered dye molecules adsorption over the homogeneous surface of the adsorbent. Value of enthalpy (ΔH°) was found as 11.983 and 12.28 kJ/mol for CV and RhB, respectively. It indicates endothermic nature of the process along with the increased entropy at the surface of the adsorbent during the process. Increase of salt concentration in adsorption medium caused the decreased percentage removal of dyes. Reported adsorbent also showed potential for the removal of toxic dyes from industrial wastewater.