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Chitosan nanoparticles are a naturally derived substance with exceptional physicochemical properties and non-toxic bioactivity, making them suitable for extensive applications. This study evaluates and compares chitosan nanoparticles and chitosan nanoparticles incorporating antimicrobial agents. Copper ions were incorporated into chitosan matrices using a modified ionic gelation method to form a nano-coating solution. The particle size of chitosan nanoparticles (CN) was 118.23 ± 0.58 nm, and the particle size of chitosan nanoparticles loaded copper ions (CNCu) was 166.65 ± 7.36 nm, with low polydispersity index values and moderate to high zeta potential values. Scanning Electron Microscope (SEM) and Transmission Electron Microscopy (TEM) were used to determine their particle size and morphology. The antioxidant activity of chitosan nanoparticles and chitosan nanoparticles loaded with copper ions was also evaluated. CNCu exhibited superior antimicrobial activity against yeasts and molds. The results suggest CN and CNCu have great pre and post-harvest fruit preservation potential.

Bromelain, a proteolytic enzyme derived from pineapple waste, which accounts for more than two-thirds of the total volume of pineapples utilized, has gained significant attention in recent years. The employment of membrane technology has surfaced as a promising approach for the production of enzymes. A complete comprehension regarding the purification and preservation of bromelain enzymes is yet to be achieved. To address this gap, the present study aimed to extract and purify bromelain from pineapple waste to enhance the value of these by-products. The continuous microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and lyophilization system were optimized to enhance enzyme recovery and purity. The filtration process increased bromelain purity by 1.37-fold and achieved a 96.5 % enzyme recovery rate, indicating its effectiveness in separating bromelain from the pineapple crude extract. The highest activity of 3279.02 GDU/g was achieved through lyophilization, combined with 10 % of skim milk as a cryoprotectant. The product was detected and quantified using Liquid Chromatography with Refractive Index Detector (LC-RID). The combination of membrane and lyophilization processes could potentially separate bromelain from pineapple waste, with promising applications in biotechnology and the food industry.

Polymer films show the best versatility, low cost, and permeability in packaging purpose. On the contrary, these synthetic materials have a lengthy environmental half-life, cannot be broken down by natural microbes, and increase the formation of solid waste. The synthetic polymer polyvinyl alcohol (PVA) is completely dissolves in water and harmless. It has several uses, including controlled medication delivery systems, polymers recycling, film creation, and packaging. Using PVA and crystalline nanocellulose (CNC) as raw materials, PVA/CNC nanofiber membranes were prepared by solvent casting. Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Water vapor permeability (WVP), thermogravimetric analysis (TGA), and tensile strength were used to describe the characteristics of the film. The tensile strength of the PVA/CNC composite film improved significantly: with 2 % CNC content, the tensile strength 157.6 % increase compared to original PVA. The WVP of PVA markedly reduced 32.4 % after adding 4 % CNC. These properties are suitable for applications in various technologies such as food and packaging.

In this study, novel cobalt-doped carbon aerogels (Co-CA) are synthesized from jackfruit core via sequential steps of hydrothermal, impregnation, and pyrolysis. The aerogels show a uniform distribution of cobalt particles on the aerogel surface without any bunching regions. The large surface area of 160 m2/g and pore diameter of 10.5 nm are determined for the Co-CA by the Brunauer-Emmett-Teller equation and Barrett-Joyner-Halenda model. The as-fabricated Co-CA exhibit an excellent methylene blue (MB) degradation efficiency via a heterogeneous Fenton-like reaction in the presence of H2O2 and carbonate ions. While chloride (Cl-) and sulfate (SO42-) ions show insignificant changes in the MB degradation efficiency, the presence of carbonate (CO32-) and phosphate (PO43-) ions causes a great impact on the MB removal efficiency with the highest value of up to 90% when CO32- concentration is considerably low at 1 mM. Compared with the condition of only H2O2 in the environment, the addition of CO32- extensively increases the rate of MB degradation by recording the time of reaching the equilibrium state in only 15 min. The dye treatment efficiency is improved over the control condition (no inorganic anions) only when the CO32- concentration is low. At the anion concentrations of 10 mM or more, the MB degradation by Co-CA is hindered since the treatment efficiency is reduced. This study successfully develops functional Co-CA owning remarkable MB removal efficiency, indicating their great potential in dye-polluted wastewater management.

Durian (Durio zibethinus) fruit processing discards out waste shells, which accounts for more than 60 % by weight of the fruit into landfills, leading to serious issues regarding environmental pollution and public health risks. Despite the extensive research available on converting this biomass source into high carbon content biochar, little has been discussed on its susceptibility towards microbial degradation and fungal growth and the effects these contaminations may have on the obtained products. In this study, two types of durian shells, composted and non-composted types are collected by an evaluation of pretreatment conditions, and carbonised for recovery of biochar material. FTIR, SEM and TGA/DTG were utilised to show significant differences in the structure and thermal properties between the composted durian shell and the non-contaminated one. By making use of these differences, for the first time ever, novel briquetting methods of mechanically pressing at normal and elevated temperature were applied on composted shells to produce biochar fuels with varying shapes and combustion properties to suit different applications. A higher yield of more than 50 % with a higher fixed carbon content of up to 51 % could be attained without any need for a binding material from the composted material by the pressing method with incorporation of heat. The results from this research can encourage developing different approaches towards making use of source materials with recalcitrant structures for specific desirable properties.

Chitosan - the second most abundant polysaccharide on Earth has been known as a kind of non-toxic, environmentally friendly, biodegradable, antibacterial, and antifungal material. Compared with bulk chitosan-based materials, nanochitosan has superior properties in terms of permeability, solubility, and bioactivity. Nanochitosan is used as a carrier encapsulating various components via complexes with NH2 and OH groups of chitosan molecules to protect, stabilize, and deliver targeted bioactive compounds. For the first time, chitosan-zinc ion nanoparticles (CSZ NPs) have been successfully synthesized by ultrasound-assisted ionic gelation to produce much smaller particles with enhanced antibacterial and antifungal activities. The fabricated CSZ NPs have a diameter from 119.3 to 212.6 nm, polydispersity index ranging from 0.2 to 0.3, and zeta potential from 16.4 to 22.4 mV. The average size of the as-fabricated CSZ NPs is two times smaller than zinc ions loaded nanochitosan without ultrasonic treatment. The spherical shape of the nanochitosan particles is confirmed, along with a wide range of elemental distributions, including C (29.74 %), O (42.14 %), Na (15.80 %), and Zn (1.11 %). The antimicrobial activities of CSZ NPs are evaluated by using the agar well diffusion method with gram-negative bacteria (E. coli, P. aeruginosa), gram-positive (E. feacalis, S. aureus, S. aureus methicillin-resistant (MRSA)), and fungi (C. albicans, A. niger). The minimum inhibitory concentration of CSZ NPs is 14 µg/mL for bacteria and more than 58 µg/mL for fungi. CSZ NPs have potential antimicrobial applications in the food industry and agriculture.

Recently, oil spills have been received numerous concerns all over the world because of its harmful influences for ecosystem and human being. Various techniques are introduced to manage this kind of pollution, including physical adsorption by porous materials. Carbon aerogel is one of those promising materials because of its great potential in extremely fast oil adsorption without any emission of toxic compounds. Cigarette waste is one of the most littered things around the world that can be endanger for the environment. For the first time, carbon aerogels have been successfully fabricated via a simple pyrolysis of eco-friendly cellulose acetate-based aerogels from cigarette butts waste from the tobacco factory. The prepared ultralight carbon aerogels exhibit significantly low density (36.34-50.50 mg/cm3) and high porosity (98.39-97.76 %). The aerogel has highly porous structure with irregular shaped pore in range of 10 to 100 µm. Carbon aerogels express good hydrophobicity with water contact angles more than 120(. The oil adsorption capacity of carbon aerogels is up to 14-21 times their own weight within 40 s, which is significantly higher than original cellulose-based aerogels (11-14 times their own weight). The oil adsorption of carbon aerogel follows pseudo-second order kinetics which adsorbs quickly in few seconds and reaches equilibrium in less than 60 min. In conclusion, the carbon aerogels from cigarette butt-derived cellulose acetate exhibit a great potential in the field of oil spills treatment.

Lignin derived from rice straw, an abundant renewable feedstock in nature, has the potential to be utilized as a substitute for fossil fuels in the production of value-added aromatic derivatives. However, depolymerization becomes one of the most difficult obstacles in the lignin-to-valuable products conversions due to the structural complexity and recalcitrance of lignin. In this work, rice straw-derived lignin was depolymerized to aromatics by using the hydrothermal liquefaction method in the ethanol-water solvent under hydrogen pressure. Effects of various process parameters on yields such as reaction time, ethanol concentration, reaction temperature, initial hydrogen pressure, and solvent-to-lignin ratio, were investigated. The suitable conditions for the highest yield of oil products (~ 75 %) were determined to be 65 vol. % ethanol, 250 °C, 60 min, 20 bar of hydrogen, and the solvent-to-lignin ratio of 35 mL/g. The obtained oil products were characterized by gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared (FT-IR). The bio-oil was mainly aromatics such as phenol, 3-ethylphenol, guaiacol and had a heating value of 22.2 MJ/kg. Hydrothermal liquefaction was demonstrated as an appropriate method for lignin depolymerization into aromatic compounds with high production yields.

Depolymerization of lignin is an important step to obtain a lignin monomer for the synthesis of functional chemicals. In the context of more lignin produced from biomass and pulp industry, converting real lignin with low purity is still required more studies. In this study, the influence of solvent composition and reaction parameters such as binary solvents ratio, time, and temperature, the solvent-to-lignin ratio on the depolymerization of rice straw lignin was investigated carefully. Essential lignin-degraded products including liquid product (LP), char (solid), and gas were obtained, and their yields were directly influenced by reaction conditions. Results show that the maximum lignin conversion rate of 92% and LP yield of 66% was under the condition of 275°C, 30 min, 75 : 1 (mL solvent/1 g lignin), and ethanol 50%. Gas chromatography-mass spectroscopy (GC-MS) analysis was used for the analysis of the depolymerization products and identified 11 compounds which are mainly phenolic compounds such as 2-ethylphenol, 3-ethylphenol, phenol, methyl 2,4,6-trimethylbenzoate. The structure changes of LP and char in various conditions were analyzed using Fourier-transform infrared (FTIR).

Each year, the global annual production of coconut fibre (CF) is around 350×103 t, while they are utilized for fine art, fertilization, and animal feed. However, there have not seen many engineering applications to utilize these materials. The coir with high cellulose content of over 40 % has potential for high-value engineering applications like fabricating cellulose-based aerogels. Recently, the cellulose aerogel from CF was formed using a sol-gel method in an NaOH/Urea solution, with an anticipated completion time of 7 d due to the time required for gelation and solvent exchange, which might take up to 4 d. This demonstrates that the present approach is subject to several time limitations. To improve this, for the first time, a novel fabrication of aerogels from the CF with chemical pre-treatment in advance has been successfully developed by using polyvinyl alcohol (PVA) and xanthan gum (XTG) as biodegradable binders. The treated CFs are dispersed homogeneously into a PVA/XTG solution, followed by freeze-drying to remove water, leaving behind a highly porous called CF aerogel. The influences of CF content on CF aerogels' physical and mechanical characteristics, as well as oil adsorption and thermal conductivity, have all been thoroughly investigated. For oil removal, the fabricated CF aerogels are surface-modified with methyltrimethoxysilane (MTMS) to enhance their hydrophobicity. This method required 2 times less time and used fewer chemicals while retaining the same oil adsorption capabilities of up to 20 g/g as previous CF aerogel and demonstrating additional good insulation of 0.040 W/(m·K). Thus, this study provides a new novel approach to synthesize an oil-absorbing and insulating CF aerogel.