I am also thankful to all the faculty members of Chemical Engineering Department for their encouragement and help at various stages during my stay in this department. I am also thankful to all other staff members of Chemical Engineering Department for their genuine help and support throughout this work. Sharma, former Scientific Officers, Chemical Engineering Department for their help and support in carrying out this work.
I also want to send my loving thanks to my father, my brother and my sister and all the family members for their constant moral support.
Ultrafiltration (UF) of Oily Water: Experimental 147 - 169
Conclusions and Scope of Future Works 251 - 259
Properties of Polymers and Solvents 261 - 266
Introduction
Membrane Synthesis and Characterization: Experimental
Ultrafiltration (UF) of Oily Water
Results and Discussion
Conclusions and Scope of Future Works
Appendix
Introduction
Membrane Synthesis and Characterization: Experimental
Membrane Synthesis and Characterization: Results and Discussion Chapter 4: Ultrafiltration of Oily Water: Experimental
Ultrafiltration of Oily Water: Results and Discussion Chapter 6: Conclusions and Scope of Future Work
The chapter then presents detailed literature review covering membrane synthesis and characterization, separation of oil from oily wastewater, and flux decline due to membrane fouling. This chapter provides the full description of the experiments involved in the preparation (eg selection of materials, selection of suitable compositions, etc.) and characterization of polysulfone (PSf) membranes. It also elaborates the ultrafiltration characterizations of the prepared membranes, such as the measurement of pure water.
Membrane Synthesis and Characterization: Results and Discussion This chapter presents the results and discussion of the experimental works on membrane
Ultrafiltration of Oily Water: Experimental
Ultrafiltration of Oily Water: Results and Discussion
Series resistance model (RIS) and constant filter models are applied to interpret the data and individual resistances are estimated. The significance of these resistances is revealed in relation to the parameters, namely, TMP and initial oil concentration. The results of cross-flow UF experiments obtained with synthetic oily water are discussed, which mainly highlight the effect of cross-flow rate on membrane performance.
Finally, the results of both batch and cross-flow UF with “produced water” using the selected membranes with the optimal TMP value are reported to understand the industrial application of the synthesized membranes.
Conclusions and scope of future work
- Background
- Overview of membranes and membrane separation processes
- Classification of membrane
- Classification of membrane separation processes
- Ultrafiltration (UF)
- Selection of membrane
- Materials for organic membranes
- Preparation of synthetic membranes: some common techniques
- Literature review
- Synthesis of membrane
- Separation of oil from oily wastewater
- Fouling mechanism
- Objectives and plan of the present work
The part of the food solution that passes through the membrane is called permeate or filtrate. The portion of the food solution that does not pass through the membrane is called the concentrate or retentate. During UF, some feed components are deposited on the membrane surface and/or in the membrane matrix resulting in a gradual decrease in permeate flux.
As a result, the retained material in the membrane pores and on the membrane is released, lifted and flushed out of the membrane module. Membrane separation processes are controlled by both the chemical nature of the membrane materials and the physical structure of the membranes. The desired separation that can be achieved with a particular membrane depends on the relative permeability of the membrane to the particular feed solution.
In the fourth method, evaporation of one of the solvents in the casting solution is carried out to cause precipitation. The choice of non-solvent is an important parameter to obtain the desired structure of the membrane. The temperature of the water used to precipitate the casting solution is another factor that affects the membrane morphology.
The weight ratio of polymer, solvent and additive in the casting solution was maintained at 15:70:15. It was found that membrane porosity increased with increasing initial PEG concentration ranging from 5 to 20 wt%. The experimental results showed that the oil retention in the membrane is more than 99%, and the oil concentration in the filtrate is below 10 ppm.
In the gel polarization model, the permeate flux is reduced by the hydraulic resistance of the gel layer.
Coca, Design and construction of a modular pilot plant for the treatment of oily wastewater, Desalination. Konieczny, The use of ultrafiltration membranes made of different polymers in the treatment of wastewater with oil emulsion. Han, Effect of propionic acid in the casting solution on the characteristics of phase inversion polysulfone membranes, desalination.
Fuente, Effect of nonsolvents on the properties of spinning solutions and polyether sulfone hollow fiber ultrafiltration membranes, J. Rhee, Effect of molecular weight of polymeric additives on the formation, permeation properties, and hypochlorite treatment of asymmetric polyacrylonitrile membranes, J. Lee, Effect of poly(ethylene glycol) 200 on the formation of an asymmetric polyetherimide membrane and its performance in permeation of aqueous solvent mixtures, J.
Mohan, Preparation, characterization and effect of annealing on the performance of cellulose acetate/sulfonated polysulfone and cellulose acetate/epoxy resin blend ultrafiltration membranes, Euro. Field, Process factors during removal of oil-in-water emulsions with cross-flow microfiltration, Desalination. Coca, Ultrafiltration of oil-in-water emulsions with ceramic membranes: Influence of pH and cross-flow velocity, J.
Golshan, Effect of operating conditions on microfiltration of oil-water emulsion with kaolin membrane, Desalination. Dempsey, Modeling the Effect of Particle Size and Charge on Filter Cake Structure in Ultrafiltration, J.
Membrane Synthesis and Characterization
Materials
PSf (30000 Da) supplied by Sigma-Aldrich Co., USA, was used as the main polymer in the membrane casting solution. Both solvents were supplied by Central Drug House (CDH) Ltd., India and used without further purification. Deionized water purified by Millipore system (Millipore, France) was used as the main non-solvent in the coagulation bath.
Method of preparation
Deionized water purified with Millipore system (Millipore, France) was used as the main non-solvent in the coagulation bath. 25°C). The steps for preparing the membranes are shown in Fig. When the solution (consisting of polymer, solvent and the additive) became homogeneous, it was kept at room temperature for 24 hours. Next, the solution was spread uniformly on a glass plate (0.01 m × 0.01 m) using a casting knife that maintained a constant clearance gap between the knife and the plate to have membrane of uniform thickness.
The constant cleaning gap can be maintained due to the special design of the knife (doctor's knife). S t e p s f o r p r e p a r a ti o n of PSf membranes by immersion precipitation .. than 30 s) before immersion in the coagulation bath containing deionized water at room temperature. Exposure of the cast film to the environment is necessary to obtain an asymmetric membrane with a somewhat denser skin to perform the ultrafiltration operation.
Keeping the film in contact with the environment for a long period will result in a fully dense membrane which would only be applicable for gas separation purposes [1]. The cast films changed their color from transparent to white immediately after immersion in the coagulation bath indicating the occurrence of precipitation (Fig. 1.8). After some time, the film separated from the glass plate as it acquired the final composition of the membrane (i.e. point D of Fig. 1.8).
Preliminary selection of composition
- Membrane characterization
- Characterization by morphological study
- Characterization by permeation studies
The morphology of the prepared membranes was investigated by microscopic observations and the performance of other standard tests. Therefore, the average pore sizes of the above membranes were detected through this analysis. The gas permeation test is one of the standard techniques mentioned in the literature [1] to determine the pore size of a membrane.
Measurement of the gas permeability coefficient as a function of the mean pressure across the membrane can be used to determine the mean pore radius of the membrane. The average pore size as well as the effective porosity of the prepared membranes is determined by the gas permeability test [6, 7]. The total gas flux through the asymmetric polymer membrane is the sum of the diffusion flux through the dense (non-porous) skin of the membrane and the flux through the pores.
The thickness of the prepared membranes was calculated from SEM photographs of cross-sections of membranes using ImageJ Software [9]. The liquid displacement test helps us to evaluate the transmembrane pores of the membranes in the wet state, i.e. the average pore size as well as the pore number and pore area distribution of the prepared membranes were determined by this method [1], also known as the combined bubble pressure and solvent permeability method [10].
Therefore, Ji,k calculated in Pi,k is the contribution of pores with radius between rk I unmixed. Feed is pumped from the feed tank into the upper compartment of the cell which.
Notations
As mentioned previously, the permeate was collected continuously from the bottom of the lower compartment, while the retentate was collected only once after completion of the experiment.
Greek symbols
Morphological parameters
- SEM observations
- Qualitative analysis
- Quantitative analysis
- Summary of SEM observation and analysis [10, 11]
- Gas permeation test
- Pressure normalized gas flux
To study the effect of increasing molecular weight of the two additives on membrane morphology, these. The morphology of the membranes prepared at different compositions was examined using a high-resolution scanning electron microscope. Due to the high mutual affinity of NMP and DMAc for water (used as a non-solvent during phase inversion), immediate disassembly results in the formation of finger-like cavities on the substrate of the prepared membranes, which has already been discussed.
From the phase separation of such a quaternary system, two phases arise - one consisting of the membrane. However, the effect of molecular weight on the growth of the upper layer is very noticeable especially for the higher range of molecular weight. It is observed that the upper surface of the membranes prepared with PEG gradually became uneven due to the appearance of some irregularly sized nodules as the molecular weight of PEG increases.
In all cases, it is observed that as the molecular weight of PEG increases, the pore size of the corresponding membranes decreases and the pore size distribution becomes narrower. The finger cavities in the sublayer are gradually suppressed by increasing the molecular weight of both additives regardless of the solvents. As the molecular weight of the additives increases, the upper layers of the membranes appear to have a nodular or spherical structure with a certain degree of roughness.
It is observed that with increase in the molecular weight of PEG, the average pore size of the corresponding membranes decreases and the pore size distribution becomes narrow. The gas permeation test is one of the standard techniques mentioned in the literature [15] to determine the pore size of a membrane.
