Recovery of Carbon Nanomaterials from an Aqueous Environment Employing Oil-Based Microemulsion and Surfactant-based Cloud Point Extraction

The current research work is an initiative taken for the remediation of water contaminated with carbon nanomaterials (CNMs) by employing microemulsion (ME) and cloud point extraction (CPE) methodologies. CNMs viz., graphene oxide (GO) and multiwalled carbon nanotube (MWCNT) dispersed in water (2000 mg/L) were extracted in the oil phase and surfactant phase based on optimized ME and CPE parameters which include oil, pH, incubation temperature, the content of non-ionic-surfactants (Triton X-100) and NaCl. The supernatant and extracted CNMs from the ME and CPE experiments were analyzed using UV-Vis spectroscopy, DLS, SEM, TEM, XRD, and Raman spectroscopy. The disappearance of characteristic peaks of GO and MWCNT in the UV-Vis, Raman, and DLS spectra of the treated water samples signifies the absence of nanoparticles in the remediated water. A highly efficient removal (similar to 97%) of GO and MWCNT from contaminated water through CPE in one cycle was achieved compared to ME (similar to 90%) in two recovery cycles. Thus, the CPE technique efficiently removes CNMs from polluted water for their benign disposal, mitigating potential ecological and health risks.