Prasanta Kumar Raul

Nano rod-shaped and reusable basic Al2O3 catalyst for N-formylation of amines under solvent-free conditions: A novel, practical and convenient ‘NOSE’ approach

An expeditious, simple, highly efficient, practical and green protocol for the N-formylation of alkyl/aryl amines and indole derivatives catalyzed by novel nano rod-shaped basic Al2O3 under solvent-free conditions has been developed. The catalyst is efficiently recycled up to the 5th run, an important point in the domain of green chemistry. The methodology provides cleaner conversion, shorter reaction times and high selectivity which makes the protocol attractive.

Vermicomposting of Tea Factory Coal Ash: metal accumulation and metallothionein response in Eisenia fetida (Savigny) and Lampito mauritii (Kinberg).

Earthworms can accumulate heavy metals in their intestines to a great extent. Impact of feed materials and duration of metal exposure on natural activity of earthworms are rather unclear; this investigation therefore addresses the impact of metal rich Tea Factory Coal Ash (TFCA) on reproduction, composting and metal accumulation ability of Eisenia fetida and Lampito mauritii. Earthworm count and cocoon production increased significantly during vermicomposting. pH of the vermicomposted mixtures shifted toward neutrality, total organic C decreased substantially and total N enhanced significantly compared to composting. High heavy metal (Mn, Zn, Cu, As) accumulation was recorded in the intestine of both the earthworm species. Moreover, gradual increase in the metal-inducible metallothionein concentration indicated the causal mechanism of metal accumulation in these species. TFCA+cow dung (CD) (1:1) were most favorable feed mixture for E. fetida and TFCA+CD (1:2) were good for L. mauritii in regard to metal accumulation and compost quality.

Defluoridation of water using nano-magnesium oxide

Nano-sized magnesium oxide (nano-MgO) was investigated for adsorption of fluoride from water. The pure and fluoride adsorbed nano-MgO were characterised by Brunauer–Emmett–Teller, high resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray analyses. The surface area of the adsorbent was found to be 92.46 m2/g. Maximum (90%) fluoride removal was obtained with 0.6 g/L dosage of nano-MgO. Fluoride adsorption by nano-MgO was found to be less sensitive to pH variations. Fluoride sorption was mainly influenced by the presence of OH− ion. The presence of other ions studied did not affect the fluoride adsorption capacity of nano-MgO significantly. It has been observed that Freundlich model was better fitted as compared to Langmuir model which indicated the multilayer adsorption of the adsorbent following a pseudo-second order kinetics. Regeneration study showed that 1 M HCl was the best eluent with 95% desorption capacity towards fluoride removal followed by NaOH (2 M) with 25% regeneration of the adsorbent.

CuO nanorods: a potential and efficient adsorbent in water purification

The present work deals with a simple in situ soft chemical synthesis of nanoscale copper(II) oxide, together with its characterization and a study of the adsorption and desorption behaviors of Pb(II) on nanoscale CuO. The nanoparticles are characterized by XRD, FESEM, TEM and BET surface area analyses. Electron microscopy clearly reveals a rod-like morphology of rhombohedral CuO, with an average diameter of ∼5 nm and a length extending up to 50 nm. BET shows the average surface area of the nanorods to be ∼52.57 m2 g−1. In an adsorption study, the influence of operational conditions, such as the contact time, the initial concentration of Pb(II), the initial pH of the solution and the temperature, on the adsorption of Pb(II) has also been examined. Studies also reveal that the uptake of Pb(II) onto CuO is a fast process; >70% of the uptake occurred within the first 10 min of contact time and uptake reached >92% within 60 min. The maximum sorption capacity of Pb(II) is 3.31 mg g−1 at 298 K. The +ve ΔS° value and the +ve ΔH° value of 37.77 kJ mol−1 indicate the endothermic nature of the adsorption process, whereas a decrease of Gibbs free energy (ΔG°) with increasing temperature indicates the spontaneous nature of the adsorption process. The adsorbent can be up to 84.1% regenerated using dilute acid and shows potential for the removal of lead from contaminated water.

High iron accumulation in hair and nail of people living in iron affected areas of Assam, India.

Human populace of Assam, India repeatedly exposed to high concentration of iron in groundwater results in adverse health effects like hemochromatosis, liver cirrhosis and siderosis. In the present study, human hair and nail analysis were carried out to establish a possible relationship between iron toxicity and its deposition among the residents. Nail and hair iron concentrations ranged from 28.2 to 1046μgg(-1) (n=114) and 26.5-838 (n=108)μgg(-1) levels, respectively, among all the study participants. The iron content of the groundwater (421-5340μgL(-1)) (n=64) used for drinking purposes was positively correlated with both nail (r=0.788, p<0.0001) and hair (r=0.709, p<0.0001) iron concentrations. Age- and sex-matched controls corresponding to each group were selected from population residing in other parts of the country where groundwater does not have excess iron. All the study groups included population drinking iron-contaminated water above the WHO/BIS limit (>300µgL(-1)) for 5 years (Group 1), for more than 5-10 years (Group 2) and for more than 10 years (Group 3). Results suggested that the participants consuming groundwater exceeding the WHO limit of iron had significantly more iron accumulation than those using groundwater containing ≤300μgL(-1) iron (p<0.01). There was statistically higher concentration of iron in the nail samples than the hair samples in all the study groups (p<0.01). There was a positive correlation in iron concentration and the residence time of the participants (p<0.01). Iron levels in the male participants were significantly higher than the female participants in the present study (p<0.01). The current findings are sufficiently compelling to warrant more extensive study of iron exposure through drinking water and adverse effects to the human in the areas where iron concentration is high.

Magnetic Ni/PPy nanocomposite as effective reusable adsorbent for removal of arsenite and fluoride from contaminated water

Magnetic nickel/polypyrrole (Ni/PPy) nanostructures have been synthesized at room temperature via an in situ oxidative polymerization of pyrrole (Py) monomers in the presence of FeCl3 oxidant in an aqueous suspension of Ni nanoflowers and characterized by XRD, FESEM, TEM, FTIR and Raman methods. Room temperature magnetic measurement shows that the magnetic properties of Ni are retained in all the nanocomposites. Ni/PPy nanostructures exhibit excellent adsorption efficiency in the removal of arsenic and fluoride from contaminated water as well as in the real ground water of Assam, India. Interestingly, Ni can be magnetically separated below its WHO prescribed toxicity value. The equilibrium data have been tested based on the Langmuir and Freundlich isotherm models. It is also found that the nanocomposite after adsorption could be regenerated by treating with acid/alkali and easily separated from the reaction mixture by the application of a magnetic field.

Vermi-sanitization of toxic silk industry waste employing Eisenia fetida and Eudrilus eugeniae: Substrate compatibility, nutrient enrichment and metal accumulation dynamics

Detoxification of silk processing effluents and sludge (SPES) through composting approaches is a new idea. This study examined the biodegradation potential of two epigeic earthworms (Eisenia fetida and Eudrilus eugeniae) in different SPES and cow dung (CD) mixtures in comparison with composting. N, P, S, Fe and Mn availability significantly increased upon vermicomposting compared to aerobic composting. The alkaline pH of the feedstocks satisfactorily neutralized under vermicomposting. The Ca-K availability and cation exchange dynamics readily stabilized due to vermicomposting. Interestingly, Eisenia fetida exhibited greater adaptability towards the toxic SPES materials than Eudrilus eugeniae, which was accompanied by 60-70% reduction of Cd, Cr, Zn and Pb levels in Eisenia system, whereas metal accumulation ability of Eudrilus eugeniae was remarkable. Moreover, both the species equally contributed in augmentation of beneficial (N-fixing and P-solubilizing) microorganisms in the feedstocks. Overall, nutrient enrichment and sanitizing potency of vermitechnology was explicitly manifested in SPES + CD (1:1) combination.