Showing papers on "Pyrolysis published in 2022"

Biochar for the removal of contaminants from soil and water: a review

Abstract: Abstract Biochar shows significant potential to serve as a globally applicable material to remediate water and soil owing to the extensive availability of feedstocks and conducive physio-chemical surface characteristics. This review aims to highlight biochar production technologies, characteristics of biochar, and the latest advancements in immobilizing and eliminating heavy metal ions and organic pollutants in soil and water. Pyrolysis temperature, heat transfer rate, residence time, and type of feedstock are critical influential parameters. Biochar’s efficacy in managing contaminants relies on the pore size distribution, surface groups, and ion-exchange capacity. The molecular composition and physical architecture of biochar may be crucial when practically applied to water and soil. In general, biochar produced at relatively high pyrolysis temperatures can effectively manage organic pollutants via increasing surface area, hydrophobicity and microporosity. Biochar generated at lower temperatures is deemed to be more suitable for removing polar organic and inorganic pollutants through oxygen-containing functional groups, precipitation and electrostatic attraction. This review also presents the existing obstacles and future research direction related to biochar-based materials in immobilizing organic contaminants and heavy metal ions in effluents and soil. Graphical Abstract

Biochar for agronomy, animal farming, anaerobic digestion, composting, water treatment, soil remediation, construction, energy storage, and carbon sequestration: a review

Abstract: In the context of climate change and the circular economy, biochar has recently found many applications in various sectors as a versatile and recycled material. Here, we review application of biochar-based for carbon sink, covering agronomy, animal farming, anaerobic digestion, composting, environmental remediation, construction, and energy storage. The ultimate storage reservoirs for biochar are soils, civil infrastructure, and landfills. Biochar-based fertilisers, which combine traditional fertilisers with biochar as a nutrient carrier, are promising in agronomy. The use of biochar as a feed additive for animals shows benefits in terms of animal growth, gut microbiota, reduced enteric methane production, egg yield, and endo-toxicant mitigation. Biochar enhances anaerobic digestion operations, primarily for biogas generation and upgrading, performance and sustainability, and the mitigation of inhibitory impurities. In composts, biochar controls the release of greenhouse gases and enhances microbial activity. Co-composted biochar improves soil properties and enhances crop productivity. Pristine and engineered biochar can also be employed for water and soil remediation to remove pollutants. In construction, biochar can be added to cement or asphalt, thus conferring structural and functional advantages. Incorporating biochar in biocomposites improves insulation, electromagnetic radiation protection and moisture control. Finally, synthesising biochar-based materials for energy storage applications requires additional functionalisation.

Surface carbon layer controllable Ni3Fe particles confined in hierarchical N-doped carbon framework boosting oxygen evolution reaction

Abstract: Developing high-efficiency and low-cost catalysts towards oxygen evolution reaction (OER) is extremely important for overall water splitting and rechargeable metal−air batteries. Herein we propose a promising organometallic coordination polymer (OCP) induced strategy to construct hierarchical N-doped carbon framework with NiFe nanoparticles encapsulated inside (N x Fe@N–C) as a highly active and stable OER catalyst. The synthesis of OCP precursor depends on the unique molecular structure of iminodiacetonitrile (IDAN), which can coordinate with metal ions to form Ni 2 Fe(CN) 6 with prussian blue analogs (PBA) structure. Unlike previous PBA-induced methods, the thickness of the carbon layer covering the surface of the metal core can be well controlled during the pyrolysis through adjusting the amount of IDAN, which builds a wonderful bridge for investigating the relationship between carbon layer thickness and catalytic performance. Both the experimental characterizations and theoretical studies validate that a suitable carbon layers thickness leads to optimal OER activity and stability. By optimizing the structure and composition, the optimized Ni 3 Fe@N–C with hierarchical framework exhibits the low overpotentials (260 ​mV at 10 ​mA ​cm −2 ; 320 ​mV at 50 ​mA ​cm −2 ), improved kinetics (79 ​mV dec −1 ), and robust long-term stability, which exceeds those of benchmark RuO 2 . • Iminodiacetonitrile and metal ions are coordinated to form Ni 2 Fe(CN) 6 ) prussian blue analogues. • Hierarchical Ni 3 Fe@N–C framework can be formed through the direct pyrolysis of Ni 2 Fe(CN) 6 ). • Thickness of carbon layer covered on Ni 3 Fe can be well controlled by adjusting IDAN amount. • Hierarchical Ni 3 Fe@N–C framework presents excellent electrocatalytic performance for the OER. • OER improvement mechanism is clarified through the experiment and theoretical combination.

Application of biochar-based photocatalysts for adsorption-(photo)degradation/reduction of environmental contaminants: mechanism, challenges and perspective

Abstract: Abstract The fast increase of population results in the quick development of industry and agriculture. Large amounts of contaminants such as metal ions and organic contaminants are released into the natural environment, posing a risk to human health and causing environment ecosystem problems. The efficient elimination of contaminants from aqueous solutions, photocatalytic degradation of organic pollutants or the in-situ solidification/immobilization of heavy metal ions in solid phases are the most suitable strategies to decontaminate the pollution. Biochar and biochar-based composites have attracted multidisciplinary interests especially in environmental pollution management because of their porous structures, large amounts of functional groups, high adsorption capacities and photocatalysis performance. In this review, the application of biochar and biochar-based composites as adsorbents and/or catalysts for the adsorption of different contaminants, adsorption-photodegradation of organic pollutants, and adsorption-(photo)reduction of metal ions are summarized, and the mechanism was discussed from advanced spectroscopy analysis and DFT calculation in detail. The doping of metal or metal oxides is the main strategy to narrow the band gap, to increase the generation and separation of photogenerated e − -h + pairs, to produce more superoxide radicals (·O 2 − ) and hydroxyl radicals (·OH), to enhance the visible light absorption and to increase photocatalysis performance, which dominate the photocatalytic degradation of organic pollutants and (photo)reduction of high valent metals to low valent metals. The biochar-based composites are environmentally friendly materials, which are promising candidates in environmental pollution cleanup. The challenge and perspective for biochar-based catalysts are provided in the end. Graphical Abstract

Biochar derived from non-customized matamba fruit shell as an adsorbent for wastewater treatment

Abstract: This study of Matamba shell reviled them as material with outstanding surface morphology, elemental and kinetic mechanism characteristics. Mutamba biochar revealed irregular honeycomb morphological transformation from the field emission scanning electron microscope after pyrolysis at 600 °C for 2 h. Energy dispersive X-ray spectroscopy revealed high content of carbon (72.68wt%), nitrogen (14.14wt%) and oxygen (10.35wt%) on the biochar surface. The available oxygen composition provides enough polarization ability for high iodine adsorption (43.65 mmol/g) from the experimental data which were significantly induced by weak van der Waals forces and π-π and π-stacking interaction on the biochar surface and its micropores. The carbon content above 50% in ash rich biochar with an increase in pyrolysis can be ascribed to elements incorporated into aromatic or heterocyclic ring system established through preferential loss of oxygen at 600 °C pyrolysis. The adsorption kinetics were conducted to evaluate the equilibrium adsorption of the novel material and Elovich and Intra particle diffusion better described well the kinetic adsorption through Iodine adsorption than pseudo first order and pseudo second order models. Elovich was the best model to fit the adsorption kinetics with 45.41 mmol/(g•min) adsorption rate. The second order Akaike Information Criterion (38.26), adjusted correlation coefficient R2 (0.9898) and sum of squares error (1.442) were used to fit the data. Consequently, the biochar in this study can serve as a promising green material for efficiently removing organic and inorganic contaminants from the environmental water ecosystem. The environmental significance of biochar will be of fundamental meaning to rural areas in developing countries in aquatic contaminants immobilization for water reuse. These results indicate that the Matamba fruit shells has the possibility to be used as an eco-friendly and low-cost effective adsorbent for anionic dye removal from the water environment. They also demonstrate the immense potential of the fruit shell waste to produce high performance biochar as an alternative green carbonaceous material that can be applied to adsorb organic and inorganic unwanted constituencies from wastewater as well as improvement of waste management in developing countries at a low cost. Its application as a pathway mitigation for diminishing greenhouse gasses and reducing the global warming potential could not be underestimated.

Characteristics and evolution of heavy components in bio-oil from the pyrolysis of cellulose, hemicellulose and lignin

Abstract: Three main components of biomass were pyrolyzed individually in a closed reaction system at 500–700 °C for 60s and 90s. Then bio-oil heavy compounds were further analyzed with Fourier transform-ion cyclotron resonance-mass spectrometry (FT-ICR-MS) and Kendrick mass defect (KMD) analysis. The evolution paths of heavy compounds for the different pyrolysis stages were proposed. It was found that the sugars and phenolic-like species in heavy compounds were the most active substances during secondary reactions. Moreover, the rising temperature promoted this secondary reaction of phenolic-like species as the decrease in their abundances growing from 13% to 54%, while contrarily inhibited it for hemicellulose as the decrease in their abundances changing from 44% to −2%. The lignin-derived lipids and unsaturated hydrocarbons that generated in the secondary reactions increased with rising temperature. KMD analysis showed that the heavy compounds of cellulose and hemicellulose prefer homologous evolution during pyrolysis, while those of lignin had more complex evolution paths like cracking and recombination.