Reaction Time Of 3h Research Articles

Oil extracted from spent coffee grounds for bio-hydrotreated diesel production

Oil extracted from spent coffee grounds is utilized as a renewable source for bio-hydrotreated fuel production. In the present work, oil yield up to 13% can be obtained by Soxhlet extraction with hexane as a solvent. As the extracted oil contained high content of free fatty acids (6.14%), therefore one step alkali-catalyzed for ester based biodiesel production is impractical. Hydrotreating of extracted oil was performed over two catalysts i.e. NiMo/γ-Al2O3 and Pd/C with different operating parameters i.e. reaction time, operating temperature, and H2/oil. It was found that the reaction time of 2h and the reaction temperature of 400°C are favorable operating conditions. The liquid products mostly consisted of n-pentadecane and n-heptadecane, which contain one carbon atom shorter than the corresponding fatty acid (Cn−1) i.e. palmitic and stearic acid, respectively. Unfavorable cracking of diesel product is pronounced at high temperature and prolonged reaction time. In addition, although increased H2/oil promoted overall reaction and hydrodeoxygenation activity (Cn−1/Cn decreased) for both catalysts, hydrocracking is enhanced over Pd/C, leading to significant increase in gasoline yield. Moreover, Pd/C gave higher olefin content in liquid product (22.3wt%) than NiMo/γ-Al2O3 (4.8wt%). However, NiMo/γ-Al2O3 shows higher isomerization activity. The amount of isoparaffins catalyzed by NiMo/γ-Al2O3 and Pd/C were 10.8 and 1.7wt%, respectively. Physiochemical analysis of the diesel fraction exhibit satisfactory properties. The density and kinematic viscosity were consistent with the specification of commercial bio-hydrogenated diesel, NExBTL, while the cetane index was much higher than conventional diesel.

Antibacterial Properties of Unique Urchin-Like CuO Nanostructures by Chemical Bath Deposition

Unique urchin-like CuO nanostructures were successfully synthesized by a simple chemical bath deposition method at low temperature of 70°C in a short reaction time of 1h. XRD pattern revealed the presence of pure crystalline monoclinic CuO. Morphological analysis revealed the formation of spherical structures composed of numerous hair-like structures arranged in an urchin-like fashion. A plausible growth mechanism was proposed in this paper. Antibacterial test revealed that the nanostructures successfully inhibited the growth of both S. aureus and E. coli.

Enhanced iron efficiency of Fe-impregnated granular activated carbon (Fe-GAC) for arsenate removal via Fe(II)–H2O2 method

In this study, Fe-impregnated granular activated carbon (Fe-GAC) were prepared through the hydrolysis of ferrous sulfate on granular activated carbon (Fe-GAC) by the Fe(II)–H2O2 or Fe(II)–O2 (air) method at different temperatures. SEM, BET, XRD, XPS and FTIR characterizations revealed that Fe-GAC through Fe(II)–H2O2 method with a reaction time of 24h resulted in more nanoscale iron hydroxide sulfate hydrate(Fe2S2O9!xH2O), whereas Fe-GAC through Fe(II)–O2 method formed nanoscale iron hydroxide sulfate hydrate with Fe2+. The impregnated iron through the Fe(II)–H2O2 method was more efficiently used for arsenate removal, and the material obtained with a reaction time of 24h was most effective, indicating Fe2+ in Fe-GAC by Fe(II)–O2 method and uneven and clustered iron hydroxide sulfate hydrate at 300–500°C resulted in the low iron efficiency. The arsenate adsorption capacity of Fe-GAC increased linearly with the iron content in the composite material (R2>0.94). The presence of Cl−, SO42−, NO3−, ClO4−, and PO43 – displayed various degrees of inhibitive effect on the adsorption of arsenate, but BrO3− promoted the adsorption of arsenate. The new preparation method and the material provide a useful alternative for improved removal of arsenate from contaminated water.

Optimal biodiesel-additive synthesis under infrared excitation using pork bone supported-Sb catalyst: Engine performance and emission analyses

Glycerol (G) acetic acid (AA) esterification was conducted in an infrared irradiation (IRI) aided batch reactor for maximization of diacetin and triacetin yield (DT) using pork bone derived hydroxyapatite supported antimony (Sb) oxide catalyst. The catalyst possessed appreciable 40m2/g specific surface area; 4.5nm modal pore diameter and 0.0485cc/g pore volume with prominent Sb2O5 crystalline phase. Under derived optimal condition, 40% Sb precursor loading, 100°C reaction temperature and 6:1 AA:G mole ratio resulted maximum DT yield (88±1%). Notably, to achieve maximum DT yield (88±1%), conventionally heated batch reactor consumed 6 times more energy (reaction time 6h at 300J/s energy input rate) in comparison with IRI reactor (reaction time 2h at 150J/s energy input rate), indicating remarkable energy-efficiency of IRI. Additionally, synthesized product as additive to palm biodiesel evinced emission reduction by 50% and 20% for CO and HC respectively with 2 degrees depression in pour point.

Thermochemical processing of a South African ultrafine coal fly ash using ammonium sulphate as extracting agent for aluminium extraction

South African coal fly ash represents an untapped secondary resource of aluminium. Continuous research is conducted to develop suitable chemical and/or geometallurgical processes for aluminium extraction, preferably accompanied by minimal silicon extraction. The thermochemical treatment of a South African ultrafine coal fly ash was investigated to test the feasibility of recovering aluminium using ammonium sulphate, a widely available, low-cost, recyclable chemical agent. The optimum processing conditions were determined to be a temperature of 500°C and a fly ash to ammonium sulphate weight ratio of 2:6 when a reaction time of 1h was used. Water leaching of the reaction product obtained under these conditions resulted in the selective recovery of 95.0% aluminium from the amorphous phase, with <0.6% Si extracted. Mullite was unlikely to have reacted with the extracting agent. Except for Si, the process was not element-selective, but the extraction of iron could be minimized by increasing the treatment temperature to 600°C without compromising Al extraction. Thermochemical treatment using ammonium sulphate may therefore represent a promising technology for extracting aluminium from coal fly ash, which could be subsequently converted to value-added products such as alumina.

Simultaneous determination of individual isothiocyanates in plant samples by HPLC-DAD-MS following SPE and derivatization with N-acetyl-l-cysteine

The procedure for the isothiocyanates (ITCs) determination that involves derivatization with N-acetyl-l-cysteine (NAC) and separation by HPLC was developed. Prior to derivatization, plant ITCs were isolated and purified using solid-phase extraction (SPE). The optimum conditions of derivatization are: 500μL of isopropanolic eluate obtained by SPE combined with 500μL of derivatizing reagent (0.2M NAC and 0.2M NaHCO3 in water) and reaction time of 1h at 50°C. The formed dithiocarbamates are directly analyzed by HPLC coupled with diode array detector and mass spectrometer if required. The method was validated for nine common natural ITCs. Calibration curves were linear (R2⩾0.991) within a wide range of concentrations and limits of detection were below 4.9nmol/mL. The recoveries were in the range of 83.3–103.7%, with relative standard deviations <5.4%. The developed method has been successfully applied to determine ITCs in broccoli, white cabbage, garden cress, radish, horseradish and papaya.

Antimony selenide nanoparticles as panchromatic sensitizer: Fast synthesis and study of their photovoltaic behavior

Nanoparticles of antimony selenide, a binary metal chalcogenide, have been synthesized hydrothermally with ethylene glycol as capping agent. In short reaction time of 1h, uniform sized particles of approximately 200nm with such morphology is reporting for the first time. The compound formation is confirmed using XRD, morphology and composition using SEM and EDAX. The optical property of the material is analyzed using UV–Vis absorption spectrum, which shows a panchromatic behavior, covering the entire spectrum with absorption extending from visible to near IR region. The bandgap energy (Eg) of the material obtained from Tauc plot is 1.2eV. On account of this panchromatic nature of Sb2Se3 nanoparticles, their performance efficiency as light harvester in solar cell is analyzed from I-V measurements under 1 Sun illumination.

Seashell-derived mixed compounds of Ca, Zn and Al as active and stable catalysts for the transesterification of palm oil with methanol to biodiesel

Heterogeneous base catalysts, composed of mixed calcium, zinc and aluminium compounds (ZSA), for the transesterification of palm oil with methanol to produce biodiesel as fatty acid methyl esters (FAME) were prepared from waste mixed seashells in the presence of zinc nitrate and alumina via dissolution-precipitation method. The effects of the catalyst calcination temperature on the physicochemical and catalytic properties were studied. Calcination of ZSA at 300°C generated calcium hydroxide as the main active phase, while the formation of CaO at higher calcination temperatures contributed to the catalyst basicity and catalytic activity. The catalyst calcined at 500°C (ZSA-500) possessed a calcium-rich surface on which nanocrystallites of CaO were dispersed. The ZSA-500 catalyst showed the highest stability to ambient air (relative humidity of 73%) exposure for 3d. The loss of catalytic activity at the higher calcination temperatures of 700 and 900°C was related to the formation of Ca12Al14O33 and the transformation of CaO to calcium carbonate during air exposure. The ZSA-500 catalyst had the highest surface area and basicity and gave the highest FAME yield (98.0±1.60wt%). Suitable conditions for transesterification over ZSA-500 at 60°C were a catalyst loading of 10wt%, methanol:oil molar ratio of 30:1 and reaction time of 3h. Moreover, the ZSA-500 catalyst could be reused after methanol washing to give a FAME yield more than 96% for at least five uses.

Metal oxide-catalyzed hydrothermal liquefaction of Malaysian oil palm biomass to bio-oil under supercritical condition

Effect of metal oxide catalysts such as CaO, MgO, MnO, ZnO, NiO, SnO, CeO2, Al2O3 and La2O3 on supercritical hydrothermal liquefaction of empty fruit bunch (EFB) derived from oil palm residues to bio-oil were studied in terms of product yields and characteristics. EFB, water and 1.0wt% metal oxide were loaded into an Inconel batch reactor, heated to 390°C to reach 25MPa at reaction time of 1h. Among the tested catalysts, four most active metal oxides with lower electronegativity such as CaO, MnO, La2O3 and CeO2 were selected, and gave maximum relative yield of bio-oil at about 1.40 times that without catalyst. Based on GC–MS and FT-IR analyses, the presence of phenol and its derivatives, ketone, other aromatic compounds and carboxylic acid in bio-oils obtained were confirmed. Thermogravimetric (TG) analysis of obtained bio-oils showed three stages of thermal degradation behaviour. Modified Reverchon-Sesti Osseo model provides good fit for the experimental yield of bio-oil formed with the four most active metal oxide catalysts.

Characterization of products evolved from supercritical water gasification of xylose (principal sugar in hemicellulose)

ABSTRACTThe catalyst decomposition of xylose (the principal sugar in hemicellulose) was examined in supercritical water for temperature from 400 to 600°C. Experiments were performed in the absence and presence of three main types of catalysts [alkali catalysts (K2CO3 and KOH) and metal impregnated activated carbons (Ni/AC) and (Ru/AC)] with a reaction time of 1h. Gasification yield reaches maximum values by using K2CO3 and KOH at the highest temperature of 600°C. The highest H2 yield and the highest CH4 yield were obtained by using Ru/AC and Ni/AC, respectively. Acetic acid and 5-methyl furfural were determined as the main aqueous products and reached maximum value by using Ru/AC.

Sono assisted electrocoagulation process for the removal of pollutant from pulp and paper industry effluent.

In the present work, the efficiency of the sonication, electrocoagulation, and sono-electrocoagulation process for removal of pollutants from the industrial effluent of the pulp and paper industry was compared. The experimental results showed that the sono-electrocoagulation process yielded higher pollutant removal percentage compared to the sonication and electrocoagulation process alone. The effect of the operating parameters in the sono-electrocoagulation process such as electrolyte concentration (1-5g/L), current density (1-5A/dm2), effluent pH (3-11), COD concentration (1500-6000mg/L), inter-electrode distance (1-3cm), and electrode combination (Fe and Al) on the color removal, COD removal, and power consumption were studied. The maximum color and COD removal percentages of 100 and 95%, respectively, were obtained at the current density of 4A/dm2, electrolyte concentration of 4g/L, effluent pH of 7, COD concentration of 3000mg/L, electrode combination of Fe/Fe, inter-electrode distance of 1cm, and reaction time of 4h, respectively. The color and COD removal percentages were analyzed by using an UV/Vis spectrophotometer and closed reflux method. The results showed that the sono-electrocoagulation process could be used as an efficient and environmental friendly technique for complete pollutant removal.

Study of oxidization of coal–pitch by O3

For the purpose of obtaining small molecular and oxygen-containing aromatic compounds, taking a toluene-extracted coal pitch as the research object, the oxidation of coal–pitch by ozone (O3) in formic acid was studied. The coal–pitch sample and the oxidized pitch residue were characterized by elementary analysis and Fourier transform infrared spectroscopy (FTIR), while the small molecular products were analyzed by a gas chromatography–mass spectrometer (GC–MS). The results show that the highest oxygen content of oxidized coal pitch had been acquired at a reaction temperature of 50°C, an O3 flow rate of 6300mg/h and a reaction time of 4h. Quite a lot of hydroxyls and carbonyls were introduced into the structure of the oxidized coal–pitch, while the small molecules produced mainly involve nonpolar aromatic compounds, aromatic anhydride and quinone compounds. It is speculated that the mechanism is direct electrophilic oxidation in which the molecules of O3 directly attack the aromatic ring at its carbon atoms with high electron density, and then generate hydroxyl or carbonyl until the aromatic ring cracks. This study shows that O3 can make the fused aromatic ring of coal–pitch become oxidized and depolymerized, and hence the ozonization of coal–pitch can be a potential method for obtaining oxygen-containing aromatic compounds.

Preparation of Pd/C nanocatalyst for hydropurification of terephthalic acid from aqueous colloid solution

An activated carbon-supported palladium catalyst for hydropurification of crude terephthalic acid was prepared by coating coconut activated carbon with Pd nanoparticles synthesized from colloid solution containing ternary surfactants. The performance and microstructure of catalysts were investigated by means of scanning electron microscope, high resolution transmission electron microscope, H2 chemisorption and high performance liquid chromatography. The results show that the Pd particles in colloidal dispersion have a narrow size distribution and the average size is about 6.45nm. The conversion rate of 4-carboxy benzaldehyde nearly reaches 100% under reaction temperature of 278°C, H2 partial pressure of 0.5MPa and reaction time of 1h. The catalyst remains nearly stable after five consecutive hydropurification tests. When the concentration of these surfactants is 0.67g/L, the catalytic performance of catalyst remains relatively high value. The ternary surfactants of Brij 35-Tween 80-CTAB provides a dense micellar layer which warps and minimizes the colloids particles and as a result the catalytic activity and stability of catalysts are increased.

Hydrothermal gasification of biomass model compounds (cellulose and lignin alkali) and model mixtures

Biomass model compounds (cellulose and lignin alkali) and their mixtures were gasified at sub- and super-critical water conditions in the absence and presence of alkali catalyst (K2CO3). Hydrothermal gasification was performed in batch reactor at temperature range of 300–600°C and pressure range of 90–410bar with a reaction time of 1h. Product yields of gaseous, aqueous and residue were investigated for model compounds (cellulose/lignin alkali) and their mixtures with weight ratios of 80/20, 60/40, 40/60 and 20/80 (wt./wt.). These mixtures were arranged to define the interaction between degradation products of model compounds of lignocellulosic biomass. In addition, gaseous and aqueous product compositions were identified to highlight prevailing reaction pathways during decomposition of model compounds. The highest hydrogen and methane yields were reached at 600°C in the presence of K2CO3.

Effect of reaction temperature on the size and morphology of scorodite synthesized using ultrasound irradiation

Synthesis of scorodite (FeAsO4·2H2O) using dynamic action agglomeration and the oxidation effect from ultrasound irradiation was investigated. The effect of different reaction temperatures (90, 70, 50, and 30°C) on the size and morphology of scorodite particles synthesized under O2 gas flow and ultrasound irradiation was explored because the generation of fine bubbles depends on the solution temperature. At 90°C, the size of scorodite particles was non-homogeneous (from fine particles (<1μm) to large particles (>10μm)). The oxidation–reduction potential (ORP) and yield at 90°C showed lower values than those at 70°C. The scorodite particles, including fine and non-homogeneous particles, were generated by a decrease in the oxidation of Fe(II) to Fe(III) and promotion of dissolution caused by the generation of radicals and jet flow from ultrasound irradiation. Using ultrasound irradiation in the synthesis of scorodite at low temperature (30°C) resulted in the appearance of scorodite peaks in the X-ray diffraction (XRD) pattern after a reaction time of 3h. The peaks became more intense with a reaction temperature of 50°C and crystalline scorodite was obtained. Therefore, ultrasound irradiation can enable the synthesis of scorodite at 30°C as well as the synthesis of large particles (>10μm) at higher temperature. Oxide radicals and jet flow generated by ultrasound irradiation contributed significantly to the synthesis and crystal growth of scorodite.

Algae derived biodiesel using nanocatalytic transesterification process

This work investigates the nanocatalytic biodiesel production from algae (Nannochloropsis sp.). The hydrothermal synthesis route was used in this study to produce nano Ca(OCH3)2 (calcium methoxide) as a model catalyst. The effect of the main reaction parameters i.e. catalyst dosage, temperatures under constant pressure, methanol molar ratio and reaction time on the yield of FAME (fatty acid methyl ester) were examined. Kinetic study of biodiesel synthesis from crude microalgae oil using nanocatalytic transesterification reaction was appraised. The results indicate that CH3O− species (a cluster of tiny plate-like architectures) in Ca(OCH3)2 catalyst, and acted as main active sites for transesterification process. In additional, Ca(OCH3)2 catalyst has excellent catalytic performance in production of biodiesel. The highest FAME yield of 99.0% was obtained over 3wt.% of Ca(OCH3)2 catalyst loading at methanol to oil molar ratio of 30:1 and reaction time of 3h at 80°C. Moreover, the catalyst displays a good stability and reutilization. A satisfactory FAME yield of 96% was achieved after use for five consecutive cycles without significant deactivation. The activation energy (Ea) of the transesterification reaction of crude Nannochloropsis oculata oil with methanol over Ca(OCH3)2 nanocatalyst was obtained as 58.62kJmol−1. The results revealed that the yield of methyl esters obtained from algae-based triglycerides was follows a pseudo first order mechanism for the forward reaction. These results suggest that the nanocatalyst is a promising for a green biodiesel production process from algae.

OPTIMASI PROSES PEMBUATAN BIODIESEL DARI ASAM LEMAK SAWIT DISTILAT (ALSD) DAN DIMETHYL CARBONATE (DMC) MENGGUNAKAN KATALIS NOVOZYM®435

Biodiesel production has rapidly grown over the last decades, and it has attracted much attention in the market as fuel that promising substitute for petroleum diesel, because its physical and chemical properties and energy content are similar to those of petroleum diesel. The main problem in producing biodiesel is its high cost which could be reduced by use of less expensive feedstock. Therefore, in this work biodiesel is synthesized by enzymatic esterification from low quality feedstock which is unrefined and much cheaper than the refined oil, such as palm fatty acid distillate (PFAD) with dialkyl carbonate using immobilized lipase (Novozym®435). Enzymatic process has certain advantages over the chemical process, as it is less energy intensive, allowing the esterification of glycerides with high free fatty acid contents (PFAD, 85-95% FFA) and no enzymatic activity loss. Methanol replaced by dialkyl carbonate, especially DMC due to esterification (methanolysis) is close to equilibrium reaction whereas using DMC the intermediate compound immediately decomposes to carbon dioxide and an alcohol, which have been investigated. Moreover, DMC are cheap, eco-friendly chemical, non-toxic properties and widely available. Factors affecting the reaction such as DMC to PFAD molar ratio, reaction temperature, reaction time and catalyst concentration were systematically analyzed by response surface methodology (RSM) with central composite design (CCD). The optimal condition is using 6:1 molar ratio of DMC to PFAD at 60 oC, for a reaction time 3h in the presence 10wt% of catalyst (based on oil weight). The results showed that synthesis of biodiesel through enzymatic esterification using PFAD suitable for biodiesel production.

Production of glycerol carbonate from glycerol with aid of ionic liquid as catalyst

The rapid growth of biodiesel industry has led to a large surplus of its major unintentional byproduct particularly glycerol. Thus, finding a new application is necessary to convert glycerol to value added products. In this study, glycerol has been subjected to a transesterification reaction to synthesis glycerol carbonate (GC) over several selected ammonium and imidazolium-based ionic liquids (ILs) as catalysts. It is believed that the variation of catalytic performance between ILs was due to the anion strength of ILs. The glycerol conversion, yield and selectivity of GC were followed the anion order of [Ac]>[Dca]>[Fmt]>[DMP]>[NO3]>[Cl]>[BF4]. Effects of reaction temperature, time, diethyl carbonate (DEC)/glycerol molar ratio and catalyst loading on glycerol conversion and GC yield have been analysed. The IL, 1-ethyl-3-methylimidazolium acetate (emim[Ac]) shows best performance under solvent-free with conversion of glycerol and GC yield reached highest at 93.50% and 88.70%, respectively under reaction temperature of 120°C reaction time of 2h, DEC/glycerol molar ratio of 2 and catalyst loading of 0.5mol%. Also, this emim[Ac] can be reused as catalyst at least three times without any significant reduction in conversion, yield and selectivity. Reaction mechanism of the transesterification reaction catalysed by emim[Ac] has been proposed in this study.

Optimization of oil extraction from waste “Date pits” for biodiesel production

Biodiesel produced from non-edible feedstocks is increasingly attractive alternative to both fossil diesels and renewable fuels derived from food crops. Date pits are one such lipid containing feedstock, and are widely available in Oman as a waste stream. This study analyses the effects of soxhlet process parameters (temperature, solvent to seed ratio and time) on the extraction of oils from waste Date pits and the subsequent production of biodiesel from it. The highest yield of oil extracted from the Date pits was 16.5wt% obtained at a temperature of 70°C, solvent to seed ratio of 4:1 and extraction duration of 7h. Gas Chromatography analysis showed that Date pits oil consisted of 54.85% unsaturated fatty acids (UFA). Transesterification of the oil extracted was undertaken at 65°C, a methanol to oil ratio of 6:1 and a reaction time of 1h for biodiesel production. Biodiesel produced from the Date pits oil was found to have a cetane number of 58.23, density 870 of kgm−3, cloud point of 4°C, pour point of −1°C, CFPP of −0.5°C and kinematic viscosity of 3.97mm2s−1 (40°C). In general, Date pit oil appears to be a potential alternative feedstock for biodiesel production.

Gummy gold and silver nanoparticles of apricot (Prunus armeniaca) confer high stability and biological activity

Gold and silver nanoparticles (Au- and Ag-NPs) were biosynthesized using the gum extract of Prunus armeniaca. These were characterized with UV–Vis spectroscopy, FTIR, SEM, EDX, XRD and atomic absorption (AA). The effect of gum and metal ions concentration, reaction temperature and time on the synthetic stability of nanoparticles was studied along with their post-synthetic stability against varying pH and salt concentrations, long term storage and extreme of temperature. Au- and Ag-NPs were also tested for antibacterial, antinociceptive and anti-inflammatory activities. Formation of Au- and Ag-NPs was confirmed from the surface plasmon resonance centered at 555 and 450nm respectively and was further corroborated from the results of FTIR, EDX, XRD and AA. SEM analysis showed that Au- and Ag-NPs were mostly spherical and in the size range of 5–40nm. It was observed that 0.5% w/v gum, 3mM Au/Ag ions solution, reaction temperature of 80°C and reaction time of 4h were suitable for the efficient synthesis of Au- and Ag-NPs. The results of post-synthetic stability revealed that Au- and Ag-NPs were stable in different concentrations of NaCl (1–3M), neutral to acidic pH (7–2) and without any long term storage (eight months) or thermal (100°C) induced degradable changes. The TGA spectrum further confirmed their thermal stability, where three successive weight losses were observed in the temperature range of 50–800°C. Au- and Ag-NPs possessed mild to moderate antibacterial activity as observed from their zone of inhibition against Staphylococcus aureus (10±0.3mm, 18±0.5mm), Escherichia coli (9±0.5mm, 10.2±0.8mm) and Pseudomonas aeruginosa (7.9±0.3mm, 11.2±0.3mm). Au-NPs significantly alleviated the acetic acid induced writhes at much lower doses of 40mg/kg (P<0.01) and 80mg/kg (P<0.001) compared to that of gum extract at 200 and 400mg/kg (P<0.001). At similar doses, Au-NPs also significantly inhibited the carrageenan induced paw edema during the 1st h (P<0.05) and 2–5h (P<0.001) of the study duration.