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This study aims to identify suitable processing conditions for converting pyrolytic solid residue from off-the-road tyres (OTR) to improve carbon materials properties that can be used in multiple applications and the recovery of minerals from OTR. Pyrolysis of OTR at 800 °C and a heating rate 2 °C.min

Hydrothermal liquefaction (HTL) of wet biomass waste (e.g., from anaerobic digestion (AD) digestate) is an efficient technology to produce bio-crude, a hydrocarbon based renewable fuel. However, the solid waste by-product has limited use and could be an environmental nuisance if not managed appropriately. Herein, we demonstrate a sustainable way of transforming the solid residue generated through HTL of AD of sugarcane bagasse digestate into potential electrodes for lithium-ion battery (LIB). Briefly, the solid residue from the HTL process was converted into hard carbon (HC@WA) or converted through KOH activation to a carbon with a higher specific surface area carbon material (HC@AA). The structural and morphological characterizations confirm the encapsulation of SiO2 nanoparticles in the carbon matrix to form composite materials. When employed as anode materials in LIB, HC@WA and HC@AA achieve specific capacities of 452 mAh/g and 319 mAh/g respectively, and with long term cycling stability. The practical feasibility of the electrode materials was assessed by fabricating full cells with commercial LiFePO4 (LFP) cathode material. The full cells delivered good specific capacities and cycling stabilities, confirming the potential of the composite materials as electrodes for LiB. Thus, the solid residue after HTL of AD digestate could be one of the sustainable sources to develop materials for energy storage systems, thereby paving the way towards zero-waste and clean energy for a circular economy.

Biomass-derived carbon catalysts have been extensively studied for the dehydration of sugars to platform chemical 5-hydroxymethyl furfural (HMF), which can be used to produce valuable chemicals and fuels. However, only limited studies have been conducted to determine their carbon molecular structures and how these influence the conversion process. Here, we prepare a chlorosulfonated carbon catalyst derived from cotton gin trash (CGT) at 400 °C for the dehydration of fructose to produce 5-hydroxymethyl furfural (HMF) in the ionic liquid, 1-butyl-3-methyl-imidazolium chloride ([BMIM]Cl). The highly efficient chlorosulfonated carbon catalyst consisting of 3 aromatic layers of furanic, phenolic rings and aliphatic–aromatic carbon structures with –COOH, phenolic OH, -SO3-, and -SO3H functional groups were found to have a similar performance as the commercial catalyst, Amberlyst-15. The carbon material was reused 5 times without loss of catalytic activity. The formation of the sugar intermediate, 3,4-dihydroxy-5-hydroxymethyl-tetrahydrofuran-2-carbaldehyde may be related to –COOH and phenolic OH groups forming hydrogen bonds with fructose, and the adsorption of fructose onto the graphitized sp2 internal carbon regions where interactions with the defects in the carbon material occur.

Achieving the goal of living in a sustainable and greener society, will need the chemical industry to move away from petroleum-based refineries to bio-refineries. This aim can be achieved by using biomass as the feedstock to produce platform chemicals. A platform chemical, 2,5-furandicarboxylic acid (FDCA) has gained much attention in recent years because of its chemical attributes as it can be used to produce green polymers such polyethylene 2,5-furandicarboxylate (PEF) that is an alternative to polyethylene terephthalate (PET) produced from fossil fuel. Typically, 5-(hydroxymethyl)furfural (HMF), an intermediate product of the acid dehydration of sugars, can be used as a precursor for the production of FDCA, and this transformation reaction has been extensively studied using both homogeneous and heterogeneous catalysts in different reaction media such as basic, neutral, and acidic media. In addition to the use of catalysts, conversion of HMF to FDCA occurs in the presence of oxidants such as air, O2, H2O2, and t-BuOOH. Among them, O2 has been the preferred oxidant due to its low cost and availability. However, due to the low stability of HMF and high processing cost to convert HMF to FDCA, researchers are studying the direct conversion of carbohydrates and biomass using both a single- and multi-phase approach for FDCA production. As there are issues arising from FDCA purification, much attention is now being paid to produce FDCA derivatives such as 2, 5-furandicarboxylic acid dimethyl ester (FDCDM) to circumvent these problems. Despite these technical barriers, what is pivotal to achieve in a cost-effective manner high yields of FDCA and derivatives, is the design of highly efficient, stable, and selective multi-functional catalysts. In this review, we summarize in detail the advances in the reaction chemistry, catalysts, and operating conditions for FDCA production from sugars and carbohydrates.

Carbon quantum dots (CQDs, C-dots or CDs) are an emerging type of nanomaterial which has received immense attention due to their numerous applications. However, most of the reported CQDs in literature typically emit single emission peak under an excitation. Multipeak emissions without any complicated techniques will be ideal for various applications in the fields of ratiometric sensing, optoelectronics, and multifunctional bio-imaging systems. Here, a fast, effective, and single-step method is developed for the bulk synthesis of CQDs using atmospheric pressure air plasmas. Structural, morphological, and chemical properties are characterized by advanced analytical techniques. The CQDs have an average diameter of about 3 nm with a narrow size distribution. Emission wavelengths of 470 nm for blue emissive CQDs and 515 nm for green emissive CQDs are observed. Concentration dependency of the CQDs suggests that the switchable mechanism is due to the formation of PTSA excimers. Dual-emissive CQDs have the potential to be used in bi-channel ratiometric determination for metal ions, pH sensing, tumor diagnosis and detection, and solid-state lighting materials. The proof-of-principle demonstration of the use of dual-emissive CQDs (DCQDs) as a fluorescent sensor of Cu2+ ions is also presented to highlight the possible applications Refereed/Peer-reviewed

This paper investigates the carbonization of cotton gin trash (CGT) into carbon structures shaped under the influence of different operating conditions including the impact of endogenous fatty acids impurities present in CGT. As expected, both KOH activation and high carbonization temperature increase the material surface area and porosity. Furan and arene groups are formed from 400 °C to 800 °C but the proportion of the furan groups are highest at 600 °C. This is due to the conversion of the fatty acids in CGT to furan units. XRD data reveals the presence of three aromatic layers at 400 °C, followed by structural rearrangement to the formation of five stacks aromatic layers at 800 °C consisting mainly of protonated and non-protonated condensed arene groups. Interestingly, a reduction in the number of aromatic structures is observed if no acid pretreatment of CGT to remove inorganic impurities is conducted prior to pyrolysis to 600 °C. Two potential applications of the synthesised carbons are shown; one for the formation of 5-hydroxymethylfurfural (80%) from fructose, which compares favorably to other porous carbon materials produced under harsher conditions, and another derived CGT carbon material which shows a good uptake of hydrogen for storage.