Extraction of TiO2 from kaolin deposits in the Central Region, Ghana: An alternative material for the formulation of climate-smart Portland cement

Abstract

This paper is one of series of papers assessing the suitability of formulating titanium dioxide climate smart Portland cement in developing countries using locally available cementitious material like kaolin. In this paper, authors highlight extraction of titanium dioxide from kaolin deposits in the Central Region, Ghana using selective flocculation techniques and later used to formulate climate-smart cement. Titanium dioxide (TiO2) a photocatalytic ingredient which studies from developed countries have shown that when nano-sized of it is added to cement is able to reduce smog-forming air pollutants, keep surfaces of buildings clean and resist sulphate attack. However, developing countries with weak economies and low technologies are not able to utilize nano-size TiO2 in the formulation of climate-smart cement. It is within this context that this study was undertaken. About 450 g of 53 μm kaolin samples were treated with dispersing agents such as sodium polyacrylate and sodium silicate in excess amount so as to produce maximum deflocculation of the kaolinite particles. The percentage of titanium dioxide extracted ranges from 86.1% for kaolin samples from Saltpond to 91.8% for kaolin samples from Assin Foso respectively; which was later used to formulate climate-smart Portland cement. The ability of the formulated TiO2-ordinary Portland climate smart cement to degrade Rhodamine B dye was tested. Mortar pastes containing various percentages of TiO2-climate smart Portland cement with Rhodamine B dye were exposed to sunlight for 0, 24, 48, 72 and 96 h respectively. The test results indicate that addition of TiO2 extracted from kaolin and used to synthesize climate -smart ordinary Portland cement is able to degrade air pollutants from vehicular exhaust such as PAHs, and as such its use in the construction industry can improve the durability of buildings and for that matter the socio-economic development of the region as well as Ghana as a whole.