## 1 Introduction  
Across the globe, imperil to pollution of water bodies is very high due to anthropogenic activities. Stringent norms and legislations have been passed in many countries to overcome or slow down the disposal of pollutants into the water system [1]. Lack of excellent water resources has propelled the treatment of wastewater to reuse for the sustainable exploitation of this natural resource [2]. Phosphorous is one of the principal elements required for the growth of animals and plants. It forms the backbone of the DNA as well as Kreb's cycle, and it plays a crucial role as a growth-limiting nutrient. In aqueous medium, 'P' resides in the form of organic phosphorus, polyphosphate, and, an organophosphate. Only orthophosphate can be easily taken up by algae and most of the plants. By microbial immobilization or hydrolysis, organic phosphorous and polyphosphates transform into orthophosphate [3]. Cleaning and detergent products also contain P in the form of tripolphosphate, which eventually gets converted to orthophosphate [4]. As there is a change in the pH values of the aqueous solution in agreement with their pK values, the ionic charge, and chemical form of orthophosphate keep on changing [3; 5; 6]. So the pH change tends to stimulate P's physicochemical functions in water. Excessive input of phosphorous or orthophosphate can lead to a massive fluctuation in the quality of water in a lake and trophic status. In many of the cases, it causes cyanobacterial periodic bloom [7; 8; 9]. A surplus amount of this nutrient in water causes eutrophication [10; 11; 12], which can harshly affect the ecological balance in a water system [13]. So far, many techniques have been introduced by various researchers in this field to effectively eliminate phosphate from an aqueous solution, like precipitation and floatation [14], enzymatic biodegradation [15], electrochemistry [16], and adsorption [17]. From all these techniques, adsorption is one of the extensively used technique for the elimination of phosphates from the water. It is a very simple, low cost, fast, and environmentally safe process [18; 19]. Conventionally, activated charcoal [20; 21] and porous silica materials [22; 23] are being used to remove phosphate from contaminated water. Adsorption is one of the widely used methods to remove phosphate from aqueous solution. The most researched adsorbing materials have the following P maximum adsorption capacity in terms of mg of P adsorbed/g of adsorbent; fly ash at pH 11-12--30-36 mg P/g [24], alum sludge at pH 4-32 mg P/g [25], alumina at pH 5.5-14 mg P/g [26], basic oxygen furnace slag at pH 7-7.2--20 mg P/g [27], 700 \({}^{\circ}\)C heated red mud--113 mg P/g [28], activated carbon at pH 4--3.2 mg P/g [29]as activated carbon is hydrophobic in nature. Activated alumina, silica sand, and anthracite coal exhibited 3333 \(\upmu\)g/g, 49 \(\upmu\)g/g, and 100 \(\upmu\)g/g, respectively [30]. Zeolites are well-defined three-dimensional structures. They form crystalline and microporous solids bearing silicon, aluminum, and oxygen in its framework, whereas water and cations are situated in the pores. Zeolites are naturally occurring materials as well as it is synthesized industrially. About 245 types of zeolite structures have been identified so far, and among which, forty of the zeolite structures are naturally occurring [31; 32]. The silica to alumina ratio for synthetic and natural zeolites is 5:1 and 1:1, respectively. The natural zeolite structures are more resistant to the acidic environment than synthetic zeolites; hence, it is easily used in the agricultural sector [33]. Synthetic zeolite is extensively used in numerous industrial applications because of its unique structure and properties. Zeolite-A manifests Linde Type-A (LTA) structure, which has a 3D pore structure with pores that are perpendicular to one another. Zeolite has technological and scientific value due to its interacting ability with different molecules and ions in the inner pores as well as outer surfaces [34].