## 8 Remediation Studies on the Efficacy of Cyclodextrin (CD) Molecules  
As contaminants are adsorbed onto soil particles, particularly at historically contaminated sites, their desorption often constitutes the rate-limiting step in remediation efforts [21; 44]. Innovative cyclodextrin adsorbents have demonstrated efficacy in the simultaneous removal of multiple toxins, comprising persistent organic pollutants (POPs), noxious elements, and organic impurities due to their rapid separation and effective adsorption capabilities [19]. Consequently, there is a growing need for the modification of cyclodext, leading to the development of various newly synthesized cyclodext through the methylation of primary and secondary hydroxyl clusters. These hydroxyl molecules can be modified to induce changes in specificity, as well as the chemical and physical features of the distinct parent cyclodext [21]. Numerous research studies have validated the utility and effectiveness of modified cyclodext in the bioremediation of soils and water contaminated with a variety of pollutants. The inquiry into the extraction of certain toxic metals utilizing cyclodextrin (CD)-based adsorbents has primarily concentrated on \(\beta\)-cyclodextrintrin (\(\beta\)-CD) rather than \(\gamma\)-cyclodextrintrin (\(\gamma\)-CD). The principal mechanism underlying the adsorption of noxious elements by crosslinked CD-based adsorbents is largely attributed to the complex interactions between the metal ions and the crosslinking agents. The \(\beta\)-CD-EDTA-chitosan composite demonstrated significant effectiveness in adsorbing mercury (Hg (II)) and cadmium (Cd (II)) through complex formation, particularly involving EDTA in conjunction with the elemental charges. The highest adsorption capacities were evaluated at 346.30 mg/g for mercury and 202.90 mg/g for cadmium, respectively [43]. A research study by [PERSON] et al. (2019) proved that glycine-modified \(\beta\)-cyclodextrintrin (G-\(\beta\)-CD) enhances the bioremediation of toxic metals in oil-dirtied soils and petroleum hydrocarbons. The application of glycine-\(\beta\)-cyclodextrintrin proved significantly effective in the simultaneous extraction of toxic metals (Cu, Pb) in oil-stained soils and petroleum hydrocarbons, particularly under mildly acidic conditions and in environments with low organic matter. This process achieved a desorption efficiency of approximately 64%. Following treatment with G-\(\beta\)-CD, there was a notable removal of more bioavailable and toxic forms of Pb and Cu from the soil matrix, which contributed to a reduction in the overall toxicity and bioavailability associated with these heavy metals [4]. [PERSON] et al. (2022) demonstrated that the innovative adsorbent material \(\beta\)-CD/hydrothermal biochar (KCB) functions effectively as a reactive barrier within an electrokinetic permeable reactive barrier (EK-PRB) remediation framework, thereby addressing the challenges posed by heavy-metal-laden soils. This adsorbent exhibited significant adsorption capacities for lead (Pb\({}^{2+}\)) and cadmium (Cd\({}^{2+}\)), achieving values of 50.44 mg/g and 33.77 mg/g, respectively. The EK-PRB system utilizing the KCB adsorbent facilitated the removal of 92.87% of Pb\({}^{2+}\) and 86.19% of Cd\({}^{2+}\) from the contaminated soil through various electrokinetic methodologies [45]. In a similar vein, [PERSON] et al. (2022) emphasized that methylated \(\beta\)-cyclodextrintrin modified biochar effectively stabilizes cadmium (Cd) and lead (Pb) in contaminated soils, exhibiting remarkable adsorption capabilities for both heavy metals across a wide pH range [46]. [PERSON] et al. (2024) reported that the synthesized derivatives of cyclodextrin, including methylated \(\beta\)-CD, hydroxypropyl \(\gamma\)-CD, hydroxypropyl \(\beta\)-CD, and sulfobutylated \(\beta\)-cyclodextrintrin, signify significant advancements in the domain of material development [47].