Hydrophobic UiO-66 composite: Surface energy modelling for oil-water interactions

Abstract

Oil spill is considered as the serious threat to aquatic ecosystem and it is quite a challenge to clean such oil spills. In order to cure this problem, we introduced a novel hydrophobic composite material making use of metal organic framework (MOF) i.e., UiO-66 and polyurethane (PU) foam. PU foam was utilized for oil absorption by incorporation of Fe3O4 particles via in-situ approach and dip coating it with polydimethylsiloxane (PDMS) and hydrophobic UiO-66 (hUiO-66) resulting into the formation of hydrophobic composite foam. The decrease in hydrophilic character and increase in hydrophobic character of PU foam was deduced using FTIR and contact angle analysis. PDMS being a low surface energy polymer accounted for the hydrophobicity of the composite material, the coating of PDMS on the material gave contact angle of 122.1o. Furthermore, Fe3O4 provides surface roughness on the surface of PU foam which is clearly visible in FESEM analysis leading to decrease in surface energy of the composite thereby increasing the hydrophobicity and absorption capacity. In order to study the surface area, pore size and pore type of the material, BET surface area analyzer was used depicting surface area of 1049.90 m2g-1 for UiO-66 and 431 m2g-1 for hUiO-66@Fe3O4@PDMS. To gain insight into the surface energy of the composite, various models such as Zisman model, OWRK model and Neumann model were utilized to determine. Moreover, the composite resulted in excellent reusability maintaining the separation efficiency of about 78.4g/g even after 36 cycles. This shows a substantial improvement in the area compared to previous research and opens the door for the production of hydrophobic foams for purposes like oil-spill cleanup in challenging circumstances. The proposed approach efficiently helpful in oil-spill cleanup, making it promising for oil leakages. Environmental implicationsThere are no risks involved to the environment in the research work. The synthesized composite aims at addressing the critical environmental issue of oil spill.