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Adsorption and co-adsorption of PEO-PPO-PEO block copolymers and surfactants and their influence on zeta potential of magnesite and dolomite

Bastrzyk A., Polowczyk I., Szelag E., Sadowski Z.

Physicochemical Problems of Mineral Processing

2012

Vol. 48, iss. 1

281-293

The influence of adsorption and co-adsorption of PEO-PPO-PEO triblock copolymers (Pluronics) as well as surfactants on the zeta potential of magnesite and dolomite aqueous suspension are addressed here. Four Pluronics of various molecular weight were used in these studies. They have been mixed with cationic (CTAB) or anionic (SDS) surfactants. The adsorption isotherms of copolymers and copolymer-surfactant mixture onto magnesite and dolomite have been determined. The adsorbed amount of Pluronics increases with the increasing concentration and reaches plateau. An increase in the adsorbed amounts of both cationic and anionic surfactants onto the mineral surfaces (magnesite and dolomite) has been observed in the presence of Pluronic copolymers. A positive nature of zeta potential was observed in the presence of cationic surfactant, except magnesite without or with a low CTAB concentration. However, an attendant copolymer causes a decrease of zeta potential due to the deformation of an electrical double layer, comparing the presence of an individual cationic surfactant. The adsorbed non-ionic Pluronic layer partially screens the surface charge of mineral particles, and thus, reduces the zeta potential. On the other hand, the adsorption of anionic surfactant and copolymer caused a decrease in the negative value of the zeta potential of both investigated minerals due to increased SDS adsorption. The viscosity measurements were also performed to determine the thickness of adsorbed layer.

Solubilizacja kwasu acetylosalicylowego przez roztwory wodne kopolimerów blokowych typu "Poloxamer"

Zgoda M.M.

Prace Naukowe Instytutu Technologii Organicznej i Tworzyw Sztucznych Politechniki Wrocławskiej. Konferencje

2000

Vol. 48, nr 22

169-172

Przeprowadzono badania nad procesem solubilizacji micelarnej kwasu acetylosalicylowego (ASA) przez wodne roztwory kopolimerów blokowych typu Poloxamer (Pluroniki i ich polskie analogi Rokopole typu 30 px). W zakresie stężeń ekspozycyjnych rozwiązano równanie Noyesa-Whitneya, które umożliwiło oszacowanie pozornej rozpuszczalności ASA - Sapp przy stężeniu poloxameru C = cmc. Rezultaty przeprowadzonych badań stanowią podstawę do wykorzystania Rokopoli jako substancji pomocniczych w technologii stałych doustnych postaci leku.

The parameters S w (real solubility), Sapp (apparent solubility) which quantitatively characterize the process of apparent solubility of acetylsalicylic acid (ASA) in the micellar solution of Poloxamer (Pluronies and polish analogues of Pluronies), were determined in equilibrial balaced conditions.The results of the investigation point at Rokopolis as an excipient, which may help to obtain new drug delivery systems.