The many uses and benefits of clays have been recognised and exploited for millennia in many cultures around the world. As well as being commonly used in construction and pottery production, they are also widely used utilized in pharmaceutical, cosmetic, engineering and healthcare applications. Montmorillonite is a clay whose properties render it suitable for multiple applications including as an active ingredient in pharmaceuticals, an ingredient in skin care products, and as a material for water treatment by adsorbing toxic heavy metals and unwanted anions.
In our work published in Nature Scientific Reports, our research group explored a new source of montmorillonite in the Koh-e-Suleiman mountain range located in South Punjab, Pakistan. A purification protocol was needed to remove any undesirable substances from the clay such as lead, arsenic and crystalline silica, which could impede industrial potential and have adverse health effects. The area of South Punjab has a large dependence on agriculture and relatively low levels of industrialisation and consequently currently faces higher levels of poverty and unemployment compared with the rest of the province. An abundant supply of this largely untouched raw clay could help with economic conditions in the region so, in addition to physicochemical characterisation, this study investigated the practicality and economic feasibility of its extraction and purification for large-scale industrial applications by comparing the properties of the small-scale extracted clay to the large-scale extracted clay, and by conducting a techno-economic analysis.
(a) Geological map of Pakistan and (b) site for raw clay sample collection.
The amount of montmorillonite present in the raw clay was ranged from 22 - 25%. This was somewhat lower than reports for other clay sources, thus the extraction and purification needed to be effective and efficient. Optimisation of grinding processes resulted in yields of >90% montmorillonite from raw samples. None of the characteristic attributes of the clays (elemental analysis, montmorillonite content and yield, particle size, nitrogen adsorption parameters and zeta potential charging) were significantly affected by the change in scale of the extraction and purification processes (from 5 g to 750 g) and were considered appropriate for pharmaceutical, biomedical, healthcare and environmental applications. Furthermore, techno-economic analysis revealed the economic benefits of extracting the clay on a large-scale with a cost of 0.01 £/g and 1.9 PKR/g compared with 0.23 £/g and 44.7 PKR/g at small-scale.
Overall, this work successfully identified and extracted montmorillonite from a new source located in the Koh-e-Suleiman mountain range of Pakistan and presents an optimised extraction and purification protocol. We anticipate that the findings in this study will improve the economic condition of the region by providing employment opportunities to locals and a valuable resource for exportation.
J. S. Nirwan 1, S. Farhaj 1, M. M. Chaudhary 2, Z. Khizer 1, S. S. Hasan 1, A. Angelis-Dimakis 3, A. Gill 4, H. Rasheed 5, N. Abbas 6, M. S. Arshad 7, T. Hussain 8, Y. Shahzad 8, A. M. Yousaf 8, T. A. Chohan 9, T. Hussain 10,11, H.A. Merchant 1, M. R. Akram 12, T. M. Khan 9, M. Ashraf 5, B. R. Conway 1, M. U. Ghori 1 *
1 Department of Pharmacy, University of Huddersfield, Huddersfield, UK
2 Lahore Waste Management Company, Lahore, Pakistan
3 Department of Chemical Sciences, University of Huddersfield, Huddersfield, UK
4 Ministry of Minerals and Mines, Lahore, Punjab, Pakistan
5 Pakistan Council of research for Water Resources (PCRWR), Ministry of Science and technology, Islamabad, Pakistan
6 University College of Pharmacy, the University of Punjab, Lahore, Pakistan
7 Faculty of Pharmacy, Bahuddin Zakariya University Multan, Pakistan
8 Department of Pharmacy, COMSAT University Islamabad, Lahore Campus, Lahore, Pakistan.
9 Institute of Pharmaceutical Sciences, University of Veterinary and Animal Sciences, Lahore, Pakistan
10 The Wolfson Centre for Bulk Solid Handling Technology, University of Greenwich, London, UK
11 System Engineering Department, Military Technological College, Muscat, Oman
12 College of Pharmacy, University of Sargodha, Sargodha 40100, Pakistan
Some authors of the paper (left to right): Mr. Jorabar Nirwan, Prof Barbara Conway and Dr Muhammad Usman Ghori.