Exploring Pristine Tucumã (Astrocaryum aculeatum) Waste as a Sustainable Adsorbent for Textile Dye Removal

Abstract

Textile dyes are one of the main industrial contaminants, and their removal from wastewater using environmentally friendly alternatives has been a challenge for decades. In this context, this study aimed to analyze the use of tucumã (Astrocaryum aculeatum) seed residue as a novel and low-cost adsorbent material for the decolorization of a textile dye solution. The seed shell was disinfected, dried, ground, and sieved. Its physical and chemical characteristics were analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and point of zero charge (pH_PZC). The influence of initial pH (4.2–9.8) and dye concentration (95–745 mg/L) in the color removal was analyzed through a central composite rotatable design (CCRD) using 10 g/L of tucumã seed shell at 150 rpm for 4 h. Both pH and dye concentration linearly influenced color removal. Lower pH values and higher dye concentrations resulted in color removals above 40%. When pH 5 and 700 mg/L of dye were used, the adsorption capacity was higher than 50 mg/g. The adsorption isotherm that best fitted the data was Freundlich isotherm, indicating that the adsorbent has a heterogeneous surface and that multilayer adsorption occurs in the tucumã residue. These results indicate that pristine A. aculeatum seed residue can potentially be used as an adsorbent in the textile industry with no chemical or thermal activation.