## 1 Introduction
These metals gradually build up in the human nervous system when exposed to polluted water and air sources, leading to lethal disorders even at extremely low levels. Consequently, it is crucial to dispose of them promptly to prevent their concentration from exceeding acceptable thresholds [23]. Numerous physical and chemical methods have been developed to reduce heavy metal concentrations, including membrane separation, accelerated oxidation, and adsorption [24,25,26,27]. However, most of these methods have inherent limitations, such as operational complexity and high costs. In comparison to other technologies, adsorption is a simpler and more convenient approach for successfully removing pollutants [28,29]. However, the cost and regeneration of activated carbon are a major hindrance for its use. Therefore, researchers have focused their attention on waste-based adsorbents for heavy metal removal due to their low cost, renewable nature, and effectiveness. Additionally, by utilizing waste materials such as agricultural by-products and forestry wastes, we can reduce environmental impact and boost the added value of waste materials [30]. This is why, in recent years, adsorbent materials have been prepared from a variety of natural low-cost materials such as coconut shells [31], wood ash [32], sugarcane [33], eggshell [34], rice hus [35], sludge [36], the pedicels of dates [37], sugar beet pulp [38], waste from the pulp and paper industry [39], gulfweed [40],apple pulp [41], palm tree derivatives [42], red oak acorn [43], mushrooms [44] etc. A single low-cost adsorbent will not be able to remove all pollutants adequately [45]. Additionally, a larger quantity of adsorbents is required throughout the removal process, as the majority of low-cost adsorbents have limited adsorption capabilities. As a result, novel, readily available, low-cost, environmentally friendly, and highly effective adsorbents are required. In addition, most past research has concentrated on heavy metal removal from wastewater, soil, or natural water. In the realm of water purification, the utilization of novel activated carbon for the removal of heavy metals represents a distinctive and innovative approach, particularly in the context of enhancing drinking water quality. While activated carbon has been widely explored for water treatment, the novelty of this study lies in its exclusive focus on addressing heavy metal contamination, specifically in drinking water, diverging from conventional research that often targets wastewater or natural sources. Plant and agricultural waste such as red oak acorns, date seeds, and peach seeds were used in this project for removing heavy metals from drinking water. Red oak, native to Canada and the US, is cost-effective and abundant. Date palm tree, a cost-effective and abundant plant, is cultivated in arid and semi-arid environments [46]. The global date production is around 9.7 million tons [47], with palm waste generated at a rate of 35 kg per tree [48]. The date palm, a staple crop, generates 750,000 tons of date seeds annually, offering potential for sustainable applications such as water treatment and environmental remediation. Using this agricultural waste for value-added products and responsible waste management is beneficial for date farmers [49; 50]. Peaches, renowned for their sweet, vibrant flavor, are celebrated globally, with global production estimated at 24.2 million in 2022-2023 [51]. There are several factors affecting the adsorption capacity of any adsorbents. The most common factors influencing the adsorption process include pH, adsorbent dosage, and the presence of other competing ions in the solution. Disinfection is common in water and wastewater treatment plants. The presence of chlorine may have consequences on the adsorption process. In addition, dissolved organic material is a known adsorbate competing against heavy metal ions.