Now showing 1 - 10 of 11
  • Publication
    An alkaline deep eutectic solvent based on potassium carbonate and glycerol as pretreatment for the isolation of cellulose nanocrystals from empty fruit bunch
    Cellulose nanocrystals (CNC) were successfully isolated from oil palm empty fruit bunch (EFB) using sulphuric acid hydrolysis preceded by alkaline deep eutectic solvent (DES) pretreatment and bleaching. In this study, an alkaline DES consisting of potassium carbonate and glycerol (molar ratio of 1:7) was used as the pretreatment solvent to promote the dissolution of lignin and hemicellulose. The processing parameters of acid hydrolysis were optimized using Box-Behnken Design. The results showed that the yield of CNC was 37.1%, under the optimal conditions of 60.0 wt% acid concentration at 46.1 °C for 58.5 min. The field emission scanning electron microscopy (FESEM), chemical composition analysis, and Fourier transform infrared (FTIR) results indicated that unwanted impurities, such as hemicellulose and lignin, were efficiently eliminated from the raw EFB fibers by DES pretreatment and bleaching. The average diameter of CNC was less than 10 nm. The raw EFB fiber, treated cellulose, and CNC showed crystallinities of 38.7%, 51.2%, and 65.3%, respectively. The CNC had lower thermal stability, which was ascribed to the sulphate group present on the CNC surface.
      1
  • Publication
    Intermolecular degradation of aromatic compound and its derivatives via combined sequential and hybridized process
    ( 2023-03-01)
    Lau Y.Y.
    ;
    ; ; ; ;
    Teng T.T.
    ;
    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.].
      50  2
  • Publication
    Insight on the structural aspect of ENR-50/TiO2 hybrid in KOH/C3H8O medium revealed by NMR spectroscopy
    ( 2020-01-01)
    Dahham O.S.
    ;
    Hamzah R.
    ;
    Abu Bakar M.
    ;
    Zulkepli N.N.
    ;
    Alakrach A.M.
    ;
    ;
    Omar M.F.
    ;
    ;
    Al-rashdi A.A.
    The ring-opening reactions (ROR) of epoxide groups in epoxidized natural rubber/titania (ENR-50/TiO2) hybrid in potassium hydroxide/isopropanol medium were examined using NMR spectroscopy and supported by the FTIR technique. The thermal behaviour of the hybrid was also studied using TG/DTG and DSC analyses. The 1H NMR results suggested that 16.82% of ROR occurred in the hybrid, while the 13C NMR results exhibited five new peaks at δ 19.5, 71.0, 73.7, 91.7 and 94.4 ppm in the hybrid. 2D NMR, such as HMQC, HMBC and COSY techniques, further scrutinized these assignments. The FTIR spectrum exhibited Ti-O-C characteristics via the peak at 1028 cm−1. The TG/DTG results showed four steps of thermal degradation at 44–148, 219–309, 331–489 and 629–810 °C due to the existence of Ti moieties along with a polymer chain mixture (intact and ring-opened epoxide groups) of ENR-50, which in turn led to an increase in the Tg value of the hybrid to 27 °C compared to that of purified ENR-50 at −17.72 °C.
      2
  • Publication
    Physial properties of nanocellulose extracted from empty fruit bunch
    The high content of cellulose in lignocellulosic waste can be further utilized to produce nanocellulose (NCC). Conventional method of dissolving lignocellulosic waste in acid solvent is detrimental to the environment. Thus, a new method for utililizing lignocellulosic waste using environmental friendly solvent should be developed. NCC can be produced by dissolution of palm oil empty fruit bunch (EFB) in green solvent, natural deep eutectic solvent (NADES). In this study, palm oil EFB was used to produce NCC by dissolving in NADES and analysed for its characterization. Atomic force microscope (AFM) and transmission electron microscope (TEM) were used to evaluate the NCC’s morphology and dimension. Under AFM analysis, the average height of NCC produced was 15.574±3.658 nm while the obtained diameter is 53.179±24.237 nm. Using TEM analysis, the NCC produced was a needle-like particles with average diameter of 17.842 ± 2.859 nm, while the length is 185.486 ± 91.776 nm. Based on TGA results, NCC produced has a thermal stability at 224 °C. From the results obtained, the dissolution of cellulose in NADES is able to produce nanocellulose with similar properties as nanocellulose produced using conventional method.
      3  29
  • Publication
    Influence of filler surface modification on static and dynamic mechanical responses of rice husk reinforced linear low-density polyethylene composites
    Filler surface modification has become an essential approach to improve the compatibility problem between natural fillers and polymer matrices. However, there is limited work that concerns on this particular effect under dynamic loading conditions. Therefore, in this study, both untreated and treated low linear density polyethylene/rice husk composites were tested under static (0.001 s-1, 0.01 s-1and 0.1 s-1) and dynamic loading rates (650 s-1, 900 s-1and 1100 s-1) using universal testing machine and split Hopkinson pressure bar equipment, respectively. Rice husk filler was modified using silane coupling agents at four different concentrations (1, 3, 5 and 7% weight percentage of silane) at room temperature. This surface modification was experimentally proven by Fourier transform infrared and Field emission scanning electron microscopy. Results show that strength properties, stiffness properties and yield behaviour of treated composites were higher than untreated composites. Among the treated composites, the 5% silane weight percentage composite shows the optimum mechanical properties. Besides, the rate of sensitivity of both untreated and treated composites also shows great dependency on strain rate sensitivity with increasing strain rate. On the other hand, the thermal activation volume shows contrary trend. For fracture surface analysis, the results show that the treated LLDPE/RH composites experienced less permanent deformation as compared to untreated LLDPE/RH composites. Besides, at dynamic loading, the fracture surface analysis of the treated composites showed good attachment between RH and LLDPE.
      1
  • Publication
    Evaluation and Enhancement of Polylactic Acid Biodegradability in Soil by Blending with Chitosan
    ( 2023-06-01) ;
    Ismail H.
    ;
    Rusli A.
    ;
    ;
    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.
      1  27
  • Publication
    Room Temperature Synthesis and Characterization of HKUST-1, Metal–Organic Frameworks (MOFs)
    ( 2023-01-01)
    Ahmad S.
    ;
    ;
    Mahdi E.M.
    ;
    ; ; ;
    Md. Akil H.
    ;
    Nosbi N.
    In the present work, HKUST-1 has been synthesized at room temperature with 1:0, 1:1, and 0:1 ratio of ethanol and water. A wide range of reaction conditions were explored in order to understand the effects of solvent and temperature. It was discovered that various precursors yielded products with various BET specific surface areas. The effect of water may therefore be explained by the decrease in reaction rate with an increasing concentration of reactants. The XRD data and SEM analysis showed that both MOFs were very crystalline in the product.
      6  29
  • Publication
    Insight on the structural aspect of ENR-50/TiO2 hybrid in KOH/C3H8O medium revealed by NMR spectroscopy
    ( 2020-01-01)
    Dahham O.S.
    ;
    ;
    Abu Bakar M.
    ;
    ;
    Alakrach A.M.
    ;
    ; ; ;
    Al-rashdi A.A.
    The ring-opening reactions (ROR) of epoxide groups in epoxidized natural rubber/titania (ENR-50/TiO2) hybrid in potassium hydroxide/isopropanol medium were examined using NMR spectroscopy and supported by the FTIR technique. The thermal behaviour of the hybrid was also studied using TG/DTG and DSC analyses. The 1H NMR results suggested that 16.82% of ROR occurred in the hybrid, while the 13C NMR results exhibited five new peaks at δ 19.5, 71.0, 73.7, 91.7 and 94.4 ppm in the hybrid. 2D NMR, such as HMQC, HMBC and COSY techniques, further scrutinized these assignments. The FTIR spectrum exhibited Ti-O-C characteristics via the peak at 1028 cm−1. The TG/DTG results showed four steps of thermal degradation at 44–148, 219–309, 331–489 and 629–810 °C due to the existence of Ti moieties along with a polymer chain mixture (intact and ring-opened epoxide groups) of ENR-50, which in turn led to an increase in the Tg value of the hybrid to 27 °C compared to that of purified ENR-50 at −17.72 °C.
      5  27
  • Publication
    Processing, tensile and morphological characteristics of polylactic acid/ Chitosan biocomposites prepared by melt compounding technique
    Biodegradable polymers of polylactic acid (PLA) and chitosan (Cs) has a great potential as alternative candidates to replace conventional synthetic plastic apart to reduce the plastic waste pollution due to the unique properties of superior mechanical strength, feasible processability and rapid degradation. In this work, PLA/Cs biocomposites were prepared via melt compounding and compression moulding techniques in the absence of any plasticizer and additive. The effect of chitosan loading (2.5, 5, 7.5, 10 php) on processing, tensile and morphological characteristics of PLA/Cs were evaluated using internal mixer, universal testing machine and field emission scanning electron microscopy (FESEM), respectively. Processing characteristic indicates PLA/Cs biocomposites demonstrated higher processing torque in comparison to neat PLA due to the increase in melt viscosity and decrease in chain mobility of the polymeric materials. Tensile test results revealed that the maximum strength (54.60 ± 0.51 MPa) and tensile elastic modulus (2.67 ± 0.01 GPa) was attained by PLA/2.5Cs biocomposite. In fact, the addition of chitosan content up to 10 php results in significant decreased in tensile strength and elongation at break of 23.38 ± 0.37 MPa and 0.96 ± 0.04 %, respectively. This is supported by the electron micrograph observation of the PLA/2.5Cs tensile fractured surfaces that exhibits uniform dispersion and good interfacial adhesion between chitosan and PLA matrix which signifies higher tensile properties. However, more agglomeration and poor filler-matrix interaction was observed with further addition of chitosan content of above 7.5 php which implies deterioration in tensile properties. The results suggest that the incorporation of low chitosan loading improve the processing, tensile and polymer compatibility in PLA/Cs biocomposites.
      5  29
  • Publication
    Comparative study on the properties of cross-linked cellulose nanocrystals/chitosan film composites with conventional heating and microwave curing
    Cross-linking of chitosan film composites was carried out by using conventional heating and microwave curing methods in this study. Non-cross-linked and glutaraldehyde (GA) cross-linked neat chitosan and cellulose nanocrystals (CNC)/chitosan film composites were cured by either conventional oven heating or microwave irradiation. Tensile strength and Young's modulus of chitosan composites were enhanced significantly by the addition of CNC and GA especially for the microwave-cured samples. The changes in chemical interaction of the chitosan film composites was determined by Fourier transform infrared (FTIR) spectroscopy. The microwave-cured GA-cross-linked chitosan film composites were more thermally stable than non-cross-linked and conventionally heated GA-cross-linked chitosan film composites due to the formation of a more stable structure between GA and chitosan. Nevertheless, the reduced antimicrobial efficacy of film composites against Escherichia coli, Bacillus subtilis, and Saccharomyces cerevisiae was observed in cross-linked film composites compared with non-cross-linked composites.
      5  26