Performance Characteristics of Electroless Plating Baths for Nickel-Ceramic Composite Membrance fabrication

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Metal composite membranes made of palladium, silver and nickel have numerous applications in process industries. Amongst these, nickel composite membranes have several applications such as production of ultrapure gases, recovery of TiO2 from waste water streams, new generation supports for dense palladium membranes etc. Electroless plating is one of the most versatile methods adopted for metal composite membrane fabrication. Despite possessing several advantages such as uniformity of coating and ease of scale-up, electroless plating suffers with the basic limitation of very slow deposition rate and hence mass transfer enhancements can be coupled for process efficacy. As opposed to the conventional performance characteristics of electroless plating baths for metalDceramic composite membrane fabrication, this work addresses systematic methodology for the assessment of electroless plating and mass transfer enhanced electroless plating processes for nickelDceramic composite membrane fabrication. Combinatorial performance characteristics of the plating baths are expressed in terms of bath conversion, plating efficiency, selective conversion, nickel plating rate, metal film thickness, average pore size (based on air permeation data), effective porosity (based on air permeation data) and percent pore densification (PPD). Various mass transfer enhancements considered in this work include agitation, sonication and hydrothermal conditions (with and without sonication). Both hypophosphite and hydrazine based plating baths have been assessed for their performance characteristics with a major objective of achieving 100% pore densification using mass transfer coupling effects. A laboratory fabricated symmetric low cost ceramic membrane support having a nominal pore size of plating characteristics are investigated for wide range of nickel solution concentrations (0.04D0.16 mol/L), loading ratios (196D393 cm2/L) and stirrer speeds (0D200 rpm). 275 nm and a porosity of 40% with wider pore size distribution is used as the support (substrate) to obtain deeper insights with respect to the deposition characteristics..
Supervisor: R. Uppaluri