A technology for water purification using walnut shells and peach pits has been proposed at SUSU. This involves cleaning wastewater from oil pollution, a significant part of which is waste from modern transport: diesel fuel, petroleum, waste lubricants and machine oils. Water pollution with oil products is one of the global problems that scientists from all over the world are pondering.
This is discussed in the article by Senior Research Fellow of the SUSU Department of Town Planning, Engineering Networks and Systems, Professor Miklas Scholz, written jointly with his colleagues from Arab countries, including from King Khalid University.
Professor Miklas Scholz is a world-renowned expert in the field of water purification, editor of the Water Encyclopedia, author of nine textbooks. His Hirsch index is 60 (internationally outstanding). He also teaches in the UK, Sweden, Poland and South Africa.
His new work was published in the PloS One international journal, included in Q2 of Scopus.
Carbon sorbent (essentially a type of activated carbon) is obtained from peach pits and nut shells.
“In fact, activated carbon is produced from various organic and sometimes mineral raw materials: walnut shells, almonds, hazelnuts, coconuts, olive kernels, coffee shells, plum, peach, apricot and cherry pits, grape seeds, sugar cane pulp, bamboo and rice husks, or pomegranate seeds,” Professor Scholz explains in the article. “However, the ratio of materials and the method of converting raw materials into a sorbent give results of varying quality.”
In the study by Professor Miklas Scholz and his colleagues, the sorbent was obtained from peach pits and nut shells using two methods: the physical and chemical ones.
In the first, physical method, the raw material is first dried at a temperature of 200°C, then it is carbonized at a temperature of 600°C using inert gas (for example, argon), and then it is cleaned from impurities. In the chemical method, reagents, such as hydrochloric acid, are used for carbonization, and then the product is processed at high temperatures in a furnace.
Scientists came to the conclusion that the highest water hardness after purification is provided by the sorbent from peach pits, obtained by the physical method, and the lowest water hardness is provided by the sorbent from walnut shells, obtained by the chemical method. Moreover, the lower the water hardness, the lower the degree of adsorption as well.
The use of a chemically obtained sorbent from peach pits gives the highest iodine number during water purification – 1230 mg/g, and the iodine number, as is known, indicates to the presence of undesirable impurities in water ‑ oils. The minimum iodine number (1020 mg/g) was found in water purified using a walnut sorbent obtained by chemical processing.
In addition, the pore size of the sorbent is important. For raw materials from peach pits, it is 22.08 μm with chemical activation and 20.42 μm with physical activation, and for raw materials from walnuts – 22.74 μm and 21.86 μm, respectively.
Scientists are planning to keep on studying sorbents obtained from peach pits and walnut shells, focusing on the kinetics and thermodynamics of the process. After all, the process of cleaning wastewater from oil products should be as environmentally friendly as possible.