Department Of Environmental Science And Technology

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Author: search.filters.author.Kumar, Rabindra

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    Advances in arsenic biosensor development - a comprehensive review
    (Elsevier Ltd, 2015) Kaur, Hardeep; Kumar, Rabindra; Babu, , J. Nagendra; Mittal, Sunil
    Biosensors are analytical devices having high sensitivity, portability, small sample requirement and ease of use for qualitative and quantitative monitoring of various analytes of human importance. Arsenic (As), owing to its widespread presence in nature and high toxicity to living creatures, requires frequent determination in water, soil, agricultural and food samples. The present review is an effort to highlight the various advancements made so far in the development of arsenic biosensors based either on recombinant whole cells or on certain arsenic-binding oligonucleotides or proteins. The role of futuristic approaches like surface plasmon resonance (SPR) and aptamer technology has also been discussed. The biomethods employed and their general mechanisms, advantages and limitations in relevance to arsenic biosensors developed so far are intended to be discussed in this review.
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    Studies in the hydrolysis of cellulose using cellulase in imidazolium based ionic liquid
    (Central University of Punjab, 2012) Kumar, Rabindra; Babu, J.N.
    Ionic liquids are the modern day revelations as a green solvent. These solvents have found many applications in biofuel strategy. The cellulose pretreatment using ionic liquid is currently being studied for future biofuels from lignocellulosic biomass. The strategy involves the dissolution of cellulose in these solvents, followed by precipitation by an anti-solvent like water or acetone, leading to the formation of amorphous cellulose which is easy to hydrolyze by biocatalytic methods. Further studies had been conducted in the inhibitory effect of ionic liquid traces present in pretreated cellulose, on the biocatalytic hydrolysis by cellulase. Apart from this, biocatalytic hydrolysis had been studied in binary aqueous-ionic liquid solution for a one-pot process for simultaneous pretreatment & hydrolysis. These process involved the study of biocatalytic hydrolysis in imidazolium based ionic liquids namely, [EMIM]OAc & [BMIM]Cl, as hydrophilic solvents. These solvents have anions with predominantly strong hydrogen bond acceptor capacity. The study reveals the deactivation of the enzyme in presence of these ionic liquids. Thus in an effort to increase the hydrolysis efficiency of the enzyme without loosing the hydrogen bond acceptor capacity of the IL, was essentially required. Thus in the present study, we have investigated one-pot biocatalytic hydrolysis of cellulose in IL with variable alkyl chain length of the cation leading to hydrophobic environment around the biocatalyst. The ILs used in the present study are [BMIM]Cl, [HMIM]Cl & [OMIM]Cl. The biocatalysis was studied in both homogenous as well as heterogeneous conditions. In homogenous conditions dissolution of cellulose was maintained throughout the reaction period. The homogenous biocatalysis was studied with or without the presence of surfactants. The results indicate that [HMIM]Cl is a promising solvent for cellulase catalyzed hydrolysis of cellulose in both homogenous & heterogeneous condition, resulting in more than 70% hydrolysis in presence of non-ionic surfactant PEG-1500 and in the binary mixture of 40% w/w [HMIM]Cl in citrate buffer, respectively.
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    1,3-Bis(cyanomethoxy)calix[4]arene capped CdSe quantum dots for the fluorogenic sensing of fluorene
    (Royal Society of Chemistry, 2017) Kumar, Rabindra; Arora, Meenu; Jain, A.K.; Babu, J. Nagendra
    Capping of 1,3-bis(cyanomethoxy)-tert-butylcalix[4]arene (CAD) onto CdSe quantum dots (QDs) was characterized by a fluorescence enhancement of the QDs (?em = 580 nm) upon surface interaction with the phenolic moiety of CAD. CAD@QD showed selective and sensitive 1.67 fold fluorescence enhancement in the presence of fluorene among fifteen PAHs. The fluorescence enhancement was characterized by monolayer adsorption of fluorene on to the surface of CAD@QD. The limit of detection for fluorene was observed to be 0.8 nM. This method was used and compared with detection of fluorene in spiked respirable dust (PM10) samples collected during an open biomass (stubble) burning event. ? The Royal Society of Chemistry.
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    Role of soil physicochemical characteristics on the present state of arsenic and its adsorption in alluvial soils of two agri-intensive region of Bathinda, Punjab, India
    (Springer Verlag, 2016) Kumar, Ravishankar; Kumar, Rabindra; Mittal, Sunil; Arora, Meenu; Babu, J. Nagendra
    Purpose: Arsenic (As) contamination of groundwater has received significant attention recently in district Bathinda, due to consequent health risk in this region. Soil is the one of the primary medium for arsenic transport to groundwater. Thus, there is an essential requirement for understanding the retention capacity and mobility of arsenic in the soils to ensure sustainability of the groundwater in the locality. Arsenic interaction with various physicochemical properties of soil would provide a better understanding of its leaching from the soil. Materials and methods: Fifty-one soil samples were collected from two regions of Bathinda district with extensive agricultural practices, namely, Talwandi Sabo and Goniana. The soils were analyzed for arsenic content and related physicochemical characteristic of the soil which influence arsenic mobility in soil. Adsorption studies were carried out to identify the arsenic mobilization characteristic of the soil. SEM-EDX and sequential extraction of arsenic adsorbed soil samples affirmed the arsenic adsorption and its mobility in soil, respectively. Multiple regression models have been formulated for meaningful soil models for the prediction of arsenic transport behavior and understand the adsorption and mobilization of arsenic in the soil matrices. Results and discussion: Region-wise analysis showed elevated levels of arsenic in the soil samples from Goniana region (mean 9.58?mg?kg?1) as compared to Talwandi Sabo block (mean 3.38?mg?kg?1). Selected soil samples were studied for As(V) and As(III) adsorption behavior. The characteristic arsenic adsorption by these soil samples fitted well with Langmuir, Freundlich, Temkin, and D-R isotherm with a qmax in the range of 45 to 254?mg?kg?1 and 116 to 250?mg?kg?1 for As(III) and As(V), respectively. Adsorption isotherms indicate weak arsenic retention capacity of the soil, which is attributed to the sandy loam textured soil and excessive fertilizer usage in this region. PCM and MLR analysis of the soil arsenic content and its adsorption strongly correlated with soil physicochemical parameters, namely, Mn, Fe, total/available phosphorus, and organic matter. Conclusions: Manganese and iron content were firmly established for retention of arsenic in soil, whereas its mobility was influenced by organic matter and total/available phosphorus. The poor adsorptive characteristic of these soils is the primary cause of higher arsenic concentration in groundwater of this region. A strong correlation between monitored arsenic and adsorbed As(III) with manganese suggests As(III) as the predominant species present in soil environment in this region. ? 2015, Springer-Verlag Berlin Heidelberg.