Desorption of Metals from Pyrophyllite and use as a Sustainable Construction Material

Developing efficient water purification technologies is critical due to the limits of present approaches and the enormous environmental and human health dangers posed by polluted water. Pyrophyllite is a natural mineral composed of aluminum and silicate hydroxides (Al2Si4O 10(OH) 2) with a high cation exchange capacity and affinity for metals from water. This study aimed to investigate the adsorption and desorption of metals from pyrophyllite in aqueous solutions as a potential solution for this problem of contamination. The concentration of metal ions in water was quantified by anodic stripping voltammetry. The row natural pyrophyllite used in experiments was obtained from the deposits "Parsovići" - Konjic (AD HARBI d.o.o., Sarajevo, Bosnia and Herzegovina). Pyrophyllite (granulation 0.045) adsorbed > 98% Pb(II) from the aqueous solution after only 10 min of contact and Cd(II) reached the maximum of 95% after 24 h. The findings of our studies have shown that the desorption of metals was higher in the solution that was shaken compared to the stationary one. Our results proved that ions of Pb(II) can be desorbed under shaking conditions after 48h about 26%, and Cd(II) at the same conditions desorbed at 44%. The desorbed pyrophyllite can be consolidated into building materials using processes such as cementitious solidification or polymer encapsulation. By adding pyrophyllite to building materials, the pollutants held inside the Pyrophyllite are successfully contained, limiting the release into the environment. This technique turns polluted pyrophyllite into ecologically beneficial construction materials, ideal for diverse infrastructure projects.Published in Bulletin of the Chemists and Technologists of Bosnia and Herzegovina as Special Issue (2024)

Pyrophyllite as a Sustainable Material for Purification of Mine-Waste Water

Wastewater from mines poses a significant problem as it often contains high concentrations of metals, which are discharged into river systems, thereby contributing to environmental pollution. Pyrophyllite is a natural hydrous aluminum silicate clay mineral (Al2Si4(OH) 10(OH) 2) with a high melting point, stable chemical properties, and low cost. The elementary sheet of pyrophyllite is composed of an aluminum-oxygen/hydroxyl octahedral layer between two tetrahedral layers of silicon-oxygen. The layered silicate structure of pyrophyllite crystals has natural adsorption activity. Mechanochemical activation (MCA) is a simple method for modification of solid materials that causes structural disorder, amorphization and increased chemical reactivity. MCA, usually performed by grinding, is an environmentally friendly process because of low energy consumption, processing temperatures and cost. This study investigates the adsorption kinetics of the divalent metal ions (Cd, Ni, Cu, Zn, and Pb) from aqueous solutions using pyrophyllite as an adsorbent. It was found that the removal depends on the mechanochemical treatment of pyrophyllite, contact time with the aqueous solution, and the mutual competition of ions. The conditions were optimized for maximum removal of metal ions from synthesized aqueous solutions. Subsequently, pyrophyllite was applied under optimal conditions for removing Zn (II) from the wastewater of the closed Red Hill mine on mountain Avala. Based on the obtained results, it can be concluded that pyrophyllite completely removes zinc from mine water in a very short time (10 minutes) and thus has great potential for applicationPublished in Bulletin of the Chemists and Technologistsof Bosnia and Herzegovina as Special Issue (2024)