Efficient removal of a textile dye from water using activated carbon derived from almond Shell waste

Abstract

Discharging organic dyes into aquatic environments has numerous adverse effects on human health and ecosystems due to their toxic properties. In the present study, almond shell-activated carbon (ASAC), derived from agricultural waste and produced in large quantities in Iran, was employed as a sustainable and inexpensive adsorbent to adsorb reactive red 120 (RR120). This work can, in addition to reducing agricultural waste, remove pollutants from water and contribute to the achievement of the Sustainable Development Goals. The prepared ASAC was characterized using FESEM, BET, EDX, and FTIR. Results showed that the maximum adsorption capacity of RR120 on ASAC was 147.43 mg g-1. The adsorption mechanism is primarily monolayer adsorption, as the isotherm model fits the Langmuir model well (R2 = 0.988). Additionally, the kinetic data fit a pseudo-second-order model (R2 = 0.999), indicating that chemical interactions control the rate of RR120 adsorption via ASAC. The maximum practical adsorption of RR120 via ASAC was 99.34 under optimum conditions: initial RR120 concentration of 10 mg L-1, pH of 4.25, adsorbent dosages of 0.3 g L-1, and contact time of 61 min. According to the thermodynamic parameter values (Delta G degrees, Delta H degrees, and Delta S degrees), the process of adsorption of RR120 on the ASAC dye was exothermic and spontaneous. Based on the results of this study, ASAC can be used as an acceptable adsorbent for removing organic dyes from aqueous solutions in practical applications.