Transfer of selected pharmaceuticals via water vapor under moderate temperatures in solar stills -

Abstract

The increase in demand and disposal of pharmaceuticals, positively correlated with the growing, developing human population led to the emergence of pharmaceuticals as a contaminant with high environmental impact. This impact is attributed to several factors: its numerous ways of entry to the environment, high stability, profound biological effects at low doses, and the incomplete removal of these contaminants by conventional water treatment methods. Moreover, very little is known about their effects on the ecosystem and human health. Many developing countries that endure problems related to water sufficiency and-or quality use solar stills as an affordable water supply method. Very little research has been done on the effectiveness of solar stills in removing pharmaceuticals. This research was aimed at understanding the transfer and-or degradation of five chemically distinct pharmaceuticals in solar stills. The studied pharmaceuticals were: Ibuprofen, Diclofenac, Carbamazepine, Ampicillin and Naproxen. Experiments were conducted under three conditions referred to as Conditions I, II and III. The first condition studied the combined effect of temperature and light in full-scale solar stills. The effect of temperature as a sole variable was investigated in condition II. The third condition covered the effect of light only via concentrated solar power (CSP) experiments. Results obtained show that solar stills are highly effective in preventing the transfer of the studied pharmaceuticals from feed solution into the distillate. Ibuprofen, having the highest Henry’s law volatility constant among the tested pharmaceuticals, was the only pharmaceutical that transferred via vapor into the distillate with the highest transfer of 2.13percent at 50°C in Condition II and 0.58percent in Condition I. In the case of Naproxen and Diclofenac, the parent compounds did not undergo transfer into the distillate phase; however, their degradation byproducts did. In addition, the results also showed that in the case of Ampicillin, Nap