Use of halloysite for agrochemical applications

Abstract

The focus of this thesis was to develop two products for use in agrochemical applications, using the naturally occurring microtubular mineral, halloysite. Firstly, it was necessary to obtain a highly tubular grade of the mineral, which was achieved by sourcing a number of samples from different regions of the world. The halloysite samples were characterised using a number of techniques such as scanning electron microscopy. X-ray diffraction, helium pycnometry, surface area analysis and inductively coupled plasma-mass spectrometry. Various physical and chemical clean up procedures were applied to the mineral to remove debris and increase the proportion of intact tubules. From these studies it was found that the halloysite Goushan NZCC sample (provided by New Zealand China Clay Ltd.) had the highest tubular content. Preliminary studies were performed on halloysite to ascertain whether it had potential for use in a number of different pharmaceutical and agrochemical applications that included: deflocculation studies, isolated film studies, tabletting studies and mercury porosimetry studies of pellets. Following these preliminary studies extensive work was carried out on the development of two agrochemical products.