PubMed · 8418752
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R G Kopanski, W D Leighan. 1993. Video technology.. https://doi.org/10.1016/s0001-2092(07)68391-4
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One of India's major concerns is the increasing level of land pollution largely due to the uncontrolled disposal of industrial solid and hazardous waste. With rapid industrialization, the generation of industrial solid and hazardous waste has increased appreciably and the nature of waste generated has become complex. Their impacts on the ecological bodies are noticeable. The article describes the details of studies conducted using Toxicity Characteristics Leaching Procedure, to estimate the toxicity effects of the metals viz., chromium, zinc, manganese, iron, nickel, cobalt and copper by the Zero Headspace Extractor for the sludges generated from effluent treatment plant of steel tube, wire and plating industries on environment constituents like groundwater, surface water and land. Toxicity Characteristics Leaching Procedure determines the mobility of organic and inorganic analytes of liquid, solid or multiphase waste from hazardous solid wastes in the form of primary and secondary extracts. These extracts are mixed in equal volume proportion and analyzed by Direct Reading 2000 spectrophotometer. The amount of heavy metals observed during the studies in the leachates were found and the results were compared with Hazardous Waste categories as per Indian Standards. TCLP regulatory limits given by United States Environment Protection Agency (USEPA) and Germany Leachate Quality Standards and it was observed that they were on higher side, needing a proper preventive concept of sludge management including handling, treatment, recovery and disposal.
Electroless nickel plating generates substantially more waste than other metal-finishing processes due to the inherent limited bath life and the need for regular bath disposal. Electrodialysis can be used to regenerate electroless nickel baths, but poor membrane permselectivity, leading to high losses of valuable bath components, continues to be a weakness of the technology. This research has investigated improving electrodialysis permselectivity for removing contaminants (sodium, orthophosphite, and sulfate) in a spent electroless nickel bath while minimizing the losses of valuable bath ions (nickel, hypophosphite, and organic acids). Ion permselectivity was explored with respect to electrodialysis operating conditions, membrane type, and cell configuration. Excellent permselectivity for sodium over nickel was attained irrespective of operating condition, membrane, or cell configuration. Studies on the effects of four different operating conditions (current density, pH, flow rate, and temperature) on anion permselectivity revealed bath pH and current density to be critical operating parameters. The type of anion exchange membrane used had a crucial effect on selectivity; one membrane (Ionac MA-3475) was identified as having superior selectivity for bath contaminants particularly for sulfate. The improvements in electrodialysis permselectivity established by this research will decrease waste generation within the electroless nickel process and increase resource productivity by minimizing the loss of valuable plating chemicals.
This paper describes the self-assembly of small objects--polyhedral metal plates with largest dimensions of 10 to 30 microm--into highly ordered, three-dimensional arrays. The plates were fabricated using photolithography and electrodeposition techniques, and the faces of the plates were functionalized to be hydrophobic or hydrophilic using self-assembled monolayers (SAMs). Self-assembly occurs in water through capillary interactions between thin films of a hydrophobic liquid (a liquid prepolymer adhesive) coated onto the hydrophobic faces of the plates; coalescence of the adhesive films reduces the interfacial free energy of the system and drives self-assembly. By altering the size and surface-patterning of the plates, the external morphologies of the aggregates were varied. Curing the adhesive furnished mechanically stable aggregates that were characterized by scanning electron microscopy (SEM). For assemblies formed by plates partially composed of a sacrificial material, a subsequent etching step furnished fully open, three-dimensional microstructures. This work validates the use of capillary interactions for three-dimensional mesoscale self-assembly in the 10-microm-size regime and opens new avenues for the fabrication of complex, three-dimensional microscructures.