The adsorption of polyvinylpyrrolidone over the surface of silica has been investigated. The impact of molar mass of the polymer, pH, and pretreatment temperature of silica particles have been evaluated by means of FTIR spectroscopy and electrophoretic measurements. The silica particles used have narrow particle size distribution. The zeta potential of the aqueous silica suspension was decreased with the increase in pH. The amount of polymer adsorbed was increased with the increase in pretreatment temperature, time, concentration, pH, zeta potential, and molar mass of the polymer. The addition of polymer to the system increased the zeta potential due to adsorption of polymer on the surface of the particles. However, the impact increased with the increase in molecular mass of the polymer. The IR spectra obtained before and after adsorption of polymer concluded that, mostly, hydrogen bonding is responsible for the adsorption phenomena; however, hydrophobic interactions also play a significant role. The mechanism has been investigated and established through FTIR spectroscopy.
For many industrial applications, an extensive research of the stabilization and destabilization mechanisms of aqueous suspensions of fine particles is crucial. The flocculation of charged particles from their aqueous suspensions is greatly influenced by the surface characteristics of the particles. For the purpose of improving the flocculation efficiency of kaolin suspensions, the impact of the proposed mechanochemical treatment, which includes homogenization and/or ultrasonication followed by the addition of polycation such as poly (diallyl dimethyl‐ammonium chloride) (PDADMAC), was examined under standard conditions. It was demonstrated that parameters including kaolin's specific surface area, surface charge density, and particle size reduction are all affected by the duration of the ultrasonication. While ultrasonication (10 min) has a significant impact on particle size distributions, 300 and 200 nm‐sized particles were also seen. A narrow flocculation window was obtained by PDADMAC at a Cp/Cs ratio of 0.1 mg/g (Cp/Cs means the ratio of mass polymer/mass substrate), while the mechanical treatment via homogenization with magnetic stirring (60 min) resulted in a larger flocculation window of kaolin caused by the polyelectrolyte used. However, mechanochemical treatment via ultrasonication followed by the addition of aforementioned polyelectrolyte played a significant role in achieving the highest turbidity removal. Hence, the settling behavior of kaolin suspension depends upon the pH, ultra‐sonication time, and the concentration of polyelectrolyte. The combination of ultra‐sonication, PDADMAC dosage, and pH (mechanic‐chemical treatment) played an excellent role in the maximum removal of turbidity, and the broadest flocculation window comprising of 0.4 to 1.6 mg/g was observed at pH 8.
The impact of individual component, i.e., plant extract (Plagiochasma rupestre), biosynthesized silver nanoparticles (AgNPs), and healing clay (bentonite) as antimicrobial agent is reported but their combined effect as a ternary system is a new approach. This study is aimed at investigating the impact of the proposed ternary system against selected human pathogens. AgNPs were synthesized by using Plagiochasma rupestre extract (aqueous) as reducing agent and neutral polymer (PVP) as stabilizer. The morphology, size, and structural properties of synthesized AgNPs were determined with XRD and SEM analysis which showed spherical monomodal particles with an average particle size of 25.5 nm. The antibacterial and antifungal activities of the individual and nanoternary system were investigated. The phytochemical screening of plant extract showed the presence of alkaloids, flavonoids, phenol, and glycosides in methanol extract as compare to aqueous and acetone extract. The antimicrobial activities of crude extracts of Plagiochasma rupestre with AgNPs and bentonite clay were studied as an appropriate candidate for treatment of microbial infections, especially bacterial and fungal diseases. The antioxidant activity of Plagiochasma rupestre aqueous extract and nanoparticles was assessed by (DPPH) free radical, and absorbance was checked at 517 nm. Crude extract has inhibitory effect towards bacteria and fungi, and bentonite clay also showed some degree of antimicrobial resistance. Strategy can be efficiently applied for future engineering and medical. The nanoternary systems showed 3 and 3.5 times higher antibacterial and antifungal activity, respectively, in comparison to Plagiochasma rupestre and bentonite clay, individually.
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