Exploring the potential of textile industry combustion residues as sustainable adsorbents: a study on thermal treatment -induced stabilization and methylene blue removal efficiency

Abstract

The Sri Lankan textile industry, while economically vital, generates significant quantities of combustion residues-fly ash (FA), bottom ash (BA), and cyclone ash (CA)-through industrial boilers. These ashes contain high inorganic compounds, heavy metals, and trace organic substances. Current improper disposal methods create significant environmental hazards, while these contaminants also prevent direct ash reuse in secondary applications. This study investigates the feasibility of inert thermal treatment to stabilize and valorize these ashes as low-cost adsorbents for wastewater treatment, supporting circular economy initiatives. Ash samples from textile boilers were characterized through moisture and ash content analysis, the rmogravimetric analysis (TGA), Fourier Transform Infrared (FTIR) spectroscopy, and methylene blue adsorption experiments. Distinct physicochemical results showed that FA exhibited high surface reactivity and BA displayed structural stability. Treated samples showed improved thermal stability and enhanced dye adsorption performance, with removal efficiencies ranging from 55% to 83%. A strong positive correlation (r = 0.897) between ash content and treatment yield, and a negative correlation (r =-0.972) with moisture content, underscored the importance of initial ash characteristics. The findings support the reuse of textile boiler ash as an effective adsorbent, paving the way for a sustainable waste management solution and environmental protection in the textile sector.