Removal of tungsten from electroplating wastewater by acid- and heat-treated sepiolite

Abstract

In this study, the removal of tungsten from electroplating wastewater by adsorption on sepiolite has been investigated. To improve its performance, the natural sepiolite, was treated using H₂SO₄, followed by a heat treatment. The results obtained from the adsorption experiments showed that the acid- and heat-treated sepiolite had much higher adsorption for tungsten compared to the untreated (natural) sepiolite. The pH and temperature were important parameters in the adsorption process: the tungsten adsorption onto the acid- and heat-treated sepiolite increased at a lower pH and higher temperature, and the maximum adsorption capacity of 48.3 mg/g was obtained at pH 4.0, 55°C, initial concentration of tungsten of 300 mg/L, and the sepiolite to liquid ratio of 0.5 g/100 mL. The acid- and heat-treated sepiolite was applied to electroplating industrial wastewater containing 265 mg/L tungsten, under the conditions of pH ≤ 6, 25–55°C, more than 98% of tungsten was removed. It was concluded that the acid- and heat-treated sepiolite is a potential adsorbent that can be commercially used to remove the residual tungsten in industrial wastewater.

Keywords:

• Tungsten
• Electroplating wastewater
• Sepiolite
• Acid and heat treatment

Acknowledgment

The authors wish to thank the National Basic Research Program of China (973 Program) of 2010CB732205, for financial support of this study.