Engineered pine nut shell derived activated carbons for improved removal of recalcitrant pharmaceuticals in urban wastewater treatment

Novel powdered activated carbons (PACs) from pine cones and pine nut shells (PNSs) were tested for the competitive adsorption of pharmaceutical compounds (PhCs) in spiked (100 µg/L) secondary effluent and mixed liquor from an urban wastewater treatment plant. Steam activated PNS77, with hierarchical pore structure and 1463 m²/g of BET area, outperformed the commercial benchmark (WP220, mineral origin) for PhCs and dissolved organic matter (DOM) control. PNS77 attained the highest adsorption capacity and rate in synthetic and real wastewaters. Competitive adsorption isotherms revealed the detrimental effect of direct site competing DOM on PhC removal. The PhCs' adsorbability increased with their hydrophobicity, regardless of the water matrix. Kinetic data allowed inferring that indirect competition due to pore constriction/blockage appeared to occur only in mixed liquor. Adsorption isotherm data modelling for ng/L range revealed 80 % removal of carbamazepine and diclofenac would be achieved dosing 8-15 mg/L PNS77 to secondary effluent, while for mixed liquor the dose must be doubled to balance the increased competition. Hydrophilic sulfamethoxazole required a higher dose (34-44 mg/L), lower in the mixed liquor. PNS77 hierarchical pore network and basic surface chemistry minimized DOM direct site competition, requiring lower doses in practical applications for wastewater treatment.

Cetyl trimethyl ammonium bromide modified magnetic biochar from pine nut shells for efficient removal of acid chrome blue K

Biochar was prepared by rapid pyrolysis using pine nut shell as raw materials. Then cetyl trimethyl ammonium bromide modified magnetic biochar material (CTAB-MC) was obtained after modifying biochar by FeCl₃ and cetyl trimethyl ammonium bromide. The CTAB-MC was characterized by SEM, FTIR, XRD and Magnetic analyses. Adsorptive property of the CTAB-MC for acid chrome blue K (AK) was studied. It was found that adsorption capacity was affected by solution pH, temperature, adsorption time, initial concentration and ionic strength. The CTAB-MC showed higher adsorption ability toward acid chrome blue K, which was up to 40% higher than that of MC. The experimental results showed that adsorption data of AK on the CTAB-MC well conformed to the Langmuir isotherm adsorption model and the pseudo-second order kinetic model. The CTAB-MC can be recycled three times. This work reveals that CTAB-MC is a promising adsorbent with broad application prospects.

Pyrolysis polygeneration of pine nut shell: Quality of pyrolysis products and study on the preparation of activated carbon from biochar

A lab-scale pyrolysis reactor was utilized to investigate the effect of pyrolysis temperature (300-700°C) on the yield, quality, and energy distribution of products issued from the pyrolysis polygeneration of pine nut shells. Afterward, activated carbon was prepared from biochar using the steam activation method. Pyrolysis temperatures ranging from 500 to 600°C were found to be optimal in inducing products with improved properties, such as higher heating values of non-condensable gas, lower water content and elevated heating values of bio-oil, and substantial fixed carbon content and greater specific surface area of biochar. In addition, it was noticed that the activation conditions had a significant effect on the yield and adsorption performance of the activated carbon. As a result, activated carbon with elevated specific surface area reaching 1057.8m(2)/g was obtained at the optimal conditions of 850°C activation temperature, 80min activation time, and 1.5 steam/biochar ratio.