Wasted scrub pad functionalized with graphene and porous BiFeO3 microparticles for the desalination/decontamination of water by solar evaporation

Abstract

Solar water evaporators were fabricated with wasted scrub pad (SP) and their performance for the desalination/decontamination of water was evaluated. Firstly, bare SP was utilized for the desalination of seawater obtained from Puerto Vallarta beach, Mexico. SP produced an evaporation rate (ER)/efficiency of 2.18 kg m−2 h−1/72.6 %, respectively, under natural solar light. Subsequently, the SP evaporator was coated with graphene (G) + porous BiFeO3 (BFO) microparticles. This SPG + BFO evaporator produced an outstanding evaporation rate/efficiency of 2.93 kg m−2 h−1/94.6 %. Thus, the evaporation rate and evaporation efficiency increased by 33 % and by 22 % after adding the graphene + BFO coating. Absorbance and Raman analysis on the evaporators’ surface revealed that the evaporators made with graphene + BFO had higher absorbance of NIR light and higher content of defects. This favored the transformation of light to heat and steam generation. Additionally, the SPG + BFO evaporator was employed for the decontamination of water. Laundry wastewater (LWW) and domestic-wastewater contaminated with coke-soda (WCS) or coffee-drink (WCD) were also decontaminated using the SPG + BFO evaporator. The LWW contained mainly suspended solids, while the WCS and the WCD contained caffeine. The clean water obtained from the evaporation of LWW, WCS and WCD was completely free of suspended solids or caffeine as demonstrated by the FTIR and absorbance measurements. Overall, the results of this investigation demonstrate that low-cost evaporators can be fabricated from wasted scrub pads and those ones are very efficient for the evaporation/decontamination of water. Giving a second use to the wasted scrub pads benefits the environment because this delays its contamination by plastics.