Activated carbon from flash pyrolysis of eucalyptus residue

Enhanced Hydrogen Evolution Reaction Using Biomass-Activated Carbon Nanosheets Derived from Eucalyptus Leaves

Carbonaceous-based metal-free catalysts are promising aspirants for effective electrocatalytic hydrogen generation. Herein, we synthesized mesoporous-activated carbon nanosheets (ELC) from biomass eucalyptus leaves through KOH activation. The microstructure, structural, and textural characteristics of the prepared materials were characterized by FE-SEM, Raman, XRD, and BET measurements. The high temperature (700 °C) KOH-activated ELC nanosheets exhibited an interconnected nanosheet morphology with a large specific surface area (1436 m2/g) and high mesoporosity. The ELC-700 catalyst exhibited an excellent electrocatalytic HER performance with a low overpotential (39 mV at 10 mA/cm2), excellent durability, and a Trivial Tafel slope (36 mV/dec) in 0.5 M H2SO4 electrolyte. These findings indicate a new approach for developing excellent biomass-derived electrocatalysts for substantially efficient green hydrogen production.

Eco-friendly synthesis of a novel adsorbent from sugarcane and high-pressure boiler water

The development of industrial process in line with the circular economy and the environmental, social and corporate governance (ESG) is the foundation for sustainable economic development. Alternatives that make feasible the transformation of residues in added value products are promising and contribute to the repositioning of the industry towards sustainability, due to financial leverage obtained from lesser operational costs when compared with conventional processes, therefore increasing the company competitivity. In this study, it is presented a promising and innovative technology for the recycling of agro-industrial residues, the sugarcane bagasse and the high-pressure water boiler effluent, in the development of a low-cost adsorbent (HC-T) using the hydrothermal carbonization processes and its application in the adsorption of herbicide Diuron and Methylene Blue dye from synthetic contaminated water. The hydrothermal carbonization was performed in a Teflon contained inside a sealed stainless-steel reactor self-pressurized at 200°C, biomass-to-effluent (m/v) ratio of 1:3 and 24 h. The synthesized material (HC) was activated in an oven at 450°C for 10 min, thus being named adsorbent (HC-T) and characterized by textural, structural and spectroscopic analyses. The low-cost adsorbent HC-T presented an 11-time-fold increase in surface area and ∼40% increase in total pore volume in comparison with the HC material. The kinetic and isotherm adsorption experiment results highlighted that the HC-T was effective as a low-cost adsorbent for the removal of herbicide Diuron and Methylene Blue dye from synthetic contaminated waters, with an adsorption capacity of 35.07 (63.25% removal) and 307.09 mg g-1 (36,47% removal), respectively.

Synthesis and Characterization of Activated Carbons Prepared from Agro-Wastes by Chemical Activation

In this present study, activated carbons were prepared from rice husks and potato peels by chemical activation with 40% phosphoric acid (H3PO4). The effects of carbonization temperature and impregnation ratio were investigated with a continuous activation period. Physicochemical characteristics such as surface morphology, surface charge, and surface functional groups were assessed. According to X-ray diffraction measurements, the results showed that the activated carbons had identical pHpzc (6.8) and that the activated carbons generated were carbonaceous. The existence of hydroxyl, carbonyl, amines, aromatic, and other functional groups, which are excellent for adsorption, was revealed by surface chemistry studies. Micrographs taken with a scanning electron microscope indicated wide opening pores with a larger mesoporous surface area and many linked pores. Rice husk activated carbon outperformed potato peel activated carbon in laboratory tests. The research has shown that the agro-wastes employed in the study are possible precursors for making locally activated carbons at a low cost, thus resolving the problem of agro-waste disposal.

Conversion of waste plastics into low emissive hydrocarbon fuel using catalyst produced from biowaste

Among the prevalent methods already in existence for the plastic waste management, catalytic pyrolysis has been proved to be an efficient one. The research work involved the synthesis of the catalyst from eucalyptus seeds, a commercially available agricultural waste product aided in pyrolysis. The raw eucalyptus seeds were cleaned, powdered, and surface-modified using sulphuric acid. Analysis of the surface-reformed eucalyptus seeds showed that they possess the characteristics equivalent to the activated carbon and micropores similar to that of zeolite which is used as a catalyst for pyrolysis. Hence, the prepared catalyst was used in the pyrolysis process and its performance was compared with that of the commercial activated carbon and zeolite. Zeolite Y generally lowers the temperature of the pyrolysis reaction to 180-190 °C, while the produced catalyst made the pyrolysis reaction possible between 120 and 130 °C. The output of the pyrolysis reaction was a hydrocarbon oil, which was analysed using gas chromatography-flame ionization detector (GC-FID). The oil was found to have a composition between C₆ and C₂₀, which includes petroleum, kerosene, and diesel. Hence, the oil obtained was proven to be more useful, as a fuel for locomotive and reheating purposes.

Activated Carbon Produced by Pyrolysis of Waste Wood and Straw for Potential Wastewater Adsorption

Pyrolysis of straw pellets and wood strips was performed in a fixed bed reactor. The chars, solid products of thermal degradation, were used as potential materials for activated carbon production. Chemical and physical activation processes were used to compare properties of the products. The chemical activation agent KOH was chosen and the physical activation was conducted with steam and carbon dioxide as oxidising gases. The effect of the activation process on the surface area, pore volume, structure and composition of the biochar was examined. The samples with the highest surface area (1349.6 and 1194.4 m²/g for straw and wood activated carbons, respectively) were obtained when the chemical activation with KOH solution was applied. The sample with the highest surface area was used as an adsorbent for model wastewater contamination removal.

A comprehensive review on physical activation of biochar for energy and environmental applications

Biochar is a solid by-product of thermochemical conversion of biomass to bio-oil and syngas. It has a carbonaceous skeleton, a small amount of heteroatom functional groups, mineral matter, and water. Biochar’s unique physicochemical structures lead to many valuable properties of important technological applications, including its sorption capacity. Indeed, biochar’s wide range of applications include carbon sequestration, reduction in greenhouse gas emissions, waste management, renewable energy generation, soil amendment, and environmental remediation. Aside from these applications, new scientific insights and technological concepts have continued to emerge in the last decade. Consequently, a systematic update of current knowledge regarding the complex nature of biochar, the scientific and technological impacts, and operational costs of different activation strategies are highly desirable for transforming biochar applications into industrial scales. This communication presents a comprehensive review of physical activation/modification strategies and their effects on the physicochemical properties of biochar and its applications in environment-related fields. Physical activation applied to the activation of biochar is discussed under three different categories: I) gaseous modification by steam, carbon dioxide, air, or ozone; II) thermal modification by conventional heating and microwave irradiation; and III) recently developed modification methods using ultrasound waves, plasma, and electrochemical methods. The activation results are discussed in terms of different physicochemical properties of biochar, such as surface area; micropore, mesopore, and total pore volume; surface functionality; burn-off; ash content; organic compound content; polarity; and aromaticity index. Due to the rapid increase in the application of biochar as adsorbents, the synergistic and antagonistic effects of activation processes on the desired application are also covered.