The sorption kinetics and thermodynamic parameters of phosphate removal from aqueous solution using quaternary ammonium–modified bottle gourd biomass as a sorbent were studied in a batch reactor. The cationic sorbent, containing trimethylammonium and hydroxypropyl groups, was obtained through the chemical reactions of the lignocellulosic Lagenaria vulgaris shell with (3-chloro-2-hydroxypropyl)trimethylammonium chloride. Experimental data of phosphate sorption from aqueous solutions of different initial concentrations (5–140 mg P L−1) have been analysed by reaction kinetics and diffusion models. The characteristic rate constants calculated by linear and non-linear regression analyses of the experimental results are presented. The phosphate sorption reaches equilibrium in 20–30 min, depending on the initial phosphate concentration. The maximum sorption capacity of quaternary ammonium–modified bottle gourd (QABG) sorbent was 18 mg P g−1 at 20 oC. The sorption system is best described by a non-linear equation of the pseudo first-order model (R2 > 0.996). The Weber–Morris model indicated that the sorption process took place in three steps, whereby the intra-particle diffusion is not the only rate-controlling step. In addition, the effect of temperature (20 oC–50 oC) on sorption kinetics was also investigated. The various thermodynamic parameters suggest that phosphate sorption is favoured and is an exothermic process. The activation energy and the sticking probability confirmed that anion exchange is the dominant mechanism. These results provide valuable information for the potential use of agricultural residues in the treatment of wastewaters.

中文翻译：

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(3-氯-2-羟丙基)三甲基氯化铵改性葫芦生物质的动力学、热力学和磷酸盐吸附机制

在间歇反应器中研究了使用季铵改性葫芦生物质作为吸附剂从水溶液中去除磷酸盐的吸附动力学和热力学参数。含有三甲基铵和羟丙基基团的阳离子吸附剂是通过木质纤维素 Lagenaria vulgaris 壳与（3-氯-2-羟丙基）三甲基氯化铵的化学反应获得的。已通过反应动力学和扩散模型分析了从不同初始浓度 (5–140 mg P L-1) 水溶液中吸附磷酸盐的实验数据。给出了通过实验结果的线性和非线性回归分析计算的特征速率常数。磷酸盐吸附在 20-30 分钟内达到平衡，具体取决于初始磷酸盐浓度。季铵改性葫芦 (QABG) 吸附剂在 20 oC 时的最大吸附容量为 18 mg P g-1。吸附系统最好用伪一阶模型的非线性方程来描述 (R2 > 0.996)。Weber-Morris 模型表明吸附过程分三个步骤进行，其中颗粒内扩散不是唯一的速率控制步骤。此外，还研究了温度 (20 oC–50 oC) 对吸附动力学的影响。各种热力学参数表明磷酸盐吸附是有利的并且是一个放热过程。活化能和粘附概率证实阴离子交换是主要机制。这些结果为农业残留物在废水处理中的潜在用途提供了有价值的信息。