Solid shrimp waste derived nanoporous carbon as an alternative bio-sorbent for oxytetracycline removal from aquaculture wastewater.

Recently, it has been critical to effectively remove oxytetracycline (OTC) from aquaculture wastewater before releasing into the environment. The adsorption process is recognized as an efficient pathway for removing OTC since it is a simple, stable, and cost-effective method. This study aims to develop nanoporous carbon entirely from shrimp waste (SW) via hydrothermal carbonization assisted with KOH activation. Existing KOH significantly increases the porosity of SW nanoporous carbon. The optimal SW porous carbon was obtained using 5 wt%KOH for activation, which had the largest surface area of 679.51 m2/g with the total pore volume of 0.458 cm3/g. Moreover, the SW porous carbon with the highest porosity was selected for the OTC adsorption. The Langmuir isotherm model and the pseudo-second-order kinetic model match the experimental data, implying that the adsorption mechanism is mono-layered adsorption due to micropores by chemisorption interaction. The adsorption capacity significantly improved by increasing the dosage of SW nanoporous carbon. The SW nanoporous carbon adsorption for OTC is primarily regulated by pore filling affected by hydrogen bonding, and π-π* interaction also plays a significant role. The SW nanoporous carbon showed an efficient OTC adsorption after 5 regeneration cycles. This work demonstrates biomass waste recycling and emphasizes the potential of aquatic food processing waste-derived nanoporous carbon for antibiotic adsorption.

Sustainable Development of ZnO Nanostructure Doping with Water Hyacinth-Derived Activated Carbon for Visible-Light Photocatalysis.

Water hyacinth (Wh) is an aquatic weed considered a nuisance in agricultural and fishing activities. Therefore, this study proposed repurposing this plant into activated carbon (AC). First, the ZnO-AC was precipitated and applied as a photocatalyst for degrading methylene blue. The preliminary photocatalytic test under UV irradiation identified the optimum ZnO-AC photocatalyst to degrade methylene blue (MB). The ZnO-AC photocatalyst recorded the highest degradation rate constant of 11.49 × 10-3 min-1, which was almost two-fold higher than that of ZnO (5.55 × 10-3 min-1). Furthermore, photocatalytic degradation of MB and carbaryl under sunlight irradiation by ZnO-AC demonstrated degradation rate constants of 74.46 × 10-3 min-1 and 8.43 × 10-3 min-1, respectively. To investigate the properties of ZnO-AC, several techniques were performed. ZnO-AC and ZnO exhibited similar results in morphology, crystalline structure, and Raman characteristics. However, ZnO-AC presented smaller pore diameters than those of ZnO, which enlarged pore surface area, and the presence of carbon-related groups implied the presence of AC on ZnO-AC surfaces. This can be attributed to the presence of AC on the ZnO surface, increasing the capture of surrounding toxic molecules and elevating the reaction density. This mechanism is attributed to promoting the degradation of toxic molecules. Therefore, using Wh as a carbon source for the transformation of AC can alternatively solve the problems of aquatic weed management and carbon storage strategies, and the application of AC in ZnO-AC photocatalysts can enhance photocatalysis.

Machine learning and statistical analysis for biomass torrefaction: A review.

Torrefaction is a remarkable technology in biomass-to-energy. However, biomass has several disadvantages, including hydrophilic properties, higher moisture, lower heating value, and heterogeneous properties. Many conventional approaches, such as kinetic analysis, process modeling, and computational fluid dynamics, have been used to explain torrefaction performance and characteristics. However, they may be insufficient in actual applications because of providing only some specific solutions. Machine learning (ML) and statistical approaches are powerful tools for analyzing and predicting torrefaction outcomes and even optimizing the thermal process for its utilization. This state-of-the-art review aims to present ML-assisted torrefaction. Artificial neural networks, multivariate adaptive regression splines, decision tree, support vector machine, and other methods in the literature are discussed. Statistical approaches (SAs) for torrefaction, including Taguchi, response surface methodology, and analysis of variance, are also reviewed. Overall, this review has provided valuable insights into torrefaction optimization, which is conducive to biomass upgrading for achieving net zero.

Catalytic deoxygenation of palm oil over metal phosphides supported on palm fiber waste derived activated biochar for producing green diesel fuel.

Palm oil conversion into green diesel by catalytic deoxygenation (DO) is one of the distinctive research topics in biorefinery towards a bio-circular-green economic model to reduce the greenhouse gas emissions. In this study, palm fiber waste was explored as an alternative precursor for the preparation of activated biochar as a support material. A new series of nickel phosphide (Ni-P) and iron phosphide (Fe-P) catalysts supported on palm fiber activated biochar (PFAC) was synthesized by wetness impregnation, and extensive characterization was performed by several techniques to understand the characteristics of the supported metal phosphide catalysts prior to palm oil deoxygenation for producing of green diesel (C15-C18 hydrocarbons). The PFAC support exhibited suitable physicochemical properties for catalyst preparation, such as high carbon content, and high porosity (S BET of 1039.64 m2 g-1 with V T of 0.572 cm3 g-1). The high porosity of the catalyst support (PFAC) significantly promotes the metal phosphide nanoparticle dispersion. The DO of palm oil was tested in a trickle bed down flow reactor under hydrogen atmosphere. The outstanding catalytic performance of supported Ni-P and Fe-P catalysts provided an impressive liquid hydrocarbon yield between 63.37 and 79.65% with the highest green diesel selectivity of 62.64%. Decarbonylation (DCO) and decarboxylation (DCO2) are the main pathways for the relative phosphide catalysts as presented by the high number of C n-1 atoms (C15 and C17 hydrocarbons). In addition, metal phosphide/PFAC catalysts could achieve great potential application as a promising alternative catalyst for biofuel production via deoxygenation for large-scale operation owing to their excellent catalytic activity, simple preparation, and utilization of sustainable resources.

Porous Biochar Supported Transition Metal Phosphide Catalysts for Hydrocracking of Palm Oil to Bio-Jet Fuel.

The upgrading of plant-based oils to liquid transportation fuels through the hydrotreating process has become the most attractive and promising technical pathway for producing biofuels. This work produced bio-jet fuel (C9-C14 hydrocarbons) from palm olein oil through hydrocracking over varied metal phosphide supported on porous biochar catalysts. Relative metal phosphide catalysts were investigated for the highest performance for bio-jet fuel production. The palm oil's fiber-derived porous biochar (PFC) revealed its high potential as a catalyst supporter. A series of PFC-supported cobalt, nickel, iron, and molybdenum metal phosphides (Co-P/PFC, Ni-P/PFC, Fe-P/PFC, and Mo-P/PFC) catalysts with a metal-loading content of 10 wt.% were synthesized by wet-impregnation and a reduction process. The performance of the prepared catalysts was tested for palm oil hydrocracking in a trickle-bed continuous flow reactor under fixed conditions; a reaction temperature of 420 °C, LHSV of 1 h-1, and H2 pressure of 50 bar was found. The Fe-P/PFC catalyst represented the highest hydrocracking performance based on 100% conversion with 94.6% bio-jet selectivity due to its higher active phase dispersion along with high acidity, which is higher than other synthesized catalysts. Moreover, the Fe-P/PFC catalyst was found to be the most selective to C9 (35.4%) and C10 (37.6%) hydrocarbons.

Nanoporous Carbon from Oil Palm Leaves via Hydrothermal Carbonization-Combined KOH Activation for Paraquat Removal.

In this study, nano-porous carbon was completely obtained from oil palm leaves (OPL) by hydrothermal pretreatment with chemical activation, using potassium hydroxide (KOH) as an activating agent. Potassium hydroxide was varied, with different ratios of 1:0.25, 1:1, and 1:4 (C: KOH; w/w) during activation. The physical morphology of nano-porous carbon has a spongy, sponge-like structure indicating an increase in specific surface area and porosity with the increasing amount of KOH activating agent. The highest specific surface area of OPL nano-porous carbon is approximately 1685 m2·g-1, with a total pore volume of 0.907 cm3·g-1. Moreover, the OPL nano-porous carbon significantly showed a mesoporous structure designed specifically to remove water pollutants. The adsorptive behavior of OPL nano-porous carbon was quantified by using paraquat as the target pollutant. The equilibrium analyzes were explained by the Langmuir model isotherm and pseudo-second-order kinetics. The maximum efficiency of paraquat removal in wastewater was 79%, at a paraquat concentration of 400 mg·L-1, for 10 min in the adsorption experiment. The results of this work demonstrated the practical application of nano-porous carbon derived from oil palm leaves as an alternative adsorbent for removing paraquat and other organic matter in wastewater.

Nitrogen-doped carbon derived from horse manure biomass as a catalyst for the oxygen reduction reaction.

A massive amount of animal biomass is generated daily from livestock farms, agriculture, and food industries, causing environmental and ecological problems. The conversion of animal biomass into value-added products has recently gained considerable interest in materials science research. Herein, horse manure (HM) was utilized as a precursor for synthesizing nitrogen-doped carbons (NCs) via hydrothermal ammonia treatment and the post pyrolysis process. The ammonia concentration varied between 0.5, 1.0, and 1.5 M in the hydrothermal process. From the comprehensive characterization results, horse manure-derived nitrogen-doped carbons (HMNCs) exhibited an amorphous phase and a hierarchical nanoporous structure. The specific surface area decreased from 170.1 to 66.6 m2 g-1 as the ammonia concentration increased due to micropore deterioration. The nitrogen content was 0.90 atom% even with no ammonia treatment, indicating self-nitrogen doping. With hydrothermal ammonia treatment, the nitrogen content slightly enhanced up to 1.54 atom%. The electrocatalytic activity for the oxygen reduction reaction (ORR) of HMNCs in an alkaline solution was found to be related to nitrogen doping content and porous structure. The ORR activity of HMNCs mainly proceeded via a combination of two- and four-electron pathways. Although the ORR activity of HMNCs was still not satisfactory and comparable to that of a commercial Pt/carbon catalyst, it showed better long-term durability. The results obtained in this work provide the potential utilization of HM as a precursor for ORR catalysts and other related applications.

Parametric Study on Microwave-Assisted Pyrolysis Combined KOH Activation of Oil Palm Male Flowers Derived Nanoporous Carbons.

Oil palm male flowers (PMFs), an abundant agricultural waste from oil palm plantation in Thailand, have been utilized as an alternative precursor to develop nanoporous carbons (NPCs) via microwave-assisted pyrolysis combined potassium hydroxide (KOH) activation. The influences of relevant processing variables, such as activating agent ratio, microwave power, and activation time on the specific pore characteristics, surface morphology, and surface chemistry of PMFs derived nanoporous carbons (PMFCs) have been investigated to explore the optimum preparation condition. The optimum condition under a microwave radiation power of 700 W, activation holding time of 6 min, and activating agent ratio of 2:1 obtained the PMFC with the highest Brunauer-Emmett-Teller (BET) surface area and total pore volume approximately of 991 m2/g and 0.49 cm3/g, composed of a carbon content of 74.56%. Meanwhile, PMFCs have a highly microporous structure of about 71.12%. Moreover, activating agent ratio and microwave radiation power indicated a significant influence on the surface characteristics of PMFCs. This study revealed the potential of oil palm male flowers for the NPCs' production via microwave-assisted KOH activation with a short operating-time condition.