Quantification of the distribution of cetylpyridinium chloride on the external and internal surfaces of montmorillonite: Relevance in antifungal activity assessment
Makaleler > Tam Makale · 2020
Yazarlar: Florencia Yarza, Cesar Fernantes Morantes, Maria L Montes, Natalia Bellotti, Joaquin Salduondo, Saadet YAPAR, Fernanda Cravero, Rosa M. Torres Sanchez
Materials Chemistry and Physics, SCI Expanded İndekslerine Giren Dergi, Uluslararası, Wos, 2020, cilt 253, ss 123390-123390
DOI: 10.1016/j.matchemphys.2020.123390
Özet
<p>Two raw bentonites, from Argentina (Mt-A) and Turkey (Mt-T), rich in montmorillonite, were loaded with</p><p>different concentrations of cetylpyridinium chloride (CP), ranging from 50% to 150% of their respective cation</p><p>exchange capacity (CEC). Their antifungal activity was tested against Alternaria alternata and Chaetomium globosum.</p><p>Thermal analysis was used to identify the different surface adsorption sites of the CP on the montmorillonite</p><p>(Mt) samples as well as to quantify the surfactant amount related to each process, which could play a key</p><p>role in the antifungal capacity of the synthesized materials. Three different CP interaction processes with the Mt</p><p>surface sites were observed. Two occurring at the outer Mt surface (electrostatic interaction between CP and the</p><p>negative surface sites of Mt (B), and van der Waals (VdW) interactions between long tails of CP molecules (A) and</p><p>one at the inner (or interlayer) Mt surface due to the cation exchange between CP and the inorganic interlayer</p><p>cations (C). The simultaneous occurrence of these processes was confirmed by the increase of the interlayer</p><p>thickness due to the entrance of CP by C process and the decrease of the initial negative zeta potential values by A</p><p>and C processes, respectively.</p><p>The antifungal activity of clays against strains of A. alternata and C. globosum, was evaluated by agar diffusion</p><p>assay. Then, the inhibition diameter was related to the actual CP load and its distribution according to A, B, and C</p><p>processes. Samples with the highest inhibition zone, Mt-A-CP150, and Mt-T-CP150, presented the greatest actual</p><p>CP loaded (103 and 110% CEC, respectively). For both samples, the CP amount related to the A process was the</p><p>lowest, with values around 10% CEC, while the major contribution occurs for the CP related to the B process</p><p>(49.9 and 57.7% CEC, respectively). The Pearson correlation coefficients ? determined between inhibition zone</p><p>diameters and CP amount related to each adsorption process indicated that the A and B processes play a key role</p><p>in the controlled release of the CP from the organoclays.</p><p>For A. alternata the ? values for A and B processes resulted in 0.84 and 0.87, while for C. globosum 0.84 and</p><p>0.91, respectively, being non-significant for C process in both cases.</p>