Murali Pujari

Equilibrium and Kinetic Studies of Ni (II) Adsorption using Pineapple and Bamboo Stem Based Adsorbents

This work addresses the preparation and characterization of inexpensive adsorbents for the removal of Ni (II) from aqueous solutions. Activated carbon based adsorbents have been prepared from plant based biomass resources, namely Pineapple stem ( Ananas Comosus ) and Bamboo Stem ( Bambuseae ). Adopting phosphoric acid and heat treatment techniques, it has been observed that the bamboo stem activated charcoal (BSAC) and pineapple stem (PS) adsorbents had a BET surface area of 116 and 11.47 m 2 /g, respectively. FTIR analysis indicated that various surface functional groups (such as C ≡ N stretching, stretching vibration of C = O, –CH3 wagging and C–O stretching vibration) contribute towards Ni (II) adsorption. Batch mode adsorption experiments were conducted for these adsorbents in the range of 50–300 mg/L Ni (II) solution concentration, 2–10 pH, 15–300 min. contact time, and 0.02–0.1 g/50 mL dosage. The BSAC adsorbent has been characterized with a metal uptake and %removal of 121.72 mg/g and 92.47, respectively, which corresponds to 45% higher metal uptake than corresponding bamboo based adsorbents presented in the literature. Further experimentation with BSAC enabled to achieve activated charcoal with surface area values similar to that of the commercial activated carbon adsorbent. The bamboo adsorbent has also been evaluated to perform similar to the commercial activated carbon for the removal and recovery of Pd (II) from synthetic electroless plating solutions. Also, a conceptual cost analysis indicated and affirmed towards the potential of the BSAC adsorbents for waste water treatment applications.

Efficacy of Novel Electroless Plating Process for Dense Pd/Cr2O3/PSS Membrane Fabrication

This work addresses the role of chromia diffusion barrier on the combinatorial plating characteristics of Pd plating baths during fabrication of dense Pd/Cr2O3/porous stainless steel (PSS) composite membranes and is compared with those obtained during fabrication of Pd/PSS membranes. Cr2O3 was deposited by electroplating technique followed with oxidation at 700°C and Pd films were deposited using a novel Pd electroless plating process that provides optimal performance. Apart from providing similar process characteristics, the Pd/Cr2O3/PSS membrane provided 15.2% lower Pd film thickness in comparison with Pd/PSS membrane for similar pore densification values.

Efficacy of reducing agent and surfactant contacting pattern on the performance characteristics of nickel electroless plating baths coupled with and without ultrasound

This article addresses furthering the role of sonication for the optimal fabrication of nickel ceramic composite membranes using electroless plating. Deliberating upon process modifications for surfactant induced electroless plating (SIEP) and combined surfactant and sonication induced electroless plating (SSOEP), this article highlights a novel method of contacting of the reducing agent and surfactant to the conventional electroless nickel plating baths. Rigorous experimental investigations indicated that the combination of ultrasound (in degas mode), surfactant and reducing agent pattern had a profound influence in altering the combinatorial plating characteristics. For comparison purpose, purely surfactant induced nickel ELP baths have also been investigated. These novel insights consolidate newer research horizons for the role of ultrasound to achieve dense metal ceramic composite membranes in a shorter span of total plating time. Surface and physical characterizations were carried out using BET, FTIR, XRD, FESEM and nitrogen permeation experiments. It has been analyzed that the SSOEP baths provided maximum ratio of percent pore densification per unit metal film thickness (PPDδ) and hold the key for further fine tuning of the associated degrees of freedom. On the other hand SIEP baths provided lower (PPDδ) ratio but higher PPD. For SSOEP baths with dropwise reducing agent and bulk surfactant, the PPD and metal film thickness values were 73.4% and 8.4 μm which varied to 66.9% and 13.3 μm for dropwise reducing agent and drop surfactant case.

Combinatorial Electroless Plating Characteristics for Dense Pd–PSS Composite Membrane Fabrication

Emphasizing upon a process–product combinatorial perspective, this article addresses the role of rate enhanced electroless plating baths for the fabrication of dense Pd/porous stainless steel composite membranes. Adopting phasewise contacting pattern of the reducing agent, plating experiments have been carried out with variegated Pd electroless plating baths at a palladium solution concentration of 0.005 M with a loading ratio of 203 cm2/L for the plating time of 2–6 h. Amongst all processes, surfactant and sonication coupled electroless plating baths provided optimal combinations of combinatorial plating process characteristics for dense Pd composite membrane fabrication.

Efficacy of Palladium Solution Concentration on Electroless Fabrication of Dense Metal Ceramic Composite Membranes Coupled with Surfactant and Sonication

This article addresses the effect of varying palladium solution concentration (0.005–0.015 mol/L) on the cost-effective fabrication of dense palladium composite membranes. Laboratory fabricated clay (kaolin) based ceramic disc were used as substrate along with a modified electroless plating technique consisting of a coupled effect of ultrasound and surfactant. Further to increase the efficacy of the process controlled addition of reducing agent was opted for all baths. It was analyzed that the optimal concentration that provided higher plating efficiencies (95.9%), higher transport efficiency (41.3%), higher plating rates (1.5 × 10−4 mol/m2 · s), minimal total plating time (10.5 h), and maximum pore densification (99.7%) corresponds to 0.01 mol/L.

Effect of Pd concentration on electroless dense Pd-PSS membrane fabrication

Abstract This work addresses the effect of palladium solution concentration on combinatorial plating characteristics of surfactant and sonication coupled electroless plating baths for the fabrication of dense palladium films on porous stainless steel substrates. All plating experiments were carried out using palladium solution concentration of 0·005 and 0·01M plating baths with cetyltrimethylammonium bromide surfactant at four critical micelle concentrations and loading ratio of 203 cm2 L−1. The evaluated combinatorial plating characteristics include selective conversion, plating efficiency, plating rate, Pd film thickness and per cent pore densification. The enhancement in palladium solution concentration was found to be insignificant to provide better combinatorial plating characteristics, and the plating bath consisting of 0·005M Pd solution concentration has provided 99·98% per cent pore densification with a Pd film thickness of 8·81 μm and plating efficiency of 80·69%.

Rate enhanced electroless fabrication of nickel ceramic composite membranes

Abstract Elaborating upon the role of surfactant and sonication, this work addresses the combinatorial plating characteristics for the fabrication of nickel ceramic composite membranes. Specific novelty corresponds to controlled addition of hydrazine hydrate as a reducing agent to nickel electroless plating bath. The experimental investigations evaluated the optimality of solution concentrations of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulphate surfactants during coupled sonication and surfactant based electroless plating. Among both surfactants, CTAB surfactant with a solution concentration of 4 CMC provided maximum combinations of pore densification (73·4%), metal film thickness (8·4 μm) and plating efficiency (89·9%). In all, it was observed that with CTAB surfactant the pore densification and plating efficiencies increased with increasing surfactant solution concentration from 1–4 CMC and were maximum at 4 CMC which drastically decreased at 6 CMC respectively probably due to surfactant adsorption on the substrate surface.