Arabian Journal of Chemistry
ISSN : 18785352
Current Publisher: Elsevier BV (10.1016)
Total articles ≅ 3,561
Latest articles in this journal
Arabian Journal of Chemistry; doi:10.1016/j.arabjc.2020.09.003
A magnetic catalyst with composition ZnO-Ni0.5Zn0.5Fe2O4-Fe2O3 was synthesized by a combustion reaction on a pilot-scale and applied in the conversion of residual oil into biodiesel by simultaneous transesterification and esterification reactions (TES). For that, statistical analysis of the factors that influence the process (catalyst concentration, alcoholic route, and temperature) was evaluated by 23 factorial experimental design. The ZnO-Ni0.5Zn0.5Fe2O4-Fe2O3 magnetic catalyst was characterized in terms of the structure, morphology, magnetic, TPD-NH3 acidity analysis and catalytic properties. The results indicate the formation of a catalyst with a surface area of 52.9 m2g-1, and density of the sample was 4.8 g/cm3 which is consisted of a mixture of the phases containing 55.87% Fe2O3, 36.96% Ni0.5Zn0.5Fe2O4, and 7.16% ZnO. The magnetic characterization indicated that the synthesized catalyst is ferromagnetic with magnetization 6.12 emu/g and coercive field of 5.3 G. In the TES reactions, the residual oil was active showing conversion to 96.16% ethyl esters and with a long useful life maintaining sustained activity after two consecutive reuse cycles with the conversion of 95.27%, 93.07% and 76.93%, respectively. The experimental design was significant and presented a 95% reliability level. The statistical analysis identified (+1) and (-1) as higher and lower level variables, respectively. The amount of catalyst used was equal to 5%, at 200°C in methyl alcohol (alcoholic route). In summary, a new catalyst composed of a mixture of magnetically active phases was developed and successfully applied in biodiesel’s synthesis from residual oil. Undoubtedly these results have a positive and significant impact on the environment and to society as a whole.
Arabian Journal of Chemistry; doi:10.1016/j.arabjc.2020.09.002
Seaweeds are known as excellent sources of unique bioactive metabolites. In the present study, proton nuclear magnetic resonance (1H-NMR) combined with principal component analysis (PCA) was used to distinguish the metabolic variations in Brown seaweed, Sargassum polycystum treated under different drying processes. The study also evaluated the phytochemistry, antioxidant, and antimicrobial effects of S. polycystum extracted in different solvents. Mutually under the different drying processes investigated, a total of 12 metabolites were identified from 1H-NMR analysis. Freeze drying emerged as the most efficient process that preserved most of the potentially beneficial metabolites in the samples. The results of the qualitative phytochemical screening of differentially dried S. polycystum extracts revealed the presence of various secondary metabolites. The 70% ethanol extract exhibited the highest total phenolic (627 ± 50.81 mg GAE/100 g dried samples) and also displayed the highest DPPH scavenging activity (61.4 ± 0.171%) at the highest concentration (3 mg ml -1) tested. Methanol extract on the other hand contained the highest total antioxidant capacity (121.00±0.003 mmol/g) followed by 70% ethanol extract (120.00 ± 0.001 mmol/g) at concentration of 1.25 mg/mL. The 70% ethanol extract also showed inhibition zone towards all bacteria samples tested compared to others solvent extracts. Based on these results, the identification of metabolites variations using PCA is considered as very useful procedure as a basis to recommend the most efficient processing (drying) method. The potential utilization of the tested Brown seaweed S. polycystum species as a source of antioxidants and antibacterial agents were also highlighted. The commercial cultivation of the species therefore, needs to be encouraged and promoted.
Arabian Journal of Chemistry; doi:10.1016/j.arabjc.2020.09.001
Influence of nitrogen precursors urea, semicarbazide and N,N’-dimethyl urea on the photocatalytic activity of the N-doped TiO2 were studied by a simple decomposition method. The nano N-TiO2 catalysts were synthesized via two different modified approaches by calcination at 500 oC. The synthesized samples were characterized by IR, UV-DRS, Raman, TG-DTA, XRD, EDX, XPS, SEM, TEM and BET analysis. Of the synthesized six samples of N-TiO2 five samples showed better photocatalytic activity towards direct sunlight photo-degradation of methylene blue (MB) and rhodamine B (RhB) than Degussa P25. The catalysts obtained using semicarbazide samples F3 and F4 having large surface area of 76 and 85.8 m2/g displayed maximum photocatalytic activity. The sample F4 was 1.5 times more active than Degussa P25 for the decolourisation of MB and 1.9 times more active for the decolourisation of RhB. The presence of nitrogen, large surface area and coupling of rutile-anatase phases were found to be the main responsible factors for the enhanced photocatalytic activity. The exclusive formation of the anatase phase in the case of urea precursor is attributed to the slow evaporation of urea due to the formation of melamine derived products. The calcination temperature is the deciding factor responsible for the photocatalytic activity of the N-TiO2 samples prepared from precursors which can potentially form the melamine and its oligomerized products on the surface of TiO2.
Arabian Journal of Chemistry; doi:10.1016/j.arabjc.2020.08.033
The coating processing condition was used for the research of coating ammonium nitrate particles by means of the surfactants as coating materials which have the same polar heads with different non-polar straight hydrocarbon tails or the same non-polar straight hydrocarbon tails with different polar heads, in order to investigate the relationships between structures of surfactants and their anti-hygroscopicity used in ammonium nitrate particles coated. Furthermore, the relationships and possibly mechanism were analyzed and discussed based on both the experimental results and the selected coating processing, basic property of materials and behaviors of material in coating processes. The experimental results indicated that, the anti-hygroscopicity performance of C16-alchol and C18-acid were best ones within the all groups of selected surfactants with polar heads. The best declines of hygroscopicity of ammonium nitrate particles coated were 29.26% for C16-alcohol and 24.0% for C18-acid. And for the later, the anti-hygroscopicity performance of C18-acid and C20-acid were best ones within the all groups of selected surfactants with longer tails, and that of C16-alcohol and C14-amine were best ones with shorter tails, their best declines were 24.0%, 20.39%, 29.26% and 18.6%, respectively. The mechanism analysis results indicated that the decline of hygroscopicity were influenced by both the coating processing condition and the material properties, such as the polarity, hydroscopicity, solublity in solves and especially the surfactivity of the used surfactants, and the later, i.e. the material properties would play an important role when the processing condition and solvent used in coating ammonium nitrate particles were fixed. Therfore, the property of coating materials which are depending on their structures and the bahaviours of coating material molecules in coating processes dominated commonly and ultimatly anti-hydroscopicity of coated ammonium nitrate particles, under a selected coating processing condition. This work provides new insights on understanding the relationship between structure of surfactants and anti-hygroscopicity performance to further improve the anti-hygroscopicity performance of ammonium nitrate particles.
Arabian Journal of Chemistry; doi:10.1016/j.arabjc.2020.08.032
Sesame seeds (Sesamum indicum L.) are probably the most ancient oil seed crops. The goal of present study was to explore the quality of Labneh made from skim milk fortified with 0%, 2%, 4%, and 6% sesame seeds powder (SSP) as alternative to fat. Control Labneh made from whole milk and their treatments with SSP were stored for 21 days at 5 ± 1°C. The physiochemical, microbiological, and organoleptic properties were determined in fresh Labneh and after 7, 14, and 21 days as well as amino acids and microstructures were measured in fresh Labneh. The results showed that sesame seed contains up to 58.9% oil, 15.81% protein, 6.83% fiber, 11.03% carbohydrates, 14.84% antioxidant activity and 32.71 mg/100g sesamol. The data presented that total solid, fat and acidity increased while protein and ash contents were decreased in control Labneh as corporation with Labneh treatments. These all values increased with increasing the amount of SSP, except the acidity value decreased with increasing the amount of SSP. In various fresh Labneh samples, the major essential amino acid was Leucine and non-essential amino acid was Glutamic than the other amino acids. Microbiological examination of Labneh revealed that the total bacterial counts increased throughout the storage period. However moulds and yeasts were not detected at the first week then slightly detected and increased at the end of storage period. Coliform bacteria and spore-forming bacteria didn't observe in all Labneh treatments as storage progressed. Scanning electron microscopy showed that the control Labneh samples had more compact structure and fusion into big aggregates without voids. Labneh made from skim milk had numerous open, loose and less dense protein networks with spaces. No major differences were observed in the Labneh made from skim milk using 2% and 4% sesame seeds due to the attachment of casein micelles in chains with comparatively few interspaced voids. Labneh made from skim milk using 6% sesame seeds more intensive and thicker casein matrix than the other Labneh treatments. Organoleptic scores revealed that Labneh fortified with 4% sesame seeds powder have the highest acceptability properties.
Arabian Journal of Chemistry; doi:10.1016/j.arabjc.2020.08.031
The presence and fate of polyaromatic hydrocarbons (PAHs) in the environment are receiving a great concern. In this study, three oil-contaminated soils (industrial area, Dukhan city, and artificial soils) were utilized to examine the effect of microwave (MW) heating and UV-C irradiation on the PAHs degradation. A rapid assessment of the impact was evaluated using Fourier transform infrared (FTIR) and multivariate analysis. The total organic matter values for the maximum PAHs reduction were evaluated based on the FTIR spectra of the contaminated soils followed with the principal component analysis (PCA). The results showed that the highest total organic carbon reduction was achieved for the industrial soil sample that required a high MW power and long MW exposure time. On the other hand, the Dukhan city soil sample, which has the lowest total organic carbon, required a high MW power and short MW exposure time followed by UV-C treatment for 20 min to reach the maximal FTIR transmittance reduction. The cluster analysis was also used to evaluate the impact of MW heating, and MW heating followed by UV-C irradiation on the degradation of PAHs. The PCA results of the industrial city sample showed that neither MW treatment (100% MW, 15 min exposure time) followed by UV-C treatment for 20 min nor 10 min is significantly different from the MW treatment (100% MW, 15 min exposure time). However, for the Dukhan sample, the UV-C treatment at 10 min after high MW power and long exposure time (100% MW, 15 min exposure time) was the most efficient treatment.
Arabian Journal of Chemistry; doi:10.1016/j.arabjc.2020.08.030
A simple and efficient route for the synthesis of coumarin derivatives (3a-3g) from reaction between substituted phenols (1a-1g) and methyl acetoacetate (2b) in presence of Citrus limon L. juice, Vitis vinifera L. juice and banana peels extract has been carried out. The homogeneity of the compounds were routinely checked by thin layer chromatography and melting points reported are uncorrected. The compounds (3a-3g) were characterized by using 1HNMR and FTIR spectral techniques and evaluated for in vitro herbicidal activity against Raphanus sativus L. (Radish seeds). The compounds (3a-3g) were also screened for their fungicidal activity against Rhizoctonia solani and Colletotrichum gloeosporioides by poisoned food techniques. Antibacterial activity was also determined against Erwinia cartovora and Xanthomonas citri by inhibition zone method. From activity data, it was found that compounds 3a and 3b were most active against Raphanus sativus L. (root) and Raphanus sativus L. (shoot) respectively. Compound 3b was found most active against R. solani fungus and Xanthomonas citri bacterium at highest concentration. Compound 3e has shown maximum percentage inhibition i.e. 83.17 against C. gloeosporioides at 2000 µg/mL concentration. Erwinia cartovora bacterium was most susceptible to compound 3g giving 8.00 mm inhibition zone at 2000 µg/mL concentration. Less reaction time, excellent yields, simple work-up, cost effective and mild reaction conditions are some merits of present protocol.
Arabian Journal of Chemistry; doi:10.1016/j.arabjc.2020.08.028
A novel multifunctional of SiO2/CuFe2O4/polyaniline composite was synthesized through the interaction between silica (SiO2), copper iron oxide (CuFe2O4), and polyaniline (PANI) as starting materials. SiO2/CuFe2O4/polyaniline composite was characterized for morphology, crystallinity, textural properties, and utilised for the removal of Fe(II), Mn(II), and Cu(II) from synthetic wastewater solutions. The roles of solution pH (2.0-6.0), interaction time (15-420 min), initial ion concentration (50-700 mg/L), and solution temperature (30-50 °C) in the adsorption process were investigated. The adsorption capacities of SiO2/CuFe2O4/PANI for the tested metal ions were high compared to SiO2, CuFe2O4, and polyaniline. Equilibrium studies indicated that Fe(II) and Mn(II) adsorption were compliant with the Langmuir model, while the Freundlich equation described the removal of Cu(II) ions. The maximum Langmuir capacities were up to 285.71, 416.67, and 454.55 mg/g for Cu(II), Fe(II), and Mn(II), respectively. The pseudo-first-order kinetic model fitted well the metal ions removal data. The rate-controlling step reflected the involvement of surface and inner pore diffusion (intraparticle) processes. Electrostatic attractions and chelation were mainly responsible for the binding of metals ions onto SiO2/CuFe2O4/PANI. The selectivity of the studied ions was governed mainly by the hydrated ionic radii and the composite adsorption active sites. SiO2/CuFe2O4/PANI can be easily reused with a slight decrease (around 2-3 %) in metal removal efficiency after four successive regeneration cycles.
Arabian Journal of Chemistry; doi:10.1016/j.arabjc.2020.08.029
Activated carbon (AC) derived from gasified Glyricidia sepium woodchip (GGSWAC) were prepared using KOH and CO2 activation via microwave radiation technique to remove atenolol (ATN) from aqueous solution. The surface area (SBET) and total pore volume (TPV) of GGSWAC were 483.07 m2/g and 0.255 cm3, respectively. The n-BET model fits well with the isothermal data indicating a multilayer adsorption with the saturation capacity of 121, 143 and 163 mg/g at 30, 45 and 60⁰C, respectively. The kinetic study showed that ATN adsorption followed Avrami model equation (R2≅0.99). Based on the thermodynamic parameters, the adsorption of ATN onto GGSWAC was endothermic (ΔHS = 234.17 kJ/mol) in the first layer of adsorption and exothermic in the subsequent layer (ΔHL = -165.62 kJ/mol). The ATN adsorption was controlled by both diffusion and chemisorption. In continuous operation, the Thomas (R2= 0.9822) and Yoon–Nelson (R2= 0.9817) models successfully predicted the ATN adsorption.