Investigation of olive stone-derived hydrochar produced via hydrothermal carbonization for methylene blue removal

IF 2.4 4区生物学 Q3 BIOTECHNOLOGY & APPLIED MICROBIOLOGY

Journal of chemical technology and biotechnology Pub Date : 2026-04-08 Epub Date: 2026-03-11 DOI:10.1002/jctb.70161

Emel Engintepe, Ayşe Nur Zambak, Ayşe Nilgün Akın

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Abstract

BACKGROUND

Hydrochar produced from olive (Olea europaea) stones via hydrothermal carbonization at 200 °C for 4 h was investigated as a sustainable adsorbent for methylene blue (MB) removal from aqueous solutions.

RESULTS

The hydrochar exhibited an amorphous carbon structure with abundant oxygen-containing functional groups, a low Brunauer–Emmett–Teller surface area (1.143 m² g⁻¹) and a zeta potential of −19.4 mV, confirming the predominance of negatively charged sites. Batch adsorption experiments were conducted at the natural pH of dye solution to examine the effects of contact time, initial concentration and temperature on MB adsorption. The maximum adsorption capacity estimated by the Langmuir model was 46.3 mg g⁻¹. The equilibrium data fitted best to the Temkin model (R² = 0.987), indicating physisorption controlled by surface functional groups, while kinetic analysis showed that the process followed the pseudo-second-order model (R² = 0.99), implying surface-controlled interactions. Thermodynamic parameters (ΔG° = −0.17 to −3.27 kJ mol⁻¹; ΔH° = +72.23 kJ mol⁻¹; ΔS° = +245.76 J mol⁻¹ K⁻¹) revealed that the adsorption was spontaneous, endothermic and entropy-driven.

CONCLUSIONS

Olive stone-derived hydrochar is a promising, low-cost and sustainable adsorbent for the removal of MB from dye-containing wastewater. Adsorption proceeded mainly via surface interactions and was dominated by physisorption, as supported by kinetic, isotherm and thermodynamic analyses. The adsorption capacity increased with temperature within the investigated range, indicating an endothermic and spontaneous process. © 2026 Society of Chemical Industry (SCI).

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水热炭化橄榄石衍生烃类去除亚甲基蓝的研究

研究了橄榄（Olea europaea）石经200℃水热碳化4小时制备的碳氢化合物作为吸附亚甲基蓝（MB）的吸附剂。结果该化合物呈无定形碳结构，含氧官能团丰富，具有较低的brunauer - emmet - teller表面积（1.143 m2 g−1）和- 19.4 mV的zeta电位，证实了负电荷位点的优势。在染料溶液的自然pH下进行了批量吸附实验，考察了接触时间、初始浓度和温度对MB吸附的影响。Langmuir模型估计的最大吸附容量为46.3 mg g−1。平衡数据最符合Temkin模型（R2 = 0.987），表明物理吸附过程受表面官能团控制；动力学分析结果符合伪二阶模型（R2 = 0.99），表明表面相互作用受控制。热力学参数（ΔG°=−0.17 ~−3.27 kJ mol−1；ΔH°= +72.23 kJ mol−1；ΔS°= +245.76 J mol−1 K−1）表明吸附是自发的、吸热的、熵驱动的。结论橄榄石烃类是一种有前途的、低成本的、可持续的含染料废水中MB的吸附剂。吸附主要通过表面相互作用进行，以物理吸附为主，动力学、等温线和热力学分析均支持这一结论。在研究范围内，吸附量随温度升高而增大，表明吸附过程为吸热自发过程。©2026化学工业学会（SCI）。

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来源期刊

Journal of chemical technology and biotechnology 工程技术-工程：化工

CiteScore

7.00

自引率

5.90%

发文量

268

审稿时长

1.7 months

期刊介绍： Journal of Chemical Technology and Biotechnology(JCTB) is an international, inter-disciplinary peer-reviewed journal concerned with the application of scientific discoveries and advancements in chemical and biological technology that aim towards economically and environmentally sustainable industrial processes.