It has not been presented in any previous application for the award of the PhD degree. This work demonstrates the feasibility of utilizing plastic waste as a membrane precursor and its use in the ultrafiltration process.
I NTRODUCTION
5 Polypropylene PP • Plastic diapers, Tupperware, Kitchenware, Margarine containers, Yogurt containers, Prescription bottles, Stadium Cups, Bottle stoppers, Takeout containers, Disposable cups and plates. Not available • Plastic CDs and DVDs, baby bottles, large multi-gallon water bottles, medical device storage containers, eyeglasses, outdoor lighting fixtures.
![Figure 1.1: Plastic market segments [2]](https://thumb-ap.123doks.com/thumbv2/azpdfnet/10442132.0/30.893.121.735.104.593/figure-1-1-plastic-market-segments-2.webp)
M EMBRANE
It is usually placed between two phases, where it allows the preferential transport of only the required components of the system, while excluding or retaining unwanted components [13]. Table 1.3 presents the membrane separation process, separation mechanism, pore size, and transport regimes based on pressure-driven membranes.
T YPES OF MEMBRANE
M EMBRANE PREPARATION TECHNIQUES
Sintering Excellent chemical, thermal and mechanical stability, inorganic and organic materials can be used. This type of membrane can be made from almost any polymer that is soluble in a suitable solvent and can be precipitated in the solvent [19].
![Table 1.4: Membrane fabrication techniques [13,17]](https://thumb-ap.123doks.com/thumbv2/azpdfnet/10442132.0/39.893.150.788.100.1073/table-1-4-membrane-fabrication-techniques-13-17.webp)
M ODIFICATIONS OF MEMBRANE
The polymer coating can be obtained by either covalent binding of the modifying polymer to the membrane substrate or by non-covalent attachment. The chemical covalent interaction of the modifier with the polymeric surface is greater than that of the physical method and it provides a long time chemical stability [27].
B ACKGROUND LITERATURE
The modification of the polyvinyl chloride (PVC) membrane was carried out by combining the hydrophilic surfactant Pluronic F127 (PF127) in the polymer solution to improve the membrane performance. The mixture was found to improve the properties and performance of PVC membranes.
R ESEARCH GAPS
Similarly, the role or effect of different solvents on membranes made from waste plastics has not been considered. A growing number of sustainable polymers such as chitosan, quaternary ammonium compounds, cellulose acetate and others are also used in the preparation of conventional polymer membranes, but the incorporation of sustainable biopolymers in the preparation of membranes from waste plastics is low. The role of additives such as sustainable polymers (gum arabic) on the morphology and characteristics of the membrane obtained from waste plastics was considered.
The idea of using waste plastic as a precursor for the production of membranes can lead to the limitation of waste plastic from our environment and serve as a sustainable way for low-cost utilization of fossil-based polymers as membrane manufacturing material.
S COPE OF THE WORK
It is worth noting that utilization of waste plastics for membrane production and their viability have been reported in assessment journals, but waste plastics such as PVC have not been captured. Therefore, it will be interesting to investigate the possibility of using such waste as a membrane material, considering the need for economic and environmental sustainability, since no cost will be spent on the plastic waste. Nevertheless, such studies have not been reported in the production of modified membranes from plastic waste with these organic materials.
Therefore, this area needs to be explored for superior membrane performance made from waste plastics using sustainable polymers for more beneficial properties.
A IM AND O BJECTIVES
Sustainability is the watchword in this 21st century, so mixing waste plastics with sustainable polymers would be beneficial.
O RGANIZATION OF THESIS
M ATERIALS
Details of the materials used to prepare the membrane are detailed in Table 2.1. Deionized water from a Milli-Q filter source was used as a solvent and in other activities where water was required for experiments. BSA with a molecular weight of 68 kDa was considered as the medium for rejection studies and was purchased from Sigma Aldrich Chemicals.
M EMBRANE FABRICATION
M EMBRANE CHARACTERIZATION
Scanning electron microscopy (FESEM) analysis is required to determine the image of the membrane structure and topography [69]. Porosity was estimated using equation (2.2), which is related to the equilibrium water content (EWC) of the membranes. The average pore size of the membrane can be calculated based on the porosity and water filtration values.
The membrane samples were clamped onto the surface of the ATR within the FTIR for the functional group analysis.
- B ACKGROUND
- E XPERIMENTAL
- R ESULTS AND DISCUSSION
- S UMMARY
Waste PVC was mixed with cellulose acetate (CA) to improve the hydrophilicity of the prepared membranes. The detail of the phase inversion process was given in the previous chapter under section 2.3. Details of the membrane's characterization procedures were presented in the previous chapter (materials and methods) captured under section 2.4.
In the case of the M0 membrane, the pore size distribution was narrow in the range of 1-20 nm.
B ACKGROUND
Several scientists have investigated the influence of the concentration of additives, molecular weights of components and solvents on the properties of the membrane. 47] studied the performance of PEG with different molecular weights on the morphology of the pristine PVC membrane prepared via a non-solvent-induced technique. The effectiveness of the polymeric membrane depends on the properties of the forming solution and the phase separation rate during the transformation process [98].
Therefore, this work focused on determining the influence of additives and diluents on the waste plastic-based membrane morphology, performance, thermal and.
E XPERIMENTAL
Likewise, HSP was calculated to evaluate the thermodynamics of the system and to create a better solvent for PVC waste in membrane fabrication. Detailed procedures for the preparation of membranes are followed in the materials and methods section. In understanding the interactions between the polymer, the solvent and the non-solvent that affects the properties of the membranes, the Hansen solubility parameter plays a role.
Shown below are the equations used for the HSP calculations for various polymer–solvent (∆𝛿𝑝, 𝑠 ) and polymer–nonsolvent (∆𝛿𝑝, 𝑛) interaction pairs.
R ESULTS AND DISCUSSION
The peak at 896 can therefore be attributed to the C-Cl of the waste PVC membrane which is present in all the manufactured membranes. While in the case of the additive polymers (PEG and PVP) with non-solvent (water) the values indicated that PVP has a better affinity than PEG corresponding to their solubility rates of 1000 mg/ml and 630 mg/ml respectively [ 15 [72]. The values of the porosity and the average pore sizes recorded have similar trends with the PWF.
Membrane flux recovery was investigated by rejecting humic acid (HA) in water.
S UMMARY
B ACKGROUND
Coagulation is one of the traditional methods of NOM removal, but coagulants must be purchased repeatedly to maintain the process [5]. Waste plastic was used to reduce membrane costs and to protect the environment as well. The versatile applications lead to the generation of a large amount of waste PVC with disposal and management problems.
In contrast to the use of expensive polymer, this work investigates the use of waste PVC as a membrane precursor that addresses the environmental problem and the economics of the membrane process.
E XPERIMENTAL
Therefore, the objectives of the research are to use an environmental pollutant (waste plastic, i.e. waste PVC) to address another environmental problem (water treatment) through the manufacture of membranes using waste PVC and improving hydrophilicity due to the inclusion of gum arabic (GA). that is a sustainable biopolymer as a green alternative. Waste PVC was chosen as an alternative source of membrane precursor in this study due to its dual benefits of reducing membrane costs and reducing adverse environmental impacts. Thus, waste PVC-incorporated GA-based membranes were fabricated via the non-solvent stimulated phase transformation process.
The interactions between the waste PVC/GA (at different loadings) were analyzed using different analytical techniques and then used for the removal of natural organic matter (humic acid) from water.
R ESULTS AND DISCUSSION
The task of the biopolymer (GA) in the development of the membrane porosity is evident like other macromolecular additives, which are identified to influence the subtle stability of thermodynamics and kinetics in a shell solution [15][100]. The incorporation of GA into the membrane solution affected the mechanical properties of the samples. The slight decrease in the mechanical strength and % elongation for the MG3 membrane can be attributed to the increased porosity of the membrane.
The benefit of integrating GA into the membrane matrix was evident from the results of PWF.
S TUDIES ON FOULING RATIOS
These parameters were calculated based on the penetration of the HA (FHA) and the corresponding pure water fluxes (FW1 and FW2). The reduction of TFR from 73 % to 66 % showed an improvement in the antifouling effect of the membranes. This is attributed to the hydrophilic behavior of the additive which inhibited the hydrophobic parts of the waste PVC.
This indicated that the incorporation of the biopolymer (GA) into the backbone of the waste PVC improved the antifouling behavior of the prepared membrane.
P ERFORMANCE COMPARISON WITH EXISTING WORK
Furthermore, most of the cited literature has a similar range in weight concentration (15 .%) of base polymer for membrane fabrication. This showed that the precursor is low cost compared to the existing literature as no cost was spent on the base polymer.
S UMMARY
C ONCLUSION
The work focused on utilizing abundant plastic waste to reduce the threat of waste plastic to environmental degradation. In another development, the effects of additives and solvents on waste plastic base membranes were determined. Overall, the work proposed that waste plastic (PVC) could provide an alternative means for membrane precursor in water filtration and that its properties could be tailored with suitable additives and solvents for targeted applications.
Overall, the outcome supports the incorporation of gum arabic as a green alternative additive for improving waste plastic-based membrane parameters in water filtration.
R ECOMMENDATION FOR FUTURE WORK
Mukhopadhyay, Improved antifouling performance of poly(vinyl chloride) (PVC/HNT) halosite nanotube (HNT) blend ultrafiltration membranes: For water treatment, J. Sujith, Poly(vinyl chloride)-based asymmetric membranes: effect of additive molecular weight and solvent strength on morphology and performance, J. Sujith, Poly (vinyl chloride) asymmetric membrane modified with poly (ethylene glycol): Effect of additive concentration on morphology and performance, Polym.
Gao, Effect of PEG additive on the morphology and performance of polysulfone ultrafiltration membranes, DES.
