Enhancing the removal of the diclofenac contaminant and accelerating the desalinization of seawater by using a biodegradable fibrous support functionalized with Sr2.7Ln0.3Fe1.4Co0.6O7-δ (Ln = La or Nd) perovskites

Abstract

A biodegradable fibrous support (oak-gall, OG) was functionalized with graphene (G) and Sr2.7Ln0.3Fe1.4Co0.6O7-δ perovskite (named SLFCO and SNFCO when Ln = La and Nd, respectively) to remove the diclofenac (DCF) contaminant from the drinking water by photocatalysis. The photocatalytic experiments revealed that the SNFCO and SLFCO powders produced DCF degradation of 100 % and 94 %, respectively, after 150 min under UV–vis irradiation. This means that making a perovskite with Nd dopant instead of La is more effective to induce the DCF degradation. Later, a composite made of OG + G was evaluated, but only a DCF degradation of 50 % was produced. Subsequently, a floatable composite made with SNFCO particles (OG + G + SNFCO) was tested and produced a complete degradation for DCF after 150 min of UV–vis irradiation, thus, adding the perovskite produced higher DCF degradation. Additionally, scavenger experiments were carried out and confirmed the formation of oxidizing agents such as ∙OH and ∙O2−, which mainly attacked the DCF molecules. Raman, absorbance, and X-ray photoelectron spectroscopy (XPS) measurements demonstrated the presence of oxygen vacancy defects in the biodegradable photocatalytic composites. Such vacancies acted as electron trapping centers, which enhanced the DCF degradation. The OG + G + SNFCO composite was also tested for the evaporation of seawater under natural solar light and produced a maximum evaporation-rate and evaporation-efficiency of 1.67 kg/m2∙h and 95 %, respectively. Adding the OG + G + SNFCO composite to the seawater accelerated its desalination ≈2 times. In fact, the Fourier-transform-infrared (FTIR) technique demonstrated the no presence of NaCl in the condensed water recovered after desalination. Hence, the results of this research indicate that a biodegradable composite functionalized with G + SNFCO is useful for the elimination of pharmaceutical drugs from the water and for seawater desalination.