Abstract
Entire elimination of pharmaceutical drugs from waste- and domestic-waters has attracted great attention due to their potent adverse effects on human health, particularly the human immune system. Many risks have been related to the presence of different types of drugs at different concentrations in wastewater. These risks include antimicrobial resistance (AMR), endocrine action, hormonal activation of cancers, and photodegradation of drugs. In this study, new nanohybrid materials consisting of graphene oxide (GO) and oxidized carbon nanotubes (OCNTs) were developed to remove a well-known drug, namely, ranitidine that treats stomach ulcers and gastrointestinal (GI) reflux disease from aqueous solutions. The characterization of synthesized nanohybrid GO-OCNTs was performed using spectroscopic (FTIR, and XRD), thermogravimetric (TGA) and microscopic (SEM) techniques. Batch adsorption experiments were used to investigate the technical feasibility of using synthesized GO-OCNTs for the removal of ranitidine from aqueous solutions. The effects of different operating conditions such as contact time, nanohybrid mass, solution temperature, solution pH, % crosslinking agent, and GO-to-OCNT ratio on the entire elimination of ranitidine were investigated. The experimental results indicated that the removal of ranitidine was very efficient, where 98.3% removal of the drug from aqueous solutions was achieved with a drug uptake of 97.8 mg g-1. Moreover, the results indicated the optimum conditions for the removal of ranitidine, which are as follows: contact time = 140 minutes, nanohybrid GO-OCNT mass = 10 mg, solution temperature = 290 K, solution pH = 6.4, % crosslinking agent = 0.5%, and GO to O-CNT ratio = 1 : 4. The equilibrium data were fitted to different adsorption isotherms and Langmuir was found to best describe our data. Dynamic studies demonstrated that ranitidine adsorption followed pseudo-second order, and the thermodynamic parameters confirmed exothermic drug adsorption as well as the physisorption process.