US 2013/0095995 A1Published application

Process For The Surface-Modification Of Flyash And Industrial Applications Thereof

AssigneeCouncil of Scientific and Industrial Research

InventorsSatyajit Vishnu Shukla, Krishna Gopakumar Werrier, Baiju Vijayan Kishakkekillkoodayii, Thachan Shijitha

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Abstract

Processes for the surface-modification of flyash and industrial applications thereof are described in this invention, which involve surface-sensitization, surface-activation, and subsequent Cu or Ag coating of as-received flyash particles in a conventional electroless bath. These new surface-modification processes offer efficient and cost-effective alternatives to conventional processes which modify the surface of flyash particles with a costlier Sn—Pd catalyst-system. Flyash processed with the inventive processes is also suitable for a greater number of industrial applications relative to that processed with the costlier Sn—Pd catalyst-system. The as-received flyash particles, processed via the inventive surface-modification processes, find industrial applications as conductive fillers for manufacturing conducting polymers, paints, adhesives, sealers, and resins used for EMI shielding of electronic devices, in lead-based composites used in the automobile industries, and as a catalyst to purify industrial waste-water by decomposing longer chains of organic molecules into smaller ones.

Claims10

Dependent claims

A process for the surface-modification of flyash containing sufficient amount of titania (TiO2) or any other semiconductor oxide on its surface, wherein said process comprises the steps of:

i. suspending flyash particles in a surface-activation bath consisting of an aqueous solution of metal-salt at pH˜10-12 obtained using an aqueous NH4OH solution (25-28 wt. %);
ii. stirring the suspension as obtained in step (i) continuously under UV, visible, or solar-radiation for a period ranging between 4-6 hours to deposit metal-clusters over the surface of flyash particles;
iii. separating the surface-activated flyash particles as obtained in step (ii) via filtration followed by washing with distilled-water several times to remove unwanted ions from the surface;
iv. stirring the surface-activated flyash particles, as obtained in step (iii) in a conventional electroless coating bath containing an aqueous solution of NaOH (5-15 g·l−1), NaKC4H4O6 (30-60 g·l−1), and a metal-salt (1-10 g·l−1);
v. adding slowly 30-40 wt. % HCHO (5-20 ml·l−1) as a reducing agent into the suspension as obtained in step (iv);
vi. stirring the suspension as obtained in step (v) continuously;
and
vii. separating the metal-coated flyash particles from the suspension as obtained in step (vi) via filtration and drying in an oven at 80-100° C. for 10-12 h to obtain the surface-modified flyash.

5 more elements

Dependencies are inferred from the claim text.