Adsorption of Zn(II) ions on Calcium Silicate Precipitation Tube (CaSPT) produced through 'silica garden' route

- CaSPT is a potential Zn(II) adsorbent in aqueous medium.
- Zn(II) loading capacity of CaSPT has been found to be 229.6 mg g− 1.
- Zn(II)-CaSPT adsorption is an endothermic and spontaneous physisorption process.
- CaSPT has been successfully tested on a real life effluent sample.

Zn(II) adsorption in aqueous medium has been reported on Calcium Silicate Precipitation Tube (CaSPT), grown by 'silica garden route'. Adsorption varies nonlinearly with adsorbent dose and initial adsorbate concentration. Adsorption data fit better with Langmuir isotherm model which returns Zn(II) loading capacity of 229.6 mg g− 1 at 0.01 g CaSPT. Adsorption kinetics follows pseudo-second order rate equation with activation energy of 8.56 kJ mol− 1, typical for a physisorption process. The adsorption process is endothermic and spontaneous. CaSPT was successfully tested with regard to Zn(II) removal on a real life effluent sample collected from an electroplating industry.