Preparation Of Regenerated Lignocellulose Composite Membranes And Its Purification Research For Oily Wastewater

With the rapid development of maritime transportation,there are occasional incidents of improper discharge of oily wastewater from ships.This not only pollutes the oceans,destroys biodiversity,but also poses a significant threat to human health and the environment of ports and waterways.Therefore,achieving purification and separation of oily wastewater is crucial for environmental protection in ports and waterways.However,traditional oil-water separation materials have drawbacks such as complex preparation,high cost,low separation efficiency,and secondary pollution.To address these issues,this paper explores the preparation of two types of lignocellulose membranes and analyzes their oil-water separation properties through wettability,chemical analysis,and surface structures.The main research works are summarized as follows:（1）Inspired by the plant cell wall,a composite membrane was prepared using lignin and cellulose from wood.Wood powder was dissolved in a deep eutectic solvent（DES）,allowing lignin to dissolve in the solvent and decomposing cellulose into micro/nano fibers.Then,the hydrophobic lignin was regenerated by adding water to the DES,and regenerated lignin was connected to micro/nano cellulose through hydrogen bonds to form regenerated lignocellulose.The regenerated lignocellulose was then filtered onto the surface of a polyvinylidene fluoride membrane to prepare the regenerated lignocellulose-PVDF membrane（LC-PVDF）.The composite membrane achieves a maximum flux of 549Lm^-2h^-1bar^-1in separating water-in-oil emulsions,with separation efficiencies exceeding99.00%for a variety of emulsified oils.This separation material effectively addresses the challenges of high material costs,complex preparation processes,low separation efficiencies,and environmental hazards currently associated with purifying oily wastewater.（2）Optimization of the regenerated lignocellulose-PVDF membrane（LC-PVDF）was achieved through the use of green degradable materials such as cotton fabric and wood powder,resulting in the production of a degradable regenerated lignocellulose composite membrane（LCPT@CF）.Regenerated lignocellulose was prepared using a simple and economical in-situ regeneration method,and then loaded onto the surface of cotton fabric using the supramolecular bonding effect of tannic acid and polyvinyl alcohol,resulting in a three-layered LCPT@CF composite membrane.LCPT@CF exhibits excellent underwater superoleophobicity,with separation efficiencies exceeding 99.90%for a variety of emulsified oils and oil-water mixtures,and a maximum flux of 313 Lm^-2h^-1bar^-1.Additionally,the composite membrane has the advantages of low cost,good recyclability,and resistance to pollution,and can be degraded in natural soil environments without harm to the environment.The oil-water separation performance and degradability of this membrane material have significant implications for promoting green and low-carbon development.