Surface modification of diatomaceous earth silica microparticles with functional silanes for metal ions sorption

Abstract

Natural diatomaceous earth (DE) particles functionalized with 3-mercaptopropyltrimethoxysilane (MPTMS) with specific selectivity for heavy/noble metals have been prepared used as enhanced metal ion adsorbent. X-ray Photoelectron spectroscopy (XPS) analysis of the mercapto-DE products revealed that the functional group (-SH) was successfully introduced to the adsorbent surface. Studies involving the extraction of Au(III) ions from aqueous solutions by pristine and MPTMS modified DE products indicated strong initial metal ions concentration and pH dependency. The Au(III) adsorption kinetics and adsorption isotherms for the MPTMS modified DE particles for Au(III) observed to follow a pseudo-second-order reaction model and Langmuirian behaviour, respectively. The adsorption reached equilibrium within 60 min with a maximum adsorption capacity of 208 mg g-1, a value found to be reasonably good. The results show that with further optimisation, a cost effectived new and environmentally benign mercapto-DE based adsorbent suitable for removing metals from aqueous solutions can be produced.