Preparation and Alkaline Activation of Cellulose Extracted from Salacca zalacca Midrib for [AuCl₄]⁻ Adsorption

Abstract

Cellulose from salacca (Salacca zalacca) midrib waste shows potential as an adsorbent for metal ions. In this study, cellulose was extracted through drying, grinding, delignification with 5% NaOH, and alkaline activation, followed by Fourier Transform Infrared (FTIR)  characterization. Adsorption experiments were conducted by contacting 5 g of activated cellulose with 30 mL of 50 ppm [AuCl₄]⁻ solution at pH 1–4. The remaining Au concentration was measured using AAS to determine adsorption efficiency. The results show very high adsorption percentages: 99.70% (pH 1), 99.28% (pH 2), 97.98% (pH 3), and 97.72% (pH 4). Pearson correlation analysis yielded a significance value of 0.034 and a correlation coefficient of 0.966, indicating that pH influences adsorption and that adsorption efficiency decreases slightly with increasing pH. Overall, alkaline-activated cellulose from salacca midrib is highly effective for Au(III) adsorption, particularly under strongly acidic conditions.