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Engineering and Applied Science Research, 49, 5, 707-719

The production and characterisation of pellets made from green tea waste from the ready-to-drink industry is investigated in this study. Physical and energetic characterisation of pellets including the length, diameter, proximate analysis (moisture, ash, volatile matter and fixed carbon content), pellet density, bulk density, calorific value, durability, compressive strength and thermogravimetric analysis were carried out to determine the quality of the bio-based fuel pellets. Pellet properties were assessed against comparison with the established Thailand and European standards. Pellet making was conducted with a hydraulic press without binder resulting in pellets with 2 diameters, 7 and 10 mm, and lengths of about 9.5 and 9.8 mm, respectively. The interesting characteristics of these biopellets were the moisture content of 8.78 – 8.82 wt%, the ash of 3.52 – 3.65 wt%, the bulk density of 586 – 603 kg/m3 and higher heating value of 19.18 – 19.86 MJ/kg. In addition, the pellets produced with both diameters had properties that complied with the standards except for the bulk density of large pellets which were slightly lower. The durability of the 7 mm diameter pellets was 90.2% while 10 mm pellet was 95.6%, which a bit lower than standard value (≥ 96%). The pellet’s compressive strengths in vertical direction were much higher than horizontal direction for both diameter pellets. These results suggest that this biomass waste was suitable for alternative fuel applications and has the potential to be developed as a commercial pellet.

The preparation of fuel pellets from the filter cake waste from the sugar industry was studied. Pelletization by a hydraulic press at a pressure of 20 to 50 bar (2 to 5 MPa) was used to produce fuel pellets with a diameter of 1 cm and height of 1. 25 cm. Energy efficiency of the resulting pellets was improved by thermal treatment called “torrefaction”. During this process, the samples were heated to between 200 and 300°C for 0.5 to 2 h under a nitrogen atmosphere. The properties of fuel pellets including calorific value, bulk density, pellet density, proximate analysis, and compressive strength were characterized. The results demonstrated that the minimum pressure needed to produce the pellets without binder was 30 bar. The calorific value was between 13,954–14,468 kJ/ kg for the resulting fuel pellet, which was significantly higher than that of the unpelletized raw material (11,197 kJ/ kg). The fuel pellets had bulk density and pellet density of between 300–440 kg/m3 and 720–890 kg/m3, respectively. Increasing the time and temperature of torrefaction resulted in the lower yields of pellets. Fuel pellets maintain their shape and did not break under the applied torrefaction conditions. Torrefied pellets resulted in higher calorific value of 16,552–22,642 kJ/kg, higher carbon content, lower pellet and bulk densities compared to the fuel pellet without thermal treatment. The compressive strength of torrefied pellets decreased due to the delicate nature of the sample. The suggested conditions for optimal torrefied pellet in thermal and physical properties are 300°C and 1 h. The prepared fuel pellets showed comparable heating values to other fuels, and had properties in agreement with Thailand standards. Therefore, filter cake as a solid waste from production process of sugar has potential as raw material for the production of solid fuel pellets.

Short chain alkenyl succinimides (ASIs) were synthesised and used as high purity chemical models to investigate the autoxidative degradation at 170 oC of polyisobutenyl succinimide dispersants (PIBSIs), a significant additive in automotive engine lubricants. Degradation products were characterised by GC-EI-MS and quantified by GC-FID. The rate of autoxidation of ASIs in a model lubricant, squalane, was also investigated. Although this is a complex molecule containing many possible sites of radical attack, all of the autoxidation products identified result from attack at the double bond or the adjacent allylic hydrogen atoms, which indicates the controlling influence of the double bond in the degradation of alkenyl succinimides, and therefore of commercial polyisobutenyl succinimide dispersants. The observed site-selective cleavage of the ASI structure, and by analogy PIBSI dispersants, would yield products that both reduce dispersancy and promote the formation of insoluble products that could have a detrimental effect on lubricant performance.

A new strategy for the synthesis of mesoporous TiO2@C nanocomposites through the direct mineralization of seaweed-derived alginic acid cryogel by TiCl4 through a solid/vapor reaction pathway is presented. In this synthesis, alginic acid cryogel can have multiple roles; i) mesoporous template, ii) carbon source, and iii) oxygen source for the TiO2 precursor, TiCl4. The resulting TiO2@alginic acid composite was transformed either into pure mesoporous TiO2 by calcination or into mesoporous TiO2@C nanocomposites by pyrolysis. By comparing with a nonporous TiO2@C composite, the importance of the mesopores on the performance of electrodes for lithium-ion batteries based on mesoporous TiO2@C composite was clearly evidenced. In addition, the carbon matrix in the mesoporous TiO2@C nanocomposite also showed electrochemical activity versus lithium ions, providing twice the capacity of pure mesoporous TiO2 or alginic acid-derived mesoporous carbon (A600). Given the simplicity and environmental friendliness of the process, the mesoporous TiO2@C nanocomposite could satisfy the main prerequisites of green and sustainable chemistry while showing improved electrochemical performance as a negative electrode for lithium-ion batteries.

Eco-friendly and cheap lithium ion battery electrode processing using a seaweed-derived mesoporous carbon additive (Starbon® A800) and binder (sodium alginate) was elaborated for LiMn2O4 (LMO) and LiNi1/3Mn1/3Co1/3O2 (NMC) lithium ion batteries. Compared to electrodes made using conventional formulations (i.e. Super P/PVDF) the 'green' electrodes can provide significantly 'upgraded' reversible capacity, almost reaching their theoretical capacity at low C-rate, likely due to good accessibility of lithium ions via the mesopores of the carbon additive. In addition, a synergistic effect was observed for a binary carbon additive system composed of Starbon® A800 with conventional carbon black (Super P), improving both the initial capacity and the rate capability of LMO and NMC electrodes.

Depolymerisation of cellulose is a critical step for biomass-based bio-refining processes to produce valuable chemicals. Herein, we propose the mechanism of the promoting effect of NaCl on the cellulose hydrolysis process based on a systematic kinetic study involving variable temperature studies and the use of deuterated agents. It has been found that the presence of NaCl simultaneously enhances the generation of acidic products from cellulose decomposition and pushes the generated protons to the surface of cellulose, dramatically increasing surface acidity and facilitating the autocatalytic hydrolysis of cellulose. Cl - disrupted the intermolecular hydrogen bonding of cellulose, especially in the first surface layer. Thus, the solid cellulose chains were peeled off layer-by-layer, leading to an accelerated hydrolysis of cellulose by the adsorbed protons. Without the need for traditional acidic catalysts, this autocatalytic depolymerisation of cellulose in water, assisted by salt provides a practically viable route to the enhanced conversion of biomass to chemicals.

The addition of water to dihydrolevoglucosenone (Cyrene) creates a solvent mixture with highly unusual properties and the ability to specifically and efficiently solubilize a wide range of organic compounds, notably, aspirin, ibuprofen, salicylic acid, ferulic acid, caffeine, and mandelic acid. The observed solubility enhancement (up to 100-fold) can be explained only by the existence of microenvironments mainly centered on Cyrene’s geminal diol. Surprisingly, the latter acts as a reversible hydrotrope and regulates the polarity of the created complex mixture. The possibility to tune the polarity of the solvent mixture through the addition of water, and the subsequent generation of variable amounts of Cyrene’s geminal diol, creates a continuum of green solvents with controllable solubilization properties. The effective presence of microheterogenieties in the Cyrene/water mixture was adequately proven by (1) Fourier transform infrared/density functional theory showing Cyrene dimerization, (2) electrospray mass-spectrometry demonstrating the existence of dimers of Cyrene’s geminal diol, and (3) the variable presence of single or multiple tetramethylsilane peaks in the 1H NMR spectra of a range of Cyrene/water mixtures. The Cyrene–water solvent mixture is importantly not mutagenic, barely ecotoxic, bioderived, and endowed with tunable hydrophilic/hydrophobic properties., Cyrene−water generates a continuum of green solvents with controllable solubilization properties centered on Cyrene’s geminal diol, making the solvent nonmutagenic, barely ecotoxic, and bioderived.