ABSTRACT
Due to the high oil spill incidence and industrial wastewater discharge including oil and emulsified oil, designing and synthesizing oil-water separation materials which can maintain stability under harsh environmental conditions with high separation efficiencies remains a great challenge. The present work developed an easy, green, cost-effective, and easily scaled-up approach for fabricating cellulose-based membranes. First, we coated polydopamine (PDA) onto fibers of filter membrane (FM). Then, the PDA-FM membrane was immersed into the mixed solution of poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) and further thermally cross-linked at 150 °C to create a superhydrophilic/underwater superoleophobic membrane (PVA/PAA@PDA-FM) to separate oil/water mixtures. The simple thermally cross-linking process promotes multiple covalent chemical bonds generation between cellulose filter membrane, PAA, PDA, and PVA, endowing membranes with excellent stability and resistance to acidity, alkalinity, and salinity. The PVA/PAA@PDA-FM membrane not only demonstrates great separation performance (>99.8%) and great flux (>1000 L m-2 h-1) in oil-water immiscible mixtures but also maintains high separation efficiency under conditions of high acidity, alkalinity, and salinity. Additionally, the PVA/PAA@PDA-FM membrane exhibits excellent separation capacity in oil-water emulsions, which can maintain the >99.6% separation efficiency even after 40 cycles in harsh environments, showing outstanding reusability. Thus, due to the multiple cross-linked networks in the membrane, the excellent performance makes the PVA/PAA@PDA-FM membrane a good application prospect in water purification and oily wastewater treatment.
ABSTRACT
An effective wave absorbing Nano-Ni/carbon nanotubes (CNTs) composite film was developed by electrodeposition using an anodic aluminum oxide (AAO)/CNTs electrode. Scanning electron microscopy images confirmed the uniform dispersion of Ni nano-particles within the CNTs, and the particle diameter increasing from 20 nm to 100 nm as the deposition time increased. XRD test results revealed that the crystal phase of the Ni nano-particles remained unchanged during different deposition time, exhibiting a Face Center Cubic (fcc) structure. The microwave electromagnetic properties of the film were evaluated using a vector network analyzer, and the return loss curve demonstrated that the Ni nano-particles/CNTs composite exhibited exceptional wave absorption capabilities. The composite film showed an effective absorption width of 13 GHz (4-17 GHz) and achieved a minimum reflection loss (RL) of -17 dB at 14 GHz.
