This paper focuses on the synthesis and mechanism of carbon nanospheres (CNS) coated with few- and multi-layered graphene (FLG, MLG). The graphitic carbon encapsulates the core/shell structure of the Ni/NiO nanoparticles via the chemical vapor deposition (CVD) method. The application of the resulting CNS and hybrids of CNS-FLG and CNS-MLG as reinforcement nanofillers in a polypropylene (PP) matrix were studied from the aspects of mechanical and thermal characteristics. In this research, to synthesize carbon nanostructures, nickel nitrate hexahydrate (Ni(NO₃)₂·6H₂O) and acetylene (C₂H₂) were used as the catalyst source and carbon source, respectively. Besides, the morphology, structure and graphitization of the resulting carbon nanostructures were investigated. On the other hand, the mechanisms of CNS growth and the synthesis of graphene sheets on the CNS surface were studied. Finally, the mechanical and thermal properties of the CNS/PP, CNS-FLG/PP, and CNS-MLG/PP composites were analyzed by applying tensile test and thermogravimetric analysis (TGA), respectively.
Global warming has become a serious issue nowadays as the trend of CO2 emission is increasing by years. In Malaysia, the electricity and energy sector contributed a significant amount to the nation's CO2 emission due to fossil fuel use. Many research works have been carried out to mitigate this issue, including carbon capture and utilization (CCUS) technology and biological carbon fixation by microalgae. This study makes a preliminary effort to screen native microalgae species in the Malaysian coal-fired power plant's surrounding towards carbon fixation ability. Three dominant species, including Nannochloropsis sp., Tetraselmis sp., and Isochrysis sp. were identified and tested in the laboratory under ambient and pure CO2 condition to assess their growth and CO2 fixation ability. The results indicate Isochrysis sp. as the superior carbon fixer against other species. In continuation, the optimization study using Response Surface Methodology (RSM) was carried out to optimize the operating conditions of Isochrysis sp. using a customized lab-scale photobioreactor under simulated flue gas exposure. This species was further acclimatized and tested under actual flue gas generated by the power plant. Isochrysis sp. had shown its capability as a carbon fixer with CO2 fixation rate of 0.35 gCO2/L day under actual coal-fired flue gas exposure after cycles of acclimatization phase. This work is the first to demonstrate indigenous microalgae species' ability as a carbon fixer under Malaysian coal-fired flue gas exposure. Thus, the findings shall be useful in exploring the microalgae potential as a biological agent for carbon emission mitigation from power plants more sustainably.
Boron removal capacity of multi-walled carbon nanotubes (MWCNTs) modified with tartaric acid was investigated in this study. Modification of MWCNTs with tartaric acid was confirmed by Boehm surface chemistry method and fourier transform infra-red (FT-IR) spectroscopy. Experiments were performed to determine the adsorption isotherm and adsorption thermodynamic parameters of boron adsorption on tartaric acid modified MWCNTs (TA-MWCNTs). The effect of variables including initial pH, dosage of adsorbent, contact time and temperature was investigated. Analysis of data showed that adsorption equilibrium could be better described by Freundlich isotherm and the maximum adsorption capacities obtained at the pH of 6.0 was 1.97 mg/g. The estimated thermodynamic values of free energy (ΔG°), entropy (ΔS°) and enthalpy (ΔH°) indicated a spontaneous and an endothermic process. Furthermore, the TA-MWCNTs was magnetized for separation of boron-contaminated adsorbent from aqueous solution by applying magnetic field. The results showed that magnetic TA-MWCNTs particles were separated effectively after adsorption from contaminated water.
In this study, the performance of glyphosate removal in an electrocoagulation batch with two electrodes formed by the same metal type, consisting of aluminum, iron, steel and copper have been compared. The aim of this study intends to remove glyphosate from an aqueous solution by an electrocoagulation process using metal electrode plates, which involves electrogeneration of metal cations as coagulant agents. The production of metal cations showed an ability to bind together to form aggregates of flocs composed of a combination of glyphosate and metal oxide. Electrocoagulation using aluminum electrodes indicated a high percentage removal of glyphosate, 94.25%; followed by iron electrodes, 88.37%; steel electrodes, 62.82%; and copper electrodes, 46.69%. The treated aqueous solution was then analyzed by Fourier Transform Infrared Spectroscopy. Percentages of Carbon, Hydrogen, Nitrogen, Sulfur remaining in the treated aqueous solution after the electrocoagulation process have been determined. The treated water and sludge were characterized and the mechanism of the overall process was concluded as an outcome. An X-Ray Diffraction analysis of dried sludge confirmed that new polymeric compounds were formed during the treatment. The sludge composed of new compounds were also verified the removals. This study revealed that an electrocoagulation process using metal electrodes is reliable and efficient.
New environmentally friendly plasticized poly(lactic acid) (PLA) kenaf biocomposites were obtained through a melt blending process from a combination of epoxidized jatropha oil, a type of nonedible vegetable oil material, and renewable plasticizer. The main objective of this study is to investigate the effect of the incorporation of epoxidized jatropha oil (EJO) as a plasticizer and alkaline treatment of kenaf fiber on the thermal properties of PLA/Kenaf/EJO biocomposites. Kenaf fiber was treated with 6% sodium hydroxide (NaOH) solution for 4 h. The thermal properties of the biocomposites were analyzed using a differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It must be highlighted that the addition of EJO resulted in a decrease of glass transition temperature which aided PLA chain mobility in the blend as predicted. TGA demonstrated that the presence of treated kenaf fiber together with EJO in the blends reduced the rate of decomposition of PLA and enhanced the thermal stability of the blend. The treatment showed a rougher surface fiber in scanning electron microscopy (SEM) micrographs and had a greater mechanical locking with matrix, and this was further supported with Fourier-transform infrared spectroscopy (FTIR) analysis. Overall, the increasing content of EJO as a plasticizer has improved the thermal properties of PLA/Kenaf/EJO biocomposites.
Bamboo fibers are utilized for the production of various structures, building materials, etc. and is of great significance all over the world especially in southeast Asia. In this study, the extraction of microcrystalline cellulose (MCC) was performed using bamboo fibers through acid hydrolysis and subsequently different characterizations were carried out using various advanced techniques. Fourier transform infrared (FTIR) spectroscopy analysis has indicated the removal of lignin from MCC extracted from bamboo pulp. Scanning Electron Microscopy (SEM) revealed rough surface and minor agglomeration of the MCC. Pure MCC, albeit with small quantities of impurities and residues, was obtained, as revealed by Energy Dispersive X-ray (EDX) analysis. X-ray diffraction (XRD) indicates the increase in crystallinity from 62.5% to 82.6%. Furthermore, the isolated MCC has slightly higher crystallinity compared to commercial available MCC (74%). The results of thermal gravimetric analysis (TGA) demonstrate better thermal stability of isolated MCC compared to its starting material (Bamboo fibers). Thus, the isolated MCC might be used as a reinforcing element for the production of green composites and it can also be utilized as a starting material for the production of crystalline nanocellulose in future.
This study aims to formulate and fabricate the optimum condition of modified kenaf core (MKC) for the removal of targeted endocrine-disrupting compounds in a batch adsorption system. Kenaf core was chemically modified using phosphoric acid as an activating agent, which involved the pyrolysis step. Results indicated a significant difference (p T1KC > T3KC, whereas that in the binary mixture system leads to T2KC > T1KC > T3KC and T1KC > T2KC > T3KC for E2 and EE2 adsorption, respectively, through hydrogen bonding and the π-π interaction mechanism. Thus, the findings revealed T2KC at a moderate level of acid concentration (0.5 M H3PO4) to be a potential biochar, with an environmentally safe and sound profile for opposing emerging pollutant issues as well as for the attainment of sustainable development goals.
In this paper, the adsorptive performance of synthesized thiourea (TU) modified poly(acrylonitrile-co-acrylic acid) (TU-P(AN-co-AA)) polymeric adsorbent for capturing p-nitrophenol (PNP) from aqueous solution was investigated. TU-P(AN-co-AA) was synthesized via the redox polymerization method with acrylonitrile (AN) and acrylic acid (AA) as the monomers, then modified chemically with thiourea (TU). Characterization analysis with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), elemental microanalysis for CHNS, zeta potential measurement, Brunauer-Emmett-Teller (BET) surface analysis and thermal analyses were carried out to determine the morphology and physico-chemical properties of the synthesized polymer. The characterization results indicated successful surface modification of polymer with TU. The performance of TU-P(AN-co-AA) for the removal of PNP was investigated under various experimental parameters (adsorbent dosage, initial adsorbate concentration, contact time and temperature). The results demonstrated that the Freundlich isotherm model and pseudo-second-order kinetic model best described the equilibrium and kinetic data, respectively. Thermodynamic studies showed that the uptake of PNP by TU-P(AN-co-AA) was spontaneous and exothermic in nature. The results of the regeneration studies suggested that the TU-P(AN-co-AA) polymer is a reusable adsorbent with great potential for removing PNP from wastewater.
As Malaysia is one of the world's largest producer of palm oil, large amounts of palm oil mill effluent (POME) is generated. It was found that negatively charged components are accountable for POME color. An attempt was made to remove residual contaminants after conventional treatment using anion base resin. Adsorption experiments were carried out in fixed bed column. Various models such as the Thomas, the Yoon-Nelson, the Wolborska and BDST model were used to fit the experimental data. It was found that only the BDST model was fitted well at the initial breakthrough time. A wavelet neural network model (WNN) was developed to model the breakthrough curves in fixed bed column for multicomponent system. The results showed that the WNN model described breakthrough curves better than the commonly used models. The effects of pH, flow rate and bed depth on column performance were investigated. It was found that the highest uptake capacity was obtained at pH 3. The exhaustion time appeared to increase with increase in bed length and decrease in flow rate.
A membrane sequencing batch reactor (MSBR) treating hypersaline oily wastewater was modeled by artificial neural network (ANN). The MSBR operated at different total dissolved solids (TDSs) (35,000; 50,000; 100,000; 150,000; 200,000; 250,000mg/L), various organic loading rates (OLRs) (0.281, 0.563, 1.124, 2.248, and 3.372kg COD/(m(3)day)) and cyclic time (12, 24, and 48h). A feed-forward neural network trained by batch back propagation algorithm was employed to model the MSBR. A set of 193 operational data from the wastewater treatment with the MSBR was used to train the network. The training, validating and testing procedures for the effluent COD, total organic carbon (TOC) and oil and grease (O&G) concentrations were successful and a good correlation was observed between the measured and predicted values. The results showed that at OLR of 2.44kg COD/(m(3)day), TDS of 78,000mg/L and reaction time (RT) of 40h, the average removal rate of COD was 98%. In these conditions, the average effluent COD concentration was less than 100mg/L and met the discharge limits.
A new sensing area for a sensor based on surface plasmon resonance (SPR) was fabricated to detect trace amounts of mercury and lead ions. The gold surface used for SPR measurements were modified with polypyrrole-chitosan (PPy-CHI) conducting polymer composite. The polymer layer was deposited on the gold surface by electrodeposition. This optical sensor was used for monitoring toxic metal ions with and without sensitivity enhancement by chitosan in water samples. The higher amounts of resonance angle unit (ΔRU) were obtained for PPy-CHI film due to a specific binding of chitosan with Pb(2+) and Hg(2+) ions. The Pb(2+) ion bind to the polymer films most strongly, and the sensor was more sensitive to Pb(2+) compared to Hg(2+). The concentrations of ions in the parts per million range produced the changes in the SPR angle minimum in the region of 0.03 to 0.07. Data analysis was done by Matlab software using Fresnel formula for multilayer system.
Oil and gas field wastewater or produced water is a significant waste stream in the oil and gas industries. In this study, the performance of a membrane sequencing batch reactor (MSBR) and membrane sequencing batch reactor/reverse osmosis (MSBR/RO) process treating produced wastewater were investigated and compared. The MSBR was operated in different hydraulic residence time (HRT) of 8, 20 and 44 h. Operation results showed that for a HRT of 20 h, the combined process effluent chemical oxygen demand (COD), total organic carbon (TOC) and oil and grease (O&G) removal efficiencies were 90.9%, 92% and 91.5%, respectively. The MSBR effluent concentration levels met the required standard for oil well re-injection. The RO treatment reduced the salt and organic contents to acceptable levels for irrigation and different industrial re-use. Foulant biopsy demonstrated that the fouling on the membrane surface was mainly due to inorganic (salts) and organic (microorganisms and their products, hydrocarbon constituents) matters.
Produced water is the largest waste stream generated in oil and gas industries. It is a mixture of different organic and inorganic compounds. Due to the increasing volume of waste all over the world in the current decade, the outcome and effect of discharging produced water on the environment has lately become a significant issue of environmental concern. Produced water is conventionally treated through different physical, chemical, and biological methods. In offshore platforms because of space constraints, compact physical and chemical systems are used. However, current technologies cannot remove small-suspended oil particles and dissolved elements. Besides, many chemical treatments, whose initial and/or running cost are high and produce hazardous sludge. In onshore facilities, biological pretreatment of oily wastewater can be a cost-effective and environmental friendly method. As high salt concentration and variations of influent characteristics have direct influence on the turbidity of the effluent, it is appropriate to incorporate a physical treatment, e.g., membrane to refine the final effluent. For these reasons, major research efforts in the future could focus on the optimization of current technologies and use of combined physico-chemical and/or biological treatment of produced water in order to comply with reuse and discharge limits.
In this research, natural nanomaterials including cellulose nanocrystal (CNC), nanofiber cellulose (NFC), and synthetic nanoparticles such as carbon nanofiber (CNF) and carbon nanotube (CNT) with different structures, sizes, and surface areas were produced and analyzed. The most significant contribution of this study is to evaluate and compare these nanomaterials based on the effects of their structures and morphologies on their electrochemical, biomedical, and thermal properties. Based on the obtained results, the natural nanomaterials with low dimension and surface area have zero cytotoxicity effects on the living cells at 12.5 and 3.125 μg/ml concentrations of NFC and CNC, respectively. Meanwhile, synthetic nanomaterials with the high surface area around 15.3-21.1 m2/g and significant thermal stability (480 °C-600 °C) enhance the output of electrode by creating a higher surface area and decreasing the current flow resistance.
The combination of compounds with different classes (hydrophobic and hydrophilic characters) in single chitosan carrier is a challenge due to the hydrophilicity of chitosan. Utilization of l-ascorbic acid (LAA) and thymoquinone (TQ) compounds as effective antioxidants is marred by poor bioavailability and uptake. Nanoparticles (NPs) solved the problem by functioning as a carrier for them because they have high surface areas for more efficient delivery and uptake by cells. This research, therefore, synthesized chitosan NPs (CNPs) containing LAA and TQ, CNP-LAA-TQ via ionic gelation routes as the preparation is non-toxic. They were characterized using electron microscopy, zetasizer, UV⁻VIS spectrophotometry, and infrared spectroscopy. The optimum CNP-LAA-TQ size produced was 141.5 ± 7.8 nm, with a polydispersity index (PDI) of 0.207 ± 0.013. The encapsulation efficiency of CNP-LAA-TQ was 22.8 ± 3.2% for LAA and 35.6 ± 3.6% for TQ. Combined hydrophilic LAA and hydrophobic TQ proved that a myriad of highly efficacious compounds with poor systemic uptake could be encapsulated together in NP systems to increase their pharmaceutical efficiency, indirectly contributing to the advancement of medical and pharmaceutical sectors.
The phenolic constituents in Piper betle are well known for their antioxidant potential; however, current literature has very little information on their stability under the influence of storage factors. Present study evaluated the stability of total phenolic content (TPC) and antioxidant activity together with individual phenolic constituents (hydroxychavicol, eugenol, isoeugenol and allylpyrocatechol 3,4-diacetate) present in dried Piper betle's extract under different storage temperature of 5 and 25 °C with and without light for a period of six months. Both light and temperature significantly influenced TPC and its corresponding antioxidant activity over time. More than 95% TPC and antioxidant activity was retained at 5 °C in dark condition after 180 days of storage. Hydroxychavicol demonstrated the best stability with no degradation while eugenol and isoeugenol displayed moderate stability in low temperature (5 °C) and dark conditions. 4-allyl-1,2-diacetoxybenzene was the only compound that underwent complete degradation. A new compound, 2,4-di-tert-butylphenol, was detected after five weeks of storage only in the extracts exposed to light. Both zero-order and first-order kinetic models were adopted to describe the degradation kinetics of the extract's antioxidant activity. Zero-order displayed better fit with higher correlation coefficients (R² = 0.9046) and the half-life was determined as 62 days for the optimised storage conditions (5 °C in dark conditions).
In this study, simultaneous adsorption of cationic dyes was investigated by using binary component solutions. Thiourea-modified poly(acrylonitrile-co-acrylic acid) (TMPAA) polymer was used as an adsorbent for uptake of cationic dyes (malachite green, MG and methylene blue, MB) from aqueous solution in a binary system. Adsorption tests revealed that TMPAA presented high adsorption of MG and MB at higher pH and higher dye concentrations. It suggested that there are strong electrostatic attractions between the surface functional groups of the adsorbent and cationic dyes. The equilibrium analyses explain that both extended Langmuir and extended models are suitable for the description of adsorption data in the binary system. An antagonistic effect was found, probably due to triangular (MG) and linear (MB) molecular structures that mutually hinder the adsorption of both dyes on TMPAA. Besides, the kinetic studies for sorption of MG and MB dyes onto adsorbent were better represented by a pseudo-second-order model, which demonstrates chemisorption between the polymeric TMPAA adsorbent and dye molecules. According to experimental findings, TMPAA is an attractive adsorbent for treatment of wastewater containing multiple cationic dyes.
In this research work, carbon nanofibers (CNFs) were synthesized on honeycomb monolith substrates using injection chemical vapor deposition (ICVD) technique. The effect of various wash-coated materials and catalyst promoter on the growth rate of CNFs on monolith substrates were examined. The characteristics of the synthesized CNFs-coated monolith composites were examined using Raman spectroscopy, Brunauer-Emmett-Teller (BET), thermogravimetric analysis (TGA), field emission scanning electron microscopy (FE-SEM), and Transmission electron microscopy (TEM) techniques. According to the textural characterization study, the specific surface area and pore volume of CNFs-coated monolith composites were significantly improved as compared to bare monolith which might be attributed to the growth of highly pure and aligned CNFs over monolith substrate. Besides that, the synthesized CNFs-coated monolith possessed extremely well thermal stability up to the temperature of 550 °C which was corresponded to the strong attachment of highly graphitized CNFs over monolith substrates.
Methyl ester sulphonates (MES) have been considered as an alternative green surfactant for the detergent market. Investigation on the purification of methyl ester sulphonates (MES) with various carbon chains of C12, C14, C16 and C16-18 derived from palm methyl ester is of great interest. These MES powders have been repeatedly crystallized with ethanol and the purity of MES has increased to a maximum of 99% active content and 96% crystallinity index without changing the structure. These crystallized MES with high active content have 1.0% to 2.3% moisture content and retained its di-salt content in the range of 5%. The crystallized MES C16 and C16-18 attained excellent flow characteristics. Morphology, structural and its crystallinity analyses showed that the crystals MES had good solubility properties, stable crystal structure (β polymorphic) and triclinic lateral structure when it is in high active content. The brittleness of MES crystals increased from a β' to a β subcell. Crystal with high brittleness has the potential to ease production of powder, which leads to a reduction in the cost of production and improves efficiency.
The development of bio-polyol from vegetable oil and its derivatives is gaining much interest from polyurethane industries and academia. In view of this, the availability of methyl oleate derived from palm oil, which is aimed at biodiesel production, provides an excellent feedstock to produce bio-polyol for polyurethane applications. In this recent study, response surface methodology (RSM) with a combination of central composite rotatable design (CCRD) was used to optimise the reaction parameters in order to obtain a maximised hydroxyl value (OHV). Three reaction parameters were selected, namely the mole ratio of epoxidised methyl oleate (EMO) to glycerol (1:5-1:10), the amount of catalyst loading (0.15-0.55%) and reaction temperature (90-150 °C) on a response variable as the hydroxyl value (OHV). The analysis of variance (ANOVA) indicated that the quadratic model was significant at 98% confidence level with (p-value > 0.0001) with an insignificant lack of fit and the regression coefficient (R2) was 0.9897. The optimum reaction conditions established by the predicted model were: 1:10 mole ratio of EMO to glycerol, 0.18% of catalyst and 120 °C reaction temperature, giving a hydroxyl value (OHV) of 306.190 mg KOH/g for the experimental value and 301.248 mg KOH/g for the predicted value. This result proves that the RSM model is capable of forecasting the relevant response. FTIR analysis was employed to monitor the changes of functional group for each synthesis and the confirmation of this finding was analysed by NMR analysis. The viscosity and average molecular weight (MW) were 513.48 mPa and 491 Da, respectively.