Hydrophobic nano sponge for efficient removal of diesel fuel from water and soil

PDMS/magnetic lignin sponge for oil/water separation

Recyclable, non-toxic, and degradable biological substrates contribute significantly to super-wetting surfaces. In this work, we prepared magnetic micro-nano super-hydrophobic surfaces through a robust solution with magnetic modified lignin particles as the supporting structure. A novel PDMS (polydimethylsiloxane)/magnetic lignin particle (lignin@Fe3O4)/PDA sponge composite was fabricated. Through dopamine (DA) self-polymerization, covalent deposition of magnetic lignin (ML), and PDMS silane modification, the magnetic super-hydrophobic polyurethane sponge composite (Sponge-P) was synthesized so that the Fe3O4 nanoscale microspheres wrapped with microscale lignin magnetic particles adhered to the sponge surface tighter and were barely dislodged. The as-prepared Sponge-P displayed excellent flexibility and a water contact angle of up to 152.2°. The super-hydrophobic sponge prepared with the proposed method was acid-base stable (pH = 2-12), self-cleaning, and suitable for high-salinity seawater. The magnetic super-hydrophobic sponge has good oil-water separation ability and can absorb 43 times its own weight of oil. In the meantime, due to the introduction of magnetic materials into lignin, we not only constructed micro-nanostructures to improve the surface super-hydrophobicity, but also made Sponge-P have the function of magnetic recovery, which has a unique advantage in treating oily wastewater.

Novel porous oil-water separation material with super-hydrophobicity and super-oleophilicity prepared from beeswax, lignin, and cotton

The traditional fluorinated porous material with super-hydrophobicity and super-oleophilicity is an effective strategy for oil-water separation. However, in recent years, fluorinated materials have been classified as "Emerging Environmental Pollutants" by U. S. Environmental Protection Agency because of difficult degradation and bio-accumulation. It is unacceptable to introduce new pollutants while solving environmental disasters. Therefore, it is great requirement to explore a low-cost, environmentally friendly, and renewable technique for the fabrication of novel porous materials with super-hydrophobicity and super-oleophilicity to separate oil-water mixtures. In this work, renewable beeswax, lignin, and cotton have been chosen to prepare the biomass-based porous materials with super-hydrophobicity and super-oleophilicity for oil-water separation. The mixture of beeswax and lignin is modified on the surface of cotton to obtain the biomass-based porous materials with super-hydrophobicity and super-oleophilicity. The beeswax and lignin provide low surface energy and micro/nanoscale structures, respectively. The introduction of lignin effectively improves the thermal stability of the porous materials. The apparent contact angle still remains to be above 150° after a long-time heating. The porous materials effectively separate oil-water mixtures and have good absorption effect for heavy oil (density greater than water). Moreover, the porous materials are easily recyclable after reactivation. This strategy of preparing oil-water separation materials from renewable natural polymers not only helps to clean the environment, but also helps to recover valuable oil.

Recyclable polyether–polyquaternium grafted SiO2 microsphere for efficient treatment of ASP flooding-produced water: oil adsorption characteristics and mechanism

In this work, an interfacially active PPA@SiO₂ microsphere for ASP flooding-produced water treatment was synthesized by grafting polyether–polyquaternium (PPA) copolymer onto mesoporous hydrated silica (SiO₂). This PPA@SiO₂ microsphere integrates both demulsification and adsorption functionalities. The physicochemical properties of the SiO₂ variants were monitored via SEM, BET, XPS, contact angle and zeta potential tests. When disposing of a simulated alkali–surfactant–polymer flooding produced water that contained 500 mg L⁻¹ oil, this functional PPA@SiO₂ microsphere exhibited an oil removal efficiency of 78.0% at 1.0 g L⁻¹ dosage, which is higher than that of pristine SiO₂ (39.1%) and hydrophobic modified SiO₂ (54.2%). This remarkable oil removal efficiency was attributed to its abilities to destabilize and aggregate the emulsified oil droplets. Oil micromorphology test results indicated that PPA@SiO₂ could aggregate the fine oil droplets into oil clusters, which significantly favors the oil–water separation efficiency. An adsorption kinetics and thermodynamics study manifested that oil adsorption onto PPA@SiO₂ was an exothermic process, mainly dominated by external surface adsorption, which agreed with the BET and micromorphology study. Furthermore, the oil adsorption mechanism has been explored and confirmed according to all the experimental results. This modification protocol significantly reduced the PPA consumption and it was also found that the loaded oil onto PPA@SiO₂ could be effectively separated through a petroleum ether extraction process, so as to recycle the carrier particles. This novel PPA@SiO₂ microsphere with its high oil removal efficiency offers technical promise and huge potential for oily wastewater treatment.

A recyclable functional microsphere was developed which significantly enhances oil–water separation and decreases chemical demulsifier consumption.