South African journal of chemistry最新文献

A novel chromogenic agent for colorimetric estimation of copper in water and pharmaceutical tablets 一种新型显色剂，用于水和药片中铜的比色测定

South African journal of chemistry Pub Date : 2023-01-01 DOI: 10.17159/0379-4350/2023/v77a17

S Fraihat

引用次数: 0

An investigation into arsenic speciation in a wetland impacted by acid mine drainage 矿山酸性水对湿地砷形态影响的研究

South African journal of chemistry Pub Date : 2023-01-01 DOI: 10.17159/0379-4350/2023/v77a15

S Chetty, M Humphries, K Blümlein, L Pillay

{"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":null,"pages":null},"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}

引用次数: 0

Volumetric and viscometric studies of binary mixtures of methanol and some alkyl acetates at varying temperatures 不同温度下甲醇和某些醋酸烷基酯二元混合物的体积和粘度研究

South African journal of chemistry Pub Date : 2023-01-01 DOI: 10.17159/0379-4350/2023/v77a16

C Ekezie, G Cookey, J Maduelosi

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In vitro antibacterial and cytotoxic activity of zinc oxide, iron oxide and silver nanoparticles synthesised from Artemisia afra 青蒿合成的氧化锌、氧化铁和银纳米颗粒的体外抗菌和细胞毒活性

South African journal of chemistry Pub Date : 2023-01-01 DOI: 10.17159/0379-4350/2023/v77a14

B Shelembe, R Moodley, H Chenia

{"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":null,"pages":null},"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}

引用次数: 0

Computational study on the antioxidant activity of five plant food benzoic acid derivatives: dearomatization and stability of H abstraction radicals 五种植物性食品苯甲酸衍生物抗氧化活性的计算研究:脱芳性和H萃取自由基稳定性

South African journal of chemistry Pub Date : 2023-01-01 DOI: 10.17159/0379-4350/2023/v77a13

B Isamura

引用次数: 0

Cu(II) catalyzed oxidation of L-phenylalanine by hexacyanoferrate(III) in cationic micellar medium Cu(II)在阳离子胶束介质中催化六氰铁酸盐(III)氧化l -苯丙氨酸

South African journal of chemistry Pub Date : 2023-01-01 DOI: 10.17159/0379-4350/2023/v77a18

A Srivastava, N Srivastava, K Srivastava

{"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":null,"pages":null},"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}

引用次数: 0

Fabrication, characterization and mechanical properties of hematite (a-Fe2O3) filled natural rubber/low-density polyethylene composites 赤铁矿(a-Fe2O3)填充天然橡胶/低密度聚乙烯复合材料的制备、表征及力学性能

South African journal of chemistry Pub Date : 2023-01-01 DOI: 10.17159/0379-4350/2023/v77a12

Henry Obasi, Franklin Opara, Genevive Onuegbu, Kate Chike, Godwin Onyeagoro

{"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":null,"pages":null},"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}

引用次数: 0