Potential Nanoparticles to Integrate with Ceramic Membranes for Treating Industrial Wastewater: A Review

Due to human indifference and reckless oily wastewater production from industry, environmental or ecological pollution has become a challenge for our planet. Oily industrial wastewater mostly released by oil fields, refineries, cars, palm oil sectors, and many others is one of the biggest dangers. Oil and water can be virtually completely separated using membrane-based technologies. However, these technologies still face challenges in upholding efficiency over extended periods due to membrane fouling induced by oil droplets mixing with the membranes. Therefore, to overcome these challenges, the creation of polymeric, ceramic, and metallic-based membrane materials with enhanced performance is the focus of research in this field. In this review, various published approaches applied for treating industrial wastewater by using Ceramic Membranes integrated with nanoparticles were focused initially. Then, a modified experimental procedure from the literature for wastewater treatment process by using ceramic membranes is discussed. The majority of studies indicate nearly total oil rejection and increased outputs. Silicon carbide (SiC), Titanium dioxide (TiO2), Aluminum Oxide (Al2O3), Iron Oxide (Fe2O3) Powdered Activated Carbon (PAC), Zirconium dioxide (ZrO2), Alumina powder (Al), Silica (SiO2), Graphene Oxide (GO), and Silver (Ag) are identified potential nanoparticles to mix with ceramic membranes for wastewater treatment application.


Introduction
The United States Environmental Protection Agency (USEPA) classifies industrial oily wastewater as one of the most hazardous sewers because significant amounts of heavy metals, grease, salts, aromatic compounds, and substances that are challenging for the environment to naturally cleanup are present in it [1].It is important to note that hydrocarbon processing facilities such as petrochemical handling, oil refining, and oil and natural gas processing facilities generate a substantial amount of oily wastewater [2].There are additional sources that produce oily water, including dairy farms, poultry farms, abattoirs or slaughterhouses, tanneries, leather industries, etc.These sources lead to the production of a lot of wastewaters, which exacerbates major ecological troubles and hinders ecosystems' ability to operate effectively [3].These wastewaters mainly contain significant levels of BOD (Biochemical Oxygen Demand), COD (Chemical Oxygen Demand), TDS (Total Dissolved Solids), TSS (Total 1305 (2024) 012001 IOP Publishing doi:10.1088/1757-899X/1305/1/012001 2 Suspended Solids), TOC (Total Organic Carbon), TPH (Total Petroleum Hydrocarbon), and other harmful byproducts, which are responsible for causing severe troubles and imbalance.For instance, Wei et al. [4] reported effluent from the petrochemical industry to have substantially higher BOD and COD levels than typical environment-friendly wastewater (338.5 mg/L and 25,660 mg/L, respectively).Another study by Aslan et al. [5] reported that the Edible oil industry wastewater contains higher BOD, COD, and TSS levels than typical environment-friendly wastewater (1932 mg/L, 12,880 mg/L, and 2850 mg/L, respectively).Moreover, several authors also detected high levels of BOD, COD, and TDS in dairy and poultry farms [6], abattoirs or slaughterhouses [7], and tanneries [8].Therefore, improving waste-treatment technologies becomes essential to overcoming environmental challenges.Traditional treatments for oily wastewater, such as dissolved air flotation [9], chemical demulsification [10], gravity separation [11], skimming [12], pH adjustment, etc., are costly and require additional operations to meet effluent quality [13], [14].Contrarily, fully integrated microfiltration (MF) membrane systems treatment is becoming more and more popular because it is practical, process serviceable, commercially available, modular, relatively insensitive to wastewater from a range of manufacturing sources, as well as treating raw water, and it has less expensive running costs.Utilizing membranes with careful planning, design, and implementation can reduce capital expenditures, decrease chemical consumption, and require minimal maintenance.Moreover, because of the mechanical or physical characteristics, chemical stability to high working situations, and thermal tolerance, ceramic MF and polyamide membranes are progressively supplanting organic and polymeric membranes in the treatment of water and wastewater [15].Furthermore, the use of ceramic membranes in water treatment applications has several benefits over polymer-based filtration systems such as low maintenance requirements, high fouling resistance, and high-temperature stability all contribute to such systems having lower lifecycle costs.However, most available commercial ceramic membranes have high production costs due to raw material and processing costs, making such systems uneconomical for most applications in water treatment Abdullayev et al. [16].As a result, there is an increasing need for new membrane technology made from inexpensive raw materials and manufacturing techniques.Using cement, unprocessed mineral feedstocks, clays, sands, and ash as the base for the creation of ceramic membranes is a promising path toward obtaining effective filtration systems that can be industrially implemented in large volumes.For the design of effective ceramic filtration based on energy-efficient processes and inexpensive raw materials, the rebalancing of mass flow, pore structure, and strength is required.The chemical makeup of the materials utilized, the existence of multiple poreforming and binding additives, and the thermal processes that membranes go through all have a significant impact on each of these variables.

Issues Associated with Wastewater Treatment Process by Using Ceramic Membranes
Despite their many benefits, these membranes are prone to fouling during continuous operation, which can be detrimental to the success and continuity of plant operations.Microbes, contaminants, dust solids, and organic solid particulates are the fundamental causes of fouling [17].In the industry, several techniques are currently used, with a focus on early treatment and prevention to be certain that the extraction efficiency of MF membrane surface does not deteriorate over time.These techniques include chemical cleaning processes, turbulence promoters, and backwashing with air or liquids [18].Combining coagulation with organic or inorganic coagulants with membrane remediation has the potential capability to improve pollutant retention while minimizing biofouling [18].In addition, the development of high-performance membranes is likely to involve high material costs and difficult fabrication conditions, which allows scientists to investigate low-cost and inexpensive membranes with high energy consumption.Currently, the membranes used for oil-water detachment suffer from a low water flux despite their many distinct benefits.

Current Works on Wastewater Treatment Using Ceramic Membranes
Numerous researchers have implemented surface modification by nanoparticles on ceramic membranes to improve their oil separation and flux.Metal oxides, such as aluminum oxide (Al2O3) and titanium dioxide (TiO2), are among the most widely employed nanoparticles in the fabrication of ceramic membranes in wastewater purification.DiGiano's research shows that coating nanoparticles over ceramic surfaces leads to larger nanoscale pore sizes than conventional ceramic sintering [19].Table 1 represents the characteristics of potential nanoparticles as coating materials for ceramic membranes.Besides that, Zhou et al. [20] coated Al2O3 membranes with ZrO2 nanoparticles through in-situ hydrolysis of ZrCl4 to investigate characteristics of ZrO2 in 2010, and this membrane demonstrated super-hydrophilic characteristics, minimized fouling, and oil separation efficacy of up to 99.2%.Thereafter, Abadi et al. [21] remedied oily effluent from an industrial plant using a tubular MF ceramic membrane (α-Al2O3) in 2011, which achieved greater than 95% efficacy in TOC (Total Organic Carbon) removal.Later on, Zheng et al. [2] used FeCl3, AlCl3, and Polymeric Aluminum Chloride (PAC) as the coagulation agent to improve t h e ultrafiltration (UF) performance of domestic wastewater.They discovered that raising coagulant concentration can improve oil removal.Another work [22] used in-situ TiO2 coating on Al2O3 membranes to improve the hydrophilic nature of the membrane in 2014.The authors reported that the modified coated membrane's oil removal efficiency and flux are higher than that of the uncoated membrane.Hu et al. [23] employed Graphene Oxide (GO) to modify the Al2O3 ceramic membrane by utilizing the vacuum approach in 2015.The authors claimed an increased flux and improved oil rejection concerning the uncoated membrane.Zsirai et al. [13] then conducted a study utilizing silicon carbide (SiC) and titanium dioxide (TiO2) for the tertiary treatment of the wastewater.According to the findings, SiC membranes performed better than TiO2 membranes in terms of sustained permeability.In a different study in 2018, as described by Fard et al. [14], the membrane's surface was not modified.However, by mixing Powder Activated Carbon (PAC) with the alumina powder during the fabrication process, a novel hybrid membrane has been produced.The modified membrane had super-hydrophilic properties and improved oil separation (more than 99%) when compared to artificial pure Al2O3 membranes.Afterward, Dong et al. [1] employed polydimethylsiloxane (PDMS) as the polymer liquid to construct a porous SiC ceramic membrane with a narrow distribution of pore sizes for oily wastewater separation utilizing the porous SiC ceramic membrane fabrication technique.They used a ceramic membrane with an average pore size of 0.59 m and were able to reject 95% of the oil.In 2021, Marzouk et al. [24] reported that dipcoating silica (SiO2) nanoparticles over ceramic TiO2 membranes have a substantial potential for extracting oil from industrial wastewater.Silver (Ag) provides excellent biofouling prevention and enhances water flux, as reported by Peng et al. [36] and Kim et al. [29].In a recent study by Wang et al. [25] in 2022, it is stated that alumina powder (Al) is becoming more popular in separation, catalysis, and adsorption with high flux of penetration.Finally, Wang et al. [38] also examined the efficacy of polyamide cross-linked Graphene Oxide (GO) sheets membranes in the treatment of wastewater.According to the findings, the synergism of GO and Microporous Polymer Networks (MPNs) was greatly advantageous for the advancement of water flux

Experimental Procedure for Wastewater Treatment Process by Using Ceramic Membranes
The detailed standard method to conduct the current research is presented in Fig. 1, which is modified by Marzouk et al. [24].The first step is the experimental evaluation for the preparation and characteristics of the considered membranes under prescribed conditions.To produce membranes with different inter-particle pore sizes, the synthesis is conducted at 100°C for varying lengths of time.Before analysis and use, the membranes are dried at 120°C and washed with deionized water.Scanning electron microscope (SEM) is used to examine the membranes and the gas bubble pressure method is applied to determine the pore size distribution (PSD).Then treatment of oil-in-water emulsion and Membrane cleaning is conducted to fulfill the objectives.Additionally, a sensitivity analysis is conducted to determine the best membrane configuration for the combined approaches.The last step is the identification of economic and energy benefits between the membranes.

Conclusion
This review covered the most recent advances in membrane technology, particularly those related to the treatment of oily wastewater.The majority of studies mention improved outputs and nearly complete oil rejection.For use with ceramic membranes for wastewater treatment, Silicon Carbide (SiC), Titanium dioxide (TiO2), Aluminum Oxide (Al2O3), Iron Oxide (Fe2O3) Powdered Activated Carbon (PAC), Zirconium dioxide (ZrO2), Alumina powder (Al), Silica (SiO2), Graphene Oxide (GO), and Silver (Ag) have been identified as potential nanoparticles.Ceramic membranes have a higher viscosity than polymeric ones as a result of their thick membranes, which tightly equate to permeability.Such material needs to be altered to achieve the benefits of handling feed at high temperatures, i.e., oil refining process water.The use of Janus membranes and membrane surface patterning for the treatment of oily wastewater is still in its infancy.One of the most potential strategies to be investigated would be to tailor the growth of this membrane Material.Surface patterning improves in-situ cleaning performance and reduces the possibility of membrane fouling.By rotating the filter backward, the accumulated foulant in Janus membranes is easily flushed.To reach their full potential, more research should be done on the advantages of these two membrane content development methodologies from both an economic and environmental standpoint.

Acknowledgment
We acknowledged the Dean of the Mechanical Engineering faculty and the Head of the Mechanical Engineering department of the Military Institute of Science and Technology for their valuable support and inspiration to conduct the review.

Figure 1 .
Figure 1.Synthesis and experimental procedure for wastewater treatment

Table 1 .
Nanoparticle characteristics as coating materials for ceramic membranes