Laboratório de Estudos em Ciências Ambientais, Departamento de Química e Ciências Ambientais, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista "Júlio de Mesquita Filho", 15054-000 São José do Rio Preto, São Paulo, Brazil; Laboratoire MIO-Equipe CEM, Université de Toulon, CS 60584, 83041 CEDEX 9 Toulon, France.
Laboratório de Estudos em Ciências Ambientais, Departamento de Química e Ciências Ambientais, Instituto de Biociências, Letras e Ciências Exatas, Universidade Estadual Paulista "Júlio de Mesquita Filho", 15054-000 São José do Rio Preto, São Paulo, Brazil; Laboratório de Materiais Funcionais Avançados (LaMFA), Departamento de Física, Universidade Federal do Ceará, 60455-900 Fortaleza, Ceará, Brazil.
Sci Total Environ. 2020 Jun 20;722:137815. doi: 10.1016/j.scitotenv.2020.137815. Epub 2020 Mar 9.
Humic acids (HA) play an important role in the distribution, toxicity, and bioavailability of metals in the environment. Humic-like acids (HLA) that simulate geochemical processes can be prepared by NaOH aqueous extraction from hydrochars produced by hydrothermal carbonization (HTC). HLA can exhibit properties such as those found in HA from soils, which are known for their ability to interact with inorganic and organic compounds. The molecular characteristics of HLA and HA help to explain the relationship between their molecular features and their interaction with metallic species. The aim of this study is to assess the molecular features of HA extracted from Terra Mulata (TM) and HLA from hydrochars as well as their interaction with metals by using Cu(II) ions as a model. The results from C NMR, elemental analysis, FTIR, and UV-Vis showed that HA are composed mostly of aromatic structures and oxygenated functional groups, whereas HLA showed a mutual contribution of aromatic and aliphatic structures as main constituents. The interactions of HA and HLA with Cu(II) ions were evaluated through fluorescence quenching, in which the density of complexing sites per gram of carbon for interaction was higher for HLA than for HA. Furthermore, the HLA showed similar values for stability constants, and higher than those found for other types of HA in the literature. In addition, the average lifetime in both humic extracts appeared to be independent of the copper addition, indicating that the main mechanism of interaction was static quenching with a non-fluorescent ground-state complex formation. Therefore, the HLA showed the ability to interact with Cu(II) ions, which suggests that their application can provide a new approach for remediation of contaminated areas.
腐殖酸（HA）在环境中金属的分布、毒性和生物有效性方面起着重要作用。可以通过 NaOH 水溶液从水热碳化（HTC）产生的水炭中提取模拟地球化学过程的腐殖酸类似物（HLA）。HLA 可以表现出与土壤中 HA 相同的性质，土壤中的 HA 以与无机和有机化合物相互作用的能力而闻名。HLA 和 HA 的分子特征有助于解释它们的分子特征与其与金属物种相互作用之间的关系。本研究的目的是评估从 Terra Mulata（TM）中提取的 HA 和水炭中 HLA 的分子特征，以及它们通过使用 Cu(II) 离子作为模型与金属的相互作用。13 C NMR、元素分析、FTIR 和 UV-Vis 的结果表明，HA 主要由芳构化结构和含氧官能团组成，而 HLA 则显示出芳构化和脂肪族结构的相互贡献是主要成分。通过荧光猝灭评估了 HA 和 HLA 与 Cu(II) 离子的相互作用，其中与每克碳相互作用的配位位点密度对于 HLA 高于 HA。此外，HLA 的稳定常数值相似，高于文献中其他类型 HA 的稳定常数值。此外，两种腐殖质提取物的平均寿命似乎与铜的添加无关，这表明相互作用的主要机制是静态猝灭，形成非荧光基态配合物。因此，HLA 表现出与 Cu(II) 离子相互作用的能力，这表明它们的应用可以为污染地区的修复提供一种新方法。
