J. Nagendra Babu

Advances in arsenic biosensor development - A comprehensive review

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.

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

PurposeArsenic (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 methodsFifty-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 discussionRegion-wise analysis showed elevated levels of arsenic in the soil samples from Goniana region (mean 9.58xa0mgxa0kg−1) as compared to Talwandi Sabo block (mean 3.38xa0mgxa0kg−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 254xa0mgxa0kg−1 and 116 to 250xa0mgxa0kg−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.ConclusionsManganese 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.

In situ reductive regeneration of zerovalent iron nanoparticles immobilized on cellulose for atom efficient Cr(VI) adsorption

Zerovalent iron nanoparticles (nZVI) (11.8 ± 0.2% w/w) immobilized on microcrystalline cellulose (C-nZVI) were synthesized and studied for Cr(VI) sorption. The material showed good atom economy for Cr(VI) adsorption (562.8 mg g−1 of nZVI). Oxidation of cellulose to cellulose dialdehyde leads to in situ regeneration of nZVI which is responsible for the atom efficient Cr(VI) sorption by C-nZVI.

Polymeric Encapsulates of Essential Oils and Their Constituents: A Review of Preparation Techniques, Characterization, and Sustainable Release Mechanisms

ABSTRACT Natural polymer based encapsulation of essential oil (EO) is one of the emerging and challenging area of research in perfumery, cosmetics, flavoring agents, preservatives, therapeutics, etc. The knowledge of formulation techniques and physico-chemical properties of the polymers are the basic requirements for the successful encapsulations of essential oils (EOs). This current review article is focused on a comparative account of various formulation techniques based on their applicability. For the first time, it also reviews various physico-chemical techniques used in the analysis of EO encapsulates to determine their stability, structure, surface morphology, and encapsulation efficiency. Further, the mechanisms involved in the release of EOs from encapsulates, along with various factors affecting their release, have also been discussed.

Removal of hexavalent chromium from aqueous solution using biomass derived fly ash from Waste-to-Energy power plant

AbstractFly ash from the agricultural waste-based Energy Power Plant has been studied for the adsorption of hexavalent chromium [Cr(VI)]. In order to maximize the Cr(VI) removal from simulated aqueous solutions, effects of various parameters i.e. adsorbent dose (10–40u2009g/L), contact time (5–90u2009min), variation in pH (1–5), and initial metal ion concentration (10–80u2009mg/L) on Cr(VI) adsorption were investigated by batch adsorption experiments. It was observed that adsorption of Cr(VI) on the selected adsorbent was dependent on pH. Before optimization of experimental conditions, the percent removal of Cr(VI) from the aqueous solution (10u2009mgu2009Cr/L) was approximately 4%, which increased to approximately 99% after optimization of experimental conditions. Maximum adsorption was observed upon adding 10u2009g/L of adsorbent to a 60u2009mgu2009Cr/L aqueous solution at pH 1.0 and contact time of 90u2009min at 200u2009rpm. Equilibrium adsorption data were well fitted in Langmuir isotherm model which substantiate monolayer adsorption of Cr(...

Removal of hexavalent chromium from aqueous solution: a comparative study of cone biomass of “Picea smithiana” and activated charcoal

AbstractThe present work investigates comparative adsorption efficiency of powdered cone biomass of Picea smithiana (PCBP) and activated charcoal (AC) for removal of hexavalent chromium (Cr) (Cr(VI)) from aqueous solution. The study indicates that PCBP has 76% removal efficiency for Cr as compared to AC. Particle size and SEM-EDX analyses were done to determine average particle size, surface morphology and elemental composition of PCBP. BET and FTIR analysis were carried out to elucidate the adsorption mechanism of Cr(VI) on PCBP. Ashing has been proposed as a method for managing waste of loaded PCBP generated in adsorption. Ashing studies showed the ash content of PCBP to contribute only 13% of the ash generated from loaded biomass. Further, a comparative study has been made indicating the adsorption efficiency of PCBP with previously reported bio-waste materials. The results of this study show that PCBP has high adsorption efficiency as compared to other bio-waste materials.

Reductive-co-precipitated cellulose immobilized zerovalent iron nanoparticles in ionic liquid/water for Cr(VI) adsorption

Microcrystalline cellulose immobilized zerovalent iron nanoparticles (CI-1-3) with different loading of 6, 12 and 24% w/w Fe0 were synthesized by NaBH4 reduction under simultaneous co-precipitation of cellulose from ionic liquid ([BMIM]Cl)-water binary mixture. SEM, TEM, FTIR, VSM, XRD and XPS analysis were carried out to characterize the material. The electron microscopy studies revealed the immobilization of iron nanoparticle in the bulk and surface of microcrystalline cellulose with a size range of 20–100xa0nm. CI-1-3 showed strong interaction between cellulose hydroxyl moiety and nZVI, immobilized on the polymer and saturation magnetization of 3xa0emu/g for CI-2. The materials were studied for Cr(VI) adsorption which revealed the qmax value of 28.57, 58.82 and 38.48xa0mg Cr(VI)/g of CI-1-3, respectively.Graphical abstract

1,3-Bis(cyanomethoxy)calix[4]arene capped CdSe quantum dots for the fluorogenic sensing of fluorene

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 (λem = 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.