Now showing 1 - 10 of 54
  • Publication
    Evaluation and Enhancement of Polylactic Acid Biodegradability in Soil by Blending with Chitosan
    ( 2023-06-01) ;
    Ismail H.
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    Rusli A.
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    This study highlights the soil burial degradation of polylactic acid/chitosan (PLA/Cs) biocomposites prepared by the melt compounding technique. The effect of various Cs loadings (2.5, 5, 7.5, 10 parts per hundred parts of polymer (php)) and soil burial periods (0, 2, 6, 12 months) on visual observation, weight loss, changes in functional groups, as well as tensile, thermal, and morphological properties were analyzed. The PLA/Cs biocomposites became brittle and showed more fragmentation with increasing Cs content and buried time. The result correlates with a remarkable increase in weight loss percentage of about ~ 192%, with Cs addition from 2.5 to 10 php at the end of soil degradation. Besides, a decrement in peak intensity at 1751 cm−1 and 1087 − 1027 cm−1 after 12 months signifies the breakdown of PLA ester bonds due to the hydrolytic degradation. This correlates to a significant drop of 60% and 55% in tensile strength and elongation at break, respectively, in the 2.5 php sample, whilst further Cs addition resulted in the broken of the biocomposites at the end of the soil degradation. Yet, no significant difference was observed in the tensile modulus. A consistent stiffness in the biocomposite suggests the degradation occurs in the amorphous region and leaves the crystalline part. This is proven by the 70% increment in crystallinity degree in all samples after 12 months of soil burial. Moreover, surface morphology showed numerous and extended crack formations. It proposes a notable deterioration effect of the biocomposite due to biodegradation. The hydrophilicity of Cs enhances water-polymer interaction, thereby accelerating the biodegradation of polymer components. Therefore, Cs could be a good candidate for facilitating PLA biodegradation in the natural soil environment.
  • Publication
    Biodegradation improvement of bioinspired crosslinked and noncrosslinked polyvinyl alcohol nanocomposites with cellulose nanocrystals extracted from rice straw through natural soil burial exposure
    ( 2022-10-01)
    Chin K.M.
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    ; ; ;
    Tan W.K.
    Polyvinyl alcohol with different cellulose nanocrystals (CNC) content extracted from rice straw were prepared by using solution casting method and their biodegradability in natural soil burial were studied. Ethanedioic acid (EA) was introduced as a crosslinker. The synthesized noncrosslinked and crosslinked PVOH/CNC nanocomposites films and their biodegradation were characterized with Fourier transform infrared spectroscopy (FTIR), tensile test, weight loss, Field Emission Scanning Electron Microscopy (FESEM), differential scanning calorimetry (DSC). The changes in chemical properties before and after biodegradation were confirmed through FTIR. Tensile test revealed that the tensile strength and elongation at break reduced as time of soil burial increases. Morphological study showed the extent of surface deterioration before and after soil burial, where the addition of CNC displayed greater deterioration. Melting temperature and crystallinity increased with addition of CNC but decreased after crosslinking. However, melting temperature and crystallinity of all nanocomposites increased after biodegradation. PVOH degrading bacteria were isolated and identified to be Bacillus cereus strain CCM 2010 and Bacillus cereus strain ATCC 14579. Biodegradation of the bionanocomposites were concluded to be in the following decreasing order: PVOH/CNC > PVOH/EA/CNC > PVOH > PVOH/EA.
  • Publication
    Effects of trans-polyoctylene rubber in polypropylene/recycled acrylonitrile butadiene/rice husk powder composites
    Composites of polypropylene/Acylonitrile butadiene rubber/Rice husk powder/ (PP/NBRr/RHP) with and without trans-polyoctylene rubber (TOR) were prepared, and the effects of trans-polyoctylene rubber were investigated. By using rice husk powder of 150300μm, five different compositions of PP/NBRr/RHP composites (i.e.100/0, 80/20, 70/30, 60/40 and 40/60 phr) were prepared in an internal mixer at 180 °C and 50 rpm rotor speed. The results indicate that the incorporation of TOR improved the tensile properties of PP/NBRr/RHPcomposites. Scanning electron microscopy of the fractured surfaces proved that TOR promoted good adhesion between the PP-NBRr matrices and RHP.
  • Publication
    Intermolecular degradation of aromatic compound and its derivatives via combined sequential and hybridized process
    ( 2023-03-01)
    Lau Y.Y.
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    ; ; ; ;
    Teng T.T.
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    Eng K.M.
    The under-treated wastewater, especially remaining carcinogenic aromatic compounds in wastewater discharge has been expansively reported, wherein the efficiency of conventional wastewater treatment is identified as the primary contributor source. Herein, the advancement of wastewater treatments has drawn much attention in recent years. In the current study, combined sequential and hybridized treatment of thermolysis and coagulation–flocculation provides a novel advancement for environmental emerging pollutant (EP) prescription. This research is mainly demonstrating the mitigation efficiency and degradation pathway of pararosaniline (PRA) hybridized and combined sequential wastewater treatment. Notably, PRA degradation dominantly via a linkage of reaction: thermal cleavage, deamination, silication and diazene reduction. Thermolysis acts as an initiator for the PRA decomposition through thermally induced bond dissociation energy (BDE) for molecular fragmentation whilst coagulation–flocculation facilitates the formation of organo-bridged silsesquioxane as the final degradation product. Different from conventional treatment, the hybridized treatment showed excellent synergistic degradability by removing 99% PRA and its EPs, followed by combined sequential treatment method with 86% reduction. Comprehensive degradation pathway breakdown of carcinogenic and hardly degradable aromatic compounds provides a new insight for wastewater treatment whereby aniline and benzene are entirely undetectable in effluent. The degradation intermediates, reaction derivatives and end products were affirmed by gas chromatography–mass spectrometry, Fourier transform infrared spectroscopy and ultraviolet–visible spectrophotometry (GC–MS, FTIR and UV–Vis). This finding provides valuable guidance in establishing efficient integrated multiple-step wastewater treatments. Graphical abstract: [Figure not available: see fulltext.].
  • Publication
    Plastics in Water Treatment
    Water is essential for many people around the world and needs to be conserved. Recently water shortages are becoming severe and urgent issues to be addressed due to the global population growth coupled with rapid economic developments. Water is considered contaminated when the presence of elevated concentrations of substances in water exceeds the prescribed limits. More efficient water treatments need to be developed to address the worsening clean water shortage. Water treatment facilities made from plastic materials proven to offer more advantages compared to alternative materials. Their unique properties such as lightweight, strength, chemical and corrosion resistance, weather and fire resistance, easy and long-lasting installations contribute to the excellent applications of the water treatment system. Plastic provides many solutions for ensuring the sustainability of water. The choice of plastic types of materials depends on their specific applications. In this article, we introduce different types of plastic and its advantages. The plastic applications in water treatments were also discussed in different fields of human activities such as in water and sewage treatments, irrigation and agriculture, potable water production, aquaculture and ultra-pure water production.
  • Publication
    Kinetic model discrimination on the biogas production in thermophilic co-digestion of sugarcane vinasse and water hyacinth
    Co-digestion between sugarcane vinasse (Vn) and water hyacinth (WH) at various mixing ratios of 0:1, 1:0, 1:3, 3:1, and 1:1 was carried out under thermophilic conditions (55 Â°C) for 60 days. The effect of various mixing ratios on the pH changes, soluble chemical oxygen demand (sCOD) reduction, and cumulative biogas production was investigated. The first order, modified Gompertz, and logistic function kinetic models were selected to fit the experimental data. Model discrimination was conducted through the Akaike Information Criterion (AIC). The study revealed that co-digestion shows better performance compared to the mono-digestion of both substrates. Vn:WH mixing ratio 1:1 with inoculum to substrate ratio (ISR) of 0.38 g VSinoculum/g VSsubstrate is the most favorable ratio, achieving sCOD reduction efficiency and cumulative biogas production of 71.6% and 1229 mL, respectively. Model selection through AIC revealed that ratio 1:1 was best fitted to the logistic function kinetic model (R2 = 0.9897) with Ym and K values of 1232 mL and 31 mL/day, respectively.
  • Publication
    Photocatalytic Degradation of Sugarcane Vinasse Using ZnO Photocatalyst: Operating Parameters, Kinetic Studies, Phytotoxicity Assessments, and Reusability
    Abstract: Photocatalytic degradation performance is highly related to optimized operating parameters such as initial concentration, pH value, and catalyst dosage. In this study, the impact of various parameters on the photocatalytic degradation of anaerobically digested vinasse (AnVE) has been determined through decolourization and chemical oxygen demand (COD) reduction efficiency using zinc oxide (ZnO) photocatalyst. In this context, the application of photocatalytic degradation in treating sugarcane vinasse using ZnO is yet to be explored. The COD reduction efficiency and decolourization achieved 83.40% and 99.29%, respectively, under the conditions of 250 mg/L initial COD concentration, pH 10, and 2.0 g/L catalyst dosage. The phytotoxicity assessment was also conducted to determine the toxicity of AnVE before and after treatment using mung bean (Vigna radiata). The reduction of root length and the weight of mung bean indicated that the sugarcane vinasse contains enormous amounts of organic substances that affect the plant's growth. The toxicity reduction in the AnVE solution can be proved by UV–Vis absorption spectra. Furthermore, the catalyst recovery achieved 93% in the reusability test. However, the COD reduction efficiency and decolourization were reduced every cycle. It was due to the depletion of the active sites in the catalyst with the adsorption of organic molecules. Thus, it can be concluded that the photocatalytic degradation in the treatment of AnVE was effective in organic degradation, decolorization, toxicity reduction and can be reused after the recovery process. Graphical abstract: [Figure not available: see fulltext.].
  • Publication
    Effect of operating temperature in the anaerobic degradation of palm oil mill effluent: Process performance, microbial community, and biokinetic evaluation
    This research paper presents the thermophilic anaerobic digestion (TAD) of palm oil mill effluent (POME), which is an extension of a previously conducted mesophilic anaerobic digestion (MAD) study. An anaerobic suspended growth closed bioreactor was operated at various hydraulic retention times (HRT) between 24 and 8 days. The effect of operating temperature on the performance, microbial identification, and biokinetic coefficients was evaluated. Performance was quantified by the production of biogas and the chemical oxygen demand (COD) reduction efficiency. Biogas production in TAD (64.56 L/day) was higher than MAD (46.76 L/day). A higher COD reduction efficiency was also achieved in TAD (90.90%) compared to MAD (89.66%). Other than that, more species of methanogenic bacteria were also identified in TAD through 16S rDNA. Furthermore, the modified Monod model implemented in the biokinetic evaluation revealed that higher values of maximum substrate utilization rate (rx,max) and maximum specific biomass growth rate (μmax) contributed to the better performance in TAD. The high rx,max value explains the higher COD reduction efficiency obtained in TAD. The critical retention time (θC) in TAD is also higher than MAD, making it less prone to the washout of active microbes when operating near low retention times. Additionally, TAD also achieved higher methane yield (YCH4) as opposed to MAD. The extension study concluded that the TAD of POME demonstrated improved performance in terms of biogas production and COD reduction when evaluated against the previously conducted MAD.
  • Publication
    Bioinspired Crosslinked Nanocomposites of Polyvinyl Alcohol-Reinforced Cellulose Nanocrystals Extracted from Rice Straw with Ethanedioic Acid
    ( 2022-01-01)
    Chin K.M.
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    ; ; ;
    Tan W.K.
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    Vannaladsaysy V.
    In this study, cellulose nanocrystals (CNC) were extracted from rice straw and incorporated into polyvinyl alcohol (PVOH) as reinforcement nanofillers. Multiple nanocomposites with different CNC contents were prepared. Extracted CNC appear as long, well-defined rodlike crystals with a high aspect ratio (41). Nanocomposites with 3 wt% of CNC significantly exhibit improved tensile strength (60.4%) and maximum degradation temperature (287°C). Moreover, they demonstrate a decrease in water vapor permeability rate and in the swelling and solubility indices of PVOH/CNC. Significant improvements were observed when nanocomposites were crosslinked specifically in terms of tensile strength (104.8%) and maximum degradation temperature (364°C). They also demonstrate greatly reduced water vapor permeability rate, swelling, and solubility indices. The optimum CNC amount for both nanocomposites is 3 wt%.
  • Publication
    Effect of cold exposure on the biofoam produced from different types of Oyster mushroom
    ( 2024-07)
    Tan Siu Siew
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    Nur Mawaddah Majib
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    Mycelium-based biofoam is a sustainable material derived from the growth of fungal mycelium on lignocellulosic agricultural waste substrate, as it has potential use in a variety of applications. The main objective of this research is to advance the sustainable alternatives for various application by investigating the mycelium growth of the biofoam produced from Pleurotus >lorida and Pleurotus sajor-caju on rice husk substrate, in improving the properties of the biofoam through innovative cold exposure. This study showed P. >lorida can produce mycelium biofoam at a faster rate, 7.022mm/day compared to P. sajor-caju 6.08mm/day). By cold exposure at 0°C and 10°C for 3 hours, every 2 days and 5 days, respectively until the mycelium are fully grown in the substrate, sample exposed to the latter condition for P. >lorida exhibits a faster growth rate at 7.3037 mm/day. However, cold exposure on biofoam produced from P sajor-caju had not improved the mycelium growth rate. Cold exposure samples at 0°C every 5 days and 10°C every 2 days have demonstrated capability in water (103.51%) and oil absorption (143.23%), proving their effectiveness in absorbing pollutants for the purpose of environmental remediation. The FTIR analysis con>irmed the presence of hydrophilic and oleophilic characteristics in the biofoam, indicating its capability to absorb water and oil. By subjecting biofoam to cold exposure, its properties can be altered, broadening its potential applications.