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<p>Herein, we report on unique surface, structural and adsorption properties for nitrogen-doped graphene oxide (NGO) nanosheets containing a low content of N produced <i>via</i> a low-temperature (35&#xa0;°C) one-pot Hummer’s method. Graphene oxide (GO) and NGO were successfully synthesized and characterized using different techniques. The results from X-ray photoelectron spectroscopy confirmed that N atoms were introduced, with concentrations ranging from 0.5 to 1.0%. Several batch adsorption parameters were varied systematically to understand the adsorption of Congo red (CR) dye on the surface of NGO nanosheets. The NGO nanoadsorbents attained high adsorption efficiency &gt; 90% for CR at pH 2 within 90&#xa0;min, while GO has 72% removal within 180&#xa0;min. The enhanced adsorption ability of the CR molecules on the NGO nanosheets at low pH was due to the electrostatic interactions between the protonated amine and oxygen functionalities in the NGO surface and dye molecules containing negatively charged sulfonic groups. Experimental data for adsorption isotherms adhered to the Langmuir model, with NGO materials achieving the highest maximum adsorption capacity of about 634.06 mg g<sup>− 1</sup> compared with that of undoped GO (297.85 mg g<sup>− 1</sup>) at pH 2. The kinetics conformed to the pseudo-second-order model. Furthermore, the NGO exhibited excellent reusability, retaining a removal efficiency of 70% after three cycles. Overall, NGO nanoadsorbents, with their high removal efficiency of CR dye and reusability, offer a potential solution for wastewater remediation.</p>

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Surface chemistry and structural controlled nitrogen-doped graphene oxide nanosheets and their influence in the adsorption of dye from aqueous solutions

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年1月31日

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  • Kholiswa Yokwana,
  • Cabangani Donga,
  • Pontsho S. Mbule,
  • Makgamathe J. Sithole,
  • Sabelo D. Mhlanga,
  • Edward N. Nxumalo,
  • Luyanda L. Noto

摘要

Herein, we report on unique surface, structural and adsorption properties for nitrogen-doped graphene oxide (NGO) nanosheets containing a low content of N produced via a low-temperature (35 °C) one-pot Hummer’s method. Graphene oxide (GO) and NGO were successfully synthesized and characterized using different techniques. The results from X-ray photoelectron spectroscopy confirmed that N atoms were introduced, with concentrations ranging from 0.5 to 1.0%. Several batch adsorption parameters were varied systematically to understand the adsorption of Congo red (CR) dye on the surface of NGO nanosheets. The NGO nanoadsorbents attained high adsorption efficiency > 90% for CR at pH 2 within 90 min, while GO has 72% removal within 180 min. The enhanced adsorption ability of the CR molecules on the NGO nanosheets at low pH was due to the electrostatic interactions between the protonated amine and oxygen functionalities in the NGO surface and dye molecules containing negatively charged sulfonic groups. Experimental data for adsorption isotherms adhered to the Langmuir model, with NGO materials achieving the highest maximum adsorption capacity of about 634.06 mg g− 1 compared with that of undoped GO (297.85 mg g− 1) at pH 2. The kinetics conformed to the pseudo-second-order model. Furthermore, the NGO exhibited excellent reusability, retaining a removal efficiency of 70% after three cycles. Overall, NGO nanoadsorbents, with their high removal efficiency of CR dye and reusability, offer a potential solution for wastewater remediation.