Electrochemical sensing of cholesterol by molecularly imprinted polymer of silylated graphene oxide and chemically modified nanocellulose polymer.

Silylated Graphene oxide-grafted-chemically modified nanocellulose (Si-GO-g-CMNC) is fabricated for selective sensing of Cholesterol. Zinc oxide (ZnO) incorporated in chemically modified nanocellulose (CMNC) for enhancing the conducting nature. The sensitivity of sensor was checked by modifying the glassy carbon electrode surface (GCE) with Si-GO-g-CMNC and the electro chemical studies were conducted with cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The physical and electrical properties of the sensor were analyzed by FTIR, Raman Spectroscopy, XRD, SEM, EDS and AFM techniques. CV analysis of [FeCN6]3-/4- showed a redox potential difference of 0.156 mV on the bare GCE, while for the electrode coated with MIP, redox peak current increased to 0.2319 mV. The values of limit of detection (LOD) obtained as 7.4 µmol/L for the detection range of 5.18-25.9 µmol/L. The optimum response time and optimum pH were found to be 10 min and 7.4, respectively. DPV analysis revealed good linearity in the cholesterol sensing range of 0.6475-10.360 × 103 µmol/L with LOD value 98.6 µmol/L.

Extraction of melamine from milk using a magnetic molecularly imprinted polymer.

A novel magnetic molecularly imprinted polymer (MMIP) for the preconcentration of melamine, a non-protein nitrogen food additive from complex matrices was synthesized and characterized using FT-IR, XRD, SEM and VSM techniques. Surface imprinting was done on vinyltrimethoxysilane coated Fe3O4 (Fe3O4-VTMS) using 2-acrylamido-2-methylpropane sulfonic acid (AMPS), N,N'-methylenebisacrylamide (MBA) and potassium persulfate (KPS) as functional monomer, crosslinker and initiator respectively. Saturation magnetization value obtained for MMIP was 1.72emug-1. Binding studies showed that MMIP exhibits good recognition to melamine compared to magnetic non imprinted polymer (MNIP). The optimum pH for the binding of melamine was found to be 4.5. Binding process was very fast and pseudo-second-order model fitted well with the kinetic data. Binding isotherm followed Langmuir isotherm model of monolayer adsorption with a maximum melamine binding efficiency of 62.25mgg-1. The HPLC-UV analysis results revealed the applicability of MMIP in solid phase extraction and determination of melamine from milk samples.

Nano-zinc oxide incorporated graphene oxide/nanocellulose composite for the adsorption and photo catalytic degradation of ciprofloxacin hydrochloride from aqueous solutions.

Purpose of this study is to report the synthetic procedure of a novel photo catalyst, nano zinc oxide incorporated graphene oxide/nanocellulose (ZnO-GO/NC) for the effective adsorption and subsequent photo degradation of ciprofloxacin (CF), an antibiotic widely used in the poultry. Self cleaning property in cellulose was achieved by introducing a nano zinc oxide incorporated graphene oxide into nanocellulose (NC) matrix. By incorporating nano zinc oxide (ZnO) in graphene oxide (GO), band gap could be tuned to 2.4eV and after the composite formation with NC, the band gap was enhanced to 2.8eV which is in the visible region. Thus the degradation of the CF was achieved under the visible light. Photo degradation was due to electron hole interaction. The step wise modification in the synthesis ZnO-GO/NC was characterized using FT-IR, XRD, SEM, EDS, AFM, DRS-UV and BET N2 adsorption isotherm techniques. The values of surface area, pore volume and pore radius were found to be 12.68m2/g, 0.026mL/g and 12.5nm, respectively. Efficiency in the adsorption process of CF onto ZnO-GO/NC was verified by batch adsorption technique. The optimum pH was found to be 5.5 and dose of the ZnO-GO/NC was optimized as 2.0g/L. Equilibrium was attained at 120min and the adsorption of drug followed second-order kinetics. Sips isotherm was the best fitted model and could explain the nature of interaction of CF with ZnO-GO/NC. The studies revealed that the degradation followed first-order kinetics and the optimum pH for the degradation process was found to be 6.0 and achieved a maximum degradation efficiency of 98.0%. The reusability of ZnO-GO/NC after five consecutive cycles indicated it to be a potential candidate for the removal and degradation of CF from aquatic environment.

Nanocellulose/nanobentonite composite anchored with multi-carboxyl functional groups as an adsorbent for the effective removal of Cobalt(II) from nuclear industry wastewater samples.

A novel adsorbent, poly(itaconic acid/methacrylic acid)-grafted-nanocellulose/nanobentonite composite [P(IA/MAA)-g-NC/NB] with multi carboxyl functional groups for the effective removal of Cobalt(II) [Co(II)] from aqueous solutions. The adsorbent was characterized using FTIR, XRD, SEM-EDS, AFM and potentiometric titrations before and after adsorption of Co(II) ions. FTIR spectra revealed that Co(II) adsorption on to the polymer may be due to the involvement of COOH groups. The surface morphological changes were observed by the SEM images. The pH was optimized as 6.0. An adsorbent dose of 2.0g/L found to be sufficient for the complete removal of Co(II) from 100mg/L at room temperature. Pseudo-first-order and pseudo-second-order models were tested to describe kinetic data and adsorption of Co(II) follows pseudo-second-order model. The equilibrium attained at 120min. Isotherm studies were conducted and data were analyzed using Langmuir, Freundlich and Sips isotherm models and best fit was Sips model. Thermodynamic study confirmed endothermic and physical nature of adsorption of the Co(II) onto the adsorbent. Desorption experiments were done with 0.1MHCl proved that without significant loss in performance adsorbent could be reused for six cycles. The practical efficacy and effectiveness of the adsorbent were tested using nuclear industrial wastewater. A double stage batch adsorption system was designed from the adsorption isotherm data of Co(II) by constructing operating lines.