The present work intended to produce new cost-effective alkali-activated adsorbents from chestnut shells with the purpose of removing fluoride from water, and to explore the effect of pyrolysis temperature on fluoride decontamination at different operational and environmental parameters. The microstructure and morphological characteristics of the resulting activated carbons were thoroughly investigated using BET, FTIR, XRD and SEM. The effectiveness of the prepared adsorbent materials in treating and remediating fluorinated water was evaluated. The impacts of several factors, including the dose of the adsorbent, the initial contamination level of fluoride, and pH on the fluoride removal efficiency were investigated. In accordance with the data, the highest adsorption was found to be at a 6 pH during 5 hours of processing duration and 0.5 g/L of dosage of adsorbent. The experimental results were well-fit by the Freundlich isotherm model and the pseudo-second-order kinetic model. The highest fluoride removal efficiency was found to be 78% at adsorption medium pH 6 and initial fluoride concentration of 10 mg/L by the adsorbent prepared at 800°C. Additional research on adsorption along with rejuvenation revealed that the reduction in adsorption potential to 10% following four repetitions of operation involving regeneration, thereby showcasing the adsorbent's versatile applicability for repeated use.