ABSTRACT Natural effluents with marked variation in their chemical composition over decomposition time in the matrix from which they are generated have a complex composition and are not totally known in most cases. Landfill leachate can be considered an effluent with complex composition, requiring imminent and more comprehensive studies on organic load degradation. Such complexity of numerous organic compounds (most of them recalcitrant humic and fulvic substances) demands a large number of kinetic equations to satisfactorily describe the temporal evolution of such conversion. Thereby, this work aims to study a kinetic approach grounded on previously consolidated chemical reactions of radical generation through the photo-Fenton mechanism. A molar balance was developed for each species in a batch photo-Fenton process and the resulting ordinary differential equations were numerically solved in MATLABTM. The kinetic model satisfactorily described an organic load conversion of the effluent under the various experimental conditions studied herein. Experimental trends could be represented by a free-radical mechanism and a degradation rate equation of first order for organic carbon, hydroxyl radical and H+. The model fittings revealed a hydroxyl radical/organic carbon stoichiometric ratio of 2:1. The kinetic study has confirmed the importance of pH levels for the reaction medium, and indicated that degradation rate depends on the medium organic composition, which provided an exponential function of conversion for the degradation rate coefficient. The model simulations corroborated the positive effect of sunlight on the radical generation through decomposition reaction with a rate coefficient in the range 4 × 10−3–2 × 10−1 s−1. GRAPHICAL ABSTRACT

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光芬顿法处理难降解废水的碳质分解：动力学方法

摘要 自然流出物的化学成分随分解时间在其产生的基质中显着变化，具有复杂的成分，并且在大多数情况下并不完全了解。垃圾渗滤液可以被认为是一种成分复杂的流出物，需要立即对有机负荷降解进行更全面的研究。众多有机化合物（其中大多数是顽固的腐殖质和富里酸物质）的这种复杂性需要大量的动力学方程来令人满意地描述这种转化的时间演变。因此，这项工作旨在研究基于先前通过光芬顿机制产生自由基的化学反应的动力学方法。在批处理 photo-Fenton 过程中为每个物种开发了摩尔平衡，并且在 MATLABTM 中对所得常微分方程进行了数值求解。动力学模型令人满意地描述了在本文研究的各种实验条件下流出物的有机负荷转化。实验趋势可以通过自由基机制和有机碳、羟基自由基和 H+ 的一级降解速率方程来表示。模型配件显示羟基自由基/有机碳化学计量比为 2:1。动力学研究证实了 pH 值对反应介质的重要性，并表明降解速率取决于介质有机组成，这为降解速率系数提供了一个指数函数。模型模拟证实了阳光对通过分解反应产生自由基的积极影响，速率系数在 4 × 10−3–2 × 10−1 s−1 范围内。图形概要