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Memantine is a pharmaceutical used to treat memory loss, one of the main symptoms of dementia and Alzheimer’s disease. The use of memantine is expected to continue to grow due to the increasing proportion of the elderly population worldwide. The aim of this work was to conduct a comprehensive study on the behaviour of memantine in the environment and the possibilities of its removal from wastewater. Abiotic elimination processes (hydrolysis, photolysis and sorption) of memantine in the environment were investigated. Results showed that memantine is stable in the environment and easily leached from river sediment. Therefore, further investigation was focused on memantine removal by advanced oxidation processes that would prevent its release into the environment. For photolytic and photocatalytic degradation of memantine, ultraviolet (UV) lamps with the predominant radiation wavelengths of 365 nm (UV-A) and 254/185 nm (UV-C) were used as a source of light. TiO2 in the form of a nanostructured film deposited on the borosilicate glass wall of the reactor was used for photocatalytic experiments. Photodegradation of memantine followed pseudo-first-order kinetics. The half-life of photocatalytic degradation by UV-A light was much higher (46.3 min) than the half-life obtained by UV-C light (3.9 min). Processes degradation efficiencies and evaluation of kinetic constants were based on the results of HPLC-MS/MS analyses, which also enable the identification of memantine oxidation products. The acute toxicity of the reaction mixture during the oxidation was evaluated by monitoring the inhibition of the luminescence of Vibrio fischeri bacteria. The results showed that memantine and its oxidation products were not harmful to Vibrio fischeri.

U ovom tekstu razmatra se kako odabrati pufer ovisno o svrsi i kako ga pripraviti, pri čemu je navedeno nekoliko načina pripremanja puferskih otopina. Uz naglašeno nužno razumijevanje konstanti disocijacije kiselina, čitateljima se nastoji približiti ispravan način pripremanja željenih puferskih otopina. To se ponajprije odnosi na uzimanje u obzir svih faktora koji mogu utjecati na neki puferski sustav. U tekstu se zato obrađuju važni pojmovi i povezuju s njihovim primjenama u znanstvenom i inženjerskom svijetu. Također, pojašnjava se pojam kapaciteta pufera i njegova uloga, pojam ionske jakosti te na što ona utječe. Navedena su bitna svojstva koja pufer treba imati te kako produljiti trajanje puferskih otopina. Na kraju se može provjeriti što su zapravo puferi te su dani zadatci s ciljem samostalne provjere usvojenosti rješavanja računskih zadataka.

Puferi su važni za mjerenje i održavanje vrijednosti pH koje je ključno u mnogobrojnim svakodnevnim znanstvenim i industrijskim djelatnostima. Stoga, cilj ovoga teksta je razjasniti fizikalno-kemijske parametre na kojima počivaju puferi. Obrađeno je kako se i zašto provodi umjeravanje članka za mjerenje pH. Navedeno je koji se problemi mogu pojaviti tijekom mjerenja pH i kako te probleme riješiti. Rad se bavi primjenom stečenog znanja u nastavi, kao i njihovom provjerom kroz primjere i računske zadatke. Navedenim praktičnim primjerima olakšano je usvajanje temeljnih pojmova vezanih uz pH i pufere. Tako je obrađeno kako pravilno definirati pH, što je Henderson-Hasselbalchova jednadžba i koja su joj ograničenja, kako vizualno provjeriti djelovanje pufera, koja je povezanost Le Chatelirova načela i pufera, o čemu treba voditi računa prilikom mjerenja pH. Među ostalim, navedena je i važnost utjecaja temperature kod umjeravanja pH-članka, mjerenja pH uzorka, ali i iskazivanja vrijednosti pH. Na kraju, navedeno je kako unaprijediti stečena znanja i vještine kroz pitanja povezana s vrijednostima pH i puferima.

The increased utilization of one-dimensional (1D) TiO2 and titanate nanowires (TNWs) in various applications was the motivation behind studying their stability in this work, given that stability greatly influences both the success of the application and the environmental impact. Due to their high abundance in aqueous environments and their rich technological applicability, surfactants are among the most interesting compounds used for tailoring the stability.The aim of this paper is to determine the influence of surfactant molecular structure on TNW stability/aggregation behavior in water and aqueous NaBr solution by dynamic and electrophoretic light scattering. To accomplish this, two structurally different quaternary ammonium surfactants (monomeric DTAB and the corresponding dimeric 12-2-12) at monomer and micellar concentrations were used to investigate TNW stability in water and NaBr. It was shown that TNWs are relatively stable in Milli-Q water. However, the addition of NaBr induces aggregation, especially as the TNW mass concentration increases. DTAB and 12-2-12 adsorb on TNW surfaces as a result of the superposition of favorable electrostatic and hydrophobic interactions. As expected, the interaction of TNWs with 12-2-12 was stronger than with DTAB, due to the presence of two positively charged head groups and two hydrophobic tails. As a consequence of the higher adsorption of 12-2-12, TNWs remained stable in both media, while DTAB showed an opposite behavior.In order to gain more insight into changes in the surface properties after surfactant adsorption on the TNW surface, a surface complexation model was employed. With this first attempt to quantify the contribution of the surfactant structure on the adsorption equilibrium according to the observed differences in the intrinsic log K values, it was shown that 12-2-12 interacts more strongly with TNWs than DTAB. The modelling results enable a better understanding of the interaction between TNWs and surfactants as well as the prediction of the conditions that can promote stabilization or aggregation.