Pervaporation Process With PDMS/PVDF Hollow Fiber Composote Membrane For The Recycle Of Phenol From Coal Chemical Wastewater

Coal chemical industries result in a large amount of high concentrationorganic wastewater, mainly phenolic compounds, alkane, aromatic hydrocarbons,heterocyclic, ammonia nitrogen and cyanide, which are hard to be treated bytraditional biological treatment. At the same time, phenolic is an important basicmaterial in organic synthesis so if large amount of phenolic substances berecovered and recycled, it would produce huge economic and environmentalbenefit. In comparison with the plate-and-frame module, the hollow fibermembrane has the advantages of high-packing density, self-contained mechanicalsupport, and economical superiority. Development of hollow fiber membranemodule is inevitable.In this article, PDMS/PVDF hollow fiber composite membrane was made bydynamic negative pressure coating method, the pervaporation performance ofPDMS was improved by the cross-linking modification. The influence ofcross-linking agent, PDMS concentration, coating time on the pervaporationperformance of the composite membrane was discussed. In the scale-upexperiment, simulated actual industrial application, discussed the influence ofaeration rate, temperature, flow rate, pressure under membrane, optimized theoperating parameter and studied the continuous operation stability ofpervaporation system and evaluated the feasibility of industrial application fromthe infrastructure investment, tons of water treatment cost, etc.The membrane, mass ratio as PDMS:(3-cyanide propyl) triethoxy silane:DBTL=20:3:1, concentration of PDMS24wt%, coated40min, pervaporationperformed the best. Actual coal chemical industry wastewater with phenolconcentration1600-1800mg/L, COD13000-15000mg/L was treated by theobtained PDMS/PVDF composite membrane, at temperature70℃, the flow rateof10L/h, pressure under membrane3KPa, phenol flux was19.24g/(m2·h),separation factor reached12.124. Used surfactant clean the severely pollutedmembrane components, phenol flux increased by about40%.In the scale-up experiment, at temperature70℃, the flow rate of150L/h,pressure under membrane5KPa, gas-water ratio0.3,75L wastewater wastreated for6h, phenol removal efficiency reached72%. The system ran stably for120h and performed well, inflow phenol concentration fluctuated between1600and1800mg/L, effluent phenol concentration ranged from400to600mg/L,phenol removal efficiency kept more than60%. Cost estimation of apervaporation device with treating capacity of10t per day, the infrastructure investment was56000yuan, tons of water treatment cost was4.53yuan,Pervaporation with industrial application has a very broad prospects.