| Abstrakt: |
Developing efficient and clean technology for the preparation of activated carbon from agricultural and forestry waste biomass is of great significance for China's dual carbon strategy. The rapid pyrolysis of agricultural and forestry waste biomass generates a large amount of biochar. The current research focus is on cost-effective and large-scale conversion of biochar into activated carbon. Using Masson pine biochar as the raw material, N2/CO2 mixed gas was used to simulate the circulating fluidized bed high- temperature flue gas, and water vapor was introduced as an activating agent to prepare activated carbon through activation of the biochar. Through single-factor experiments, the influence of water vapor flow rate, activation temperature, and activation time on the iodine adsorption value and yield of activated carbon were explored to determine the optimal preparation conditions. The physicochemical properties and structure of the activated carbon were characterized using an automatic physical and chemical adsorption instrument, scanning electron microscope, and Fourier transform infrared spectroscopy. The effects of pH, adsorption time, activated carbon dosage and initial Cu2+ concentration (mass concentration) on the adsorption performance of activated carbon for Cu2+ were investigated. The adsorption mechanism of Cu2+ on activated carbon was studied using kinetic and isotherm models. The research shows that under the optimal preparation conditions (high-temperature flue gas flow rate of 100 mL/min, water vapor flow rate of 0.9 mL/min, activation temperature of 850 °C and activation time of 2.5 h), the activated carbon yield is 7.32%, the iodine adsorption value is 1914 mg/g, and the specific surface area is 1556 m²/g. The functional groups on the surface contain various chemical bonds such as O--H, C--O, C=C and C=O bond. Under the optimal adsorption process conditions (pH of 5.5, adsorption time of 30 minutes, activated carbon dosage of 1.5 g/L and initial Cu2+ concentration of 10 mg/L), the maximum removal rate of Cu2+ is 99.97%, and the residual Cu2+ concentration is 0.003 mg/L, which complies with China's drinking water standards ( < 1 mg/L). The pseudo-second-order kinetic model and Langmuir model can better fit the adsorption process, indicating that the adsorption is a monolayer chemical adsorption, and the intraparticle diffusion is not the only rate-controlling step. [ABSTRACT FROM AUTHOR] |
