Extraction and surface modification of cellulose fibers and its reinforcement in starch-based film for packaging composites.

BACKGROUND: Cellulose extraction from gloss art paper (GAP) waste is a recycling strategy for the abundance of gloss art paper waste. Here, a study was conducted on the impact of ultrasonic homogenization for cellulose extraction from GAP waste to improve the particle size, crystallinity, and thermal stability. RESULTS: At treatment temperature of 75.8 °C, ultrasonic power level of 70.3% and 1.4 h duration, cellulose with properties of 516.4 nm particle size, 71.5% crystallinity, and thermal stability of 355.2 °C were extracted. Surface modification of cellulose GAP waste with H3PO4 hydrolysis and 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO) oxidation was done followed by starch reinforcement. Surface hydrophobicity and mechanical strength were increased for H3PO4 hydrolysis and TEMPO oxidation starch-cellulose. No reduction of thermal properties observed during the treatment, while increment of crystallinity index up to 47.65-59.6% was shown. Neat starch film was more transparent, followed by starch-TEMPO film and starch-H3PO4 film, due to better homogeneity. CONCLUSIONS: The cellulose GAP reinforced starch film shows potential in developing packaging materials and simultaneously provide an alternative solution of GAP waste recycling.

Enhanced crystallinity and thermal properties of cellulose from rice husk using acid hydrolysis treatment.

Cellulose was extracted from rice husk (RH) using an integrated delignification process using alkaline treatment and acid hydrolysis (concentrated HNO3) for lignocellulosic biomass dissolution. Cellulose yield and quality were assessed through analysis of lignocellulosic content, thermogravimetric, functional group, X-ray diffraction, and surface morphology. HNO3 treatment showed an increment (2.01-fold) in the cellulose content and some enhancement in the crystallinity of cellulose (up to 40.8%). A slight increase was observed in thermal properties from 334.6 °C to 339.3 °C. Economic analysis showed chlorine extraction produce higher cellulose recovery (58%) as compared to HNO3 (26.7%) with the total cost of operation using HNO3 was double compared to chlorine extraction. The economic feasibility of HNO3 can be improved using various progress in the pre-treatment process, chemical recycling and cellulose recovery process since adopting it is crucial for environmental sustainability.

Enhancement of biomass yield and lipid accumulation of freshwater microalga Euglena gracilis by phenolic compounds from basic structures of lignin.

Introducing biomass-derived additives into microalgae cultivation to increase its yield has been regarded as a more cost-effective and environment-friendly method compared with gene-editing and nutrients supplementation. In this research, feasibility of three major phenolic compounds from lignin's basic structures (guaiacyl-, hydroxyphenyl- and syringyl- types) for freshwater microalga Euglena gracilis cultivation was evaluated. The results indicated that trans-4-hydroxy-3-methoxycinnamic acid (HMA), 4-hydroxybenzaldehyde (HBA), and syringaldehyde (SRA) could all promote microalgae growth in a phytohormone-like role, and the highest promotion effect was achieved under HMA treatment. HMA at 0.5 g·L-1 enhanced the cell biomass yield by 2.30 times, while HBA and SRA at the concentration of 0.1 g·L-1 increased the yield by 1.30 and 1.21 times, respectively. In addition, increased carotenoids and lipid biosynthesis were also observed under the treatments of phenolic compounds, which would contribute to the microalgae biofuel production, since the growth and lipid accumulation of E. gracilis were simultaneously enhanced.

Oil palm fiber biodegradation: physico-chemical and structural relationships.

MAIN CONCLUSION: X-ray microtomography results revealed that delignification process damaged the oil palm fibers, which correlated well with reduction of lignin components and increase of the phenolic content. Biodegradation investigation of natural fibers normally focuses on physico-chemical analysis, with less emphasis on physical aspect like fiber structures affect from microbial activity. In this work, the performance of Pycnoporus sanguineus to delignify oil palm empty fruit bunch fibers through solid-state fermentation utilizing various ratio of POME sludge was reported. In addition to tensile testing, physico-chemical and X-ray microtomography (µ-CT) analyses on the oil palm fibers were conducted to determine the effectiveness of the degradation process. The best ratio of fiber to fungi (60:40) was chosen based on the highest lignin loss and total phenolic content values and further investigation was performed to obtain fermentation kinetics data of both laccase and manganese peroxidase. µ-CT results revealed that delignification process damaged the pre-treated and untreated fibers structure, as evident from volume reduction after degradation process. This is correlated with reduction of lignin component and increase of the phenolic content, as well as lower stress-strain curves of the pre-treated fibers compared to the untreated ones (from tensile testing). It is suggested that P. sanguineus preferred to consume the outer layer of the fiber, before it penetrates through the cellular structure of the inner fiber.

Over production of fermentable sugar for bioethanol production from carbohydrate-rich Malaysian food waste via sequential acid-enzymatic hydrolysis pretreatment.

In Malaysia, the amount of food waste produced is estimated at approximately 70% of total municipal solid waste generated and characterised by high amount of carbohydrate polymers such as starch, cellulose, and sugars. Considering the beneficial organic fraction contained, its utilization as an alternative substrate specifically for bioethanol production has receiving more attention. However, the sustainable production of bioethanol from food waste is linked to the efficient pretreatment needed for higher production of fermentable sugar prior to fermentation. In this work, a modified sequential acid-enzymatic hydrolysis process has been developed to produce high concentration of fermentable sugars; glucose, sucrose, fructose and maltose. The process started with hydrothermal and dilute acid pretreatment by hydrochloric acid (HCl) and sulphuric acid (H2SO4) which aim to degrade larger molecules of polysaccharide before accessible for further steps of enzymatic hydrolysis by glucoamylase. A kinetic model is proposed to perform an optimal hydrolysis for obtaining high fermentable sugars. The results suggested that a significant increase in fermentable sugar production (2.04-folds) with conversion efficiency of 86.8% was observed via sequential acid-enzymatic pretreatment as compared to dilute acid pretreatment (∼42.4% conversion efficiency). The bioethanol production by Saccharomyces cerevisiae utilizing fermentable sugar obtained shows ethanol yield of 0.42g/g with conversion efficiency of 85.38% based on the theoretical yield was achieved. The finding indicates that food waste can be considered as a promising substrate for bioethanol production.

Enhanced fermentable sugar production from kitchen waste using various pretreatments.

The kitchen waste fraction in municipal solid waste contains high organic matter particularly carbohydrate that can contribute to fermentable sugar production for subsequent conversion to bioethanol. This study was carried out to evaluate the influence of single and combination pretreatments of kitchen waste by liquid hot water, mild acid pretreatment of hydrochloric acid (HCl) and sulphuric acid (H2SO4) and enzymatic hydrolysis (glucoamylase). The maximum total fermentable sugar produced after combination pretreatment by 1.5% HCl and glucoamylase consisted of 93.25 g/L glucose, 0.542 g/L sucrose, 0.348 g/L maltose, and 0.321 g/L fructose. The glucose released by the combination pretreatment method was 0.79 g glucose/g KW equivalent to 79% of glucose conversion. The effects of the pre-treatment on kitchen waste indicated that the highest solubilization was 40% by the combination method of 1.5% HCl and glucoamylase. The best combination pre-treatment gave concentrations of lactic acid, acetic acid, and propionic acid of 11.74 g/L, 6.77 g/L, and 1.02 g/L, respectively. The decrease of aliphatic absorbance bands of polysaccharides at 2851 and 2923 cm(-1) and the increase on structures of carbonyl absorbance bands at 1600 cm(-1) reflects the progress of the kitchen waste hydrolysis to fermentable sugars. Overall, 1.5% HCl and glucoamylase treatment was the most profitable process as the minimum selling price of glucose was USD 0.101/g kitchen waste. Therefore, the combination pretreatment method was proposed to enhance the production of fermentable sugar, particularly glucose from kitchen waste as the feedstock for bioethanol production.