Key Engineering Materials Vol. 797

Abstract: Previous studies have evidenced that coconut copra is a potential biosorbent for removal of dissolved organic carbon from peat swamp runoff attaining an average removal of 96 %. The capability of coconut copra in removing heavy metals including cadmium (Cd), chromium (Cr) and nickel (Ni) is scarcely reported. In this paper, response surface methodology was applied to evaluate the optimum conditions for removal of Cd, Cr and Ni from aqueous solution using raw coconut copra. Batch adsorption experiments were conducted according to inscribed central composite design. Response surface models further identified the optimum dosage, pH and contact time for Cd removal is 1.5 g, pH 11 and 60 min, Cr removal is 0.1 g, pH 8.48 and 60 min while Ni removal is 0.1 g, pH 11 and 15 min. Bimodality is observed in response surface graphs, implying the possible existence of two equilibrium phase during the adsorption process. Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models were employed to describe the adsorption behaviour. Results revealed that raw coconut copra can remove 4.55 mg/g of Cd, 8.71 mg/g of Cr and 26.46 mg/g of Ni. The adsorption processes are physical adsorption.

Abstract: In this study, FO membrane was fabricated by Layer-by-Layer (LbL) coating technique using Poly (sodium 4-styrene-sulfonate)(PSS) and Poly (diallyl-dimethylammoniumchloride) (PDADMAC) as the active polyelectrolytes. Different concentrations of polyelectrolytes and deposition time of polyelectrolytes were investigated. The success of the coated layer was confirmed using ATR-FTIR and FESEM images. The membrane performance was determined by water flux and reverse solute diffusion (RSD) using pure water and 1.75M Na₂SO₄ as feed and draw solution, respectively. It was observed that the highest water flux, 6.76 L/ was recorded at the lowest polyelectrolytes concentration and longer deposition time. Meanwhile, the minimum RSD was achieved by the membrane fabricated at the longest deposition time and highest polyelectrolyte concentration.

Abstract: Phytonutrients extracted from natural resources are receiving much attention among researchers due to their highly antioxidative characteristics which prevent several degenerative diseases including cardiovascular diseases and cancers. These nutraceutical compounds can be used in food, pharmaceutical and cosmetic products as natural antioxidants, preservatives, colourings and functional foods. Though much works have been reported on the extraction process, there are concerns on the health and safety risks posed by the commonly used organic solvents derived from petrochemical industry. Thus, there is a need to recover the phytonutrients using green, sustainable, efficient and low cost solvents that are safe for human consumption. This work discusses natural deep eutectic solvent (NADES) as a potential solvent to extract both polar and non-polar phytonutrients simultaneously from natural resources. Previous attempts (in the most recent 3 years) to make use of NADES as an extractant to obtain phytonutrients are presented. The synthesis process of NADES and current challenges when employing NADES are also being reviewed.

Abstract: This study was conducted to characterize the industrial wastewater containing Copper (II) ion and to evaluate the effect of different thickness of polysulfone as the support membrane in the fabrication of thin film composite membrane (TFC), on the removal of Copper (II) ion. From the wastewater analysis, it showed that the concentration of copper (II) ion are out of the acceptable range of Environmental Quality (Industrial Effluent) Regulations 2009. For the TFC, the polysulfone support membrane was prepared at two thicknesses, 60μm and 90μm. For each thickness, two formulations of thin layer were coated on it; i) A polymer blend of Polyvinyl Alcohol and Chitosan, and ii) Hybrid membrane as thin layer. Before undergo the treatment process, the pH of the wastewater sample was altered to 7 as the pre-treatment. The final result shows that composite membrane with hybrid membrane as thin layer with 90μm thickness of polysulfone membrane was the best membrane because it could remove 99.67% of copper (II) ion. Finally, the treated water can be discharged to the groundwater because the concentration of copper ion is less than 1 ppm, which it has fulfilled the Environmental Quality regulations. Keywords— Chitosan, Copper ion, composite membrane, hybrid membrane, industrial wastewater

Abstract: In this work, a new type of mixed matrix membranes comprising of amino-functionalized CAU-1 as filler and cellulose acetate as polymer phase were fabricated for CO₂ separation from N₂. The crystallinity and morphology of the resultant fillers were verified by using X-ray diffraction (XRD) and scanning electron microscope (SEM). The energy-dispersive X-ray (EDX) results showed that, sedimentation and agglomeration of fillers were found at loading of more than 5 wt%. Subsequently, the gases permeation results revealed that, an increase in CO₂ permeability and CO₂/N₂ selectivity of 149% and 81%, respectively, were achieved for the membrane loaded with 5 wt% of CAU-1-NH₂, as compared to pure cellulose acetate membrane.

Abstract: In this study, two types of hybrid graphene-based zeolitic imidazolate framework-8 (ZIF-8) nanofillers were prepared via a green in-situ synthesis method. A recycle mother liquor (ML) of ZIF-8 which still contains expensive raw materials used for the synthesis of ZIF-8 such as Zn²⁺, Hmim and methanol was reutilized for the synthesis of graphene oxide-ZIF-8 (GO-ZIF-8-ML) and reduced graphene oxide-ZIF-8 (rGO-ZIF-8-ML) to minimize chemicals wastage. The as-synthesized GO-ZIF-8 and rGO-ZIF-8 fillers were then characterized by using fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffractometer (XRD) and thermogravimetric analyser (TGA) and compared with the pure components such as GO, rGO and ZIF-8. No significant changes in the chemical structures of GO-ZIF-8 and rGO-ZIF-8 and the XRD peaks were found to match well with ZIF-8. This indicates that during the in-situ process, both GO and rGO, which serve as a template for anchoring of ZIF-8 do not affect the formation of ZIF-8 and the hybrid nanofillers synthesized were homogenized. TGA results revealed that the as-synthesized GO-ZIF-8-ML and rGO-ZIF-8-ML have better structural stability. The morphology observed from SEM analysis demonstrated that the synthesized ZIF-8 was successfully anchored on the surface of GO and rGO. The hybrid nanofillers showed better properties as compared to pure components.

Abstract: Crystallization technique is one of the potential techniques to deal with wastewater treatment. In this work, progressive freeze concentration (PFC) technique was studied for its effectiveness in wastewater treatment from food industry. In PFC, pure water is produced in the form of ice crystal block and leave behind a higher concentration solution. The effect of coolant temperature and stirring speed on the effective partition constant (K) and solute recovery (Y) were investigated. Glucose solution was used as simulated wastewater sample. The best conditions were found at the moderate coolant temperature of -10°C and maximum stirring speed of 500 rpm, resulted in the lowest K value and highest Y, lead to the highest efficiency on the wastewater treatment.

Abstract: In Malaysia, waste management via recycling is highly promoted, however, recycling bins are not fully utilized as almost all the recycling bins provided are filled with other wastes. As institutional waste is a part of municipal solid waste (MSW), this composition study will be crucial to obtain a conventional management of the waste. In other words, waste composition studies are vital for a more effective and proper management of the waste generated. Hence, the objectives of the research are to analyse the trend of the recycle waste composition obtained during both semester session and semester break and to determine the recycle waste composition collected at UiTM engineering complex. Sorting of the solid wastes from the recycle bins are done manually before weighing of each waste category. The trend shows that paper has the highest composition both during semester session and semester break which is at 65% and 84% respectively followed by plastic bottle with 25% and 13% and aluminum can at 10% and 3%. A sample of recyclable wastes is taken from each recycle bins to the instrumental analysis laboratory for ultimate analysis. The ultimate analysis result shows 43.68% carbon and 1.27% nitrogen for paper wastes, which give a C/N ratio of 34.67. This indicates that paper wastes are compostable when mixed with yard wastes. In determining the economic benefits of recycling, potential revenue of RM78.37 can be obtained from a 10-week period of study and hence, if recycling practice is made compulsory, the revenue can be increased.

Abstract: The effect of organic nutrient on the biodegradation of hydrocarbon contaminated marine sediment in Malaysia was investigated. Biodegradation was assessed in microcosm experiments containing 10% (w/w) of crude oil amended with fertilizers in three ways, which were with inorganic nutrients (NP), organic matter in the form of plant-based (Elaeis guineensis) and fish-amendments (Scomber australasicus). It was observed that hydrocarbon degradation occurred in all treatments, with the highest biodegradation rates in S. australasicus supplemented sediment. The addition of S. australasicus managed to reduce the oil concentration to 48% while the addition of E. guineensis and inorganic NP reduced the final oil concentration to 66% and 63% respectively. All three amendments show faster degradation rate compared to the control. Isolation of the soil sample on specific nutrient agar, centrimide, revealed the presence of Pseudomonas aeruginosa that are well known for its ability to degrade hydrocarbon in crude oil.