Synthesis of iron oxide nanoparticles by the recently developed green approach is extremely promising because of its non-toxicity and environmentally friendly behavior. In this study, nano scaled iron oxide particles (α-Fe2O3) were synthesized from hexahydrate ferric chloride (FeCl3.6H2O) with the addition of papaya (Carica papaya) leaf extract under atmospheric conditions. The synthesis of iron oxide nanoparticles was confirmed by systematic characterization using FTIR, XRD, FESEM, EDX and TGA studies. The removal efficiency of remazol yellow RR dye with the synthesized iron oxide nanoparticles as a photocatalyst was determined along with emphasizing on the parameters of catalyst dosage, initial dye concentration and pH. Increasing the dose of iron oxide nanoparticles enhanced the decolorization of the dyes and a maximum 76.6% dye degradation was occurred at pH 2 after 6 h at a catalyst dose of 0.8 g/L. Unit removal capacity of the photocatalyst was found to be 340 mg/g at dye concentration of 70 ppm and at a catalyst dose of 0.4 g/L. The synthesized nanoparticles showed moderate antibacterial activity against Klebsiella spp., E.Coli, Pseudomonas spp., S.aureus bacterial strains. Although the cytotoxic effect of nanoparticles against Hela, BHK-21 and Vero cell line was found to be toxic at maximum doses but it can be considered for tumor cell damage because it showed excellent activity against the Hela and BHK-21 cell lines.

Despite significant contributions to the national economy of Bangladesh, various urban developments, massive industrial and growing shipping activities are making the water of many urban rivers, including Karnaphuli River, extremely polluted. To find out the pollution sources and their possible health effects, 45 water samples were collected from 15 sampling stations. Investigation of six physicochemical parameters (pH, temperature, total dissolved solids, conductivity, salinity, and turbidity) through in-situ measurements and eight heavy metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) status using atomic absorption spectrophotometer (AAS) was carried out in this research. Both the physicochemical parameters and heavy metals exceeded the World Health Organization (WHO)’s permeable threshold limit. The calculated hazard quotient (HQ) and hazard index (HI) ingestion values indicate non-carcinogenic risk both for adults and children, but dermal exposure was within the safety limit. Carcinogenic risk analysis revealed that Cd could cause a risk of cancer in those using the river water for a long period. Spatial analysis and metal pollution index (MPI) results exhibit that downstream of the river water is more polluted than upstream of the river. Overall, the findings of this study imply that polluted water is a threat to human health and the results will also help to undertake proper management strategies and incorporate monitoring programs that study river water for the implementation of safety measures to protect human health.

In this study, zinc oxide (ZnO) nanoparticle was synthesized by a novel route of microwave assisted method using ascorbic acid and PVA as capping agent and stabilizing agent. A prominent peak at 378 nm by UV absorption ensured the synthesis of ZnO nanoparticles. The crystalline property revealed that synthesized ZnO nanoparticle is highly crystalline having wurtzite structure. A significant band at ~ 498 to 557 cm⁻¹ in FTIR was assigned to the characteristic stretching mode of Zn–O bond. EDX spectrum showed that ZnO nano particles were composed only with Zinc and oxygen. SEM image disclosed that ZnO nanoparticles were spherical in shape with an average particle size of 70–90 nm for the combined effect. The antimicrobial and ant-biofilm application of synthesized ZnO nanoparticle was studied against Salmonella typhi, Klebsiella spp. SK4, E. coli RN89, E. coli (gram-negative) and S. aureus-8a (gram-positive) bacteria and exhibited excellent activity against the strains. Prepared nanoparticle also found to possess outstanding photocatalytic activity against methylene blue degradation under sunlight with a T₅₀ and T₈₀ value of 71.44 and 165.87 min respectively.

Heavy metal pollution is one of the major environmental issues in recent decades owing to the rapid increase in urbanisation and industrialisation. Sediments usually act as sinks for heavy metals due to their complex physical and chemical adsorption mechanisms. In this study, heavy metals like lead (Pb), Zinc (Zn), Cadmium (Cd), Copper (Cu) and Iron (Fe) in the surface sediment from 15 location (upstream and downstream) on the Perak River, Malaysia were investigated by means of inductively coupled plasma optical emission spectroscopy (ICP-OES). The geostatistical prediction map showed the range of Pb, Zn, Cd, Cu and Fe concentration in upstream area was 14.56–27.0 µg/g, 20–51.27 µg/g, 1.51–3.0 µg/g, 6.6–19.12 µg/g and 20.24–56.58%, respectively, and in downstream areas was 27.6–60.76 µg/g, 49.04–160.5 µg/g, 2.77–4.02 µg/g, 9.82–59.99 µg/g and 31.34–39.5%, respectively. Based on the enrichment factor and geoaccumulation index, Cd was found to be the most dominant pollutant in the study area. Pollution load index, sediment quality guidelines and sediment environmental toxicity quotient data showed that the downstream sediment was more polluted than the upstream sediment in the Perak River. The multivariate analysis showed that Pb, Zn and Cu mainly originated from natural sources with minor contribution from human activities, whereas Fe and Cd originated from various industrial and agricultural activities along the studied area.

Antioxidants play an important role in protecting cellular damage by reactive oxygen species. The aim of the present study is to assess the phytochemical nature, antioxidant and antibacterial activities of petroleum ether, chloroform, methanol, and aqueous extracts of Crotalaria pallida stem. The preliminary screening of the various extracts was carried out using standard methods. Total phenolic content (TPC) was determined by the modified Folin-Ciocalteu method and antioxidant activities were assayed using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, reducing power assay, total antioxidant capacity (TAC) and reduction of ferric ions. Antibacterial activity of different extracts were assayed against Gram-positive and Gram-negative bacterial strains by observing the zone of inhibition using disc diffusion method, where Staphylococcus aureus, Bacillus cereus, Escherichia coli and Pseudomonas aeruginosa were used as bacterial strains. Petroleum ether, chloroform, methanol and aqueous extracts of stem exhibited remarkable antioxidant activity in terms of all the assays tested. Petroleum ether extract (PEE) showed DPPH radical scavenging activity with IC50 value of 126.96 µg/ml. In antibacterial assay, the PEE and chloroform extract (CE) showed mild to moderate antibacterial activity against all the bacterial strains except B. cereus while methanol extract (ME) showed no inhibitory effect against any of the tested bacteria. PEE, CE and ME of C. pallida stem were found to be the most effective free radical quencher and a potent source of natural antioxidants as well as antibacterial activity. Thus justifying their traditional use in green therapeutics.

Oriental Journal of Chemistry is a peer reviewed quarterly research journal of pure and applied chemistry. It publishes standard research papers in almost all thrust areas of current chemistry of academic and commercial importance. It provides a platform for rapid publication of quality research papers, reviews and chemistry letters. Oriental Journal of Chemistry is abstracted and indexed in almost all reputed National and International agencies.