Handanahally Basavarajaiah Muralidhara

Potential applications of cellulose and chitosan nanoparticles/composites in wastewater treatment: A review.

This work concerns the investigation of potential candidature of cellulose and chitosan-based nano-sized materials for heavy metals and dyes removal. Cellulose and chitosan being the first two abundant biopolymers in nature offer wide opportunities to be utilized for high-end applications such as water purification. The nano-sized cellulose and nano-sized chitosan present superior adsorption behavior compared to their micro-sized counterparts. This area of research which explores the possible usage of nano-biopolymers is relatively new. The present review article outlines the development history of research in the field of cellulose and chitosan, various methods employed for the functionalization of the biopolymers, current stage of research, and mechanisms involved in adsorption of heavy metals and dyes using nanocellulose and nanochitosan. The significance of research using nano-biopolymers and future prospects are also identified.

Plating on acrylonitrile–butadiene–styrene (ABS) plastic: a review

ABS is an engineering plastic that has butadiene part uniformly distributed over the acrylonitrile-styrene matrix. It possesses excellent toughness, good dimensional stability, easy processing ability, chemical resistance, and cheapness. However, it suffers from inherent shortcomings in terms of mechanical strength and vulnerability to environmental conditions. Furthermore, it is non-conducting and easily fretted. Plating on ABS can serve to enhance the strength and structural integrity as well as to improve durability and thermal resistance resulting in metallic properties on the ABS material. ABS is described as the most suitable candidate for plating because it is possible to deposit an adherent metal coating on it by only the use of chemical pretreatment process and without the use of any mechanical abrasion. This article aims to review the history of ABS plastics, properties of ABS, processes and mechanisms of plating, and studies of plating on ABS involving mainly eco-friendly methods of plating by discussing the literature published in recent years. The details of electroplating of ABS carried out in the authors’ laboratory are also presented.

Hydrothermal Synthesis of Hierarchical Copper Oxide Nanoparticles and its Potential Application as Adsorbent for Pb(II) with High Removal Capacity

In this study, copper oxide nanoparticles with hierarchical morphologies (CuO) have been synthesized via a hydrothermal route. The morphology and microstructure of the as prepared samples were characterized by XRD, SEM, TEM, and SAED. CuO exhibited excellent performance for the removal of Pb(II) from aqueous solution. The effects of initial Pb(II) concentration and contact time on CuO were investigated from batch tests. The results indicate that the equilibrium adsorption data were best fitted by the Langmuir isothermal model, with the maximum adsorption capacity of 1428.5 mgg−1 which is found to be one of the highest values reported elsewhere in the literature; adsorption kinetics follows the pseudo-second-order kinetic equation and intra-particle diffusion model. A possible adsorption mechanism was predicted by using FTIR, EDX techniques. Large adsorption capacity for heavy metal ion and effective regeneration ability suggesting CuO is a very promising adsorbent for metal ion removal and wastewater cleanup.

Highly porous carbon from a natural cellulose fiber as high efficiency sorbent for lead in waste water

The persistence of hollow centre in the carbon obtained from milkweed floss provides exceptional sorption characteristics, not seen in common biomasses or their derivatives. A considerably high sorption of 320mg of lead per gram of milkweed carbon was achieved without any chemical modification to the biomass. In this research, we have carbonized milkweed floss and used the carbon as a sorbent for lead in waste water. A high surface area of 170m2g-1 and pore volume of 1.07cm3g-1 was seen in the carbon. Almost complete removal (>99% efficiency) of lead could be achieved within 5min when the concentration of lead in the solution was 100ppm, close to that prevailing in industrial waste water. SEM images showed that the carbon was hollow and confocal images confirmed that the sorbate could penetrate inside the hollow tube.

Cost effective and shape controlled approach to synthesize hierarchically assembled NiO nanoflakes for the removal of toxic heavy metal ions in aqueous solution

Hierarchical mesoporous NiO nanoflakes (NiOs) have been synthesized in high yield via a simple, economical and environmentally friendly hydrothermal route. The as-prepared NiOs were characterized by powder X-ray diffraction (PXRD), scanning electronic microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction patterns (SAED), X-ray energy dispersive spectroscopy (EDS) and nitrogen adsorption–desorption techniques (Brunauer–Emmett–Teller, BET). Adsorption of heavy metal ions onto the as-prepared sample from aqueous solutions was investigated using differential pulse anodic stripping voltametry (DPASV) technique and discussed. The product possesses a BET surface area of 69.27 m2 g−1. It is found that NiOs exhibited the excellent performance for the removal of Hg(II), Pb(II) and Cd(II) from aqueous solution. The equilibrium adsorption data of Hg(II), Pb(II) and Cd(II) on the as-prepared NiOs were analyzed by Langmuir and Freundlich models, suggesting that the Langmuir model provides the better correlation of the experimental data. The adsorption capacities for removal of Hg(II), Pb(II) and Cd(II) were determined using the Langmuir equation and found to be 1324 .5, 1428 .9 and 1428 .5 mg g−1, respectively. Adsorption kinetics of all the metal ions followed pseudo second-order model. Moreover, NiOs can be recycled by simple acid treatment, which could retain the high removal efficiency in three successive cycles. This study suggests that nanoflakes could be explored as a new adsorbent with high efficiency and recyclability for removing heavy metal ions from aqueous solution.

KINETICS AND MECHANISTIC STUDY OF OXIDATION OF AMOXICILLIN BY CHLORAMINE-T IN ACID MEDIUM

This spectroscopic study presents the kinetics and degradation pathways of oxidation of amoxicillin (AMOX) by chloramines-T (CAT) in acidic medium at a constant ionic strength of 0.105 mol dm-3 at 298 K. Reaction between AMOX and CAT in acidic medium exhibits 1:1 stoichiometry (AMOX:CAT). The reaction is of a first-order in both [CAT] and [AMOX]. The order with respect to acid concentration was fractional. The effects of added products, ionic strength and dielectric constant have been studied. The main oxidation product of AMOX was identified by IR, 1H NMR and mass spectra. The reaction constants involved in the different steps of the mechanisms were calculated. Activation parameters with respect to slow step of the mechanisms were computed and discussed.

ZnO-NiO nanocomposites as highly recyclable adsorbent for effective removal of Pb(II) and Cd(II) from aqueous solution

In continuation to our recent study on the synthesis and characterization of ZnO-NiO nanocomposites (ZNO), in the present study the nanocomposites has been evaluated for the removal of Pb(II) and Cd(II) from the aqueous solution. The conditions for the sorption have been optimized and kinetic and thermodynamic studies were performed to understand the adsorption behavior of the nanocomposites. Though the Pb(II) and Cd(II) sorption by the nanocomposites takes place in wide pH range, pH 7 was found most favorable and at this pH the adsorption equilibrium data were modeled using the Langmuir and Freundlich isotherms. The data fitted more satisfactorily to Langmuir isotherm indicating unilayer adsorption. Based on Langmuir model, Qmax was calculated to be 1519.7 mgg-1. The adsorption showed pseudo second order kinetics indicating chemisorptions. The nanocomposites were successfully recycled for three consecutive adsorption-desorption cycles with only a marginal loss in its efficiency indicating its high reusability.

Cerium dioxide and composites for the removal of toxic metal ions

The presence of contaminants in potable water is a cause of worldwide concern. In particular, the presence of metals such as arsenic, lead, cadmium, mercury, chromium can affect human health. There is thus a need for advanced techniques of water decontamination. Adsorbents based on cerium dioxide (CeO2), also named ‘ceria,’ have been used to remove contaminants such as arsenic, fluoride, lead and cadmium. Ceria and composites display high surface area, controlled porosity and morphology, and abundance of functional groups. They have already found usage in many applications including optical, semiconductor and catalysis. Exploiting their attractive features for water treatment would unravel their potential. We review the potential of ceria and its composites for the removal of toxic metal ions from aqueous medium. The article discusses toxic contaminants in water and their impact on human health; the synthesis and adsorptive behavior of ceria-based materials including the role of morphology and surface area on the adsorption capacity, best fit adsorption isotherms, kinetic models, possible mechanisms, regeneration of adsorbents; and future perspectives of using metal oxides such as ceria. The focus of the report is the generation of cost-effective oxides of rare-earth metal, cerium, in their standalone and composite forms for contaminant removal.

Synthesis and characterization of copper oxide nanoparticles: In the study of voltammetric response of biomolecules

Copper oxide nanoparticles synthesized via hydrothermal method and used to modify a carbon paste electrode are reported. The structural characterization of nanopowder by XRD clearly shows the formation of monoclinic phase with high crystallinity. The morphological structure is characterized by field emission scanning electron microscope shows the formation of flake like structures. The modified electrode is used for the determination of dopamine and ascorbic acid separately using cyclic voltammetry. The voltammograms obtained during the oxidation studies revealed that nano CuO exhibits better catalytic function towards the oxidation of dopamine and ascorbic acid. The overlapping voltammetric response of both the biomolecules at the bare electrode gets resolved into well defined voltammetric peaks with enhanced oxidation currents.