Copper(II) removal from aqua solution using rice straw derived biochar

Abstract

Biochar derived from rice straw has potential application as a cheap adsorbent for removal of Cu(II) from aqueous solution. In this study, rice straw was used to derive biochar by operating at different pyrolysis temperatures (300, 400, and 500 °C) and studied different biochar physicochemical properties. Biochar yield decrease from 57.87 to 37.19% by increasing temperature from 300 to 500 °C. The content of carbon and ash, pH, and surface area of biochar increased from 68.72 to 81.48%, 32.70–46.52%, 8.23–11.4, 48.3–101.29, respectively. Batch adsorption was adopted for biochar produced at different temperatures, and biochar derived at 500 °C showed the greater adsorption capacity (29.8 mg g−1). RBC500 was selected to study the initial metal concentration effects (5–320 mg L−1) and time of contact (30–240 min) on removal efficiency of Cu(II). The optimum results from the study showed that for Cu adsorption was pH = 5, adsorbent dose 0.1 g L−1, and contact duration of 180 min. A strong fit to the kinetics (R2 = 0.99) was shown by pseudo-second-order model, and strong fit to the adsorption isotherms was shown by Langmuir model (R2 = 0.99) of Cu(II) adsorption.