Asian Journal of Green Chemistry

Abstract Nitrate is one of the most crucial pollutants in the urban and rural drinking water resources. Many techniques have been used to remove these contaminants. In this study, granular activated carbon (GAC) modified with the mixture of ZnCl₂, CaCl₂ and MgCl₂ is utilized for the removal of nitrate from the water. Results of removing this adsorbent by batch method and changing the effective factors including contact time, adsorbent dose, nitrate concentration, pH, and temperature were investigated. Two theoretical adsorption isotherms namely Langmuir and Freundlich were used to describe the experimental results. The Langmuir isotherm model explained the sorption process well and showed the best coefficient of determination (0.9947). The nitrate sorption kinetic data were successfully fitted to pseudo-second order kinetic model. Adsorption was maximized between pH ranges 4-8. The overall results demonstrated potential applications of modified GAC for nitrate removal from the aqueous solutions.

Abstract Spirulina has attracted a great attention as it contains many nutrients, such as protein, vitamins and minerals. Spirulina contains peptides that have therapeutic and beneficial effects on the human body. Some medicinal properties of the biological peptides of Spirulina platensis include antioxidants, antifungal, antimicrobial, anti-diabetes and anticoagulant activity. This study provides an overview of the biological peptides derived from Spirulina and some biological activities with health benefits. In this study peptide Ile-Gln-Pro from spirulina platalsis was isolated using an alkalase enzyme and investigate its inhibitory effect on the angiotensin I-converting enzyme (ACE). This peptide was purified by gel filtration chromatography and Reverse-phase high-performance liquid chromatography (RP-HPLC) Enzymatic kinetic studies showed a non-competitive inhibitory activity of this peptide, and the Ki value was 5.8 μm.

Abstract In this study, the benzopyrano[3,2-c]chromene-6,8-dione derivatives were synthesized by one-pot multi-component reaction of 1,3-cyclohexanedione, arylaldehydes, and 4-hydroxycoumarin under the solventless condition using Cu(II)-Schiff base/SBA-15 as a reusable heterogeneous catalyst in high yields. These kinds of catalysts are built from mesoporous silica SBA-15 which is covalently anchored with Cu(II)-Schiff base complex. The high yields, simple work-up procedure, reuseability of the catalyst, and environmentally friendly conditions are the main advantages of this method as compared to the other techniques. The products were identified by using1H NMR, mass and IR spectra, which were compared to those reported previously.

Abstract The Fe₃O₄ nanoparticles and the supported ionic liquid (Fe₃O₄-IL) were produced and used as efficient magnetic catalysts to synthesize the benzimidazole derivatives under solvent and solvent-free conditions. Quantitative conversion of the reactants was achieved under solvent-free conditions; catalyst reusability, through convenient magnetic decantation, showing an insignificant loss in activity. The catalyst can be readily isolated by using an external magnet and no obvious loss of activity was observed when the catalyst was reused in seven consecutive runs.

Abstract One-pot synthesis of Hantzsch 1,4-dihydropyridines (1,4-DHP) under solvent-free conditions catalyzed by HKUST-1 metal-organic frameworks are reported here. This method provides 1,4-dihydropyridines in good to excellent yields with little catalyst loading. The present methodology offers several advantages, including ease of the preparation and handling of the catalyst, simple and easy work-up, short reaction times, high yields of the products and recyclability of the catalyst.

Abstract In the present study, kinetics of synthesis of spiro[cyclobutane-1,2’-indene]-1’,3’-dione was successfully carried out by spirolation of indene-1,3-dione with 1,3-dibromo propane using aqueous potassium hydroxide and catalyzed by a newly synthesized multi-site phase-transfer catalyst viz., 1,3,5-tribenzyl-1,3,5-triethyl-1,3,5-triazinane-1,3,5-triiu tribromide (MPTC), under ultrasonic (40 kH_Z, 300 W) assisted organic solvent condition. The pseudo first-order under the ultrasound irradiation (40 kHz, 300 W) in a batch reactor, the overall reaction was greater than that of without ultrasound.

Abstract Applying environmentally benign materials such as plant extracts used to synthesize silver nanoparticles (Ag-NPs) offers numerous benefits i.e. being eco-friendly and having compatibility for pharmaceutical and other biomedical applications. Metallic nanoparticles are used in different applications including; in electronics, catalysis, and in photonic. Silver metal has a great toxicity against a wide range of microorganisms, particularly silver nanoparticle which has promising antimicrobial properties. Silver nanoparticles are found to be effective as possessing anti-inflammatory, anti-angiogenesis, antiviral, and anti-platelet activities against cancer cells. The synthesized Ag-NPs of Cassia tora L. roots were characterized using UV-vis spectra, FT-IR, TEM, and XRD analysis. The antimicrobial activities were assessed by disc diffusion method. The Ag-NPs were also examined against the fresh cultures of one Gram-positive and three Gram-negative bacteria.

Abstract The increased concentrations of heavy metals in soil pose a threat to human life through the food chain. Soil and plant samples from the coastal area of Benghazi city were collected and analyzed using flame atomic absorption spectroscopy (FAAS) for their heavy metal contents. The metal content of Cu, Cr, Ni, Zn, and Pb has been determined in the soil in the vicinity of plant roots, plant roots, and leaves. Biological absorption coefficient (BAC), bioconcentration factor (BCF), and translocation factor (TF) have been calculated to evaluate the ability of Suaeda vera to extract the metals from soil. The results showed that Suaeda vera Forssk. Ex J.F. Gmel is more suitable for phytoextraction than the phytostabilisation. Phytoremediation as a green technology has many advantages over the other methods of heavy metals removal from soils.

Abstract In the present work, semiempirical computational methods were employed to investigate the properties of a complex formed by co-adsorption of protoporphyrin IX zinc (II) and 4-(dicaynomethylene)-6-(P-methylstyryl)-4H-pyrane to elucidate its potential as sensitizer in dye sensitized solar cells. At first, PPZ-TiO₂ adsorption complex was formed via -COO^- anchoring groups to determine its adsorption energy, electronic absorption spectrum. Then it was compared with the reported literature. Afterwards 4-(dicaynomethylene)-6-(P-methylstyryl)-4H-Pyrane was co-adsorbed onto TiO₂ along with protoporphyrin IX zinc (II) and computational calculations were done to obtain total energy, energies of HOMO/LUMO and theoretical electronic absorption spectrum of the compound. The results showed that the new complex has the potential to be used as an efficient light absorbing antenna in dye sensitized solar cells with an adsorption energy of -31714.5 kcal/mol and can provide a material with broad absorption range up to 615 nm. In addition, the HOMO/LUMO energy levels of two dyes adsorbed on TiO₂, were found optimal for the flow of electrons in a cascade manner to the inorganic core materials.

Abstract To resolve the efficacies of antibacterial, antifungal, and antioxidant activities of aqueous leaf extract of Ocimum basilicum mediated biosynthesis of silver nanoparticles (Ag-NPs). Aqueous and synthesized Ag-NPs were tested by disc diffusion method against the bacterial and fungal pathogens. Antioxidant activity of synthesized Ag-NPs and aqueous plant extract were determined. The scavenging radicals were estimated by DPPH method. The synthesized Ag-NPs were characterized by XRD, FT-IR, FESEM and EDX. XRD peaks at 2θ values of 27.6°, 32.2°, 38.16°, and 46.04° representing the (110), (111), (121), and (200). FT-IR absorption peak located at 2910 cm^-1 are due to C–H stretch of alkenes and a peak at 1669 cm^-1 due to -C=C- band of alkenes and a peak at 1614 cm^-1 is assigned to N-H bend of 1° amines and a peak at 1092 cm^-1 due to C–N stretch of aliphatic amines and a peak at 875 cm^-1 are due to C–H stretch of aromatics. TEM study reveals that most of the nanocrystals formed were spherical and polyphedral in shape antibiotics inhibition zones against the bacteria Staphylococcus aureus, Escherichia coli, Klebselia pneumonia, Proteus mirabilis, Proteus valgar is using the nanoparticles 8.9, 9.2, 7.8, 8.1, and 7.4 mm. Ag-NPs exhibited strong antibacterial activity antifungal activity versus Asfergillus flavus, Asfergillus terreus, Asfergillus niger, Asfergillus fumigates exhibited a 7.8, 7.5, 6.9, and 7.1 mm inhibition zone using the Ag-NPs. Green synthesized Ag-NPs provides a promising approach can satisfy the requirement of large-scale industrial production bearing the advantage of low-cost, eco-friendly and reproducible.