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Insights on contamination and reuse of spent clay filter

In a project with a large manufacturer of petroleum jelly we studied the composition of spent clay that is left after filtration of crude oil. We also developed a lab-scale process for potential reuse of the clay filter. We undertook a tailor made approach to clean, separate and chemically analyse the spent and regenerated clays. Next to that we also used several analytical and spectroscopic techniques to identify the chemical components adsorbed on the clay.


Filtration using clays is a commonly applied industrial process. The impurities are generally physically adsorbed on the clay. The chemistry behind the filtration process is often not fully understood. As a result, after the filtration the used clay is disposed as waste. By gaining chemical insight into the impurities filtered on the clay it is possible to choose the right solvent to physically separate absorbents and clay. This way the clay can be recovered, and costs can be saved. Most importantly, adopting such a recycling process makes the industry overall more sustainable as less amount of clay is required.


Natural clays are often used for filtration of products which have application in the cosmetics and food industry. Structurally, clays are metal (e.g. Al, Na, Mg, Li) phyllosilicates characterized by high mechanical stability, high surface area and thermal inertness. Although its natural origin makes it environmentally friendly, clay regeneration mechanism is unknown but essential for transition to more sustainable life-cycle and implementation of circular economy approach.


For this project we combined the expertise of solid state, organic and analytical chemistry research groups at the University of Amsterdam. We optimized extraction of apolar and polar components from used clay and performed a diverse set of chemical analysis on extraction products. We were able to regenerate the clay and identify chemicals that were absorbed during filtration. Chemical analysis included 1D and 2D Nuclear Magnetic Resonance, Field Desorption Mass Spectroscopy, Time of Flight Mass Spectroscopy and Gas Chromatography coupled with High Resolution Mass Spectroscopy. XRD and ICP AAS studies were also undertaken.



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