nan Inamuddin

Kinetics, isotherm and thermodynamic investigations for the adsorption of Co(II) ion onto crystal violet modified amberlite IR-120 resin

The adsorption characteristics of crystal violet (CY)-modified amberlite IRA-120 resin for the removal of Co(II) ion from aqueous medium at different experimental conditions were established by means of batch method. The adsorption uptake was increased with the increase in contact time and temperature. The adsorption process was controlled by pseudo-first-order kinetic model. Adsorption isotherms were expressed by Langmuir and Freundlich adsorption models. The Freundlich adsorption model fitted the experimental data reasonably well compared to the Langmuir model. A well-known thermodynamic equation was used to assess the ΔG0 (standard free energy change), ∆H0 (enthalpy change), and ∆S0 (entropy change). The thermodynamic data was indicative of the spontaneous nature of the endothermic sorption process of Co(II) ion onto CY-modified amberlite IRA-120 resin.

ZnSe-WO3 nano-hetero-assembly stacked on Gum ghatti for photo-degradative removal of Bisphenol A: Symbiose of adsorption and photocatalysis

In this research work we report Gum-ghatti supported ZnSe-WO3 nano-hetero-assembly for solar powered degradation of endocrine disruptor Bisphenol S (BPA). The photocatalyst was characterized by Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HRTEM), Small area electron diffraction (SAED), X-Ray diffraction (XRD), Fourier transform infra red spectroscopy (FTIR), Photoluminescence (PL), Energy dispersive X-ray (EDX), UV-vis spectrophotometry and Brauner Emmet Teller surface area analyzer (BET). We achieve a Z-scheme photocatalyst (ZnSe-WO3) with a higher charge flow and visible absorption. Gum ghatti acts as a superadsorbent and a sink for charge carriers. The removal of BPA has been studied under three experimental protocols where 99.5% removal was achieved by symbiose of photocatalysis-adsorption-ozonation in just 45min hetero-assembly has a high surface area, stability and reduced carrier recombination. The results have been analyzed by scavenger effect, mass spectrometry, kinetics and total organic carbon (TOC) analysis. 49.4% of TOC was removed and COD was reduced to 16.7% after 2h in symbiotic condition. From the band edges and scavenger effect it was inferred that superoxide radical anions are major attacking species. The work paves way for designing of novel photocatalysts with increasing biogenic quotient and higher efficiency.

Development of sulfonated poly(vinyl alcohol)/polpyrrole based ionic polymer metal composite (IPMC) actuator and its characterization

In the present study, a novel sulfonated poly(vinyl alcohol)/polypyrrole polymer membrane sandwiched between platinum (SPVA-Py-Pt) is fabricated for a bending actuator which can be used in microrobotic applications. To examine the suitability of SPVA-Py-Pt based ionic polymer metal composite (IPMC) for microrobotic applications, ion exchange capacity (IEC), water uptake, proton conductivity, water loss, cyclic voltammetry (CV), linear sweep voltammetry (LSV), Fourier transform infrared spectroscopy (FTIR), thermal stability, and tip displacement studies are performed. The water holding capacity of the IPMC membrane is found to be 82.23% at room temperature for 8 h of immersion time. The IEC and proton conductivity of the IPMC membrane is found to be 1.2 meq g−1 and 1.6 × 10−3 S cm−1, respectively. Maximum water loss from IPMC is achieved as 31% at 5 V for a time period of 16 min. Based on electromechanical characterization, the maximum tip displacement of SPVA-Py-Pt IPMC (size 30 mm length, 10 mm width, 0.08 mm thickness) is 18.5 mm at 5.25 V. The major advantages of this new type of IPMC are good film-forming capability, short processing time, low cost of fabrication, good flexibility, high thermo-mechanical stabilities, good ion exchange and water holding capacities and proton conductivity as compared to other types of IPMC actuators. The comparison with other type of IPMC actuators is also summarized. A multi SPVA-Py-Pt IPMC based micro-gripping system is developed that shows the potential of microrobotic applications.

Fabrication of bioanode by using electrically conducting polythiophene via entrapment technique

A glassy carbon electrode (GCE) was tailored with conducting polymer polythiophene and further immobilized by an enzyme glucose oxidase (GOx). A thin film of polymer was developed by electrochemical polymerization of thiophene monomer. During electrochemical polymerization of the monomer the enzyme GOx and the redox active mediator ferritin (Frt) were entrapped within this polymer matrix. In this novel approach, the entrapment of enzyme and mediators within a polymer matrix occurs without chemical reaction that could affect their activity. The entrapment of enzyme and mediator within the conducting polymer matrices increases the surface area of the electrode. The tailored GCE/Ptp/Frt/GOx electrode showed a high catalytic activity. The increased surface area causes a high rate of electron transfer between the electrode and Frt engaged as an electron transfer mediator. The electrochemical properties of the electrode were determined by cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The fabricated bioanode showed a current density of 3.9mA cm−2 at 1.0 V vs. Ag/AgCl in a 45 mM glucose solution and suggests proficient chances in biofuel cells (BFCs) applications.

Studies on the Preparation and Analytical Applications of Various Metal Ion-Selective Membrane Electrodes Based on Polymeric, Inorganic and Composite Materials—A Review

Ion-selective membrane electrodes commonly known as electrochemical sensors are important in view of the ability to make direct or indirect measurement of various metal ions. The fact is that the use of ion-selective electrodes for such type of measurements requires relatively inexpensive equipment, which makes ion-selective electrodes attractive to scientists in many disciplines. Thus, potentometric sensors can offer an inexpensive and convenient method for the analysis of heavy metal ions in solutions providing acceptable sensitivity and selectivity. For this purpose, many organic, inorganic, chelating, intercalating and composite materials were studied as electroactive materials for the preparation of ion-selective membrane electrodes. The present study provides a detailed review of literature for the fabrication, characterization and analytical applications of ion-selective membrane electrode based on different electro active components.

Electrochemical studies of biocatalytic anode of sulfonated graphene/ferritin/glucose oxidase layer-by-layer biocomposite films for mediated electron transfer

In this study, a bioanode was developed by using layer-by-layer (LBL) assembly of sulfonated graphene (SG)/ferritin (Frt)/glucose oxidase (GOx). The SG/Frt biocomposite was used as an electron transfer elevator and mediator, respectively. Glucose oxidase (GOx) from Aspergillus niger was applied as a glucose oxidation biocatalyst. The electrocatalytic oxidation of glucose using GOx modified electrode increases with an increase in the concentration of glucose in the range of 10-50mM. The electrochemical measurements of the electrode was carried out by using cyclic voltammetry (CV) at different scan rates (20-100mVs(-1)) in 30mM of glucose solution prepared in 0.3M potassium ferrocyanide (K4Fe(CN)6) and linear sweep voltammetry (LSV). A saturation current density of 50±2mAcm(-2) at a scan rate of 100mVs(-1) for the oxidation of 30Mm glucose is achieved.

Poly (3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) Zr(IV) phosphate composite cation exchanger : sol-gel synthesis and physicochemical characterization

An organic-inorganic composite cation exchanger poly (3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) Zr(IV) phosphate was prepared by the sol-gel method for removal of cadmium, a toxic heavy metal pollutant causing adverse effects on human health. The synthesized material was characterized by various techniques such as thermo gravimetric analysis/differential thermal analysis/differential thermo gravimetry (TGA/DTA/DTG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). Organic polymer PEDOT:PSS binds with the inorganic counterpart and prevents the leaching of the inorganic parts, hence PEDOT:PSS Zr(IV) phosphate composite cation exchanger has improved ion exchange capacity than inorganic ion exchanger. The composite cation exchanger was found selective towards Cd(II) ions. The nature and composition of contacting solvents influence the selectivity of composite cation exchanger. The composite cation exchanger may be used for the removal of cadmium a toxic heavy metal ion.

Fouling-resistant membranes for water reuse

Abstract Producing drinkable water is a major issue due to pollution and limited availability of fresh water. Membrane-based desalination is an efficient method to produce drinkable water from saline water and wastewater. Nonetheless, this method is limited by membrane fouling. Deposited foulants cause lower production flux and increase the cost. Hence, recent research has aimed to improve membrane antifouling properties. Here we review fouling-resistant membranes with focus on the membrane fouling phenomena; enhancement of interfacial polymerization procedures and assortment of new initiating monomers; modifying the membrane surface using physical and chemical methods; fabrication of composite membranes using inorganic materials; and modification with zwitterionic materials.

Study and preparation of highly water-stable polyacrylonitrile–kraton–graphene composite membrane for bending actuator toward robotic application

In this article, polyacrylonitrile–kraton–graphene (PAN-KR-GR) ionomeric polymer membrane sandwiched between Pt electrode-based ionic polymer–metal composite (IPMC) actuator is developed. The aim of this study is to design and prepare multifunctional ionic polymer–metal composite membrane for robotic application. The water uptake capacity and ion exchange capacity of polyacrylonitrile–kraton–graphene ionomeric membrane is 133.33% at 45 °C for 8 h of immersion and 1.4 meq g−1 of dry membrane, respectively. Proton conductivity and maximum water loss of ionic polymer–metal composite membrane is 5.26 mS cm−1 and 38% after applying 7 V for 12 min, respectively. Scanning electron micrographs shows the smooth and uniform coating of platinum (Pt). Cyclic voltammetry, linear sweep voltammetry, Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and tip displacement of PAN-KR-GR-Pt IPMC membrane are also examined. A multifinger-based gripping system for dexterous handling is developed for robotic application.

Nicotinic acid adsorption thermodynamics study on carboxymethyl cellulose Ce(IV) molybdophosphate composite cation-exchanger

The thermodynamics of nicotinic acid adsorption from aqueous solution on carboxymethyl cellulose Ce(IV) molybdophosphate composite cation exchanger were studied. The composite cation exchanger was synthesized by sol–gel method and thereby characterized using scanning electron microscopy, thermogravimetric analysis, X-ray powder diffraction and fourier transform infra red spectroscopy. The analytical applicability and thermodynamic parameters, such as Freundlich constant, thermodynamic equilibrium constant (Kο), standard free energy changes (ΔG°), standard enthalpy changes (ΔH°) and standard entropy changes (ΔS°) of this composite cation exchanger have been evaluated. The thermodynamic parameters showed that the adsorption of nicotinic acid onto composite cation exchanger is feasible, spontaneous and exothermic, suggesting their suitability for the potential application of nicotinic acid removal from waste water.