Synthesis of raspberry-like structure zinc oxide nanoparticles via glycol-solvothermal, low-temperature solvothermal and coprecipitation methods

Highly crystalline ZnO nanoparticles with a pure phase and raspberry-like structure were synthesized using three different techniques (glycol-solvothermal, low-temperature solvothermal, and coprecipitation methods). Physisorption analysis and field emission scanning electron microscopy confirmed the large specific surface area of the ZnO nanoparticles with a mesoporous–macroporous structure due to the interstices of aggregated and agglomerated secondary and tertiary ZnO particles. The ZnO nanoparticles from the coprecipitation method presented the best performance among the three products, owing to their highest purity and crystalline phase, large Brunauer–Emmett–Teller surface area (23.0 m2${\cdot }$g$^{-1}$) and pore volume, and the finest mesoporous–macroporous structure. ZnO nanoparticles can be used in various applications such as catalysis, biosensing, imaging, drug delivery, and pollution absorption for the purpose of environmental remediation

Synthesis of raspberry-like structure zinc oxide nanoparticles via glycol-solvothermal, low-temperature solvothermal and coprecipitation methods

Highly crystalline ZnO nanoparticles with a pure phase and raspberry-like structure were synthesized using three different techniques (glycol-solvothermal, low-temperature solvothermal, and coprecipitation methods). Physisorption analysis and field emission scanning electron microscopy confirmed the large specific surface area of the ZnO nanoparticles with a mesoporous–macroporous structure due to the interstices of aggregated and agglomerated secondary and tertiary ZnO particles. The ZnO nanoparticles from the coprecipitation method presented the best performance among the three products, owing to their highest purity and crystalline phase, large Brunauer–Emmett–Teller surface area (23.0 m2${\cdot }$g$^{-1}$) and pore volume, and the finest mesoporous–macroporous structure. ZnO nanoparticles can be used in various applications such as catalysis, biosensing, imaging, drug delivery, and pollution absorption for the purpose of environmental remediation

Reka bentuk pasir pantai mesoliang bagi penyahoksigenan bermangkin minyak masak terpakai kepada bahan api keterbaharuan

Kajian ini memfokus kepada reka bentuk mangkin dwilogam NiCo tersokong atas permukaan pasir pantai terawat HCl (P-HCl) untuk tindak balas penyahoksigenan minyak masak terpakai bagi menghasilkan hidrokarbon cecair gasolin, diesel dan bahan api jet. Mangkin dwilogam berkandungan Ni (10 %bt.) dan Co (10 %bt.) disediakan melalui kaedah pengisitepuan bagi menghasilkan mangkin NiCo/P-HCl. Po, P-HCl dan NiCo/P-HCl telah dilakukan pencirian fizikal dan aktiviti pemangkinan telah diuji melalui tindak balas penyahoksigenan. Prestasi mangkin dinilai dari segi peratusan hasil tindak balas dan kepilihan mengikut julat karbon gasolin (C8-C11), diesel (C11-C17) dan bahan api jet (C8-C16). Perawatan HCl telah bertindak balas dengan logam oksida yang mempunyai keelektropositifan yang lebih tinggi (Al2O3 dan Fe2O3), seterusnya menyebabkan pengurangan komposisi logam oksida tersebut, masing-masing sebanyak 10.0% dan 12.5%. Pengurangan komposisi logam oksida telah mempengaruhi keporosan penyokong pasir yang telah dirawat. Setelah pemuatan logam Ni dan Co, mangkin berstruktur mesoliang (5.9 nm) terhasil dengan peningkatan luas permukaan (22.5 m2/g) dan isi padu liang (0.032 cm3/g). Mangkin NiCo/P-HCl telah berjaya menukarkan minyak masak terpakai kepada hidrokarbon cecair sebanyak 71%, mengikut keutamaan kepilihan produk iaitu bahan api jet (86%), diesel (83%) dan gasolin (17%). Penukaran minyak masak terpakai kepada produk bahan api keterbaharuan bakal memberikan nilai tambah dan menyokong kepada inisiatif teknologi hijau serta kitaran ekonomi yang mampan

Renewable diesel via solventless and hydrogen-free catalytic deoxygenation of palm fatty acid distillate

This work involved the utilization of a byproduct from the palm oil refining process as reaction feedstock in a solventless and hydrogen-free catalytic deoxygenation (DO) over NiO–ZnO catalyst in producing diesel-like hydrocarbons as advanced biofuels. The catalyst supporter was synthesized using coprecipitation methods to form highly crystalline meso-macrostructured ZnO particles. The catalyst support was wet-impregnated with different loadings (wt %) of NiO to prepare the NiO–ZnO catalyst. X-ray diffraction patterns verified the persistence of good crystallinity and phase purity of the support, with fine NiO crystallites of size 14–22 nm. Synthesized NiO–ZnO catalysts demonstrated Type IV isotherm with H3 hysteresis loop with mesoporous-macroporous properties. The Brønsted and Lewis acidic sites of NiO–ZnO offer a synergy effect between the active site and catalyst supporter. Both N2 adsorption isotherm and electron microscopy analysis revealed the increase of the crystallite size of the catalyst by increase the NiO loadings. The catalytic activity of the NiO–ZnO catalyst was tested in a semi-batch reactor at 350 °C for 2 h in N2 atmospheric. The oxygenated compounds of palm fatty acid distillate (PFAD) have been successfully removed to form linear hydrocarbons as green diesel compounds. The synergistic effect between NiO and ZnO significantly enhanced the catalytic activity for substrate DO. The hydrocarbons product yield reached 83.4%, with a diesel range (C11–C17) selectivity of 86.0%. The green diesel, which contains diesel-range hydrocarbons, is suitable as an alternative fuel product for vehicle engine usage. It is possible to be upscaled and compatible with the existed petrochemical refinery facilities. Hence, this is a promising work could be an economic potential and give value added to the palm oil byproduct sectors

Assessment of selected herbicides and chelating agents in water using gas chromatography-electron capture detector (GC-ECD)

Water contamination by herbicides and chelating agents is increasing mainly due to the increasing agricultural activities. Water contamination by these compounds has become a concern due to their adverse effects to the environment and humans. Seven sampling sites of water sources in Selangor and Johor were chosen for the study. Contamination level of Mecoprop (MCCP), Nitrilotriacetic acid (NTA) and Ethylenediaminetetraacetic acid (EDTA) in these water body areas was determined by using Gas Chromatography-Electron Capture Detector (GC-ECD). Our results indicated that water samples of Sungai Melot in Selangor showed the highest presence of EDTA. MCCP was detected at a high level at Sungai Sarang Buaya, Johor while NTA showed similar level of concentration at three different sites, Ladang 10, Ladang Sayur and Mardi, Selangor

Preparation and characterization of zinc oxide nanoparticles

Zinc oxide nanoparticles are important inorganic particles which receive great interest over the past few years because of the wide nanotechnology application in various fields of material physics and chemistry. The physicochemical properties of resulting ZnO nanoparticles can be controlled by the synthesis route, method of preparation and parameters related to condition processing. In this study, ZnO nanoparticles were successfully synthesized by three different methods namely polyol method, solvothermal method and co-precipitation method. X-ray diffraction (XRD) patterns show that the all resulting ZnO nanoparticles materials which were synthesized by all the three different methods are pure phase with good crystalinity and completely matched the hexagonal-wurzite structure. The presence of a broad and sharp absorption band at around 440 cm-1 in the FTIR spectrum further confirmed the existence of ZnO phase. In polyol method, ZnO nanoparticles were successfully synthesized under hydrothermal condition. Zinc acetate (ZnAc) was dissolved and heated in three different glycol solutions, namely ethylene glycol (EG), diethylene glycol (DEG) and trietyleneglycol (TEG). The effect of different glycol solutions and calcination on the formation of ZnO nanoparticles was investigated. Single-modal narrow particle size distribution of ZnO nanoparticles with average particles size of 2 ± 1 nm, 12 ± 1nm and 13 ± 1 nm were obtained when EG, DEG and TEG were used in the synthesis, respectively. The broadness of the size distribution of the ZnO nanoparticles can be given as EG > DEG >TEG. The specific surface areas of all the resulting materials however show very similar values ranging from 12.2 to 13.5 m2g-1. The low-temperature solvothermal process was employed as the second method to synthesize ZnO nanoparticles. The initial concentration of zinc acetate was controlled and this process is based on the decomposition of zinc acetate and sodium hydroxide (NaOH) in a mixture solution of ethanol and EG. The effect of different zinc acetate concentration and the effect of organic solvent mixtures solution between ethanol and EG can be shown by a single modal narrow particle size distribution with the average size below 25 ± 1 nm. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis revealed that less macroscopic agglomeration of ZnO nanoparticles, indicating that the effect of low temperature process in the mixtures solution also contributed to the higher specific surface area of about 40 m2g- 1. Further effect of high calcinations temperature on the physicochemical properties of the resulting ZnO nanoparticles shows more crystalline and pure phase. However, the increasing particles size resulted in the decreasing of specific surface area due to the compact agglomeration of ZnO particles. Lastly, an intermediate zinc oxalate phase was synthesized by oxalate coprecipitation from nearly saturated solution of zinc acetate and 2-propanol of oxalic acid solution. Highly crystallized and pure phase ZnO nanoparticles were successfully synthesized by thermal treatment at 400 to 600 oC for 4 hours. Single-modal narrow particle size distribution of ZnO nanoparticles with the average particles size of 3± 1 nm , 28 ± 1 nm and 25 ± 1 nm are obtained at 400, 500 and 600 oC, respectively. FESEM and TEM also revealed the different surface structure and morphology of ZnO nanoparticles obtained at calcination temperatures. A huge reduction of specific surface area of ZnO nanoparticles from 22.9 m2g-1 to 2.6 m2g-1 was observed when the calcination temperature is increased from 400 to 600 oC. This study verified, a good crystallinity, high purity, small particle size and large specific surface area of ZnO nanoparticles can be obtained using all the methods. The effect of preparation parameters in each method gives the most influence to physichochemical properties of the resulting material

Surface-silanised and alkoxylated micro-mesoporous Ni/hierarchical nanozeolites for oleic acid hydrodeoxygenation

In this work, we report a novel and green method for the synthesis of hierarchical nanozeolites for the hydrodeoxygenation of oleic acid to diesel-range hydrocarbons. Hierarchical nanozeolites based on HZSM-5 and HBEA with appropriate mesopores (8–20 nm) were synthesised through the surface silanisation of zeolitic seeds. In this method, organosilane (hexadecyltrimethoxysilane) was used as a growth inhibitor while biomass-derived alcohols (1-decanol and isobutanol) were used to improve the miscibility and dispersion of the organosilane. 1H MAS NMR analysis confirmed the silanisation and alkoxylation of the zeolitic seeds. The physicochemical properties of the catalysts were analysed by XRD, N2 porosimetry, NH3-TPD, pyridine-DRIFTS, XPS and TEM, and the catalytic performance of bifunctional 10 wt.% Ni/h-HZSM-5 and Ni/h-HBEA were then evaluated in the HDO of a bulky feedstock, oleic acid. The hierarchical zeolites supported Ni catalysts achieved more than 86% conversion of oleic acid. Compared with their microporous nanozeolite counterparts, Ni/h-HBEA and Ni/h-HZSM-5 exhibited comparable or higher Brønsted/Lewis acid ratios, leading to high selectivity towards C18 alkanes (65% and 71%, respectively); they also demonstrated similar catalytic yields. More importantly, while their microporous analogues lost much of their activity after the first cycle, Ni/h-HZSM-5, in particular, displayed excellent stability, even after four cycles. Thus, our approach appears to be a promising way of preparing catalyst supports for efficient hydrotreatment of bulky substrates