## 1 Introduction  
Over the last decades, water pollution has emerged as a significant global challenge, posing a crucial threat to both the planet and human well-being as a result of increased industrialization activity around the world and attendant discharges of toxic substances directly into water sources without any treatment, which have led to a decrease in the amount of water suitable for human consumption [1, 2]. A report released by UN-Water anticipated that by 2025 approximately two-thirds of the global population will experience water stress. The report further projected that approximately 1.8 billion individuals would experience absolute water scarcity in their living conditions [3]. Thus, wastewater treatment has become crucial for a sustainable existence. Many techniques have been used for this purpose, including photodegradation [4, 5], adsorption [6, 7], distillation [8, 9], electrolysis [10, 11], and membranes [12, 13]. Adsorption is the most commonly used method for treating dye-containing wastewater dyeing wastewater due to its simple operation, low cost, and effectiveness, according to the literature [14]. Adsorbents such as zeolites, activated carbon (AC), polymers, and biomaterials have long been utilized in traditional wastewater treatment processes. However, these materials have a limited adsorption efficiency. Finding more effective adsorbents has therefore become crucial [15, 16]. Based on the literature, it is evident that the incorporation of nanomaterials in membranes has shown a remarkable improvement in their properties, such as water permeability, mechanical strength, and separation efficiency, in addition to reducing fouling of the membrane [17; 18; 19]. Polymer nanofibers have been explored in recent years as one of the most promising materials for water treatment membranes due to their unique physicochemical properties, such as nanoscale size, high surface area, and large porosity [20]. In this regard, an electrospinning technique has been used to generate nanofibers from various types of polymers. Moreover, by introducing nanomaterials as additives into polymer nanofiber membranes, the prepared nanocomposite membrane can possess additional features [21]. The eventual composites are expected to have a huge potential to purify water. This perhaps is due to their cost-effectiveness, high chemical reactivity, and surface area, in addition to excellent mechanical strength [22]. The present research involves repurposing PET cups for the production of PET nanofibers through electrospinning. Despite their prior use, their efficiency was lacking. Consequently, a concept emerged to merge them with gold nanoparticles to enhance their efficacy and optimize their performance in eliminating methylene molecules. This process aims to eliminate PET and methylene waste, thereby contributing to environmental improvement. There have been reports on the utilization of phosphine-ligand-stabilized, modified gold-coated magnetic nanoparticles as catalysts for the reduction and subsequent extraction of methylene blue in wastewater from the textile industry. These nanomaterials exhibit the ability to not only reduce the presence of toxic methylene blue dye in textile wastewater but also effectively eliminate the dye from the wastewater solution [23]. [PERSON] and [PERSON] have successfully prepared a porous foam of poly (dimethylsiloxane) (PDMS) embedded with Au nanoparticles for the purpose of eliminating organic compounds from water. The results showed that Au-PDMS nanocomposite foam was significantly effective against odorous sulfur-containing contaminants and was resistant to harsh chemical environments [24]. Methylene blue (MB) is a heterocyclic aromatic chemical that exists as a dark green powder. It is widely used in biology, chemistry, and the textile dyeing industry. It has been present in human and veterinary pharmacopeia for a long time. In the end, MB is discharged into the nearby environment causing real health problems. Exposure to MB can cause injuries to humans and animals [25].