Prasanta Rath

Use of sequential leaching, mineralogy, morphology and multivariate statistical technique for quantifying metal pollution in highly polluted aquatic sediments - a case study: Brahmani and Nandira Rivers, India.

The particle size distribution, geochemical composition and sequential leaching of metals (Fe, Mn, Ni, Cu, Co, Cr, Pb, Zn and Cd) are carried out in core sediments (<88 microm) from the Brahmani and Nandira Rivers, India. To confirm the contamination of downstream sediments by fly ash, mineralogical and morphological characterizations were carried out. High environmental risk of Co, Pb and Ni is due to their higher availability in exchangeable fraction. The metals like Zn, Cu and Mn represent an appreciable portion in the carbonate phase. Metals such as Zn, Pb, Cd, Co and Ni are associated with reducible phase may be due to adsorption. The organic bound Cu, Zn, and Pb seem to be second dominant fraction among non-lithogenous in Nandira sediments. Factor analysis data reveals that textural parameters, Fe-Mn oxy/hydroxides, organic precipitation and coal fly ash disposals, are individually responsible for the enrichment of heavy metals. The relationships among the stations are highlighted by cluster analysis to identify the contamination levels.

Application of factor analysis in geochemical speciation of heavy metals in the sediments of a lake system - Chilika (India): a case study.

Abstract The geochemical association of some trace metals (Fe, Mn, Ni, Cu, Cr, and Pb) were sequentially extracted from bulk sediments of the Chilika lagoon, India. The low elemental concentration, except Pb, in the exchangeable phase suggests poor availability to bottom dwellers. However, slightly higher abundance of Pb in the exchangeable phase at station 4 (9.9%) and station 6 (9.5%) is mainly related with waste from major fishing jetties. The carbonate-bound phase reflects heavy metal distribution of detrital origin along with biological decomposition in the lagoon. A relatively higher percentage of Mn in the reducible phase is attributed to the flocculation of its colloids. The concentrations of Cu, Ni, and Pb show their higher affinity to the organic-bound fraction. The absolute metal concentrations in the residual fraction was Fe > Mn > Ni > Cu > Pb > Cr, which reflects the predominance of physical weathering, a high erosion rate, and a high sedimentation rate in the lagoon. According to Risk Assessment Code, Pb, Cr, and Mn at almost all sites remain in the medium-risk category and can pose some environmental problems, mainly to the benthic community. Multivariate statistics (i.e., factor analysis, FA) was applied to the data set of geochemical fractionation of heavy metals in sediments of a coastal wetland. In this study we present the usefulness of the FA technique for evaluation and interpretation of a large, complex metal fractionation dataset and the apportionment of pollution sources and factors, with a view toward better information on chemical processes occurring in brackish environments. The roles of textural characteristics, organic precipitation, oxy-hydroxide formation and the processes of flocculation and adsorption into fine sediments in different geochemical phases were evaluated. The interpretation of the distribution of metals in different phases related to the relative location of sampling and the environmental characteristics of the fluvial as well as the lagoonal environment.

Polymer supported nickel complex: Synthesis, structure and catalytic application

AbstractIn the present investigation, a new synthetic route for a novel recyclable free [3-MOBdMBn-Ni] and polystyrene-anchored [P-3-MOBdMBn-Ni] nickel complexes is presented. The free and polymer-anchored metal complexes were synthesized by the reaction of nickel (II) with one molar equivalent of unsupported N N′-bis (2-Hydroxy-3-methoxybenzaldehyde) 4-Methylbenzene-1,2-diamine (3-MOBdMBn) or polymer-supported (P-3-MOBdMBn) Schiff-base ligand in methanol under nitrogen atmosphere. The advantages of these polymer-supported catalysts are the low cost of catalyst and recyclability up to six times, due to easy availability of materials and simple synthetic route. The higher efficiency of complexation of nickel on the polymer-anchored 3-MOBdMBn Schiff base than the unsupported analogue is another advantage of this catalyst system. The structural study reveals that nickel(II) complex of 3-MOBdMBn is square planar in geometry. The catalytic activity of nickel complex towards the oxidation of phenol was investigated in the presence of hydrogen peroxide. Experimental results indicate that the reactivity of P-3-MOBdMBn-Ni was dramatically affected by the polymer support compared to free 3-MOBdMBn-Ni. The rates of oxidation (Rp) for unsupported and supported catalysts are 1.37 × 10−6 mole dm−3 s−1 and 2.33 × 10−6 mole dm−3 s−1 respectively. Graphical AbstractThe catalytic activity of free [3-MOBdMBn-Ni] and polystyrene-anchored [P-3-MOBdMBn-Ni] nickel complexes were tested towards oxidation of phenol and the effect of the H2O2 concentration/phenol concentration/catalyst concentration is presented.

Spatial distribution and potential biological risk of some metals in relation to granulometric content in core sediments from Chilika Lake, India

The article presents first systematic report on the concentration of selected major elements [iron (Fe) and manganese (Mn)] and minor elements [zinc (Zn), copper (Cu), chromium (Cr), lead (Pb), nickel (Ni), and cobalt (Co)] from the core sediment of Chilika Lake, India. The analyzed samples revealed higher content of Pb than the background levels in the entire study area. The extent of contamination from minor and major elements is expressed by assessing (i) the metal enrichments in the sediment through the calculations of anthropogenic factor (AF), pollution load index (PLI), Enrichment factor (EF), and geoaccumulation index (Igeo) and (ii) potential biological risks by the use of sediment quality guidelines like effect range median (ERM) and effect range low (ERL) benchmarks. The estimated indices indicated that sediment is enriched with Pb, Ni, Cr, Cu and Co. The enrichment of these elements seems to be due to the fine granulometric characteristics of the sediment with Fe and Mn oxyhydroxides being the main metal carriers and fishing boats using low grade paints, fuel, and fishing technology using lead beads fixed to fishing nets. Trace element input to the Chilika lake needs to be monitored with due emphasis on Cr and Pb contaminations since the ERM and ERL benchmarks indicated potential biological risk with these metals.

BisGMA/jute fibre/fly ash hybrid composites

Purpose – This paper aims to prepare BisGMA (bisphenol-A glycidyldimethacrylate)/jute fibre/fly ash hybrid composites with improved mechanical and corrosive properties. Design/methodology/approach – BisGMA prepolymer was first synthesised using diglycidyl ether of bisphenol-A and methacrylic acid. Then 2-hydroxy ethylacrylate-treated jute fibre and sodium hydroxide-treated fly ash were incorporated in the fabrication of composites using dicumyl peroxide, cobalt naphthenate and N,N-dimethyl aniline as catalyst, accelerator and promoter, respectively. The composition of BisGMA, jute fibre and fly ash was kept constant, whereas treated and untreated jute fibre and fly ash were used alternatively. Findings – Treatment of both jute and fly ash leads to improved mechanical properties of composites. However, treated fabric plays a dominant role compared to treated fly ash as filler. Among all the composites, the one having both treated jute fibre and treated fly ash is the most suitable composite for structural ...