Ecosphere Resilience Research Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda 10250, Sri Lanka; Postgraduate Institute of Sciences, University of Peradeniya, Peradeniya 20400, Sri Lanka.
Ecosphere Resilience Research Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda 10250, Sri Lanka; Instrument Center, Faculty of Applied Sciences, University of Sri Jayewardenepura, Nugegoda 10250, Sri Lanka.
Environ Pollut. 2023 Mar 1;320:121054. doi: 10.1016/j.envpol.2023.121054. Epub 2023 Jan 9.
Exposure to excess fluoride is a controversial public health concern as it can cause dental/skeletal fluorosis as well as renal toxicity. The study intended to evaluate the synergistic interaction of clay intercalation and thermochemical modification on corncob biochar to remove fluoride from aqueous solutions. Layered double hydroxide was assorted with thermally activated (torrefaction and pyrolysis) corncob biochar at 1:1 (w/w) ratio to obtain composites called LDH-CCBC250 and LDH-CCBC500. Physicochemically characterized adsorbents were assessed against the pH (3-9), reaction time (up to 12 h) and initial fluoride concentration (0.5-10 mg L) for defluoridation. The porous structure of biochar was found to be richer compared to biocharcoal. The adsorption performance of LDH-CCBC500 was 6-fold higher compared to LDH-CCBC250 signifying the pronounced effect of thermal activation. Fluoride adsorption was pH dependent, and the best pH was in the range of pH 3.5-5.0 and there was no ionic strength dependency. Fluoride uptake by LDH-CCBC500 follows pseudo-second order and Elovich kinetic models, which suggests a chemisorption process followed by physisorption. The most expected way to eliminate fluoride by LDH-CCBC500, which had a maximum adsorption capacity of 7.24 mg g, was cooperative chemical adsorption upon the Langmuir and Hills isotherm (r = 0.99) parameters. Layered double hydroxide intercalated corncob biochar derived from slow pyrolysis is best performing in acidic waters.
过量氟化物的暴露是一个有争议的公共卫生问题，因为它会导致牙齿/骨骼氟中毒和肾毒性。本研究旨在评估粘土插层和热化学改性对玉米芯生物炭协同去除水溶液中氟化物的相互作用。将层状双氢氧化物与热激活（热解和热解）玉米芯生物炭以 1:1（w/w）的比例混合，得到称为 LDH-CCBC250 和 LDH-CCBC500 的复合材料。对吸附剂的物理化学特性进行了评估，考察了 pH 值（3-9）、反应时间（长达 12 小时）和初始氟浓度（0.5-10 mg/L）对除氟的影响。结果表明，生物炭的多孔结构比生物炭更为丰富。与 LDH-CCBC250 相比，LDH-CCBC500 的吸附性能提高了 6 倍，表明热激活的显著影响。氟化物吸附受 pH 值影响，最佳 pH 值范围为 3.5-5.0，且不存在离子强度依赖性。LDH-CCBC500 对氟化物的吸附符合准二级和 Elovich 动力学模型，表明这是一种化学吸附随后是物理吸附的过程。LDH-CCBC500 去除氟化物的最可能方式是通过 Langmuir 和 Hills 等温线（r=0.99）参数的协同化学吸附，其最大吸附容量为 7.24mg/g。由慢速热解制备的层状双氢氧化物插层玉米芯生物炭在酸性水中表现最佳。
