## 1 Introduction  
Activated carbon (AC) with a high surface area is widely used as an industrial adsorbent, removing odor, taste, and impurities from drinking water via the absorption from liquids or gases [1]. Due to their well-developed porosity and large surface area, activatedcarbons have been used for the separation of gases, the removal of organic pollutants from drinking water, the recovery of solvents, acting as a catalyst support, gas storage, super-capacitor electrodes, and so on [2]. Activated carbon produced from agricultural products has the economically low cost and environmental effect of converting low-value agricultural waste into useful adsorbents, as well as reducing the reliance on coal and petroleum coke products for activated carbon preparation. Different types of activated agents such as H\({}_{3}\)PO\({}_{4}\), KOH, FeCl\({}_{3}\), ZnCl\({}_{2}\), HCL, H\({}_{2}\)SO\({}_{4}\), and many more are used for the preparation of activated carbon [3]. However, H\({}_{3}\)PO\({}_{4}\) is used mostly as an activated agent that changes the thermal degradation of biomass. The H\({}_{3}\)PO\({}_{4}\) activator agent increases the number of defects that serve as anchoring sites for metal particles and also increases the surface area. H\({}_{3}\)PO\({}_{4}\) acts as a catalyst, promoting the bond cleavage reaction and promoting the cross-linking through cyclization and condensation [4]. Worldwide olive trees are a common agricultural crop. Spain has the most dedicated land to this crop at 2.6 Mha and produces over 72% of the world's olives. Around 11 million olive trees are planted globally, yielding 3000 kg/ha of annual pruning residue production [5]. _Lantana camara_ is a lignocellulosic substance composed of lignin, cellulose, and hemicellulose [6]. In the middle Himalayan forests, _Lantana camara_ has a different vegetation composition [7]. Bicyclogermacrene (19.4%), isocaryophyllene (16.7%), valecene (12.9%), germacrene D (12.3%), and carophyllene isomers were detected in _Lantana camara_'s essential oil composition [8]. _Lantana camara_ has been described as one of the world's ten worst weeds and has covered large areas in Africa, Australia, and India. There are over 650 species in more than 60 countries [9]. In India's Vindhyan dry deciduous tropical forest, 37 species of _Lantana_ are found, divided into three categories: low (0-30%), medium (30-60%), and high (61-100%) [10]. The quality of any solid biomass is totally dependent on the chemical composition of the specific biomass. For this, various factors are considered in which proximate analysis (fixed carbon, volatile matters, and moisture content), ultimate analysis (C, H, O, S, and N), organic and inorganic ingredients, and many more are so important to identify the properties of the biomass [11]. In addition, the quality of the activated carbon also depends on the wood analytical approach in which biomass cellulose, hemicellulose, and lignin structure are important [12]. Some of the most common biomass sources for activated carbon production are palm shells, almond shells, coconut shells, pomelo peels, carrot peels, pomegranate peels, date seeds, and many more. Among all these biomass sources, lantana camara and olive trees are the most abundant sources of biomass for the preparation of activated carbon [13]. Researchers suggested that activated carbon prepared from _lantana camara_ has the ability to adsorb tartrazine, which is considered to be highly toxic for human health. Tartrazine acts as hyperactivity and causes thyroid cancer, asthma, and many other behavioral problems [9]. Therefore, in this article, olive trees and _Lantana camara_ are used for the preparation of activated carbon. Table 1 shows the chemical composition of the biomass on a dry basis that is most often used to make activated carbon. AC produced from olive trees and _Lantana camara_ is both cost-effective and environmentally friendly.