Recycling waste macadamia nut shells as a low hydrothermally engineered activated carbon for the efficient removal of a RIT navy blue textile dye from aqueous solutions

Abstract

Significant concentrations of toxic dyes present in textile manufacturing effluents are discharged into natural water bodies (lake and rivers) every day and results in the pollution of aquatic ecosystems. New and cost-effective sustainable water treatment strategies are urgently needed to tackle this global issue. The present study investigates the feasibility of using activated carbon produced from macadamia nutshells, a major agricultural waste product, to remove a commercially available textile RIT navy blue dye from aqueous solutions. This activated carbon was synthesized using a low-temperature hydrothermal (LTH) method that used H _2 SO _4 as the activating agent. The textural and chemical properties of the engineered activated carbon were investigated by nitrogen adsorption–desorption measurements, XRD, SEM, TGA, Raman, and FT-IR spectroscopy. The activated carbon (MAC) had a micro-porous structure with a BET surface area of 478 m ^2 g ^−1 for the MAC 10 sample. The linear pseudo-first order model described the kinetics of the adsorption process. The Langmuir model was found to be the most proper model for describing the adsorption isotherm data and revealed the activated carbon absorbent had a theoretical adsorption capacity of 57.8 mg g ^−1 . The study found the activated carbon has the potential to remove toxic dyes from wastewater, reduce agricultural waste, and this addresses the Sustainable Development Goals of the United Nations.

Keywords

• macadamia nutshells
• dye adsorption
• sustainability
• wastewater
• activated carbon