Calcium silicate sorbent from secondary waste ash: heavy metals-removal from acidic solutions

Environ Technol. 2006 Oct;27(10):1089-99. doi: 10.1080/09593332708618724.

Abstract

The layer lattice, ion-exchange material, Al-substituted 11 A tobermorite, has been synthesised via an alkaline hydrothermal route from a secondary waste ash arising from newsprint recycling. The hydrogarnet, katoite (Ca3Al2SiO12H8), was also formed. Batch sorption analyses have confirmed that the Al-substituted 11 A tobermorite-bearing product is an effective sorbent for Co2+, Cd2+ and Zn2+ ions from acidified aqueous media. Kinetic sorption data were analysed in accordance with the pseudo-first- and pseudo-second-order models and steady state data were fitted to the Langmuir and Freundlich isotherms. The Langmuir and pseudo-second-order models provided the most appropriate descriptions of the sorption processes. The maximum uptake capacities for Co2+, Cd2+ and Zn2+ at 20 degrees C were found to be 10.47, 2.92 and 3.09 mg g(-1), respectively, and the respective apparent pseudo-second-order rate constants were estimated to be 5.08 x 10(-3), 1.10 x 10(-3) and 1.13 x 10(-3) g mg(-1) min(-1).

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adsorption*
  • Cadmium / chemistry
  • Calcium / chemistry
  • Calcium Compounds / chemistry*
  • Copper / chemistry
  • Kinetics
  • Metals, Heavy / chemistry*
  • Models, Chemical
  • Newspapers as Topic*
  • Silicates / chemistry*
  • Waste Management / methods*
  • Zinc / chemistry

Substances

  • Calcium Compounds
  • Metals, Heavy
  • Silicates
  • Cadmium
  • tobermorite
  • Copper
  • Zinc
  • Calcium