The mouse tail model was used to measure and compare antipsoriatic activity of Acalypha wilkesiana and Culcasia scandens with that of earlier reported Kigelia africana stem methanol extract by the same authors, with the objective of finding out which of these plant extracts can be a better drug option for the treatment of psoriasis. The results obtained showed that topically administered extracts (50-200 mg/ml) induced a significant and dose-dependent increase in %orthokeratosis in the epidermis of the mice tails. % orthokeratosis values were 35.5-43.4 (A. wikesiana), 29.7-47.4 (K. africana), 31.9-36.5 (C. scandens) for the methanol ointments; 29.3-36.2 (A. wikesiana), 32.3-58.2 (K. africana), 29.40-56.2 (C. scandens) for the hexane extracts. In general, the methanol extracts produced higher % othokeratosis. No deterioration in the general condition of the mice in any group was observed. However, erythema was observed on the tails of the mice on which the K. africana stem methanol extract ointment (200 mg/ml) was applied. No tail erythema was observed in any other group. Application of the ointments resulted in the softening of the tails. In general, the irritation potentials of the ointments were relatively low when compared to that induced by dithranol a drug commonly used in the treatment of psoriasis. Only the A. wilkesiana methanol extract ointment (200 mg/ml) showed greater than 40% drug activity. Thus, A. wilkesiana appears to be the better plant for use in possible drug development for the management and cure of psoriasis because A. wilkesiana ointment showed more prospects of being an antipsoriatic topical agent when compared to C. scandens or K. africana, as the drug activity of the methanol extract of this plant was greater than 40% and quite similar to that of K. africana without the corresponding irritation potential or erythema. Key words: Psoriasis, mouse-tail model, Acalypha wilkesiana, Culcasia scandens, Kigelia africana, dithranol drug activity, irritation potential.
{"title":"Comparative evaluation of the antipsoriatic activity of Acalypha wilkesiana, Culcasia scandens with Kigelia africana using the mouse tail model","authors":"F. Oyedeji, O. S. Bankole-Ojo","doi":"10.5897/AJPAC2017.0717","DOIUrl":"https://doi.org/10.5897/AJPAC2017.0717","url":null,"abstract":"The mouse tail model was used to measure and compare antipsoriatic activity of Acalypha wilkesiana and Culcasia scandens with that of earlier reported Kigelia africana stem methanol extract by the same authors, with the objective of finding out which of these plant extracts can be a better drug option for the treatment of psoriasis. The results obtained showed that topically administered extracts (50-200 mg/ml) induced a significant and dose-dependent increase in %orthokeratosis in the epidermis of the mice tails. % orthokeratosis values were 35.5-43.4 (A. wikesiana), 29.7-47.4 (K. africana), 31.9-36.5 (C. scandens) for the methanol ointments; 29.3-36.2 (A. wikesiana), 32.3-58.2 (K. africana), 29.40-56.2 (C. scandens) for the hexane extracts. In general, the methanol extracts produced higher % othokeratosis. No deterioration in the general condition of the mice in any group was observed. However, erythema was observed on the tails of the mice on which the K. africana stem methanol extract ointment (200 mg/ml) was applied. No tail erythema was observed in any other group. Application of the ointments resulted in the softening of the tails. In general, the irritation potentials of the ointments were relatively low when compared to that induced by dithranol a drug commonly used in the treatment of psoriasis. Only the A. wilkesiana methanol extract ointment (200 mg/ml) showed greater than 40% drug activity. Thus, A. wilkesiana appears to be the better plant for use in possible drug development for the management and cure of psoriasis because A. wilkesiana ointment showed more prospects of being an antipsoriatic topical agent when compared to C. scandens or K. africana, as the drug activity of the methanol extract of this plant was greater than 40% and quite similar to that of K. africana without the corresponding irritation potential or erythema. \u0000 \u0000 Key words: Psoriasis, mouse-tail model, Acalypha wilkesiana, Culcasia scandens, Kigelia africana, dithranol drug activity, irritation potential.","PeriodicalId":7556,"journal":{"name":"African Journal of Pure and Applied Chemistry","volume":"63 1","pages":"37-41"},"PeriodicalIF":0.0,"publicationDate":"2017-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74061478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cypermethrin is a synthetic, pyrethroid insecticide and used for agricultural practices. The leaching of this pesticide through soil is of great concern because of the possibility of contaminating ground and surface water. The mobility of pesticide in soil being the main environmental reservoir varies among soil orders and the concept is still under investigation. Hence, this study was aimed at investigating the sorption capability of Alfisol and Inceptisol at different soil depth when leached with simulated rainwater of different pH values. The leachates were determined for cypermethrin concentration using a new UV/Visible spectrometry method. The CEC, organic matter content of Alfisol were 4.05±0.03 cmol/kg and 1.74±0.02%, while the corresponding characteristics of Inceptisol were 4.45±0.05 cmol/kg and 1.03±0.01%, respectively. pH of Alfisol and Inceptisol soil orders were 5.92 and 6.25, respectively. Simulated rainwater (pH 4) of 50, 100 and 150 mL leached out 37.0±0.1, 43.1±0.1 and 59.4±0.2% of cypermethrin, respectively from Alfisol at soil depth of 10 cm. At pH 6.8, the corresponding volumes of simulated rainwater leached out 31.8±0.1, 35.4±0.1 and 37.4±0.1% of cypermethrin, respectively. For each soil order, these proportions of sorbed cypermethrin decreased progressively as soil depth increased from 10-30 cm. The proportions of cypermethrin sorbed by Inceptisol were more than the corresponding proportions sorbed by Afisol. Afisol has high clay and organic contents, which might be responsible for its surpassing potential to sorb cypermethrin compared to Inceptisol. Key words: Pyrethroid insecticide, leaching, Alfisol-Inceptisol soil orders, simulated rainwater, UV/Visible spectrometry.
{"title":"Sorption of Cypermethrin from Alfisol and Inceptisol using acidified simulated rainwater in a soil column set-up","authors":"A. Ipeaiyeda, A. O. Fasiku","doi":"10.5897/AJPAC2017.0724","DOIUrl":"https://doi.org/10.5897/AJPAC2017.0724","url":null,"abstract":"Cypermethrin is a synthetic, pyrethroid insecticide and used for agricultural practices. The leaching of this pesticide through soil is of great concern because of the possibility of contaminating ground and surface water. The mobility of pesticide in soil being the main environmental reservoir varies among soil orders and the concept is still under investigation. Hence, this study was aimed at investigating the sorption capability of Alfisol and Inceptisol at different soil depth when leached with simulated rainwater of different pH values. The leachates were determined for cypermethrin concentration using a new UV/Visible spectrometry method. The CEC, organic matter content of Alfisol were 4.05±0.03 cmol/kg and 1.74±0.02%, while the corresponding characteristics of Inceptisol were 4.45±0.05 cmol/kg and 1.03±0.01%, respectively. pH of Alfisol and Inceptisol soil orders were 5.92 and 6.25, respectively. Simulated rainwater (pH 4) of 50, 100 and 150 mL leached out 37.0±0.1, 43.1±0.1 and 59.4±0.2% of cypermethrin, respectively from Alfisol at soil depth of 10 cm. At pH 6.8, the corresponding volumes of simulated rainwater leached out 31.8±0.1, 35.4±0.1 and 37.4±0.1% of cypermethrin, respectively. For each soil order, these proportions of sorbed cypermethrin decreased progressively as soil depth increased from 10-30 cm. The proportions of cypermethrin sorbed by Inceptisol were more than the corresponding proportions sorbed by Afisol. Afisol has high clay and organic contents, which might be responsible for its surpassing potential to sorb cypermethrin compared to Inceptisol. \u0000 \u0000 Key words: Pyrethroid insecticide, leaching, Alfisol-Inceptisol soil orders, simulated rainwater, UV/Visible spectrometry.","PeriodicalId":7556,"journal":{"name":"African Journal of Pure and Applied Chemistry","volume":"60 1","pages":"30-36"},"PeriodicalIF":0.0,"publicationDate":"2017-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74203864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The industrial application of a vegetable oil is determined by the oil properties. This work was undertaken to alter the properties of Jatropha curcas Kernel oil and possibly find new applications for it. The seed kernels were roasted to different temperatures (140 to 230°C) and the physicochemical properties of the cold hexane and hot water extracted oils were studied. The oil yield, saponification, iodine, acid and peroxide values were affected by roasting temperature and method of extraction and these showed significant difference (p < 0.05). The calculated fuel properties: cetane number and calorific value were improved upon roasting, with cold hexane extracted oils yielding better results. Roasting improved the properties of the oil as diesel substitute but its suitability for use in paints and surface coatings formulation was reduced. The hot water extracted oil showed improved properties for soap production. Key words: Jatropha curcas, roasting temperature, oil extraction, physicochemical properties.
{"title":"Effect of roasting temperature on the physicochemical properties of Jatropha curcas Kernel oil extracted with cold hexane and hot water","authors":"L. M. Nwokocha, Adewale Adegbuyiro","doi":"10.5897/AJPAC2017.0721","DOIUrl":"https://doi.org/10.5897/AJPAC2017.0721","url":null,"abstract":"The industrial application of a vegetable oil is determined by the oil properties. This work was undertaken to alter the properties of Jatropha curcas Kernel oil and possibly find new applications for it. The seed kernels were roasted to different temperatures (140 to 230°C) and the physicochemical properties of the cold hexane and hot water extracted oils were studied. The oil yield, saponification, iodine, acid and peroxide values were affected by roasting temperature and method of extraction and these showed significant difference (p < 0.05). The calculated fuel properties: cetane number and calorific value were improved upon roasting, with cold hexane extracted oils yielding better results. Roasting improved the properties of the oil as diesel substitute but its suitability for use in paints and surface coatings formulation was reduced. The hot water extracted oil showed improved properties for soap production. \u0000 \u0000 Key words: Jatropha curcas, roasting temperature, oil extraction, physicochemical properties.","PeriodicalId":7556,"journal":{"name":"African Journal of Pure and Applied Chemistry","volume":"17 1","pages":"19-29"},"PeriodicalIF":0.0,"publicationDate":"2017-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88518468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sylvia Gwebu, N. Tavengwa, M. Klink, F. Mtunzi, J. M. Sekomeng, Modise, V. Pakade
Determination of the levels of heavy metals in sewage sludge is necessary prior to application of the sludge to agriculture because of the inherent risk of heavy metal toxicity to soil, plants and humans. The heavy metals (Cu, Cd, Pb and Zn) in sewage sludge were quantified using inductively coupled plasma optical emission spectroscopy (ICP-OES) following extraction with modified-BCR and ultrasonic assisted-BCR extraction methods. The quantities of heavy metals obtained from the two extraction methods were compared. The ICP-OES results indicated that in the exchangeable fraction in both extraction methods the amount of zinc released ranged from 19-227 mg kg-1, and this represented the highest concentration of metals in this fraction. Clarifier sludge contained more zinc (2375 mg kg-1) than raw sludge (310 mg kg-1). An improvement in the amount of zinc (120.8 mg kg-1) and lead (98.7 mg kg-1) released in the reducible fraction in raw sludge samples was obtained with UA-BCR extraction. UA-BCR showed that the raw sludge contained about 17 mg kg-1 of Cd while only about 0.625 mg kg-1 was released using the modified BCR extraction. Some of the metals quantified were higher than the permissible levels, and the sludge not be used for soil enrichment. The results of this study demonstrated that the modified-BCR and the ultrasonic assisted-BCR extraction methods should be used in conjunction since one method alone might not be efficient in matrix breaking and releasing metal ions into solution. This may lead to incorrect conclusions about the presence or absence of metal ions in sewage sludge. Key words: Heavy metals, ultrasonication, sequential extraction, sludge, clarifier samples
{"title":"Quantification of Cd, Cu, Pb and Zn from sewage sludge by modified-BCR and ultrasound assisted-modified BCR sequential extraction methods","authors":"Sylvia Gwebu, N. Tavengwa, M. Klink, F. Mtunzi, J. M. Sekomeng, Modise, V. Pakade","doi":"10.5897/AJPAC2016.0712","DOIUrl":"https://doi.org/10.5897/AJPAC2016.0712","url":null,"abstract":"Determination of the levels of heavy metals in sewage sludge is necessary prior to application of the sludge to agriculture because of the inherent risk of heavy metal toxicity to soil, plants and humans. The heavy metals (Cu, Cd, Pb and Zn) in sewage sludge were quantified using inductively coupled plasma optical emission spectroscopy (ICP-OES) following extraction with modified-BCR and ultrasonic assisted-BCR extraction methods. The quantities of heavy metals obtained from the two extraction methods were compared. The ICP-OES results indicated that in the exchangeable fraction in both extraction methods the amount of zinc released ranged from 19-227 mg kg-1, and this represented the highest concentration of metals in this fraction. Clarifier sludge contained more zinc (2375 mg kg-1) than raw sludge (310 mg kg-1). An improvement in the amount of zinc (120.8 mg kg-1) and lead (98.7 mg kg-1) released in the reducible fraction in raw sludge samples was obtained with UA-BCR extraction. UA-BCR showed that the raw sludge contained about 17 mg kg-1 of Cd while only about 0.625 mg kg-1 was released using the modified BCR extraction. Some of the metals quantified were higher than the permissible levels, and the sludge not be used for soil enrichment. The results of this study demonstrated that the modified-BCR and the ultrasonic assisted-BCR extraction methods should be used in conjunction since one method alone might not be efficient in matrix breaking and releasing metal ions into solution. This may lead to incorrect conclusions about the presence or absence of metal ions in sewage sludge. \u0000 \u0000 Key words: Heavy metals, ultrasonication, sequential extraction, sludge, clarifier samples","PeriodicalId":7556,"journal":{"name":"African Journal of Pure and Applied Chemistry","volume":"72 1","pages":"9-18"},"PeriodicalIF":0.0,"publicationDate":"2017-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90313213","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Simultaneous citrate reduction of various ratios of silver and platinum ions leads to the formation of core-shell nanostructured bimetallics (BM). Transmission electron microscopy (TEM) and X-ray diffraction XRD data of the BMs depicted crystalline core-shell nanoparticles consisting of Ag core and Pt shell with an average size of 22.2 nm in contrast to the Pt NPs and Ag NPs monometallics average sizes of 2.5 and 60.0 nm respectively. Tauc’s calculated optical band gaps ranged from 3.55 to 4.02 eV while the electrochemical based on Breda’s equation had a range of 1.45 to 1.80 eV. These band gaps range variation maybe due to inter atomic interaction, morphology and quantum confinement. Generally, bimetallics had higher band gaps relative to monometallics. The Ag: Pt ratio of 3:1 had the highest optical band gap and the smallest particle size. While the ratio of 1:3 had the highest electrochemical band gap as well as the largest particle size among the BMs. Suggesting band gap dependence on amount of Ag and Pt for optical and electrochemical respectively. Key words: Optical, electrochemical, band gaps, bimetallic, nanoparticles.
{"title":"Electrochemical and optical band gaps of bimetallic silver-platinum varying metal ratios nanoparticles","authors":"F. Okumu, M. Matoetoe","doi":"10.5897/AJPAC2016.0700","DOIUrl":"https://doi.org/10.5897/AJPAC2016.0700","url":null,"abstract":"Simultaneous citrate reduction of various ratios of silver and platinum ions leads to the formation of core-shell nanostructured bimetallics (BM). Transmission electron microscopy (TEM) and X-ray diffraction XRD data of the BMs depicted crystalline core-shell nanoparticles consisting of Ag core and Pt shell with an average size of 22.2 nm in contrast to the Pt NPs and Ag NPs monometallics average sizes of 2.5 and 60.0 nm respectively. Tauc’s calculated optical band gaps ranged from 3.55 to 4.02 eV while the electrochemical based on Breda’s equation had a range of 1.45 to 1.80 eV. These band gaps range variation maybe due to inter atomic interaction, morphology and quantum confinement. Generally, bimetallics had higher band gaps relative to monometallics. The Ag: Pt ratio of 3:1 had the highest optical band gap and the smallest particle size. While the ratio of 1:3 had the highest electrochemical band gap as well as the largest particle size among the BMs. Suggesting band gap dependence on amount of Ag and Pt for optical and electrochemical respectively. \u0000 \u0000 Key words: Optical, electrochemical, band gaps, bimetallic, nanoparticles.","PeriodicalId":7556,"journal":{"name":"African Journal of Pure and Applied Chemistry","volume":"1 1","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2017-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80493654","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A biochar based adsorbent prepared from Eichhornia crassipes-molasses bio-composite was tested for its ability to remove methylene blue from aqueous solutions. Molasses were used as a granulating media for powdered biomass making it easier to prepare the biochar under set conditions. The Biochar adsorbent was prepared by igniting biomass granules at 400°C. A maximum adsorption capacity of 44.13 mgâg-1 was achieved at an optimum pH 8, with a bio-sorbent dosage of 0.8 g and an initial concentration of 50 mgâL-1. Experimental data fitted well onto Freundlich adsorption isotherm with an R2 value of 0.9819. Adsorption processes followed pseudo-second order kinetics with an R2 value of 0.9877. FT-IR spectra reveal typical absorption bands around 1563, 1375 and 1028 cm-1. SEM image show the biochar consisted of irregular particles with a microporous structure and appeared to be fibrous. BET results showed that biochar particles had a surface area of 0.8923 m2âg-1, a pore volume of 0.00246 cm3âg-1 and a pore diameter of 10.87 nm. Key words: Bio-sorbent, biochar, Eichhornia crassipes, methylene blue, isotherm.
{"title":"Removal of methylene blue from aqueous solutions using biochar prepared from Eichhorrnia crassipes (Water Hyacinth)-molasses composite: Kinetic and equilibrium studies","authors":"Mupa Mathew, Rutsito D. Desmond, Musekiwa Caxton","doi":"10.5897/AJPAC2016.0703","DOIUrl":"https://doi.org/10.5897/AJPAC2016.0703","url":null,"abstract":"A biochar based adsorbent prepared from Eichhornia crassipes-molasses bio-composite was tested for its ability to remove methylene blue from aqueous solutions. Molasses were used as a granulating media for powdered biomass making it easier to prepare the biochar under set conditions. The Biochar adsorbent was prepared by igniting biomass granules at 400°C. A maximum adsorption capacity of 44.13 mgâg-1 was achieved at an optimum pH 8, with a bio-sorbent dosage of 0.8 g and an initial concentration of 50 mgâL-1. Experimental data fitted well onto Freundlich adsorption isotherm with an R2 value of 0.9819. Adsorption processes followed pseudo-second order kinetics with an R2 value of 0.9877. FT-IR spectra reveal typical absorption bands around 1563, 1375 and 1028 cm-1. SEM image show the biochar consisted of irregular particles with a microporous structure and appeared to be fibrous. BET results showed that biochar particles had a surface area of 0.8923 m2âg-1, a pore volume of 0.00246 cm3âg-1 and a pore diameter of 10.87 nm. \u0000 \u0000 \u0000 \u0000 Key words: Bio-sorbent, biochar, Eichhornia crassipes, methylene blue, isotherm.","PeriodicalId":7556,"journal":{"name":"African Journal of Pure and Applied Chemistry","volume":"38 1","pages":"63-72"},"PeriodicalIF":0.0,"publicationDate":"2016-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72884738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Antibiotic resistance by microorganisms has triggered the need to discover new antibiotics to replace the old ones. The study was designed to prepare copper-paracetamol complexes which will serve as lead compounds towards the discovery of novel antibiotics. Copper sulphate was reacted with paracetamol in the presence of sodium nitrate in borate buffer to give products which were separated into three layers when extracted with a set of organic solvents. The topmost, third layer was separated and further washed with 1:1:1 petroleum ether, ethanol and benzene to obtain a yellow extract. The first and second layers were also air dried to obtain products 1 and 2. The maximum wavelength of absorption of products 1, 2, yellow extract and paracetamol were 250, 350, 280 and 300 nm respectively. The infrared absorption peaks suggested that, the metal coordination products formed were different from the reactants (paracetamol and cupper). The atomic absorption spectra of the extracts further indicated the association of copper with paracetamol to form the coordination complexes. Products 1, 3 and the yellow extract inhibited E. coli and staphylococcus growth. In all four products were separated and their possible structures have been proposed in the text. Key words: Copper, paracetamol, coordination complex, antibacterial and drug leads.
{"title":"Copper-paracetamol complexes: Promising lead antibacterial drug candidates","authors":"S. M. Adadey, J. Sarfo","doi":"10.5897/AJPAC2016.0701","DOIUrl":"https://doi.org/10.5897/AJPAC2016.0701","url":null,"abstract":"Antibiotic resistance by microorganisms has triggered the need to discover new antibiotics to replace the old ones. The study was designed to prepare copper-paracetamol complexes which will serve as lead compounds towards the discovery of novel antibiotics. Copper sulphate was reacted with paracetamol in the presence of sodium nitrate in borate buffer to give products which were separated into three layers when extracted with a set of organic solvents. The topmost, third layer was separated and further washed with 1:1:1 petroleum ether, ethanol and benzene to obtain a yellow extract. The first and second layers were also air dried to obtain products 1 and 2. The maximum wavelength of absorption of products 1, 2, yellow extract and paracetamol were 250, 350, 280 and 300 nm respectively. The infrared absorption peaks suggested that, the metal coordination products formed were different from the reactants (paracetamol and cupper). The atomic absorption spectra of the extracts further indicated the association of copper with paracetamol to form the coordination complexes. Products 1, 3 and the yellow extract inhibited E. coli and staphylococcus growth. In all four products were separated and their possible structures have been proposed in the text. \u0000 \u0000 \u0000 \u0000 Key words: Copper, paracetamol, coordination complex, antibacterial and drug leads.","PeriodicalId":7556,"journal":{"name":"African Journal of Pure and Applied Chemistry","volume":"69 1","pages":"56-62"},"PeriodicalIF":0.0,"publicationDate":"2016-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87210266","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Four new boroxine adducts ((B3O3(Ph)3PzH) (1), (B3O3(Ph)3(PztBu,iPrH)2) (2), (B3O3(PhF2)3PzH). PzH (3) and (B3O3(PhF2)3(PztBu,iPrH)2) (4)) using phenylboronic acid, 3,5-difluorophenylboronic acid, 1H-pyrazole (PzH) and 3-tert-butyl-5-isopropyl pyrazole (PztBu,iPrH) were prepared and characterized by elemental analysis, IR, 1H-NMR and X-ray diffraction. The crystallographic study reveals that PzH and PztBu,iPrH are bonded to boroxine molecule through B-N dative bond. It also demonstrates the different type of hydrogen bond interactions between adjacent molecules. The thermal stability of these adducts was investigated by TGA. Key words: Boroxine, crystal structures, hydrogen bonding, thermal study.
{"title":"Preparation, structural and thermal studies of boroxine adducts having aryl boronic acids and pyrazoles","authors":"H. Hassan","doi":"10.5897/AJPAC2016.0687","DOIUrl":"https://doi.org/10.5897/AJPAC2016.0687","url":null,"abstract":"Four new boroxine adducts ((B3O3(Ph)3PzH) (1), (B3O3(Ph)3(PztBu,iPrH)2) (2), (B3O3(PhF2)3PzH). PzH (3) and (B3O3(PhF2)3(PztBu,iPrH)2) (4)) using phenylboronic acid, 3,5-difluorophenylboronic acid, 1H-pyrazole (PzH) and 3-tert-butyl-5-isopropyl pyrazole (PztBu,iPrH) were prepared and characterized by elemental analysis, IR, 1H-NMR and X-ray diffraction. The crystallographic study reveals that PzH and PztBu,iPrH are bonded to boroxine molecule through B-N dative bond. It also demonstrates the different type of hydrogen bond interactions between adjacent molecules. The thermal stability of these adducts was investigated by TGA. \u0000 \u0000 Key words: Boroxine, crystal structures, hydrogen bonding, thermal study.","PeriodicalId":7556,"journal":{"name":"African Journal of Pure and Applied Chemistry","volume":"41 1","pages":"42-55"},"PeriodicalIF":0.0,"publicationDate":"2016-08-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85769714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Nanopolyaniline (NPA) has been synthesized by chemical oxidative polymerization of aniline and characterized using Fourier transmission infrared (FTIR), X-ray diffraction (XRD) and ultra-violet visible techniques. XRD patterns confirm that NPA has crystallite size of 37 nm with monoclinic structure and UV-visible spectra indicate its band gap energy is 1.96 electron volts. Photocatalytic efficiency of as-synthesized NPA was studied using degradation of phenol as a probe. Effects of photocatalyst load, pH and phenol initial concentration on the degradation of phenol were investigated. Using phenol initial concentration (50 mg L-1) and optimum photocatalyst load (200 mgL-1) and pH 10, degradation of phenol at 3 h was 93.5%. Degradation of phenol follows first order kinetics with rate constant (k) 1.62×10-2 min-1. Key words: Degradation, photocatalytic efficiency, polyaniline, phenol, X-ray diffraction (XRD).
{"title":"Photocatalytic activity of nanopolyaniline (NPA) on phenol degradation","authors":"Tesfa Oluma Fufa, A. Mengesha, O. P. Yadav","doi":"10.5897/AJPAC2016.0690","DOIUrl":"https://doi.org/10.5897/AJPAC2016.0690","url":null,"abstract":"Nanopolyaniline (NPA) has been synthesized by chemical oxidative polymerization of aniline and characterized using Fourier transmission infrared (FTIR), X-ray diffraction (XRD) and ultra-violet visible techniques. XRD patterns confirm that NPA has crystallite size of 37 nm with monoclinic structure and UV-visible spectra indicate its band gap energy is 1.96 electron volts. Photocatalytic efficiency of as-synthesized NPA was studied using degradation of phenol as a probe. Effects of photocatalyst load, pH and phenol initial concentration on the degradation of phenol were investigated. Using phenol initial concentration (50 mg L-1) and optimum photocatalyst load (200 mgL-1) and pH 10, degradation of phenol at 3 h was 93.5%. Degradation of phenol follows first order kinetics with rate constant (k) 1.62×10-2 min-1. \u0000 \u0000 Key words: Degradation, photocatalytic efficiency, polyaniline, phenol, X-ray diffraction (XRD).","PeriodicalId":7556,"journal":{"name":"African Journal of Pure and Applied Chemistry","volume":"35 1","pages":"33-41"},"PeriodicalIF":0.0,"publicationDate":"2016-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80936382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Eugene Uwiringiyimana, O. Sylvester, I. V. Joseph, F. V. Adams
This paper summarizes the effect of inhibitors on the corrosion of stainless steels and aluminium alloys in different media. Stainless steels and aluminium alloys have a wide range of applications in construction, transport, domestic appliances, medical, and energy related fields. The exposure of stainless steels and aluminium alloys to corroding environments however, results in the degradation of the materials. Inhibitors are used to mitigate the corrosion of these alloys in various corrosive media and enhance their durability. Corrosion inhibitors can either be anodic inhibitors, cathodic inhibitors, mixed inhibitors, or volatile corrosion inhibitors. This review showed that inhibition efficiency increases with increase in inhibitor concentration irrespective of alloy tested. However, adsorption of inhibitors on the alloys’ surface depends on the alloy type. Adsorption of inhibitors on the surface of stainless steels obeyed Langmuir adsorption isotherms, while those of aluminium alloys obeyed Langmuir, Temkin, Flory-Huggins and Freundlich isotherms. This study is important for different industrial fields where stainless steels and aluminium alloys are utilized. Key words: Aluminium, corrosion, corrosive media, inhibitor, stainless steels.
{"title":"The effect of corrosion inhibitors on stainless steels and aluminium alloys: A review","authors":"Eugene Uwiringiyimana, O. Sylvester, I. V. Joseph, F. V. Adams","doi":"10.5897/AJPAC2016.0676","DOIUrl":"https://doi.org/10.5897/AJPAC2016.0676","url":null,"abstract":"This paper summarizes the effect of inhibitors on the corrosion of stainless steels and aluminium alloys in different media. Stainless steels and aluminium alloys have a wide range of applications in construction, transport, domestic appliances, medical, and energy related fields. The exposure of stainless steels and aluminium alloys to corroding environments however, results in the degradation of the materials. Inhibitors are used to mitigate the corrosion of these alloys in various corrosive media and enhance their durability. Corrosion inhibitors can either be anodic inhibitors, cathodic inhibitors, mixed inhibitors, or volatile corrosion inhibitors. This review showed that inhibition efficiency increases with increase in inhibitor concentration irrespective of alloy tested. However, adsorption of inhibitors on the alloys’ surface depends on the alloy type. Adsorption of inhibitors on the surface of stainless steels obeyed Langmuir adsorption isotherms, while those of aluminium alloys obeyed Langmuir, Temkin, Flory-Huggins and Freundlich isotherms. This study is important for different industrial fields where stainless steels and aluminium alloys are utilized. \u0000 \u0000 Key words: Aluminium, corrosion, corrosive media, inhibitor, stainless steels.","PeriodicalId":7556,"journal":{"name":"African Journal of Pure and Applied Chemistry","volume":"26 1","pages":"23-32"},"PeriodicalIF":0.0,"publicationDate":"2016-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87428097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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