Fabrication Of Novel Electrospun PDMS/PMMA/MWCNTs Composite Membrane And Its Application In Wastewater Treatment

Membrane technology has gained much popularity over the past few decades for the treatment of water and wastewater.A variety of synthetic polymers are available for fabrication of membrane.Amongst,polydimethylsiloxane(PDMS)and poly(methyl methacrylate)(PMMA)are widely used polymers due to its intrinsic properties such as high elasticity and superhydrophobicity.In order to fabricate membrane,a suitable method is required which must be efficient and cost effective.Therefore,electrospinning is considered as a straightforward and inexpensive process to electrospun PDMS/PMMA nanofibrous membrane.Since the surface of electrospun membrane is subjected to high feed wastewater flow,mechanical properties of membrane should be strong enough not to be deteriorated due to high wastewater flow.On the contrary,electrospun PDMS/PMMA nanofibrous membrane in fragile nature could be easily broken due to low mechanical strength.Therefore,Multi-walled carbon nanotubes(MWCNTs)are considered best fillers to enhance the mechanical properties of membrane.At first stage,novel PDMS/PMMA nanofibrous membrane was fabricated with MWCNTs attachment using electric field of electrospinning machine.After the membrane fabricated,the membranes with different MWCNTs contents were characterized by scanning electron microscopy,universal testing machine,contact angle measurement,3D automatic optical profiler,and pore size analyzer.While the phenol separation and degradation and salt rejection performance was determined via membrane aromatic recovery system(MARS)and extractive membrane bioreactor(EMBR).Results indicated that the tensile property of composite PDMS/PMMA/MWNCTs nanofibrous membrane was drastically increased six times with a water contact angle(WCA)of 163.3° due to increased roughness parameters compared to neat membrane.However,porosity and fiber diameter of PDMS/PMMA/MWCNTs membrane decreased with the increase of MWCNTs content.The strong interfacial adhesion of MWCNTs with the membrane fibers was the primary reason to enhance the mechanical properties of composite PDMS/PMMA/MWCNTs nanofibrous membrane.Further,the prepared electrospun PDMS/PMMA/MWCNTs membrane was utilized in the MARS to determine the phenol recovery and salt rejection performance.Obtained results showed that the phenol recovery of M-7(with 20 wt.% MWCNTs)was 34.5% higher than that of neat PDMS/PMMA membrane,while maintaining salt rejection of 99.97% after 24 h continuous operation of MARS.The probable reason of increased phenol separation efficiency using MWCNTs was the adsorption/desorption capability of MWCNTs that helped to accelerate the diffusion process more quickly.In addition,a novel EMBR system was designed to determine the phenol degradation efficiency and microbial response using PDMS/PMMA/MWCNTs membrane.Results indicated that phenol extraction efficiency of composite PDMS/PMMA/MWCNTs membrane was found 121.14–289.97 and 103.28–226.41 mg/L/d with and without sludge inoculum,respectively under feed phenol concentration of 1000–4000 mg/L.In the presence of activated sludge,the phenol permeation efficiency was increased by 14.74%–21.91% compared to without sludge inoculum.At the same time,complete biodegradation of phenol was observed during the treatment of 1000–4000 mg/L phenol concentration.It has been also found that attachment of biomass and the microorganism on the membrane surface and fibers enhanced with the increase of feed phenol concentration.The probable reason might be due to hydrophobic nature of membrane surface that attracted the flocs in the sludge medium.Following the study of fabrication of novel electrospun PDMS/PMMA/MWCNTs composite membrane and its application in wastewater treatment,the prepared membrane was proved exclusively beneficial for phenol removal,degradation and salt rejection.In addition,the mechanical properties of novel membrane were found better than the neat membrane.The stability of MWCNTs in the membrane matrix further ensured the novel design of composite PDMS/PMMA/MWCNTs nanofibrous membrane.The formation of biofilm on the membrane surface was also found to be beneficial for phenol removal.Thus,it is reasonable to believe that the novel PDMS/PMMA/MWCNTs membrane can effectively be utilized for wastewater treatment.