Pub Date : 2023-01-01DOI: 10.17159/0379-4350/2023/v77a17
S Fraihat
The current study intends to develop a novel, simple and selective colorimetric method to identify the presence of copper on the basis of a newly-synthesized Schiff base prepared from the condensation of 1,3-phthalaldehyde with 2-aminophenol. The new chromogenic agent was studied using elemental analysis, IR, NMR, MS, and UV-VIS absorption. The new chelate produces a stable colored complex with Cu(II) ions with a 1:1 composition using the continuous variation method. The colored complex exhibited a strong absorption peak at 440 nm and this phenomenon empowers copper analysis to be conducted in natural water, and pharmaceutical solutions directly via the colorimetric method. The author analyzed and optimized all the factors that tend to influence the sensitivity of the method. Such factors include pH, time, the concentration of the ligand and temperature. The process, proposed in the study, was then evaluated in terms of precision, accuracy and selectivity. The study outcomes are as follows: linear dynamic range 0.8-22 ug mL-1; limit of quantitation 0.970 ug mL-1; and limit of detection 0.293 ug mL-1.
本研究拟在1,3-邻苯二醛与2-氨基酚缩合合成席夫碱的基础上，建立一种新的、简单的、选择性的比色法来鉴定铜的存在。采用元素分析、红外、核磁共振、质谱和紫外-可见吸收等方法对该显色剂进行了研究。该络合物与Cu(II)离子以1:1的比例连续变化生成稳定的有色络合物。有色配合物在440 nm处有很强的吸收峰，这一现象使铜可以直接通过比色法在天然水和药物溶液中进行分析。对可能影响该方法灵敏度的各种因素进行了分析和优化。这些因素包括pH值、时间、配体浓度和温度。在研究中提出的过程，然后在精密度，准确度和选择性方面进行了评估。研究结果如下:线性动态范围0.8 ~ 22 ug mL-1;定量限0.970 ug mL-1;检出限0.293 ug mL-1。
{"title":"A novel chromogenic agent for colorimetric estimation of copper in water and pharmaceutical tablets","authors":"S Fraihat","doi":"10.17159/0379-4350/2023/v77a17","DOIUrl":"https://doi.org/10.17159/0379-4350/2023/v77a17","url":null,"abstract":"The current study intends to develop a novel, simple and selective colorimetric method to identify the presence of copper on the basis of a newly-synthesized Schiff base prepared from the condensation of 1,3-phthalaldehyde with 2-aminophenol. The new chromogenic agent was studied using elemental analysis, IR, NMR, MS, and UV-VIS absorption. The new chelate produces a stable colored complex with Cu(II) ions with a 1:1 composition using the continuous variation method. The colored complex exhibited a strong absorption peak at 440 nm and this phenomenon empowers copper analysis to be conducted in natural water, and pharmaceutical solutions directly via the colorimetric method. The author analyzed and optimized all the factors that tend to influence the sensitivity of the method. Such factors include pH, time, the concentration of the ligand and temperature. The process, proposed in the study, was then evaluated in terms of precision, accuracy and selectivity. The study outcomes are as follows: linear dynamic range 0.8-22 ug mL-1; limit of quantitation 0.970 ug mL-1; and limit of detection 0.293 ug mL-1.","PeriodicalId":21882,"journal":{"name":"South African journal of chemistry","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135507769","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}
Pub Date : 2023-01-01DOI: 10.17159/0379-4350/2023/v77a15
S Chetty, M Humphries, K Blümlein, L Pillay
The formation of acid mine drainage (AMD) and release of toxic contaminants, such as arsenic (As), is a serious environmental problem encountered worldwide. In this study, we investigate the crucial role the Klip River wetland system plays in attenuating As arising from gold mining activities within the Witwatersrand Basin in Johannesburg, South Africa. Mining operations in the region commenced over 130 years ago and have been associated with the widespread pollution of water resources by AMD. We investigated As concentrations, bioavailability and speciation in a peat core from the Klip River wetland as well as in samples from the main tributaries and tailing storage facilities (TSFs) in the upper catchment. Total As concentrations in tributary and TSFs samples ranged between 10.1-89.9 mgkg-1 and 77.4-106 mg kg-1, respectively, with concentrations in the wetland varying between 1.91-73.8 mg kg-1. In general, As bioavailability was low in both catchment (19%) and wetland (4%) samples, with elemental associations suggesting the majority is bound in an immobile form to organic matter and sulfide. As(v) was the predominant species detected in all samples (0.0901-16.6 mg kg-1), with As(m), MMA and DMA present in lower concentrations. Strong correlations between As and S suggest that speciation and methylation are dependent on both chemical and microbial activity. The study highlights the vital role that wetlands can play in sequestering As in the environment.
{"title":"An investigation into arsenic speciation in a wetland impacted by acid mine drainage","authors":"S Chetty, M Humphries, K Blümlein, L Pillay","doi":"10.17159/0379-4350/2023/v77a15","DOIUrl":"https://doi.org/10.17159/0379-4350/2023/v77a15","url":null,"abstract":"The formation of acid mine drainage (AMD) and release of toxic contaminants, such as arsenic (As), is a serious environmental problem encountered worldwide. In this study, we investigate the crucial role the Klip River wetland system plays in attenuating As arising from gold mining activities within the Witwatersrand Basin in Johannesburg, South Africa. Mining operations in the region commenced over 130 years ago and have been associated with the widespread pollution of water resources by AMD. We investigated As concentrations, bioavailability and speciation in a peat core from the Klip River wetland as well as in samples from the main tributaries and tailing storage facilities (TSFs) in the upper catchment. Total As concentrations in tributary and TSFs samples ranged between 10.1-89.9 mgkg-1 and 77.4-106 mg kg-1, respectively, with concentrations in the wetland varying between 1.91-73.8 mg kg-1. In general, As bioavailability was low in both catchment (19%) and wetland (4%) samples, with elemental associations suggesting the majority is bound in an immobile form to organic matter and sulfide. As(v) was the predominant species detected in all samples (0.0901-16.6 mg kg-1), with As(m), MMA and DMA present in lower concentrations. Strong correlations between As and S suggest that speciation and methylation are dependent on both chemical and microbial activity. The study highlights the vital role that wetlands can play in sequestering As in the environment.","PeriodicalId":21882,"journal":{"name":"South African journal of chemistry","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136207159","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}
Pub Date : 2023-01-01DOI: 10.17159/0379-4350/2023/v77a16
C Ekezie, G Cookey, J Maduelosi
The degree of molecular interactions between mixed solvent molecules and thus ideal behavior results from the molecular architecture and chemical nature of component solvents. This understanding is essential in the design and applications of both pure and mixed solvent systems. Density and viscosity measurements of pure and binary mixtures of methanol and n-methyl acetate, n-butyl acetate, and n-pentyl acetate were carried out at different compositions of methanol and temperatures of 25, 30, 35, 40 °C. The experimental data obtained were correlated to the Redlich-Kister equation from where the excess functions; excess molar volumes, excess viscosities, excess Gibbs free energies of activation for viscous flow, fitting coefficients and standard deviations were obtained. The viscosity values were correlated with Hind et al, Kendral and Monroe, Grunberg and Nissan and Frenkel semi empirical models to ascertain the best fit for the systems. The results obtained have been discussed in terms of the structural differences and nature of the interactions between molecules of the mixed solvents.
{"title":"Volumetric and viscometric studies of binary mixtures of methanol and some alkyl acetates at varying temperatures","authors":"C Ekezie, G Cookey, J Maduelosi","doi":"10.17159/0379-4350/2023/v77a16","DOIUrl":"https://doi.org/10.17159/0379-4350/2023/v77a16","url":null,"abstract":"The degree of molecular interactions between mixed solvent molecules and thus ideal behavior results from the molecular architecture and chemical nature of component solvents. This understanding is essential in the design and applications of both pure and mixed solvent systems. Density and viscosity measurements of pure and binary mixtures of methanol and n-methyl acetate, n-butyl acetate, and n-pentyl acetate were carried out at different compositions of methanol and temperatures of 25, 30, 35, 40 °C. The experimental data obtained were correlated to the Redlich-Kister equation from where the excess functions; excess molar volumes, excess viscosities, excess Gibbs free energies of activation for viscous flow, fitting coefficients and standard deviations were obtained. The viscosity values were correlated with Hind et al, Kendral and Monroe, Grunberg and Nissan and Frenkel semi empirical models to ascertain the best fit for the systems. The results obtained have been discussed in terms of the structural differences and nature of the interactions between molecules of the mixed solvents.","PeriodicalId":21882,"journal":{"name":"South African journal of chemistry","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136207628","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}
Pub Date : 2023-01-01DOI: 10.17159/0379-4350/2023/v77a14
B Shelembe, R Moodley, H Chenia
The synthesis of nanoparticles using medicinal plants is a potential pathway for developing environmentally friendly drugs with minimal side effects. The aim of this study was to isolate heptadecyl-trans-p-coumarate from the medicinal plant, Artemisia afra, utilise it and its extract to synthesise silver nanoparticles (AgNPs), zinc oxide nanoparticles (ZnONPs) and iron oxide nanoparticles (Fe2O3NPs) that were evaluated for antibacterial and cytotoxic activity. AgNPs synthesised from the coumarate and extract were mostly spherical with an average size of 12 nm and 29 nm, respectively. ZnONPs were mostly rods, plates and spheres with average sizes of 31 nm (extract) and 22 nm (coumarate). Fe2O3NPs were hexagons and spheres with average sizes of 31 nm (extract) and 24 nm (coumarate). Nanoparticles improved the antibacterial activity of the extract and coumarate against Escherichia coli, Pseudomonas aeruginosa, Chromobacterium violaceum and Staphylococcus aureus. Shape of nanoparticles influenced activity; rod-shaped ZnONPs and platelet-like Fe2O3NPs synthesised using the extract exhibited better antibacterial activity. Spherical ZnONPs synthesised using the coumarate and spherical AgNPs showed greater cytotoxicity. The results suggest a synergistic effect between the metal nanoparticles and capping agents. Overall, this study confirms the use of Artemisia afra for the biosynthesis of silver, zinc oxide and iron oxide nanoparticles.
{"title":"In vitro antibacterial and cytotoxic activity of zinc oxide, iron oxide and silver nanoparticles synthesised from Artemisia afra","authors":"B Shelembe, R Moodley, H Chenia","doi":"10.17159/0379-4350/2023/v77a14","DOIUrl":"https://doi.org/10.17159/0379-4350/2023/v77a14","url":null,"abstract":"The synthesis of nanoparticles using medicinal plants is a potential pathway for developing environmentally friendly drugs with minimal side effects. The aim of this study was to isolate heptadecyl-trans-p-coumarate from the medicinal plant, Artemisia afra, utilise it and its extract to synthesise silver nanoparticles (AgNPs), zinc oxide nanoparticles (ZnONPs) and iron oxide nanoparticles (Fe2O3NPs) that were evaluated for antibacterial and cytotoxic activity. AgNPs synthesised from the coumarate and extract were mostly spherical with an average size of 12 nm and 29 nm, respectively. ZnONPs were mostly rods, plates and spheres with average sizes of 31 nm (extract) and 22 nm (coumarate). Fe2O3NPs were hexagons and spheres with average sizes of 31 nm (extract) and 24 nm (coumarate). Nanoparticles improved the antibacterial activity of the extract and coumarate against Escherichia coli, Pseudomonas aeruginosa, Chromobacterium violaceum and Staphylococcus aureus. Shape of nanoparticles influenced activity; rod-shaped ZnONPs and platelet-like Fe2O3NPs synthesised using the extract exhibited better antibacterial activity. Spherical ZnONPs synthesised using the coumarate and spherical AgNPs showed greater cytotoxicity. The results suggest a synergistic effect between the metal nanoparticles and capping agents. Overall, this study confirms the use of Artemisia afra for the biosynthesis of silver, zinc oxide and iron oxide nanoparticles.","PeriodicalId":21882,"journal":{"name":"South African journal of chemistry","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136207831","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}
Pub Date : 2023-01-01DOI: 10.17159/0379-4350/2023/v77a13
B Isamura
In this study, we report a computational investigation of the antioxidant activity of five plant food benzoic acid derivatives, namely gallic acid (GA), para-hydroxybenzoic acid (PHBA), protocatechuic acid (PCA), syringic acid (SA), and vanillic acid (VA). Based on a series of computed thermodynamics parameters, we have developed a comparative debate regarding their free radical scavenging activity in the gas phase and polar solutions (considering water and methanol solvents). This discussion expands to the elucidation of both the most preferred mechanism and the order of antioxidant activity in each environment. Paradoxically, calculations using the harmonic oscillator model of aromaticity (HOMA) suggest that H abstraction radicals gain stability as the central benzene ring loses structural aromaticity. Finally, spin densities and Fukui function f0 appear to be good indicators of the local reactivity of the five antioxidants toward free radicals.
{"title":"Computational study on the antioxidant activity of five plant food benzoic acid derivatives: dearomatization and stability of H abstraction radicals","authors":"B Isamura","doi":"10.17159/0379-4350/2023/v77a13","DOIUrl":"https://doi.org/10.17159/0379-4350/2023/v77a13","url":null,"abstract":"In this study, we report a computational investigation of the antioxidant activity of five plant food benzoic acid derivatives, namely gallic acid (GA), para-hydroxybenzoic acid (PHBA), protocatechuic acid (PCA), syringic acid (SA), and vanillic acid (VA). Based on a series of computed thermodynamics parameters, we have developed a comparative debate regarding their free radical scavenging activity in the gas phase and polar solutions (considering water and methanol solvents). This discussion expands to the elucidation of both the most preferred mechanism and the order of antioxidant activity in each environment. Paradoxically, calculations using the harmonic oscillator model of aromaticity (HOMA) suggest that H abstraction radicals gain stability as the central benzene ring loses structural aromaticity. Finally, spin densities and Fukui function f0 appear to be good indicators of the local reactivity of the five antioxidants toward free radicals.","PeriodicalId":21882,"journal":{"name":"South African journal of chemistry","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136209053","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}
Pub Date : 2023-01-01DOI: 10.17159/0379-4350/2023/v77a18
A Srivastava, N Srivastava, K Srivastava
The kinetics of Cu(II) accelerated oxidation of L-phenylalanine (Pheala) oxidation in cetyltrimethylammonium bromide (CTAB) by hexacyanoferrate(III) was investigated by registering the decline in absorbance at 420 nm. Employing the pseudo-first-order condition, the reaction's advancement has been examined as an indicator of[CTAB], [Cu(II)], [OH-], [Pheala], [Fe(CN)63-], temperature, and ionic strength. The results show that [CTAB] is the critical parameter with a discernible influence on reaction rate. Pheala interacts with [Fe(CN)6]3- in a 1:2 ratio, and this reaction exhibits first-order dependency with regard to [Fe(CN)63-]. In the investigated concentration ranges of Cu(II), [OH-], and [Pheala], the reaction demonstrates fractional-first-order kinetics. A positive salt effect is indicated by the linear rise in reaction rate with additional electrolytes. CTAB catalyzes the process substantially, and once at its peak, the rate remains basically constant as [CTAB] grows. Reduced repulsion between surfactant molecules' positive charge heads brought on by the negative-charged [Fe(CN)6]3-, OH-, and [Cu(OH)4]2- molecules may be responsible for the witnessed drop in CTAB CMC.
{"title":"Cu(II) catalyzed oxidation of L-phenylalanine by hexacyanoferrate(III) in cationic micellar medium","authors":"A Srivastava, N Srivastava, K Srivastava","doi":"10.17159/0379-4350/2023/v77a18","DOIUrl":"https://doi.org/10.17159/0379-4350/2023/v77a18","url":null,"abstract":"The kinetics of Cu(II) accelerated oxidation of L-phenylalanine (Pheala) oxidation in cetyltrimethylammonium bromide (CTAB) by hexacyanoferrate(III) was investigated by registering the decline in absorbance at 420 nm. Employing the pseudo-first-order condition, the reaction's advancement has been examined as an indicator of[CTAB], [Cu(II)], [OH-], [Pheala], [Fe(CN)63-], temperature, and ionic strength. The results show that [CTAB] is the critical parameter with a discernible influence on reaction rate. Pheala interacts with [Fe(CN)6]3- in a 1:2 ratio, and this reaction exhibits first-order dependency with regard to [Fe(CN)63-]. In the investigated concentration ranges of Cu(II), [OH-], and [Pheala], the reaction demonstrates fractional-first-order kinetics. A positive salt effect is indicated by the linear rise in reaction rate with additional electrolytes. CTAB catalyzes the process substantially, and once at its peak, the rate remains basically constant as [CTAB] grows. Reduced repulsion between surfactant molecules' positive charge heads brought on by the negative-charged [Fe(CN)6]3-, OH-, and [Cu(OH)4]2- molecules may be responsible for the witnessed drop in CTAB CMC.","PeriodicalId":21882,"journal":{"name":"South African journal of chemistry","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135504848","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}
Pub Date : 2023-01-01DOI: 10.17159/0379-4350/2023/v77a12
Henry Obasi, Franklin Opara, Genevive Onuegbu, Kate Chike, Godwin Onyeagoro
In this study, natural rubber (NR) and low-density polyethylene (LDPE) were melt blended in a 2-roll mill to fabricate NR/LDPE composites with liquid natural rubber (LNR) and hematite (a-Fe2O3) as compatibilizer and filler respectively. The effects of liquid natural rubber (LNR) on the mechanical properties and morphology of NR/LDPE composites were investigated. NR/LDPE composites were prepared in three different compositions of 70/30, 50/50 and 30/70, with filler content at varying concentrations (3, 5 and 7 g) while LNR was kept at 10 g for the modified composites. Results obtained showed increment in the tensile strength, tensile modulus, compressive and flexural properties but with decrease in the elongation at break the a-Fe2O3 and LDPE contents increase. The modification of the composites with LNR further enhanced the mechanical properties. FTIR spectrum of LNR revealed a peak at 3395 cm-1 suggesting the hydroxyl (OH) end group attached to the LNR chain due to the photochemical degradation of NR to yield LNR. FTIR spectra of the selected composites showed the presence of iron oxide bond (Fe-O) at 571 cm-1, 467 cm-1 and 463 cm-1 due to the incorporation of a-Fe2O3 filler particles in the composites. SEM images showed improved matrix/filler interfacial adhesion induced by the LNR compatibilizer.
{"title":"Fabrication, characterization and mechanical properties of hematite (a-Fe2O3) filled natural rubber/low-density polyethylene composites","authors":"Henry Obasi, Franklin Opara, Genevive Onuegbu, Kate Chike, Godwin Onyeagoro","doi":"10.17159/0379-4350/2023/v77a12","DOIUrl":"https://doi.org/10.17159/0379-4350/2023/v77a12","url":null,"abstract":"In this study, natural rubber (NR) and low-density polyethylene (LDPE) were melt blended in a 2-roll mill to fabricate NR/LDPE composites with liquid natural rubber (LNR) and hematite (a-Fe2O3) as compatibilizer and filler respectively. The effects of liquid natural rubber (LNR) on the mechanical properties and morphology of NR/LDPE composites were investigated. NR/LDPE composites were prepared in three different compositions of 70/30, 50/50 and 30/70, with filler content at varying concentrations (3, 5 and 7 g) while LNR was kept at 10 g for the modified composites. Results obtained showed increment in the tensile strength, tensile modulus, compressive and flexural properties but with decrease in the elongation at break the a-Fe2O3 and LDPE contents increase. The modification of the composites with LNR further enhanced the mechanical properties. FTIR spectrum of LNR revealed a peak at 3395 cm-1 suggesting the hydroxyl (OH) end group attached to the LNR chain due to the photochemical degradation of NR to yield LNR. FTIR spectra of the selected composites showed the presence of iron oxide bond (Fe-O) at 571 cm-1, 467 cm-1 and 463 cm-1 due to the incorporation of a-Fe2O3 filler particles in the composites. SEM images showed improved matrix/filler interfacial adhesion induced by the LNR compatibilizer.","PeriodicalId":21882,"journal":{"name":"South African journal of chemistry","volume":"135 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136207830","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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