Removal of phenol and 4-chlorophenol by surfactant-modified natural zeolite

Organic xenobiotics removal in constructed wetlands, with emphasis on the importance of the support matrix

“…The high ion exchange capacity of zeolites, their extensive porosities and specific surface areas, as well as their relatively cheap prices, make natural zeolites attractive adsorbents [208][209][210][211][212][213][214][215][216][217][218][219][220][221][222]. However, synthetic zeolites are also widely tested, especially because through synthesis a useful control can be obtained over the Si/Al ratio in the zeolite composition.…”

“…However, surface modification can change the surface functionality by adding cationic surfactants or other hydrophobic groups thus making them applicable for adsorption of various anions and organics. The most common surface modifiers are salts of a variety of quaternary amines such as hexadecyltrimethylammonium (HDTMA, the most popular surfactant) [210][211][212][213][214]224,226,[234][235][236], octadecyldimethylbenzylammonium (ODMBA) [216][217][218], stearyldimethylbenzylammonium (SDBA) [219,224] or benzyltetradecyl ammonium (BDTDA) [212]. Other posibilities are cetylpyridinium salts [211,220], cyclodextrins [208] and chlorosilanes [209].…”

Carboxylated carbon nanotubes as an efficient and cost-effective adsorbent for sustainable removal of insecticide fenvalerate from contaminated solutions

“…In fact, Freundlich equation was explained the equilibrium adsorption, which is must commonly written as [26][27][28][29]:…”

“…where the Temkin isotherm constant is A (L g -1 ), the gas constant is R (8.314 J mol -1 K -1 ), the heat of adsorption is Temkin constant (J mol -1 ), and the absolute temperature is T (K) [25][26][27]. The linear form of Temkin isotherm is as follow:…”

“…where B = RT/b [24][25][26]. A and B constants can be determined by plotting q e against lnC e ( Table 1).…”