Volumen 3 (2019): Heft 1 (June 2019)

The remediation of organic and inorganic pollutants from the aqueous environment has touched a certain level with the development of research. Environmental pollution is increasing day by day due to industrial activities which cause a negative effect on human health and the ecosystem. Nowadays, heavy metals have a special concern due to its toxicity, persistence and bioaccumulation in nature. Toxic metals like chromium, nickel, arsenic, lead, mercury, cadmium are the main contaminants of water because they are non-biodegradable in nature. Nickel is also a toxic metal, mostly used in industries because of its anticorrosion behaviour. As a consequence nickel is present in the wastage of electroplating, tableware, metal finishing, plastics manufacturing, nickel-cadmium batteries, fertilizers and mining industries and these waste have dangerous impact on the human health and environment and causes the diseases i.e. diarrhea, anemia, hepatitis, kidney damage, gastrointestinal distress, skin dermatitis, and central nervous system dysfunction. In the present review article, several techniques are discussed for the treatment of nickel from the industrial environment. The elimination of nickel from wastewater is not important only for economic purposes but also for environmental safety.

This study was carried out to investigate the distribution and contents of sixteen priority polycyclic aromatic hydrocarbons (PAHs) in water from Amassoma axis of the Nun River, Bayelsa State, Nigeria. The PAH contaminations in the river water samples was performed using GC-MS method. The results were similar for all of the three sampling stations. Six LMW PAHs: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene and five HMW PAHs: fluoranthene, pyrene benzo (a)anthracene, chrysene and benzo(a)pyrene were found. The ∑ PAHs concentration ranged from 0.111mg/L to 0.26mg/L. In this study, PAH fingerprint ratios for determining both petrogenic and pyrogenic (pyrolytic) PAH accumulation in the environment and Toxic equivalency factor (TEF) used to estimate relative toxicity of a PAH compared to that of BaP was employed. The Ph/An ratio for water samples were 0.00, 0.33 and 0.00 in three stations, while associated figures for Fl/Py ratio values were 0.67, 0.83 and 0.50 respectively. Pearson correlation matrice analysis reveals a positive correlation between the PAHs; this could indicate a common source for some of the PAHs, however, some were negatively correlated with each other. This behavior could indicate non-point source. A comparative analysis of PAHs concentrations in the water samples with WHO standards revealed that the results obtained in this study were within the permissible levels, however, carcinogen PAHs present in the water of the Amassoma axis, Nun River may pose a threats to human health.

This investigation deals with the chemical composition and microstructural analysis of the iron object, a spear excavated from Sanur, Tamil Nadu- a megalithic site dated 300 B.C. to 50 A.D. Phase analysis and microstructural examination were carried using XRD, optical and variable pressure scanning electron microscope (VP-SEM). Optical micrograph shows the equiaxed grain structure along with the Newman bands. Formation of Newman bands suggests that the original artifact was forged at high temperature followed by cooling, although not so rapid to produce the marked hardening. The absence of carbides at the grain boundary, within the grains and lower value of micro-hardness indicates that the iron spear was not subjected to the carburizing treatment. Results of corrosion characterization revealed that deterioration of excavated iron artifact is associated with the presence of chlorine in corrosion products. However, compact nature of the outer rust (goethite) was helpful in protecting the object. The formation of goethite [ ∝-FeOOH] layer may prevent the iron matrix suffering from attacks by other environmental factors due to its good continuity. In addition, less aerated environment of storage and no history of any cleaning of object were also helpful in preventing the iron spear from further deterioration.

The present work was aimed at evaluating the adsorption properties of malachite green and congo red dyes by polyacrylonitrile carbon fibre sorbents. The sorbents were activated and oxidized using potassium hydroxide and ammonium persulfate, respectively at mild conditions. Consequently, the sorbents were characterized for surface area, surface functional groups and thermal decomposition. The activated sorbent displayed a 18.8 mg/g (94 %) of malachite green removal at Co = 20 mg/L, while both modified sorbents showed a 17.5 mg/g (87.5 %) removal of congo red at the same concentration. All sorbents showed a rapid equilibrium of malachite green and congo red dyes in water. Also, the sorbents are somewhat tolerable against different solution pH conditions despite a slight change due to possible electrostatic interactions. Thus, the materials could be successfully employed to treat dyes-laden wastewater.

Plant-mediated synthesis of silver nanoparticles through green chemistry approach has evolved into a new era of research; however, the heterogeneous size and dispersity of silver nanoparticles have limited its applications, such as surface-enhanced Raman scattering, plasmon resonance, and more specifically in the medical field of target drug delivery and therapeutic activity. Here-we investigated the effect of purification and separation modes on the dispersity, size, and morphology of silver nanoparticles, synthesized by plant extract (Nyctanthes arbor-tristis). Transmission electron microscopy revealed silver nanoparticles with an average diameter of 13.0 nm when synthesized through ethanol precipitation, which is advantageously smaller. This result suggests that the silver nanoparticles size can be fine-tuned by changing the separation mode during purification from plant extract. Due to uniformity, our obtained nanoparticles can be expected to show higher catalytic activity towards photochemical reactions, drug delivery and antibacterial activity due to the absence of inactive coating layer (capping agent).