Self-activation of potassium/iron citrate-assisted production of porous carbon/porous biochar composites from macroalgae for high-performance sorption of sulfamethoxazole

Overcoming ammonia inhibition via biochar-assisted anaerobic co-digestion of thermally-treated thickened waste activated sludge and food waste

The convergence of sustainability and climate change has catalyzed the pursuit of inventive strategies for waste management and sustainable energy production. Hereby, we explored the effect of coupling biochar addition and thermal pretreatment in anaerobic mono-digestion and co-digestion of thermally pretreated thickened waste activated sludge (PTWAS) with food waste (FW). Six semi-continuous lab-scale digesters were operated for 161 days at various organic loading rates (OLR of 2, 3, 4 and 8 kgCOD/m3/day) with and without biochar (BC) addition. Coupling biochar addition and co-digestion of 30%FW +70% PTWAS, increased methane yield (MY) by 87.5% to 0.15 LCH4/gCOD added, when the systems experienced high ammonia concentration of 2.4 g/L at OLR of 8 kgCOD/m3/d. The non-competitive ammonia inhibition constant (Ki) ranged from 0.250 g/L to 0.345 g/L. The maximum COD-to-BC ratio to overcome inhibition was 16.5 g COD substrate/g BC corresponding to TN-to-BC ratio of 0.84 g TN substrate/g BC. These results imply that biochar addition to the anaerobic co-digestion of thermally pretreated TWAS and FW can promote high-rate anaerobic digestion by relieving ammonia and VFA inhibition.

Pyrolytic conversion of cattle manure into value-added products and application of biochar for adsorption of sulfamethoxazole

This study investigated the thermochemical conversion of cattle manure (CM) to propose a sustainable platform for its valorization, and explored the applicability of CM-derived biochar (CMB) as an environmental medium for the adsorptive removal of sulfamethoxazole (SMZ). CM pyrolysis was conducted under two atmospheric conditions (N2 and CO2), and the pyrogenic products were quantified and characterized. Real-time syngas monitoring revealed that CO2 enhanced CO generation from the CM, leading to the formation of a highly porous carbon structure in the produced biochar (CMBCO2). The adsorptive removal of SMZ by CMBCO2 was highly dependent on the pH conditions. The adsorption kinetics of SMZ onto CMBCO2 reached equilibrium within 540 min, following a pseudo-second-order model. The SMZ adsorption isotherms fit the Langmuir-Freundlich model, highlighting the importance of chemisorption in the adsorption process. X-ray photoelectron spectroscopy revealed that SMZ was adsorbed by non-electrostatic mechanisms, including hydrogen bonding, Lewis acid-base interactions, surface complexation, and π-π electron-donor acceptor interactions. This study presents an exemplary strategy for converting livestock waste into valuable resources, enabling the harvesting of energy resources and the production of treatment media for environmental remediation.

Synergistic mechanisms for the superior sorptive removal of aquatic pollutants via functionalized biochar-clay composite

This study investigated the successful synthesis of functionalized algal biochar-clay composite (FBKC). Subsequently, the sorption performance of FBKC towards norfloxacin (NFX) antibiotic and crystal violet dye (CVD) from water was extensively assessed in both batch and continuous flow systems. A series of characterization techniques were carried out for FBKC and the utilized precursors, indicating that the surface area of FBKC was increased thirty-fold with a well-developed pore structure compared to the original precursors. FBKC demonstrated a maximum sorption capacity of 192.80 and 281.24 mg/g for NFX and CVD, respectively. The suited fitting of the experimental data to Freundlich and Clark models suggested multi-layer sorption of NFX/CVD molecules. The mechanistic studies of NFX/CVD sorption onto FBKC unveiled multiple mechanisms, including π-π interaction, hydrogen bonding, electrostatic attraction, and surface/pore filling effect. The estimated cost of 5.72 €/kg and superior sorption capacity makes FBKC an efficient low-cost sorbent for emergent water pollutants.

One-Pot Mechanochemical Synthesis of Carbons with High Microporosity and Ordered Mesopores for CO2 Uptake at Ambient Conditions

Mechanochemical synthesis of ordered mesoporous carbons with tunable mesopores and well-developed irregular microporosity is investigated. This synthesis was carried out by the self-assembly of ecofriendly chemicals such as tannin and glyoxal used as carbon precursors, and triblock copolymer as a soft templating agent. The structural properties of the resulting carbons were tailored by using different block copolymers (Pluronic F127, and P123) as soft templates. The various weight ratios of tannin and block copolymer were employed to tune the textural properties of these carbons. The tannin: Pluronic F127 ratios (1:0.75, 1:1, 1:1.1) gave the ordered mesoporous carbons among a wide variety of the samples studied. The ordered mesoporosity was not observed in the case of Pluronic P123 templated mesoporous carbons. The CO2-activated carbon samples obtained for both Pluronic templates showed a high specific surface area (close to 900 m2/g), large pore volume (about 0.6-0.7 cm3g-1), narrow pore size distribution, and high CO2 uptake of about 3.0 mmol g-1 at 1 bar pressure and ambient temperature.

3D porous carbon-embedded nZVI@Fe2O3 nanoarchitectures enable prominent performance and recyclability in antibiotic removal

Overcoming the instability and poor recyclability during the practical applications of contaminant scavengers is a challenging topic. Herein, a three-dimensional (3D) interconnected carbon aerogel (nZVI@Fe₂O₃/PC) embedding a core-shell nanostructure of nZVI@Fe₂O₃ was elaborately designed and fabricated via an in-situ self-assembly process. The porous carbon with 3D network architecture exhibits strong adsorption towards various antibiotic contaminants in water, where the stably embedded nZVI@Fe₂O₃ nanoparticles not only serve as magnetic seeds for recycling, but also avoid the shedding and oxidation of nZVI in the adsorption process. As a result, nZVI@Fe₂O₃/PC efficiently captures sulfamethoxazole (SMX), sulfamethazine (SMZ), ciprofloxacin (CIP), tetracycline (TC) and other antibiotics in water. In particular, an excellent adsorptive removal capacity of 329 mg g^-1 and a rapid capture kinetics (99% of removal efficiency in 10 min) under a wide pH adaptability (2-8) are achieved using nZVI@Fe₂O₃/PC as an SMX scavenger. nZVI@Fe₂O₃/PC displays exceptional long-term stability given that it shows excellent magnetic property after it is stored in water solution for 60 d, making it an ideal stable scavenger for contaminants in an etching-resistant and efficient manner. This work would also provide a general strategy to develop other stable iron-based functional architectures for efficient catalytic degradation, energy conversion and biomedicine.