Abstract
Elimination of dyes in water resources must be averted and for that different treatment technologies are implicated. Among several methods, adsorption has an important place in dye removal. The increasing demand for low-cost and efficient treatment methods has given rise to inexpensive alternative adsorbents. In the present study, almond shells, almond stems, and fig stems were used as a new nonconventional and low-cost biosorbents for cationic and anionic dye adsorption in a batch process at 25 degrees C. The adsorption characteristics of Prunus amygdalus and Ficus carica by-products were studied with respect to the variation in initial pH of dye solutions, biosorbent dosage, contact time, initial dye concentration, and salt concentration. The adsorption kinetics was analyzed using pseudo-first-order and pseudo-second-order models. The kinetic data were best described by the pseudo-second-order model. The equilibrium behavior of Basic Red 46 and Acid Blue 25 adsorption were examined by the Langmuir, Freundlich, Koble-Corrigan, and Redlich-Peterson isotherm models. It was found that the equilibrium data fitted well with the Langmuir model. The results revealed that the almond shells, almond stems, and fig stems could be used as low-cost alternative biosorbents for textile wastewater treatment.