In this study, different pretreatment strategies of sugarcane bagasse prior to citric acid modification were investigated in terms of Pb2+ adsorption capacity. Pretreatment strategies included the use of NaOH, HCl, and C2H5OH in various concentrations. In order to fundamentally understand how these pretreatment methods affect the modification of sugarcane bagasse by citric acid as well as the Pb2+ adsorption capacity of sugarcane bagasse, three main components of sugarcane bagasse namely cellulose, hemicellulose, and lignin were isolated and esterified by citric acid under the same conditions. ATR-FTIR, XPS, SEM, and an analysis of the number of carboxylic acid groups were used to investigate the physicochemical and chemical properties of the materials. These three components were proved to participate in adsorption and induce the esterification with citric acid. Hence, pretreatment with ethanol and 0.01 M NaOH which could retain cellulose, hemicellulose, and lignin in sugarcane bagasse achieved a high Pb2+ adsorption capacity, i.e., 122.4 and 97 mg/g after the esterification with citric acid. In contrast, pretreatment with 0.5 M NaOH and 0.1 M HCl removed lignin and hemicellulose, leading to the lowest value of approximately 45 mg/g for citric acid esterified-pretreated sugarcane bagasse. XPS analysis and number of carboxylic group measurement confirmed the esterification between bagasse and citric acid. To understand the adsorption mechanism of adsorbent, two kinetic models including pseudo-first-order model and pseudo-second-order model were applied. The experimental data were well described by the pseudo-second-order model. The adsorption isotherm data were fitted Langmuir and Freundlich.

中文翻译：

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柠檬酸对甘蔗渣的酯化作用以吸附Pb2 +：不同化学预处理方法的效果。

在这项研究中，根据Pb2 +吸附能力，研究了柠檬酸修饰前甘蔗渣的不同预处理策略。预处理策略包括使用各种浓度的NaOH，HCl和C2H5OH。为了从根本上了解这些预处理方法如何影响柠檬酸对甘蔗渣的改性以及甘蔗渣的Pb2 +吸附能力，在柠檬酸的作用下，将甘蔗渣的三个主要成分即纤维素，半纤维素和木质素进行了分离和酯化。相同的条件。ATR-FTIR，XPS，SEM和对羧酸基团数量的分析用于研究材料的理化性质。证明这三个成分参与吸附并诱导柠檬酸酯化。因此，用乙醇和0.01M NaOH预处理可以保留纤维素，半纤维素和木质素在甘蔗渣中的作用，实现了较高的Pb2 +吸附能力，即柠檬酸酯化后的吸附能力为122.4和97 mg / g。相反，用0.5 M NaOH和0.1 M HCl预处理则除去了木质素和半纤维素，导致柠檬酸酯化预处理的甘蔗渣的最低值约为45 mg / g。XPS分析和羧基数目的测定证实了蔗渣和柠檬酸之间的酯化。为了理解吸附剂的吸附机理，应用了两个动​​力学模型，包括伪一级模型和伪二级模型。用伪二级模型很好地描述了实验数据。吸附等温线数据拟合为Langmuir和Freundlich。