What is it about?
The current study focuses on the understanding of leaching kinetics of metal in the LTCC in general and silver leaching in particular along with wet chemical reduction involving silver nanoparticle synthesis. Followed by metal leaching, the silver was selectively precipitated using HCl as AgCl. The precipitated AgCl was dissolved in ammonium hydroxide and reduced to pure silver metal nanopowder (NPs) using hydrazine as a reductant. Polyvinylpyrrolidone (PVP) used as a stabilizer and Polyethylene glycol (PEG) used as reducing reagent as well as stabilizing reagent to control size and shape of the Ag NPs. An in-depth investigation indicated a first-order kinetics model fits well with high accuracy among all possible models. Activation energy required for the first order reaction was 21.242 kJ mol-1 for Silver. PVP and PEG 1% each together provide better size control over silver nanoparticle synthesis using 0.4 M hydrazine as reductant, which provides relatively regular morphology in comparison to their individual application. The investigation revealed that the waste LTCC an industrial waste can be recycled through the reported process even in industrial scale. The novelty of reported recycling process is simplicity, versatile and eco-efficiency through which waste LTCC recycling can address various issues like; (i) industrial waste disposal (ii) synthesis of silver nanoparticles from waste LTCC (iii) circulate metal economy within a closed loop cycle in the industrial economies where resources are scarce, altogether.
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Why is it important?
• Various waste component of LTCC was analyzed. • Leaching kinetics for Ag was investigated and optimized. • Selectively Ag was recovered by leaching-precipitation-wet chemical reduction. • Ag-NPs was synthesized through wet-chemical reduction. • A cost-effective and sustainable eco-efficient industrial valorization process.
Perspectives
1. Reported recycling process signifies simplicity, versatile and eco-efficient process, through which various issues like; (i) waste disposal through valorizations of silver as NPs (ii) circularize the economy by bringing back the material to production stream, and (iii) sustainable green economy and the futuristic carbon economy, can address simultaneously. 2. Through the case study, a total recycling process has been developed for all kind of LTCC waste, which can easily recycle all component of the industrial LTCC waste. 3. Without any special facilities or specialty chemicals, through the small-scale industrial facility, the waste can be converted to product/raw material for the same industry. 4. Current process synthesizes the Ag-NPs from the industrial waste resources in contrary to from the pure chemicals as reported by numerous author in the literature. 5. Understanding of fundamental characteristics like leaching kinetics and wet chemistry involve can provide a better avenue for an understanding of the waste recycling by hydrometallurgy and can be applied to the diversified waste contains Ag.
Dr Basudev Swain
Institute for Advanced Engineering (IAE)
Read the Original
This page is a summary of: Synthesis of Submicron Silver Powder from Scrap Low-Temperature Co-Fired Ceramic an E-waste: Understanding the Leaching Kinetics and Wet Chemistry, Chemosphere, December 2017, Elsevier,
DOI: 10.1016/j.chemosphere.2017.12.034.
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