Preparation of Rice Paddy Stalks-Based Activated Carbon to Remove Phenol from Aqueous Solutions

The accumulation of rice paddy stalks (RPS) as a waste product during rice cultivation has become a significant environmental concern in recent times. However, by utilizing rice paddy stalks as a raw material for the synthesis of activated carbon, significant waste reduction and the promotion of sustainable waste disposal practices can be achieved. In the present study, RPS served as a precursor material in the development of activated carbon. The study involved three sets of preparation experiments, where the activation temperatures of 500, 700, and 900 °C, heating rates of 10, 15, and 20 °C/min, and contact times of 1, 2, and 3 h were varied. The obtained activated carbon properties were scrutinized through Fourier Transform Infrared Spectroscopy (FTIR) to analyze the functional groups, and Brunauer–Emmett–Teller (BET)to analyze the surface area. The effectiveness of the activated carbon derived from rice paddy stalks (RPS) was examined by assessing its capacity for phenol removal from aqueous solutions through batch experiments. The starting concentrations of phenol were diversified between 50 and 200 mg/L, while other pertinent parameters relevant to adsorption were held constant. The activated carbon with optimal properties was achieved at 900 °C activation temperature, 15 °C/min heating rate, and 3-h contact time. Characterization analysis showed a high surface area of 216.9 m²/g, total micropore volume of 116.99 cm³/g, and pore diameter of 6.87 nm. Batch studies revealed a high phenol adsorption capacity of 70.4 mg/g. Furthermore, the N2 adsorption–desorption isotherm showed a Type III pattern, indicating the presence of macrospores in the structure. The findings of this study highlighted the potential for sustainable disposal of rice paddy stalks and the production of activated carbon.