Factors affecting drug adsorption on beta zeolites

Abstract

The adsorption behaviour of three commonly used drugs, namely ketoprofen, hydrochlorothiazide and atenolol, from diluted aqueous solutions on beta zeolites with different SiO2/Al2O3 ratio (i.e. 25, 38 and 360) was investigated by changing the ionic strength and the pH, before and after thermal treatment of the adsorbents. The selective adsorption of drugs was confirmed by thermogravimetry and X-ray diffraction. The adsorption capacity of beta zeolites was strongly dependent on both the solution pH and the alumina content of the adsorbent. Such a remarkable difference was interpreted as a function of the interactions between drug molecules and zeolite surface functional groups. Atenolol was readily adsorbed on the less hydrophobic zeolite, under pH conditions in which electrostatic interactions were predominant. On the other hand, ketoprofen adsorption was mainly driven by hydrophobic interactions. For undissociated molecules the adsorption capability increased with the increase of hydrophobicity.

Insights into Adsorption of Chlorobenzene in High Silica MFI and FAU Zeolites Gained from Chromatographic and Diffractometric Techniques

“…It can be seen that the kinetics of the adsorption process was very fast; the equilibrium was reached in about 10 min. Similar behaviors were also observed for the adsorption of other aqueous contaminants, such as dichloroethane and toluene onto ZSM-5 and Y zeolites [5][6][7][8][9][10]13].…”

“…We have previously verified [5][6][7][8][9][10]13] that uptake data of the investigated zeolites can be fitted by the pseudo-second order model as:…”

“…Actually, the physical method based on adsorption processes is a recuperative method exploited for in situ water treatments which combines high flexibility of the system, efficiency even at low concentration levels, low energy, cheap operating costs, and possible waste reductions [3]. Different adsorbent materials can be employed, and their efficiency depends on the host-guest interactions between sorbent and sorbate [4][5][6][7][8][9][10][11][12][13]. In general, carbonaceous adsorbents are low cost materials, widely employed in remediation technology.…”

Effect of Silica Alumina Ratio and Thermal Treatment of Beta Zeolites on the Adsorption of Toluene from Aqueous Solutions

“…In particular, the thermal treatment considerably increases the adsorption efficiency of all BEAs toward TOL in the low concentration range. This finding has also been observed also for polar compounds such as pharmaceuticals [6]. It has been suggested that part of the adsorption properties of BEA zeolites originates from faults in the zeolitic structure [35].…”

“…Among several techniques developed for BTEX removal from waters, adsorption is one of the most efficient methods, thanks to satisfactory efficiencies even at low concentrations [3], easy operation and low cost [4]. Recently, high-silica zeolites have been shown to be environmental friendly materials able to efficiently sorb several organic pollutants from water, such as pharmaceuticals [5][6][7], polycyclic aromatic hydrocarbons [8], phenols [9] and petrol-derived compounds [10][11][12].…”