Enhancing sulfamethizole adsorption on graphitic carbon nitride via coffee hydrochar incorporation and electric field application in different water matrices

Abstract

This study addresses the urgent need for sustainable and efficient water treatment solutions by developing a new green material with enhanced adsorption capabilities through the incorporation of hydrocarbons derived from banana peels (HC-P) or coffee waste (HC-C) into graphitic carbon nitride (GCN). In addition to its dual functionality of electrosorption and catalytic activity, this environmentally friendly synthesis avoids the use of organic solvents and metals, reducing its environmental footprint and costs. Initial tests on sulfamethizole (SMZ) adsorption and electrosorption were conducted with both hydrochars, with HC-C demonstrating superior performance. The optimization of HC-C content in the composite revealed that 10 wt%(GCN@HC-C10) provided the best results. Using this composite around 95% SMZ removal under electrosorption at 1.2 V was achieved in only 120 min. The compound was then immobilized on a carbon felt electrode (GCN@HC-C10/CF), which facilitated its practical application and reuse in real water systems. The durability of GCN@HC-C10/CF was validated by five cycles, and its photocatalytic regeneration under visible LED light resulted in minimal reduction of adsorption capacity (<8%). The hybrid electrosorption-regeneration process successfully mineralized SMZ during photoregeneration, highlighting the potential of GCN@HC-C10/CF for efficient and sustainable pollutant removal. To our knowledge, there are no previous studies reporting green catalytic materials with dual functionality such as the one presented here. Finally, tests on real water samples (tap and river) underline the applicability of the material in various water purification contexts, positioning it as a promising candidate for water purification applications.