Effect of hydrous manganese oxide (HMO) functional groups on oily wastewater treatment

The innovative exploitation of diverse inorganic materials in environmental applications has received great scientific attention as a result of the rapid growth of nanotechnology and the expanding variety of nanomaterials currently being produced and developed. The idea of developing multifunctional nanocomposite membranes that can do more than just separate things has been made possible using inorganic nanoparticles as fillers in polymeric matrix. In this work, the nanocomposite was utilized to separate an oil/water emulsion. With the intention of enhancing the capabilities of PVDF-based membrane for oil/water emulsion filtration, synthesized hydrous manganese oxide (HMO) nanoparticles were mixed with poly(vinylidene fluoride) (PVDF) polymer to form mixed matrix membrane (MMM). With the addition of HMO nanoparticles, the MMM showed that the membrane wetting properties, hydrophilicity and oleophobicity, were greatly improved owing to the high amount of –OH functional groups. Subsequently, the improved surface hydrophilicity leads to greater water flux of PVDF/HMO MMM (402.0 ± 11.75 L/m² h; oil rejection efficiency = 93.8%) in comparison to pristine PVDF membrane (42.4 ± 3.73 L/m² h; oil rejection efficiency = 96.2%). Furthermore, compared to pristine PVDF membrane, the flux recovery rate (FRR) and reversible fouling (R_r) of the MMM were increased by two–three times, while the irreversible fouling (R_ir) was reduced by half. This demonstrates that the HMO nanoparticles in the nanocomposite improved the water affinity and reduced low possibility of fouling problem. Hence, the modified nanocomposite membrane can be applied in oily wastewater treatment and competed with the current technologies.