## 1 Introduction  
Water is a vital substance for all living organisms [1], and it plays an essential role in medical, energy and agricultural fields [2]. Through natural and anthropogenic activities, there has been an increase in contaminants and water bodies have deteriorated. Heavy metals, pesticides, dyes, pharmaceutical waste, and other emerging pollutants, have become a burden on the ecological environment [3; 4; 5]. These harmful contaminants could be bio-accumulated in the food chain and cause adverse human health impacts [6]. Pharmaceutical residues in water have become life-threatening, and directly affect the ecosystem and human health [7]. They get released in an aqueous environment through treatment plants and industrial effluent. Removal of toxic xenobiotic pollutants has become a growing concern in water treatment. Moreover, the concentration of pharmaceutical contaminants in water resources is directly connected to human consumption patterns, population growth, industrial activities, and wastewater treatment [8]. Recently, low concentrations have been found to possess higher toxicity and their removal from the aqueous environment has become a matter of urgency. To remove such pollutants, some biological, chemical, and physical approaches, including adsorption, filtration, coagulation, flocculation, and precipitation, have been utilized [9; 10; 11; 12; 13]. Furthermore, it is reported in many studies that pesticides are toxic substances for the environment and human health [14]. The frequent use of pesticides poses a threat to ecosystems and directly affects wildlife, birds, domestic animals, livestock, fish, and soil [15]. In addition, many pesticides could be stable over time, transported in water and air, and ultimately contaminate areas far from their point of origin [16]. The enormous increase in the world population from 1900 to 2000 (1.5 billion to 6.9 billion) has also increased pressure on food demand; hence, the usage of pesticides has increased exponentially to meet production and economic profit levels [17]. Therefore, the removal of pesticides is a crucial research domain [18; 19], so, various treatment techniques have been used to remove them. Currently, advanced oxidation processes (AOPs) [20], photochemical degradation [21], chlorination [22], and adsorption are favored techniques. Dyes also pose considerable concerns to the environment and ecosystem due to their high toxic levels, and some of the colorants have products after their reactions. They may cause adverse impacts on aquatic life by disrupting biological processes [23; 24]. As a result, heavy metals are more complicated to remove than the dyes, and thus they accumulate in water and soil [25; 26]. They could also cause toxicosis in humans by contaminating water and crops [27; 28]. Researchers pay special attention to the heavy metals present in ground and surface water [29]. Heavy metals, such as As(III), As(V), Cu(II), Ni(II), Co(II), Cd(II), Pb(II), Cr(III), etc., can be discharged directly and indirectly into water bodies [30; 31; 32]. Since they are carcinogenic and non-biodegradable, they can affect the growth of biological tissues in living organisms [33; 34]. People have been so focused on industrial development that they stopped paying attention to the environment, and hence pollutants became stronger, more resistant, and progressively deposited in organisms [35; 36]. Consequently, researchers have fixated on the research domain related to developing cost-effective removal techniques for heavy metals, organic pollutants, and dyes. Bio-filtration and traditional activated sludge processes are less efficient in removing all types of contaminants [37]. Membrane treatment and Active Oxidation Processes (AOPs) have shown higher efficiency in removing organic pollutants from waters [38; 39; 40; 41]. Compared with other treatment processes, adsorption technology has been widely utilized for its efficient and economic characteristics.