Iron-modified activated carbon derived from agro-waste for enhanced dye removal from aqueous solutions

Background and aim: Finding a cost-effective adsorbent can be an obstacle to large-scale applications of adsorption. This study used an efficient activated carbon adsorbent based on agro-waste for dye removal. Methods: Pistachio shells as abundant local agro-wastes were used to prepare activated carbon. Then, it was modified with iron to improve its characteristics. Acid red 14 was used as a model dye in various conditions of adsorption (AR14 concentration 20-150 mg L-1, pH 3-10, adsorbent dosage 0.1-0.3 g L-1, and contact time 5-60 min). Results: A mesoporous adsorbent was prepared from pistachio shells with 811.57 m(2) g(-1) surface area and 0.654 cm(3) g(-1) pore volume. Iron modification enhanced the characteristics of activated carbon (surface area by 33.3% and pore volume by 64.1%). Adsorption experiments showed the high effectiveness of iron-modified activated carbon for AR14 removal (>99%, >516 mg g(-1)). The adsorption followed the pseudo-second kinetic model (k = 0.0005 g mg(-1) min(-1)) and the Freundlich isotherm model (K-f =152.87, n = 4.61). Besides, the reaction occurred spontaneously (Delta G(0) = -36.65 to -41.12 kJ mol(-1)) and was exothermic (Delta H-0 = -41.86 kJ mol(-1) and Delta S-0 = -3.34 J mol(-1) K-1). Conclusion: Iron-modified activated carbon derived from pistachio shells could be cost-effective for the treatment of industrial wastewater containing dyes.

Automated summary

This study utilized iron-modified activated carbon derived from pistachio shells for the removal of Acid Red 14 dye, showing high efficiency and cost-effectiveness in treating industrial wastewater.