Abstract
This work describes the preparation of eco-friendly activated carbons from redwood (Pinus sylvestris L.) sawdust and cellulose extracted from the same source, activated with H(3)PO(4) under optimized carbonization conditions. The materials were comprehensively characterized by FTIR, SEM, TGA, XRD, and BET analyses, revealing superior textural uniformity and surface functionality for the cellulose-derived carbon (AC-CRW) compared with its wood-based counterpart (AC-RW). Adsorption experiments demonstrated consistently higher methylene blue uptake by AC-CRW, with the Langmuir isotherm and pseudo-first-order kinetics providing the best fit. Under optimal conditions (24 h impregnation, 1 : 2 impregnation ratio, 650 °C), AC-CRW achieved a maximum capacity of 314.07 mg g(-1), markedly surpassing AC-RW (218.78 mg g(-1)). Thermodynamic analysis further confirmed that adsorption was spontaneous, endothermic, and entropy-driven, with higher ΔH° and ΔS° values for AC-CRW underlining its superior thermal sensitivity. Regeneration tests showed excellent reusability, with AC-CRW retaining 93.5% of its initial efficiency after five cycles. These findings highlight the benefit of cellulose isolation in tailoring porous carbons and establish Pinus sylvestris-derived activated carbons as sustainable, high-efficiency adsorbents for dye-contaminated wastewater treatment.