A study on the removal of common analgesics from waste water, using zeolites Clinoptilolite and Beta

Abstract

Over the last few decades the use of pharmaceuticals has increased to a high level. Used by both humans and animals, pharmaceutical active compounds (PACs) are not completely metabolised inside their bodies. Consequently, PACs are excreted through urine or faeces and together, with the products of metabolisation, they enter wastewaters as biologically active substances. Pharmaceuticals form a large group of compounds that are often polar molecules, therefore, are usually soluble in water. Thus, many PACS cannot be completely removed from wastewaters; hence, are found globally in a wide range of environmental samples including: sewage treatment plant effluents, surface, ground and even in drinking water.

The amounts of PACs detected in the environment are usually very low; they are often detected in trace concentrations (ng/L). However, the long-term discharge of PACS may cause potential risk to both aquatic and terrestrial organisms. Therefore, this research focuses on the removal of the common analgesics; acetaminophen and ibuprofen using zeolites as the absorbent. Zeolites have attracted great attention as they are affordable materials that can be modified so to adjust or even tailor their adsorptive possibilities. The zeolites clinoptilolite and beta (BEA) were used as the absorbents and were ion-exchanged with Cu (II), Fe (III) and NH4+ ions, with the aim of removing acetaminophen and ibuprofen from water. IR, XRD, HPLC and BET experiments were performed to measure uptake of the pharmaceuticals. It was found that both zeolites were able to adsorb the pharmaceuticals in question, however, HPLC results showed clinoptilolite to be the better adsorbent. The best uptake was exhibited by Cu-exchanged clinoptilolite with the highest adsorption affinity towards ibuprofen. It is believed that ibuprofen degraded during the adsorption experiments to produce ions that form stable complexes with the cations.