Pawar Suman, Theodore Thomas
Department of Chemical Engineering, Siddaganga Institute of Technology, Tumakuru, India.
School of Chemical Engineering, Vellore Institute of Technology, Vellore, Tamil Nadu, India.
Heliyon. 2024 Sep 6;10(18):e37540. doi: 10.1016/j.heliyon.2024.e37540. eCollection 2024 Sep 30.
The present work focuses on preparation of hydroxyapatite from pomegranate peels by precipitation method. The hydroxyapatite derived from pomegranate fruit peels (HA-PP) was characterized by XRD, FT-IR, SEM-EDS and BET techniques. The HA-PP has mesoporous in structure and had an area of 99.021 m/g. Further HA-PP was used as adsorbent for the removal of Cr (VI) ion particles from KCrO. The adsorption trials were executed and found the optimized solution using response surface methodology (RSM). The experiments included parameters like pH 2, initial chromium concentration 200 mg/L, adsorbent loading 0.8 g, and contact time 60 min, respectively. Cr (VI) removal was 89.4 % at the optimum combination of these process parameters. A mathematical and statistical optimizing technique response surface methodology (RSM) was applied to verify the interactive effects of various parameters on the adsorption capacity. The analysis of variance (ANOVA) was used to predict the adequacy of the model (F 82.16) shows developed model is valid with R value 0.987, and p-value (>0.1). In this the Langmuir adsorption isotherm and the pseudo-second-order kinetic model are well explained for Cr (VI) adsorption onto HA-PP. This reaction is spontaneous and endothermic, as indicated by the negative change in the standard free energy (ΔG = -0.1732) and ΔH (+4.71) value at the selected temperature. The ΔS (+15.89) further confirms that the randomness increased at the solid-solution interface during adsorption.
本研究聚焦于通过沉淀法从石榴皮中制备羟基磷灰石。采用X射线衍射（XRD）、傅里叶变换红外光谱（FT - IR）、扫描电子显微镜 - 能谱仪（SEM - EDS）和比表面积分析仪（BET）技术对源自石榴果皮的羟基磷灰石（HA - PP）进行了表征。HA - PP具有介孔结构，比表面积为99.021 m²/g。进一步将HA - PP用作吸附剂，用于从K₂Cr₂O₇中去除Cr（VI）离子颗粒。进行了吸附试验，并使用响应面法（RSM）找到了优化的溶液。实验分别包括pH值为2、初始铬浓度为200 mg/L、吸附剂用量为0.8 g以及接触时间为60分钟等参数。在这些工艺参数的最佳组合下，Cr（VI）的去除率为89.4%。应用数学和统计优化技术响应面法（RSM）来验证各种参数对吸附容量的交互作用。方差分析（ANOVA）用于预测模型的充分性（F = 82.16），结果表明所建立的模型有效，R值为0.987，p值（>0.1）。在此，朗缪尔吸附等温线和伪二级动力学模型能很好地解释Cr（VI）在HA - PP上的吸附。该反应是自发的且吸热的，在所选定温度下标准自由能的负变化（ΔG = -0.1732）和ΔH（+4.71）值表明了这一点。ΔS（+15.89）进一步证实了吸附过程中固 - 液界面的随机性增加。
