T.S. Anirudhan

Adsorption and hydrolytic activity of trypsin on a carboxylate-functionalized cation exchanger prepared from nanocellulose.

Immobilization of enzymes on polymer supports has been considered as a powerful technique in biomedical applications. In this study, a cellulose-based hydrogel, poly(acrylic acid)-modified poly(glycidylmethacrylate)-grafted nanocellulose (PAPGNC) was synthesized by graft copolymerization technique and well characterized. A pancreatic serine protease trypsin (TRY) was immobilized onto PAPGNC, under different optimized conditions. The optimum pH for TRY adsorption was found to be 6.5, and the adsorption attained equilibrium within 90 min. The kinetic data were found to follow pseudo-first-order model, which is based on solid capacity. The well agreement of equilibrium data with Langmuir isotherm model confirms the monolayer coverage of TRY onto PAPGNC surface, and the maximum adsorption capacity was found to be 140.65 mg/g at 30 °C. The temperature dependence indicates an endothermic process. The relative activity of immobilized TRY in the hydrolysis of casein was higher than that of the free enzyme over broader temperature ranges. The immobilized TRY had high temperature and long-storage stability as compared to free TRY. Spent adsorbent was effectively degenerated using 0.1 M KSCN with the retention in catalytic activity of 87% even after four cycles. The present investigation shows that PAPGNC is a valuable polymer support for the recovery of TRY from aqueous solutions and subsequent casein hydrolysis.

Effective removal of mercury(II) ions from chlor-alkali industrial wastewater using 2-mercaptobenzamide modified itaconic acid-grafted-magnetite nanocellulose composite

A novel adsorbent, 2-mercaptobenzamide modified itaconic acid-grafted-magnetite nanocellulose composite [P(MB-IA)-g-MNCC] was synthesized for adsorbing mercury(II) [Hg(II)] ions selectively from aqueous solutions. Fourier transforms infrared spectroscopy, X-ray diffraction, scanning electron microscopy and thermogravimetric studies were performed to characterize the adsorbent. The optimum pH for Hg(II) adsorption was found to be 8.0, and the adsorption attained equilibrium within 60 min. The kinetic data were found to follow pseudo-second-order which assumes the ion exchange followed by complexation mechanism. The temperature dependence indicates an exothermic process. The well agreement of equilibrium data with Freundlich adsorption model confirms the multilayer coverage of Hg(II) onto P(MB-IA)-g-MNCC. The maximum adsorption capacity was found to be 240.0 mg/g. Complete removal of Hg(II) from aqueous solution was possible with an adsorbent dosage of 2.0 g/L. Spent adsorbent was effectively degenerated with 0.1M HCl. The present investigation shows that P(MB-IA)g-MNCC is a promising adsorbent for the removal and recovery of Hg(II) ions from aqueous solutions.

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.

Synthesis, characterization, cellular uptake and cytotoxicity of a multi-functional magnetic nanocomposite for the targeted delivery and controlled release of doxorubicin to cancer cells

The primary inadequacy of chemotherapeutic drugs is their relative non-specificity and potential side effects towards healthy tissue. To overcome this, in this study a novel drug delivery system, namely, carboxymethyl chitosan capped magnetic nanoparticle intercalated montmorillonite nanocomposites (CMCS-capped-MNP/MMT) was developed and characterized by transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectroscopy, X-ray diffraction, small-angle X-ray scattering, zeta potential analysis and a superconducting quantum interference device. The optimum pH value for the encapsulation of doxorubicin (DOX) into CMCS-capped-MNP/MMT was examined. The controlled release behavior of DOX was examined at 5.0 and 7.4 pH. The release rate of the loaded drug molecules was slow at pH 7.4 but increased significantly at acidic pH 5.0. The cytotoxicity of DOX-loaded-CMCS-capped-MNP/MMT towards MCF-7 cancer cells was investigated. The results showed that DOX-loaded-CMCS-capped-MNP/MMT retained significant antitumor activities. The cellular uptake of the fluorescent coumarin 6-loaded CMCS-capped-MNP/MMT on HeLa cells was analyzed with confocal laser scanning microscopy (CLSM) and flow cytometry and the results showed that MMT enhanced the cellular uptake efficiency. The effects of DOX and DOX-loaded-CMCS-capped-MNP/MMT on H9c2 cell death were investigated by using a microplate reader. The heating characteristics of the magnetic nanocomposites were investigated in a high frequency alternating magnetic gradient; a stable maximum temperature of 45 °C was successfully achieved within 40 min. The study demonstrated that CMCS-capped-MNP/MMT is not only a good delivery system for DOX but also appears to be a promising strategy for protecting against oxidative injury observed in DOX induced cardiotoxicity.

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.

Synthesis and characterization of a novel pH-controllable composite hydrogel for anticancer drug delivery

A novel pH-sensitive composite hydrogel (CH) namely 2-Acrylamido-2-methylpropane sulfonic acid (AMPS) grafted N-maleoylchitosan (MACTS) intercalated montmorillonite has been synthesized by in situ intercalation graft copolymerization of AMPS with MACTS intercalated MMT (MACTS/MMT) by using potassium persulfate (KPS) as a free radical initiator, in the presence of N,N-methylenebisacrylamide (MBA) as a crosslinking agent. A hydrophilic anticancer drug, 5-fluorouracil (5-FLU), has been chosen to investigate the loading and release properties of the CH. The CH formation and 5-FLU loading ability of CH have been confirmed by FTIR. X-Ray diffraction (XRD) analysis supports the intercalation reaction of MACTS with MMT, since after intercalation reaction there is an increase in basal spacing. A scanning electron microscopy (SEM) image of drug loaded CH shows a smoother surface whereas blank CH has a cracked and rough surface, this reveals the high affinity of 5-FLU to CH. The encapsulation efficiency of CH reaches the maximum value of 94.0% with CH prepared using 4.0 g of MACTS/MMT, 1.5 g of AMPS, 0.75 g of MBA and 75.0% of drug loading. Swelling profiles obtained show that the CH swelling rate increases with increase of pH up to 6.4 and then starts to decrease. Release profiles of 5-FLU from CH have been studied under both simulated gastric and intestinal pH conditions. The results obtained show that the release rate of the loaded drug molecules was slow at pH 2.4 but increased significantly at pH 7.4. The cell viability test displayed that the 5-FLU loaded CH exhibited an enhanced cell inhibition than that of pure 5-FLU. The studies described in the paper demonstrate the potential viability of a pH-sensitive CH carrier for colon specific anticancer drugs.

Synthesis and evaluation of iron-doped titania/silane based hydrogel for the adsorptional photocatalytic degradation of Victoria blue under visible light.

Novel photocatalyst, poly(itaconic acid-co-2-acrylamido-2-methylpropane-1-sulfonic acid) iron doped titania/silane was successfully prepared by the polymerization of iron doped titania/silane and two functional monomers, itaconic acid and 2-acrylamido-2-methylpropane-1-sulfonic acid in aqueous solution using ethylene glycol dimethacrylate as cross-linker and benzoylperoxide as initiator. The sample was characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Diffuse reflectance spectroscopy (DRS) techniques. Effects of various factors like pH, adsorbent dose, contact time, and ionic strength on the adsorption capacity of photocatalyst for Victoria blue (VB) were studied by batch adsorption experiments. The kinetic data were found to follow pseudo-second-order kinetic model with low chi square, χ(2) values and R(2) values closer to unity. The equilibrium data were in well agreement with Langmuir isotherm model and maximum adsorption capacity was found to be 153.89 mg/g. The swelling capacity of the adsorbent with changes in pH, time and temperature was also investigated. The kinetics of photocatalytic degradation of VB by the photocatalyst found to follow first-order kinetics. The regeneration and repeated use of photocatalyst were also examined upto four cycles. The prepared photocatalyst was found to be efficient photocatalyst-cum-adsorbent for the degradation of VB from aqueous solutions under solar light.

Thorium(IV) Recovery from Water and Sea Water Using Surface Modified Nanocellulose/Nanobentonite Composite: Process Design

Thorium(Th) contamination in the ground water an emerging environmental issue and Th recovery from sea water and nuclear wastewater is of high significance, as it is a major player in the energy sector. For the adsorption and recovery of Th, polymer grafted bio materials are reported as most efficient materials. P(IA/MAA)-g-NC/NB was prepared and all the steps in the synthetic routes were monitored using FTIR, SEM–EDS, and XRD, TG. Efficiency in removal of Th(IV) by P(IA/MAA)-g-NC/NB was tested by batch adsorption technique. The pH dependent Th(IV) adsorption process, was optimized at 4.5 and adsorption equilibrium was achieved within 120xa0min. Experimental kinetic data correlates well with pseudo-second-order equation, indicates adsorption was chemical process via ion exchange followed by complexation reaction, also could explain the film diffusion process of adsorption. Sips isotherm proved to best fit for the adsorption of Th(IV) onto P(IA/MAA)-g-NC/NB with maximum adsorption capacity of 95.19xa0mg/g. Thermodynamic studies revealed the endothermic nature, feasibility and spontaneity of the adsorption process. ΔHx and ΔSx were decreased to a small extent from −5.567 to −3.439xa0kJ/mol and increased from 11.18 to 18.39xa0J/mol, respectively, with increase in surface loading from 50 to 70xa0mg/g, indicating that the surface of the onto P(IA/MAA)-g-NC/NB is having energetically heterogeneous surface and there may be some lateral interactions between the adsorbed Th(IV) ions Repeated adsorption–desorption study over six cycles, adsorption percentage decreases from 99.0 to 94.6xa0%, proved the efficiency of P(IA/MAA)-g-NC/NB as an effective adsorbent for the removal and recovery of Th(IV) from aqueous solutions. Complete removal of Th(IV) ions from seawater containing 10xa0mg/L with a dose of 0.25xa0g/L P(IA/MAA)-g-NC/NB achieved. Batch adsorption system as double stage reactor designed from the adsorption isotherm data of Th(IV) by constructing operational lines. From these could be concluded that P(IA/MAA)-g-NC/NB is a promising candidate for the effective removal and removal of Th(IV) from industrial effluents phase and sea water. The maximum adsorption capacity Qs for Ceralite IRC-50 calculated which was found to be 179.67xa0mg/g which are considerably lower than those for P(IA/MAA)-g-NC/NB.

Adsorptive Separation of Lysozyme from Aqueous Solutions Using Sulphonyl and Carboxyl Functionalized Stearyl Alcohol Grafted Epichlorohydrin

In the present work ability of the two novel adsorbents, sulphonyl and carboxyl functionalized stearyl alcohol-grafted epichlorohydrin, SA-g-E-SO3H, SA-g-E-COOH; to remove lysozyme (LYZ) from aqueous solution was assessed. The adsorbent characterization was done using FTIR, XRD, SEM and TGA analyses. The adsorption efficiency was influenced by solution pH and the optimum operating pH was found to be 4.0 for SA-g-E-SO3H and 5.0 for SA-g-E-COOH and their adsorption efficiency was evaluated using the various isotherm and kinetics models. The Sips isotherm model and pseudo-second-order kinetic model were found to be the best for describing the equilibrium and kinetic behaviors of the adsorption process. Batch adsorption/desorption studies in acidic medium, for over six cycles showed excellent regeneration capability of the adsorbents and could lead to the development of viable and promising technology for the adsorptive recovery of LYZ from aqueous solutions. The efficiency of the adsorbents for the LYZ adsorption was verified using egg white. The result obtained from this study revealed that adsorption ability of 25xa0mg of SA-g-E-COOH is 98.4xa0% which is more than that of SA-g-E-SO3H (96.2xa0%). The efficiency of SA-g-E-SO3H to remove LYZ from aqueous solution was found to be higher compared to SA-g-E-COOH.

Synthesis and characterization of amidoxime modified chitosan/bentonite composite for the adsorptive removal and recovery of uranium from seawater

A novel amidoxime functionalized adsorbent, poly(amidoxime)-grafted-chitosan/bentonite composite [P(AO)-g-CTS/BT] was prepared by in situ intercalative polymerization of acrylonitrile (AN) and 3-hexenedinitrile (3-HDN) onto chitosan/bentonite composite using ethylene glycol dimethacrylate (EGDMA) as cross linking agent and potassium peroxy disulphate (K2S2O8) as free radical initiator. The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), BET surface area analyser and X-ray photoelectron spectroscopy (XPS). Nitrile groups from two monomers converted to amidoxime groups and therefore, increases the adsorption efficiency of uranium(VI) [U(VI)] from seawater. The optimum pH for U(VI) adsorption was found to be 8.0. The adsorbent dosage of 2.0u202fg/L was sufficient for the complete removal of U(VI) from seawater. The kinetic data fitted well with pseudo-second-order kinetic model which assumes the presence of chemisorption. The equilibrium attained within 60u202fmin and well agreement of equilibrium data with Langmuir adsorption model confirms monolayer coverage of U(VI) onto P(AO)-g-CTS/BT. The maximum adsorption capacity was found to be 49.09u202fmg/g. Spent adsorbent was effectively regenerated using 0.1u202fN HCl. Six cycles of adsorption-desorption experiments were conducted to study the practical applicability and repeated use of the adsorbent. The feasibility of the adsorbent was also tested using natural seawater. The results show that P(AO)-g-CTS/BT is a promising adsorbent for the removal of U(VI) from seawater.