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- MakaleYalnız künye2026Valorization of tea industry waste into boric acid–activated carbon for phenol removal from aqueous solutions
Duran, Celal; Ozdes, Duygu; Ozdemir, Olcay; Onal, Yunus; Gundogdu, Ali
The tea industry generates substantial quantities of solid waste with limited high-value industrial applications. In this study, tea industry waste was converted into boric acid-activated carbon (BA–TAC) through a simple one-step chemical activation process and evaluated as an adsorbent for phenol removal from aqueous solutions. BA–TAC exhibited a mixed micro–mesoporous structure with a BET surface area of 592.59 m2 g−1. The adsorption performance was investigated as a function of solution pH, contact time, and initial phenol concentration. Adsorption kinetics were evaluated using pseudo-first order, pseudo-second order, Elovich, Avrami, and intraparticle diffusion models, whereas equilibrium data were analyzed using Langmuir, Freundlich, and Sips isotherms. Linear, pseudo-linear, and non-linear regression approaches were comparatively evaluated, demonstrating the limitations of conventional linearization and the superiority of direct non-linear regression. Moreover, the so-called linearized forms of multi-parameter models such as Sips are not truly linear because iterative parameter estimation remains necessary. The maximum experimental phenol adsorption capacity reached 101.80 mg g−1 despite the moderate BET surface area of BA–TAC. The experimentally determined natural pH and pHpzc values, together with the limited desorption efficiency, indicated that adsorption was governed predominantly by surface chemical interactions rather than electrostatic attraction alone. XPS analysis confirmed the incorporation of boron-containing surface functionalities, highlighting their contribution to phenol adsorption. Overall, this study demonstrates the successful valorization of tea industry waste into a functional boron-modified activated carbon while providing methodological guidance for reliable adsorption kinetics and equilibrium modeling, thereby supporting sustainable waste valorization.
- MakaleYalnız künye2013Physicochemical characteristics of a novel activated carbon produced from tea industry waste
Gundogdu, Ali; Duran, Celal; Senturk, H. Basri; Soylak, Mustafa; Imamoglu, Mustafa; Onal, Yunus
Tonnes of waste are generated during tea production in Turkey, one of the black tea producing countries in the world. These wastes are not used for any purposes throughout industrial sector. The objective of this study is to bring in economic value to waste materials by producing activated carbons from wastes of a tea plant and to characterize their physicochemical properties. Three types of activated carbons were produced by chemical activation using zinc chloride from tea industry wastes (TIW). Mesoporous structure and surface area rise as the ratio of ZnCl2/TIW increases. When the ratios of ZnCl2/TIW were selected as 1/2:1, 1:1, and 2:1, mesoporous activated carbons are found in the percentages of 10.9%, 39.9% and 77.7% with BET surface areas of 706, 1066 and 1141 m(2) g(-1), respectively. The resultant activated carbons were characterized by analyses of proximate-ultimate, FT-IR, SEM, TGA, methylene blue-iodine numbers, and surface functional groups. (C) 2013 Elsevier B.V. All rights reserved.