Acetic Research Articles

Biowaste management by hydrothermal carbonization and anaerobic co-digestion: Synergistic effects and comparative metagenomic analysis

The feasibility of anaerobic co-digestion in semicontinuous mode of two major urban biowaste, food waste (FW) and garden and park waste (GPW) (75 % FW and 25 % GPW) as well as the co-digestion of FW with the process water originated from the hydrothermal carbonization of GPW (95 % FW and 5 % process water), both on a COD basis, has been assessed. The effect of varying organic loading rate (OLR) from 1.5 to 3.5 g COD/L·d on methane yield, gross energy recovery, and microbiome population was evaluated. For comparison, anaerobic digestion of FW was also conducted to determine the best strategy for sustainable biowaste management. This study showed an optimal OLR of 2.5 g COD/L·d. Acetic and propionic acid content increased as OLR raised for each condition studied, while methane yield decreased at the highest OLR tested indicating overloading of the system. The anaerobic co-digestion of FW and process water showed a 10 % increase on methane production compared to anaerobic digestion of FW (324 vs. 294 mL CH4 STP/L·d). Moreover, it enhances the process due to a greater abundance and diversity of hydrolytic and acidogenic bacteria belonging to Bacterioidota, Firmicutes, and Chloroflexi phyla, as well as promotes the hydrogenotrophic pathway under higher propionic concentrations which is not usually favoured for methane production. The integration of hydrothermal carbonization of GPW with the anaerobic co-digestion of 95 % FW and 5 % of process water results in the highest potential energy recovery and could be a good strategy for sustainable management of urban biowaste.

Use of a hydrotalcite isopropanol dispersion for deacidification and preservation of cellulose cultural heritage objects - Preliminary study

Preservation of cellulose cultural objects, particularly books, is a field of research with about 100 years of history. The most dangerous in terms of their lifespan is the use of acidic wood-based paper which represents a problem in both quality and durability. Acid hydrolysis of polymeric cellulose chains is a key factor responsible for loss of visual appearance quality and mechanical strength. Sulphate and aluminium ions together with generated formic, acetic, and other higher carboxylic acids accelerate the rate of degradation catalytically as well as autocatalytically. Alkaline species (alkali and alkali earth hydrogen carbonates, oxides, organocompounds, and amines) suppress the degradation processes. This paper refers to the utilisation of hydrotalcites (HT, MgxAl2(OH)2x+4CO3, x > 6) as deacidifying agents in a non-halogenated low toxic carrier – isopropanol. Preparation of an HT dispersion, its characterisation, and application to (acidic) test paper are described. Due to its ion exchange and neutralization capabilities, HT increased pH of test papers from about 4 to at least 6. Similarly to the action of HT as antacids, it is possible to suppose the neutralizing capability in deacidifying of aged-acid papers, even at pH lower than 7. A higher increase of pH was achieved only with extremely high loadings of HT; 16 g / m2 allowed to reach a surface pH value equal to 7.8. Both the optical properties and mechanical strength of treated samples were improved at loadings up to 3 g / m2.

Control of Microcystis aeruginosa by Daphnia: Experimental evidence and identification of involved infochemicals.

Infochemicals refer to chemicals responsible for information exchange between organisms. We evaluated the effects of Daphnia magna and Daphnia galeata infochemicals on Microcystis aeruginosa for 15d. The Daphnia infochemicals were obtained from spent medium after culturing Daphnia in Elendt M4 medium for 48 h. Both Daphnia infochemicals significantly increased (p <0.05) the intracellular reactive oxygen species level and microcystin-LR concentration in M. aeruginosa. This cellular effect increased colony formation of M. aeruginosa, thereby inhibiting the growth of M. aeruginosa. D. galeata infochemicals provoked significantly greater (p <0.05) adverse effects on M. aeruginosa than those of D. magna infochemicals, which were further exaggerated by pre-exposure of Daphnia to M. aeruginosa. This result seems to be related to the different compositions and concentrations of Daphnia infochemicals. Several Daphnia infochemicals, such as methyl ferulate, cyclohexanone, 3, 5-dimethyl, hexanedioic acid, and bis(2-ethylhexyl) ester, showed a high correlation with M. aeruginosa cell concentration (| r | >0.6), suggesting that they may play a key role in controlling harmful cyanobacteria. Additionally, pre-exposure of D. magna and D. galeata to M. aeruginosa produced oleic acid, methyl ester, and n-hexadecanoic acid, with a highly correlation with M. aeruginosa cell concentration (| r | >0.6). p-tolyl acetate and linoleic acid were detected only in the pre-exposed D. galeata infochemicals. These findings suggest that some of Daphnia infochemicals identified in this study can be a promising tool to control M. aeruginosa growth. However, further studies are required to verify the specific actions of these infochemicals against cyanobacteria.

Insights into the effect of nitrate photolysis on short-chain fatty acids production from waste activated sludge in anaerobic fermentation system: Performance and mechanisms

Nitrate photolysis has become an efficient, low-cost and promising technology for emerging contaminants removal, while its performance and mechanism for waste activated sludge (WAS) treatment is still unknown. This study innovatively introduced nitrate photolysis for WAS disintegration, and investigated the effect of nitrate addition (150-375 mg N/L) for short-chain fatty acids (SCFAs) production during anaerobic fermentation (AF). The results showed that nitrate photolysis significantly promoted the SCFAs production from WAS, and peaked at 280.7 mg/g VSS with 7-d fermentation with 150 mg N/L addition (150N-UV), which increased by 8.8-35.0% and 10.7-23.3% compared with other photolysis groups and sole nitrate groups. Effective release of the soluble organics was observed in the nitrate photolysis groups during AF, especially soluble proteins, reaching 1505.4 mg COD/L at 9 d in 150N-UV group, promoted by 7.0∼15.7% than nitrate/nitrate photolysis groups. The model compounds simulation experiment further demonstrated the positive effect of nitrate photolysis on organics hydrolysis and SCFAs accumulation. The result of the radical capture and quenching verified the reactive oxygen species contributed more compared with reactive nitrogen species. Functional group analysis confirmed the effective bioconversion of the macromolecular organics during the fermentation. Moreover, the nitrate photolysis enhanced the enrichment of the functional consortia, including anaerobic fermentation bacteria (AFB), e.g., Fnoticella, Romboutsia, Gracilibacter and Sedimentibacter, and nitrate reducing bacteria (NRB), e.g., Acinerobacter and Ahniella. The macrogenetic analysis further revealed that glycolysis, amino acid metabolism, acetate metabolism and nitrogen metabolism were the dominating metabolic pathways during fermentation, and the abundance of the relevant genes were enhanced in 150N-UV group.

Effect of iron, naphthalene acetic acid on growth and Economics of green gram

Effect of iron, naphthalene acetic acid on growth and Economics of green gram

Comparison of lactic and propionic acid hydrolysis for production of xylo-oligosaccharides and ethanol from polysaccharides in Toona sinensis branch

Xylan-type hemicellulose hydrolysis by an organic acid solution for the production of xylo-oligosaccharides (XOS) is efficient and eco-friendly, but the effects of different organic acids on XOS production from Toona sinensis branch (TB) biomass is limited. In this work, under the conditions of 170 °C for 60 min, 33.1 % and 38.7 % XOS yields were obtained from polysaccharides present in TB by 2 % lactic acid (LA) and 6 % propionic acid (PA), respectively. Then 77 % of the lignin was removed by hydrogen peroxide−acetic acid pretreatment system, and 39.5 % and 44.7 % XOS yield were obtained from polysaccharides in delignification TB by 2 % LA and 6 % PA, respectively. It was found that PA hydrolysis, especially from delignified TB, resulted in higher XOS yield and purity compared to LA hydrolysis. Moreover, the content of byproducts (xylose, hydroxymethyl-furfural and furfural) in PA hydrolysate was lower. Following the hydrolysis process, the simultaneous saccharification and fermentation of the TB solid residue achieved an ethanol yield of 71.5 %. This work proposes an integrated process to preferentially converts the TB hemicellulose into valuable XOS and then converts the cellulose into ethanol. This process had the advantage of eliminating the need for isolation and purification, and the potential to obtain multiple products from the same raw material.

Analysis of the performance and microbial community of continuous dark fermentation combined with steady static magnetic field

The effect of external static magnetic field on hydrogen production and its mechanism were studied by continuous dark fermentation with no pretreatment excess sludge as inoculum. The results showed that under conditions of 37 ± 1 ℃, HRT 8h, OLR 15g/(L· d) and no control of influent pH, 78 mT external static magnetic field by adding magnets on both sides of the reactor could accelerate the enrichment of Ethanoligenens and improve the activity of reduced coenzyme I (96%), ferredoxin oxidoreductase (29%) and pyruvate: ferredoxin oxidoreductase (7%) so that the maximum hydrogen productivity could reach 1.657L H2/L, which was 5 times higher than that of non-magnetic group. Moreover, the n-caproic acid production could also increase due to the enrichment of carbon chain elongation microorganisms. The decline of hydrogen production was mainly due to hydrogenotrophic methanogenesis and acetic acid accumulation. This study was benefit to understand the interaction mechanism between magnetic field and microorganisms during the process of biological hydrogen production.

Occurrence of Sphingomonas olei with elemental S oxidation capability in sodic soil: Potential role in sodicity reclamation and plant growth promotion

The success of the sodic soil reclamation using elemental S (S°) depends on the population of the native S° oxidizers. Augmenting the native flora of the sodic soils with effective S° oxidizers can enhance the success of the sodic soil reclamation. Present study reports for the first time the S° oxidation potential of the Sphingomonas olei strain 20UP7 isolated from sodic soils with pHs 9.8 and ECe 3.6 dS m–1. Inoculation with S. olei strain 20UP7 caused 13.0–24.2 % increase in S° oxidation in different sodic soils (pHs 9.1–10.5). It improved the concentration of the Ca2+, Mg2+, PO43– and declined the HCO3– and total alkalinity of the soil solution. This isolate also showed appreciable P and Zn solubilization, indole acetic acid, ammonia, and titratable acidity production in the growth media. It tended to the formation of biofilm around sulphur particles. The PCR amplification with gene–specific primers showed the occurrence of soxA, soxB, and soxY genes with a single band corresponding to length of 850, 460, and 360 base pairs, respectively. The integration of the S. olei strain 20UP7 with S° caused 21.7–25.4 % increase in the rice and wheat yield compared to the soil treated with S° alone. This study concludes that the S. olei, native to high saline–sodic soils can be utilized for improving the sodicity reclamation and plant growth promotion using elemental S based formulations.

Optimization of deep eutectic solvent based ultrasonic assisted microextraction for determination of zearalenone residues in foods

A sensitive and simple ultrasonic assisted microextraction procedure based on the use of green deep eutectic solvents (DESs) was designed for the extraction of zearalenone (ZEN) residues in grains, foods and milks. Optimization of key parameters and experimental modelling were achieved by Box-Behnken design (BBD) based on surface response methodology. DES-UA-ME procedure was based on the extraction of ZEN molecules into DES prepared from a mixture of phenyl acetic acid and trimethyl glycine in a 2:1 molar ratio at pH 3.8 under ultrasonication for 11min at 33oC. After the phase separation step, the DES-rich phase containing ZEN was placed in an UV-Vis spectrophotometer for quantitative analysis of ZEN at 260nm. The analytical merits of the DES-UA-ME procedure were investigated using optimum conditions for both standard calibration solutions (SCS) and matrix-matched calibration solutions (MMCS). Linearity for the SCS and MMCS was 3-800ngmL-1 (r2:0.995) and 5-450ngmL-1 (r2:0.992), respectively. The limit of detection (LOD) and limit of quantification (LOQ) for SCS were 0.9ngmL-1 and 3ngmL-1, respectively, while the LOD and LOQ for MMCs were 1.6ngmL-1 and 5ngmL-1, respectively. Enrichment factors for SCS and MMCS was 157 and 139 for, respectively. Validation of the DES-UA-ME procedure was tested by analysis of two certified reference materials containing ZEN. There was no significant difference between the measured amounts and the reference amounts. In the final stage, the DES-UA-ME procedure was applied to selected samples separately for both SCS and MMCS.

Addition of lactic acid bacteria modulates microbial community and promotes the flavor profiles of Kombucha

This study explores the impact of innovative food processing on food-derived bioactive components through integrating lactic acid bacteria (LAB) in kombucha fermentation. The study showcased how this technique, involving four LAB strains, drastically transformed the beverage’s chemical composition, favoring its flavor properties and microbial diversity. LAB integration significantly lessened total and acetic acid content, enhancing kombucha’s flavor, especially with the effective strain Lactiplantibacillus plantarum. LAB’s presence fostered the production of alcohols and esters further enhancing the kombucha’s flavor. Post-72-hour quality shifts detected through Principal Component Analysis were potentially attributed to the LAB’s role in generating volatile compounds. High-throughput sequencing denoted Zygosaccharomyces, Pichia, Komagataeibacter, and Gluconacetobacter as leading microbial genera, with Pichia correlating strongly with flavor compounds. The study also unveiled six key volatile compounds and their metabolic pathways. Thus, this pilot investigation presents essential insights for future strategies to enhance kombucha flavor, also shedding light on the health-promoting foods sector.

Cryo-storage of porcine hides at the industrial scale for tissue engineering and regenerative medicine application

BACKGROUND: The industrial scale cryo-storage of raw tissue materials requires a robust, low-cost and easy-to-operate method that can facilitate the down-stream process. OBJECTIVE: The study was aimed to develop the multifunctional protective solutions (MPS) for transportation at ambient conditions and also subsequent cryo-storage below −20°C of raw porcine hides for tissue engineering and regenerative medicine. MATERIALS AND METHODS: Protective solutions with antimicrobial activity and proteinase-inhibiting activity were developed and tested for its efficacy in preserving the extracellular matrix of porcine dermis from microbial spoilage, proteolytic degradation, freeze damage and excessive dehydration during shipping and cryo-storage. The MPSs contained phosphate-buffered saline with ethylene diamine tetra acetic acid (EDTA) added as chelator and proteinase inhibitor, as well as glycerol or maltodextrin (M180) as cryoprotectants. RESULTS: MPSs prepared with EDTA and glycerol or M180 had significant antimicrobial activity and proteinase-inhibiting activity during the period of shipping and handling. Glycerol and M180 prevented eutectic salt precipitation and excessive freeze dehydration upon cryo-storage of porcine hides. Without glycerol or M180, hides could be freeze-dehydrated to the low hydration at ˜0.4 g/g dw, and formed irreversible plications after freezing. A critical hydration (0.8˜0.9 g/g dw) was observed for the extracellular matrix of porcine dermis, and dehydration to a lower level could impose enormous stress and potential damage. The soaking of porcine hides in MPSs decreased water content as glycerol and M180 entered into dermis. Upon equilibration, the glycerol content in the tissue was about 94% of the incubating glycerol solution, but the M180 content in the tissue was only about 50% of the incubating M180 solution, indicating that M180 did not get into the entire aqueous domain within dermis. MPSs reduced ice formation and increased the unfrozen water content of porcine raw hides upon cryo-storage. CONCLUSION: MPSs prepared with EDTA and glycerol or M180 have antimicrobial activity and proteinase-inhibiting activity, which can be used for transportation and cryo-storage of raw hides at the industrial scale. Glycerol at 7.5% w/v and M180 at 20% w/v were sufficient to prevent freeze damage and excessive freeze dehydration.

Regulation of photoassimilate transportation and nitrogen uptake to decrease greenhouse gas emissions in ratooning rice with higher economic return by optimized nitrogen supplies

Mechanized harvesting of the main crop rice, with low stubble height in rice ratooning is scaling up, especially in Southeast China with a higher population density and less cultivated land. Currently, the common nitrogen fertilization for ratoon rice is concentrated within 20 days before and after the harvest of the main crop. However, this fertilization pattern may not be suitable for low stubble regenerative rice due to its extended growth period, leading to diminished nitrogen utilization efficiency and heightened greenhouse gas emissions, particularly nitrous oxide (N2O) emissions. It is imperative to explore a nitrogen fertilizer management model for clean production of low stubble ratoon rice (RR). In this study, we examined the effects of nitrogen fertilizer application rates and methods (single or split application) on yield and greenhouse gas emissions during the regrowth season. We employed a multi-criteria assessment approach combined with field measurements, energy analysis, environmental assessment, and economic evaluation on ratoon rice under various nitrogen fertilizer treatments. The results showed that the ratoon rice produced the highest total energy output under 67.5N+22.5N (Fertilize with 67.5kg nitrogen ha-1 and 22.5kg nitrogen ha-1 3 days after main season rice harvesting and during the heading stage of ratoon rice) treatment compared to the 90N+0N (conventional fertilization, apply 90kg nitrogen ha-1 fertilizer 3 days after harvesting at once) treatment. It was also found that reducing nitrogen application during the tillering stage reduced CH4 emissions, fertilization during the heading stage of the ratoon rice did not increase CH4 emissions, Since fertilization during the heading stage of ratoon rice did not lead to an increase in the partitioning of photoassimilates (photosynthetic product assimilates) to the rhizosphere soil, significant differences in sugar and acetic acid levels were not observed in the rhizosphere soil. As a result, no change was found in the expression of the methanogenic mcrA gene in the microbial community. The study also demonstrated that the 67.5N+22.5N treatment was able to promote the absorption of nitrogen nutrients, reduction in N2O emissions by 16.61%, subsequently increasing resource use efficiency, final yield and net ecosystem economic benefit by 5.96%, 7.19% and 5.57%, respectively, thereby decreasing carbon and nitrogen footprints by 6.64% and 3.50% compared with the 90N+0N treatment in the ratoon rice. These results suggest that a reasonable ratoon rice cultivation scheme is a promising farming system that can simultaneously improve resource use efficiency and economic profits, reduce greenhouse gas emissions and environmental footprint, while still maintaining the high productivity in ratoon rice.

Microscale titration of acetic acid using digital colorimetry and paper-based analytical devices

Microscale titration of acetic acid using digital colorimetry and paper-based analytical devices

Cytotoxic potential and metabolomic profiling of alkaloid rich fraction of Tylophora indica leaves

Tylophora indica (Burm f.) Merrill, belong to family Asclepiadaceae, is considered to be a natural remedy with high medicinal benefits. The objective of this work is to assess the metabolomic profile of T. indica leaves enriched in alkaloids, as well as to evaluate the in vitro cytotoxicity of these leaves using the MTT assay on human breast MCF-7 and liver HepG2 cancer cell lines. Dried leaves of T. indica were extracted by sonication, using methanol containing 2 % (v/v) of acetic acid and obtained fraction was characterized by HPTLC and UPLC-MS. The UPLC-MS study yielded a preliminary identification of 32 metabolites, with tylophorine, tylophorine B, tylophorinine, and tylophorinidine being the predominant metabolites. The cytotoxicity of the extract of T. indica was evaluated on HepG2 and MCF-7 cell lines, yielding inhibitory concentration (IC50) values of 75.71 μg/mL and 69.60 μg/mL, respectively. Data suggested that the phytochemical screening clearly showed presence of numerous secondary metabolites with moderate cytotoxic efficacy. In conclusion, the future prospects of T. indica appear promising for the advancement of phytopharmaceutical-based anticancer medications, as well as for the design of contemporary pharmaceuticals in the field of cancer chemotherapy.

Conversion of the greenhouse gases CH4 and CO2 to CH3COOH using transition metal Clusters: Two birds with one stone

Density functional theoretical studies are performed to investigate the conversion of carbon dioxide and methane to acetic acid using group 10 transition metal clusters in their free and carbon-supported states. The adsorption of CH4 is more feasible than CO2 for most of the clusters and the reaction is initiated with the adsorption of CH4 over the catalysts. Energy barrier for the reaction is reduced significantly using the clusters compared to that in free state which is further reduced when coronene is used as a carbon support. Among various metal clusters, the barrier is found to be the lowest for Ni3.

Phytohormone and amino acid content in golden apple snail (Pomaceae canaliculata L.) extract which fermented at several effective microorganism 4 (EM4) concentrations

This study aims to determine the phytohormone and amino acid content of golden apple snail (GAS) extract fermented using several concentrations of EM 4 Active. GAS were taken from rice fields in Tegalgede Village, Jember. Analysis of phytohormone and amino acid content using LCMS at Bioscience laboratory, Politeknik Negeri Jember. EM4 was activated for 7 days using 5% sugar with distilled water as a solvent. The active EM4 results were taken in several concentrations: 0, 5, 10, 15, 20 and 25% and fermented in GAS extract for 14 days. This research was designed using CRD non-factorial design, consisting of 6 Active EM4 concentrations and repeated 4 times. The results of the research showed that there was the phytohormone IAA (Indole Acetic Acid) with the highest concentration of 0.838% in GAS extract fermented using 25% active EM4, while fermentation without EM4 (0%) contained only 0.641% IAA. Other analysis results showed that 12 types of amino acids were detected, namely arginine, tyrosine, alanine, cysteine, glutamic acid, methionine, glycine, leucine-isoleucine, aspartic acid, proline, threonine and valine. The analysis results showed that the 0% (control) treatment had a higher average amino acid value than fermentation using EM4.

Prevotella enterotype associates with diets supporting acidic faecal pH and production of propionic acid by microbiota

Metabolism of dietary fibres by colon microbiota plays an important role for human health. Personal data from a nutrition study (57 subjects) were analysed to elucidate quantitative associations between the diet, faecal microbiome, organic acid concentrations and pH. Ratios of the predominant acids acetate, butyrate and propionate ranged from 1:0.67:0.27 to 1:0.17:0.36. Pectin-rich diets resulted in higher faecal acetate concentrations. Negative correlation between faecal pH and BSS was observed. Higher faecal pH and lower acid concentrations were related to the higher abundance of amino acid degrading Clostridium, Odoribacter and Eubacterium coprostanoligenes, which are weak carbohydrate fermenting taxa. Propionic acid correlated especially to high abundance of Prevotella and low abundance of proteobacteria. The acetate to propionate ratio of the Prevotella enterotype was about half of that of the Bacteroides enterotype. Based on the results we suggest the measurement of faecal pH and organic acid composition for research and diagnostic purposes.

Chain elongation in continuous microbial electrosynthesis cells: The effect of pH and precursors supply

Microbial electrosynthesis (MES) enables the production of carbon-neutral chemicals using CO2 as a carbon source. Acetic acid is the main MES product, but recent studies show the direct production of elongated carboxylic acids, e.g., butyric and caproic acid. However, the production of elongated acids in MES systems is still inefficient due to the low growth rates of acetogenic bacteria and to limited solventogenic rates. Subsequently, researchers have produced elongated carboxylic acids directly from acetic acid or have operated MES systems at low pH to favor solventogenesis. However, the effect the addition of different chain elongation precursors and the operation pH exerts in the bioelectrochemical production of elongated acids remains unclear. To investigate this, three pH-controlled MES systems were operated in this study with continuous liquid and gas supply. MES systems elongating acetic acid at pH 6 achieved higher butyric (0.71 vs. 0.42 g L−1) and caproic acid (0.71 vs. 0.42 g L−1) titers in the absence of CO2 sparging. Additionally, lowering the pH to 5 in the MES systems fed with CO2 and acetic acid improved the elongated acids titers, reaching 0.72 g L−1 butyric and 0.33 g L−1 caproic acid. The 16 S rRNA analysis showed the community was dominated by Oscillibacter at pH 6, and by Clostridium at pH 5. Furthermore, the first scanning electron microscopy pictures revealing biofilm stratification in MES cathodes were taken in this study, where homogeneous rod-shaped bacteria biofilm layers, in contact with the graphite cathode, were covered by heterogeneous biofilm layers.

Pyridazine derivatives as effective anti-corrosion additives for carbon steel in 1 M HCl: Electrochemical, surface and theoretical studies

The study aimed to investigate the corrosion inhibition performance of two new pyridazine derivatives namely ((E)-2-(3-(4-(carboxymethoxy)-3-methoxystyryl)-5-(2-chlorobenzyl)-6-oxopyridazin-1(6H)-yl)acetic acid (CO6) and (E)-6-(4-hydroxy-3-methoxystyryl)pyridazin-3(2H)-one (CO39) for carbon steel (C.S) in 1M HCl by combining electrochemical techniques, surface analysis and theoretical studies. The electrochemical impedance spectroscopy (EIS) data indicated that the inhibitory efficiencies of CO6 and CO39 increased with increasing inhibitor concentration but decreased with increasing temperature, achieving 97.0 % and 95.3 %, respectively. The results of the potentiodynamic polarization (PDP) measurements show that the two pyridazine derivatives acted as mixed inhibitors. In addition, experimental studies have shown that CO6 and CO39 reduce corrosion rates by adsorbing on the steel surface following Langmuir adsorption isotherms. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) indicated that a protective layer had been developed on the surface of the carbon steel, which prevented corrosion from progressing. Quantum chemical computations and the molecular structures of the inhibitors were employed to investigate the mechanism of inhibition. The adsorption of the compounds investigated on C.S was validated by theoretical calculations including density functional theory (DFT) and molecular dynamics simulation (MDS).

Production of oil palm mesocarp fiber-based hydrogel using selected cross-linking acids

Abstract Over the years, studies showed that hydrogels can be produced through synthetic route to overcome the limitations in obtaining natural-based hydrogels. Biomass resources offer potential alternatives as renewable feedstocks due to their outstanding biodegradability and biocompatibility. Oil palm mesocarp fiber (MF) is the biomass residue obtained after the pressing of palm fruits during palm oil extraction. There is approximately 11 % MF generated from palm fruits after oil extraction. However, the applications of MF are limited. This study aimed to investigate the development of hydrogels from holocellulose MF instead of commonly used cellulose which involving several pretreatment steps, through acid cross-linkers. Holocellulose MF was selected as polymer for chemical cross-linking with two inexpensive and nontoxic hydrophilic organic acids, citric acid and acetic acid for hydrogel production. Comparison study was carried out to evaluate the physicochemical properties, and degree of swelling, as well as gel content in different media for both acids in the production of hydrogel from holocellulose MF. Results indicated that the optimum concentrations of citric acid and acetic acid for gel content and degree of swelling were 5 M and 2 M, respectively. Both optimized hydrogels exhibited comparable profiles in terms of morphology, thermal stability and functional groups, in addition to showing similar degree of swelling profile in different media, i.e., salt solution, acidic, neutral to alkaline, implying their distinctive characteristics. In summary, holocellulose MF is suitable for the production of hydrogel with citric acid and acetic acid as crosslinkers for different desired applications.