Carbon-Dots (C-Dots) have drawn much attention in recent years owing to their remarkable properties such as high biocompatibility, low toxicity, nano-scale size, and ease of modification with good tuneable photoluminescence performance. These unique properties have led C-Dots to become a promising platform for bioimaging, metal ion sensing and an antibacterial agent. C-Dots can be prepared using the top-down and bottom-up approaches, in which the latter method is commonly used for large scale and low-cost synthesis. C-Dots can be synthesized using sustainable raw materials or green biomass since it is environmentally friendly, in-expensive and most importantly, promotes the minimization of waste production. However, using biomass waste to produce high-quality C-Dots is still a matter of concern waiting for resolution, and this will be the main focus of this review. Fundamental understanding of C-Dots such as structure analysis, physical and chemical properties of C-Dots, various synthesis methodology and type of raw materials used are also discussed and correlated comprehensively. Additionally, factors affecting the bandgap of the C-Dots and the strategies to overcome these shortcomings are also covered. Moreover, formation mechanism of C-Dots focusing on the hydrothermal method, option and challenges to scale up the C-Dots production are explored. It is expected that the great potential of producing C-Dots from agricultural waste a key benefit in view of their versatility in a wide range of applications.

No abstract

No abstract

The presence of oxygen from air infiltration during the carbonization process of biomass is expected to be detrimental to biochar yield and properties. Experimental study was carried out on oil palm shell in a fixed-bed pyrolyser under various oxygen concentrations ranging from 0% to 11 % by varying the nitrogen and oxygen fractions in the pyrolysing gas mixture. The two critical parameters: the bed temperature and holding time were also varied. Process optimization was carried out by Response Surface Methodology (RSM) by employing Central Composite Design (CCD) using Design Expert 6.0 Software. The effect of oxygen ratio and holding time on biochar yield within the temperature range studied were statistically significant. The optimum condition of 30.0 % biochar yield of palm shell was predicted at pyrolysis temperature of 420 °C, oxygen percentage of 2.3% and holding time of two hours. This prediction closely agreed with the experiment finding of 31.1% biochar yield.

The objective of this study is to investigate the mechanical and thermal properties of thermoplastic film (TPS) from Taccaleontopetaloides starch. T.leontopetaloides was opted as starch source due to its abundance in nature, cheap and non-staple food in Malaysia. Biochar from rice husk was incorporated with T. leontopetaloides starch as a novel idea to enhance the properties of the thermoplastic film and solving the agricultural waste disposal problem. The TPSs were developed through solution casting method. Incorporation of biochar into TPS (TPS-BChr) composite significantly improved the tensile strength and elongation at break (EAB) properties of TPS. Thermal analysis showed that TPS10%-BChr composite had the highest maximum degradation temperature and the highest amount of residue (23.94%) compared to other TPS’s compositions. These results showed that incorporation of biochar into TPS significantly improved the mechanical and thermal properties of the TPS.

No abstract

No abstract

Composite catalyst ZnO/TiO 2 of molar ratio 0.75% was synthesized via sol gel method. The effect of preparation method on the crystal morphology was investigated. The catalyst particles were calcinated at 500 o C,550 o C and 600 °C for 3 hours. The XRD results revealed that calcination temperature controls the crystalline phase in terms of homogeneity and surface area of catalyst produced. The particle size was found to increase with calcination temperature suggesting the effect of different calcination temperatures on catalytic activity for complete degradation of phenol. The result found that ZnO/TiO 2 catalyst calcinated at 600 o C resulted in 70% phenol degradation within five hours of irradiation time under visible light. The kinetic behavior of phenol degradation was found to fit with pseudo first order Langmuir-Hinshelwood kinetic model. Keywords: sol gel, ZnO/TiO 2 catalyst, photocatalytic degradation, visible light, kinetic Abstrak Pemangkin komposit ZnO/TiO 2 dengan 0.75% nisbah molar telah di sintesis melalui kaedah sol gel. Kesan kaedah penyediaan pada morfologi kristal itu telah di selidiki. Zarah-zarah pemangkin telah dikalsinkan pada suhu 500 o C, 550 o C dan 600 o C selama 3 jam. Keputusan XRD menunjukkan suhu pengkalsinan mengawal fasa kristal dari segi kesamaan dan kawasan permukaan pemangkin dihasilkan. Saiz zarah didapati meningkat sejajar dengan peningkatan suhu pengkalsinan mencadangkan kesan suhu pengkalsinan yang berbeza pada aktiviti pemangkin untuk penyingkiran penuh fenol. Keputusan mendapati pemangkin ZnO/TiO 2 yang dikalsinkan pada 600 o C boleh menyebabkan 70% fenol terdegradasi bagi tempoh lima jam masa penyinaran di bawah cahaya nampak. Kelakuan kinetik degradasi fenol didapati sesuai dengan pseudo peringkat pertama model kinetik Langmuir -Hinshelwood.