# Effective Adsorption of Phenoxyacetic Herbicides by Tomato Stem-Derived Activated Carbons
## 1 Introduction
[17] investigated the production of AC from various natural biomass sources, including tomato stems and leaves, using phosphoric acid (H\({}_{3}\)PO\({}_{4}\)) chemical activation at 450 \({}^{\circ}\)C and an impregnation ratio of 1:2 (g/g). In particular, activated carbon derived from tomato stems (TS-AC) exhibited a significantly higher surface area (1248 m\({}^{2}\)/g) compared to that from tomato leaves (305 m\({}^{2}\)/g), highlighting the potential of tomato stems as a precursor. Similarly, [PERSON] [18] explored the impact of microwave radiation on AC production from various biomass raw materials, including tomato stems and leaves, using phosphoric acid (H\({}_{3}\)PO\({}_{4}\)) activation (2:1 precursor mass ratio). The duration of the microwave treatment (1-4 min at 900 W) strongly correlated with the type of precursor, microwave exposure, and AC properties. In particular, TS-AC demonstrated a significantly increased surface area after more long-lasting microwave exposure, peaking at 813.1 m\({}^{2}\)/g after 3 min before slightly decreasing to 705.4 m\({}^{2}\)/g at 4 min. This trend was observed alongside consistent pore size distribution across varying exposure times. TS-AC was also produced from charred tomato stems through chemical activation with phosphoric acid (1:1 activating agent to precursor ratio) at 470 \({}^{\circ}\)C for 2 h [19]. A high specific Brunauer-Emmett-Teller (BET) surface area of 850 m\({}^{2}\)/g and a total pore volume of 0.5904 cm\({}^{3}\)/g enabled the synthesized TS-AC to adsorb phenol from water successfully. [PERSON] et al. [20] investigated the influence of the FeCl\({}_{2}\) impregnation ratio (from 1:1 to 3:1) and temperature (from 500 to 800 \({}^{\circ}\)C) on the porous structure of TS-AC. The study revealed that increasing the FeCl\({}_{2}\)-to-precursor ratio up to 2.5 enhanced both the specific surface area and micropore volume, with a subsequent decrease at higher impregnation ratios. Analogously, the TS-AC properties were enhanced with an increase in activation temperature up to 700 \({}^{\circ}\)C, followed by a deterioration at temperatures exceeding this value. Optimal activation conditions (2.5:1 impregnation ratio, 700 \({}^{\circ}\)C, 1 h process duration) resulted in TS-AC with a specific BET surface area of 971 m\({}^{2}\)/g and a micropore volume of 0.425 cm\({}^{3}\)/g, demonstrating the importance of controlled activation parameters. Activators are critical in the activation process, with their reactivity varying significantly depending on biomass type and temperature [11]. Consequently, distinct activated carbons with varying physicochemical properties can be derived from the same precursor by altering synthesis conditions, particularly the activator. While acid and salt activation of tomato stems have been explored, to our knowledge, using a base as an activator remains unreported. This gap in research underscores the high relevance of this study. Tomato stems are an easily accessible precursor source. In 2023, tomato cultivation in Poland accounted for 6150.63 hectares [21]. After harvesting tomatoes, the bushes are most often treated as waste. It is justified to confirm the concept of obtaining activated carbon from tomato stems by analyzing current research directions aimed at using various waste raw materials as precursors of carbon materials and considering the area of tomato cultivation. The research is part of activities aimed at developing and applying technologies for industrial purposes. This study investigated the feasibility of producing activated carbons from tomato stem biomass through chemical activation using potassium hydroxide (KOH) and sodium hydroxide (NaOH). The research focused on analyzing the influence of the type of alkaline activating agent and activation temperature (550 \({}^{\circ}\)C, 650 \({}^{\circ}\)C, and 750 \({}^{\circ}\)C) on the porous structure, surface morphology, and chemical properties of the resulting carbon materials.