Optimized preparation of activated carbon from furfural residue using response surface methodology and its application for bisphenol S adsorption

Furfural residue (FR), a solid waste, was applied as the precursor to prepare activated carbon by steam activation. The Box-Behnken design (BBD) approach-based response surface methodology (RSM) was utilized to optimize the preparation conditions to evaluate their effects on the performance of activated carbon from furfural residue (FRAC). The optimum preparation conditions of FRAC were found as follows: activation temperature of 922 °C, activation time of 62 min, and the mass ratio of char to H2O of 1:4.5, resulting in 1,501.84 mg/g of iodine adsorption capacity and 1,662.41 m2/g of specific surface area. The FRAC was characterized and then the adsorption performance of BPS on FRAC was investigated. Langmuir and Koble-Corrigan isotherm models were well fitted to the experimental data, and the adsorption kinetics process was perfectly described by the pseudo-second-order model. Thermodynamic parameters showed that the adsorption of BPS was a spontaneous exothermic process. Besides, the regeneration efficiency of FRAC was over 97% after five consecutive cycles. The maximum monolayer adsorption capacity of FRAC for BPS was 3.2848 mmol/g at 298 K, indicating that the FRAC was an excellent adsorbent for the removal of BPS from aqueous solutions.

Pyrolysis of Furfural Residues and Possible Utilization Pathway

The manuscript attempts to understand the evolution of NOx precursors: NH3 and HCN from Pyrolysis of furfural residue (FR). The pyrolysis process was carried out in a thermogravimetric analyzer (TGA) coupled to Fourier-transform infrared (FTIR) spectrometer. The combination revealed insightful information on the evolution of NH3 and HCN. This could help us better understand the characteristics of FR derived from furfural production especially with regard to NH3 and HCN. Nitrogen is considered a minor component in biomass wastes; in this study nitrogen content is about 0.57%. However, the pollution potential poised by low nitrogen content is huge through both direct and indirect processes. Thus, this study presents results that were found with regard to FR pyrolysis in pure nitrogen environment. At the heating rate of 40°C/min−1, the only NOx precursor detected was HCN at 713 cm−1 as per the database provided by National Institute of Standards and Technology (NIST). NH3 was not detected. The particle size of FR used ranged between 0.15–0.25 mm.

Pelletization of Biomass Feedstocks: Effect of Moisture Content, Particle Size and a Binder on Characteristics of Biomass Pellets

Pelletization of low value added biomass materials such as furfural residue (FR) and sawdust was performed by using a lab scale pelletizer. Effects of moisture content (MC), particle size and a binder on quality parameters (e.g. pellet density, strength and hardness) and on energy consumption were investigated. Quality of pellets was analysed and compared. MC was found to be the more dominant parameter affecting pellet density, strength and hardness of furfural residue pellets (FRPs) and sawdust pellets (SPs), followed by particle size and a binder. Highest particle density of 1.419 g/cm3 for FRPs (0.5–1.41 mm) and 1.243 g/cm3 for SPs (0.25–0.5 mm) was achieved at MC of 8% and 18%. Highest decrease in relaxed density was observed at MC of 13% for FRPs and 28% for SPs. True density of FRPs and SPs made from particles of 0.25–0.5 mm was found higher than 0.5–1.41 mm. The highest strength and hardness (6.29 MPa and 401.3 N/mm2) for FRPs was achieved at 5.5% MC and particles 0.25–0.5 mm. Optimum strength (6.03 MPa) and hardness (96.06 N/mm2) for SPs was obtained at 18% MC and particles 0.25–0.5 mm. The lowest energy consumption (16.16 J/g) for FRPs (0.25–0.5 mm) and 20.22 J/g for SPs (0.5–1.41 mm) was achieved at MC of 13% and 28%. Addition of binding agent to FR sawdust decreased energy consumption of FRPs and SPs. SPs quality was enhanced with the use of a binder. Heating value of FRPs were found higher than SPs.