## 1 Introduction  
Due to the enormous amounts of oily and salty wastewater produced by frequent maritime oil spill accidents as well as oil mining, production, and refinery activities, oil pollution is a serious issue on a global scale [1]. The opportunities for treating produced water are therefore increasing and driven mainly by reuse demand and regulation. The US Environmental Protection Agency (EPA) has enacted regulations that limit the amount of oil released into effluents to no more than 42 mg/L [2]. As a result, creating efficient and sustainable methods to treat wastewater that has been contaminated by oil is in high demand in order to meet stringent regulations as well as to protect the environment. Traditional oil/water separation techniques, such as hydrocyclones and air floatation, have some disadvantages, such as low separation efficiency or high operating costs [3]. Membrane techniques that operate with a \"size-sieving\" effect, such as nanofiltration (NF), ultrafiltration (UF), and microfiltration (MF), have been frequently utilized to purify water [4]. MF and UF membranes have limitations in terms of the size of oil droplet removal. These membranes may remove oil droplets that have micrometer size. In addition to that, MF and UF membranes can be effective in removing oil from a stable oil emulation. Commercial UF membranes, on the other hand, have a significant fouling issue or low permeate fluxes. This is due to the fact that the pores in the UF membranes can be plugged by the oil droplets. As a result, these types of membranes have limitations in terms of service time and separation efficiency [5]. One of the major challenges in treating oily water using membrane technology is the fouling problem. Fouling is the process by which undesired particles become attached or adsorbed to the membrane which causes a reduction in the permeate flux and prevents the membrane from performing its desired application [6]. The fouling can be accumulated due to different types of foulants. Biofouling occurs when microorganisms accumulate on the membrane. In organic fouling, the foulant is an organic matter such as oil and organic chemicals. In particulate fouling, colloidal and suspended solid particles accumulate on the membrane. Scaling on membrane occurs when salts precipitate on the membrane surface. There are two main membrane-fouling behavior types: reversible and irreversible fouling. In the reversible type, the fouling is caused by weak attachment of particles or solutes on the membrane surface or in the pores, while in irreversible fouling the physical or chemical attachments of particles or solutes are stronger than that in reversible fouling. Both types of fouling cause permeate flux decline. In reversible fouling, the flux decline can be easily recovered by water backwashing; however, in the irreversible fouling the flux decline can be recovered by washing with aggressive conditions using acid or alkali solution. Unfortunately, even after watching with aggressive conditions, the membrane cannot recover its initial permeability. For oily water treatment, scientists suggested that improving the hydrophilicity in membranes can reduce fouling [7]. Recently, superwetting membranes for efficient oil/water separation have been demonstrated by studying surface chemistry and material roughness to create superhydrophobic-superoleophilic or superhydrophobic-superolephobic membrane surfaces [8]. It is important to examine the wetting behavior of oil as well as water on the surface of the membrane material. The wetting behavior is determined by measuring the contact angle that gives an indication about the degree of wetting when a solid and liquid interact. Materials with a contact angle lower than 90\({}^{\circ}\) have high wettability, while materials with a contact angle higher than 90\({}^{\circ}\) have low wettability. A material is said to be hydrophilic (water wet material) if the water contact angle of the material is below 90\({}^{\circ}\)[9].