Mollo Vuyo Moses, Mnguni Mthokozisi, Boikanyo Diseko, Nomngongo Philiswa Nosizo, Ramontja James
Department of Chemical Sciences, University of Johannesburg, Johannesburg, South Africa.
Department of Science and Innovation-National Research Foundation South African Research Chair Initiative (DSI-NRF SARChI) in Nanotechnology for Water, University of Johannesburg, Johannesburg, South Africa.
Front Chem. 2025 Apr 11;13:1547169. doi: 10.3389/fchem.2025.1547169. eCollection 2025.
Triclosan is a common antibacterial drug identified as a major contaminant in South African waters, notably in Gauteng and KwaZulu Natal provinces. This contaminant comes from personal care products and pharmaceuticals. It has been frequently detected in local streams and wastewater treatment plants, posing a threat to aquatic ecosystems and human health. Studies have emphasised the necessity of addressing the presence of triclosan in water bodies to lessen its harmful impacts on the environment.
In this study, NaAlg/MnS bio-nanocomposite hydrogel beads incorporated with different amounts of MnS NPs (0.02-0.2 g) were synthesised via the ionic gelation method and employed as an adsorbent for the removal of triclosan from aqueous solutions. The surface charge, morphology, thermal stability, crystallinity, and functional groups of NaAlg/MnS bio-nanocomposite hydrogel beads were characterised by SEM equipped with EDX, TEM, Thermogravimetric analysis, FTIR, XRD, and zeta sizer (mV).
The experimental results demonstrated that incorporating 0.02-0.2 g of MnS NPs in the bio-nanocomposite hydrogels led to enhanced mechanical structure, porosity, and swelling ability for the adsorption of triclosan compared to pristine NaAlg hydrogel. The response surface methodology was used to optimise the experimental parameters affecting the batch adsorption of triclosan onto the surface of the adsorbent. Basic pH conditions were suitable for removing triclosan in aqueous solutions via hydrogen bonding with the carboxyl functional groups of the bio-nanocomposite beads. The pseudo-second order, Freundlich, and Sips models better explained the adsorption kinetics and equilibrium isotherm data. The maximum adsorption capacity estimated using the Langmuir isotherm model was 132 mg/g. The thermodynamic parameters (enthalpy (∆H) and entropy (∆S)) were found to be 44.042 kJ/mol and 207.018 J/Kmol, respectively, which means the reaction is endothermic and increases randomisation at the solid/liquid interface. The Gibbs free energy (∆G) was negative throughout the studied temperature range, indicating that the adsorption process was spontaneously and energetically favoured.
三氯生是一种常见的抗菌药物，被确定为南非水域的主要污染物，特别是在豪登省和夸祖鲁 - 纳塔尔省。这种污染物来自个人护理产品和药品。它经常在当地溪流和污水处理厂中被检测到，对水生生态系统和人类健康构成威胁。研究强调了应对水体中三氯生的存在以减轻其对环境有害影响的必要性。
在本研究中，通过离子凝胶法合成了掺入不同量MnS纳米颗粒（0.02 - 0.2 g）的NaAlg/MnS生物纳米复合水凝胶珠，并将其用作从水溶液中去除三氯生的吸附剂。通过配备能谱仪的扫描电子显微镜（SEM）、透射电子显微镜（TEM）、热重分析、傅里叶变换红外光谱（FTIR）、X射线衍射（XRD）和zeta粒度分析仪（mV）对NaAlg/MnS生物纳米复合水凝胶珠的表面电荷、形态、热稳定性、结晶度和官能团进行了表征。
实验结果表明，与原始的NaAlg水凝胶相比，在生物纳米复合水凝胶中掺入0.02 - 0.2 g的MnS纳米颗粒可增强机械结构、孔隙率和对三氯生吸附的溶胀能力。采用响应面法优化了影响三氯生在吸附剂表面批量吸附的实验参数。碱性pH条件适合通过与生物纳米复合珠的羧基官能团形成氢键来去除水溶液中的三氯生。准二级动力学模型、弗伦德利希模型和西普斯模型能更好地解释吸附动力学和平衡等温线数据。使用朗缪尔等温线模型估计的最大吸附容量为132 mg/g。发现热力学参数（焓（∆H）和熵（∆S））分别为44.042 kJ/mol和207.018 J/Kmol，这意味着该反应是吸热的，并且增加了固/液界面的随机性。在所研究的温度范围内，吉布斯自由能（∆G）均为负值，表明吸附过程是自发且在能量上有利的。
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