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Recyclable adsorbent of BiFeO_3/Carbon for purifying industrial dye wastewater via photocatalytic reproducible

Green Energy & Environment 2019年第1期4卷 66-74页

作者： Shuang Jiao Yiming Zhao Chensha Li Binsong Wang Yang Qu Key Laboratory of Functional Inorganic Materials Chemistry (Heilongjiang University) Ministry of Education School of Chemistry and Materials ScienceInternational Joint Research Center for Catalytic Technology Key Laboratory of Functional Inorganic Materials Chemistry(Heilongjiang University) Ministry of Education School of Chemistry and Materials ScienceInternational Joint Research Center for Catalytic Technology

It is essential to prepare highly-efficiency reproducible adsorbent for purifying industrial dye wastewater. In this work, biscuit with a layered porous structure as a template is applied to prepare a photocatalytic recyclable adsorbent of BiFeO3/Carbon nanocomposites for purifying simulative industrial dye wastewater. It is found that the structure of the prepared BiFeO3/Carbon nanocomposite is related to the natural structure of the biscuit, annealing temperatures and immersing times, demonstrated by XRD, TEM, UV-Vis and adsorptive activities. Kinetics data shows that the adsorption rate of the adsorbent to the dye is rapid and fitted well with the pseudo-second-order model, that more than 80% of dyes can be removed in the beginning 30 min. The adsorption isotherm can be perfectly described by the Langmuir model as well. It can be seen from the adsorption data that the adsorption performance can reach over 90% at pH ? 2–12, which can imply its universal utilization. The prepared BiFeO_3/Carbon nanocomposites have also displayed excellent capacities(over 90% within 30 min) for adsorption of seven different dyes and their mixed one. According to the five times photocatalytic reproducible experiments, it is proved that BiFeO_3/Carbon nanocomposites show the excellent stability and reproduction for purifying simulative industrial dyes, even the sample have been placed for one year. These research results indicate that the adsorbent BiFeO_3/Carbon can be a suitable material used in treating industrial dye wastewater potentially.

关键词： Reproducible adsorbent BiFeO3/Carbon nanocomposites Photocatalysis Purifying industrial dye wastewater pseudo-second-order model

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Application of Response Surface Methodology for Optimization of Fluoride Removal Mechanism by Newely Developed Biomaterial

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American Journal of Analytical Chemistry 2013年第8期4卷 404-419页

作者： Ria Bhaumik Naba Kumar Mondal Soumya Chattoraj Jayanta Kumar Datta Department of Environmental Science The University of Burdwan Burdwan India

The adsorption capacities of new biomaterials derived from lemon leaf (Citrus sp.) toward fluoride ions have been explored by varying different physicochemical parameters such as pH, initial concentration, adsorbent dose, contact time, stirring rate and temperature. The entire study was done through batch process. Maximum fluoride adsorption of 96.9% - 98.8% was achieved with an initial concentration of 10 mg/L. Langmuir isotherm model well expressed fluoride ad- sorption onto LLD-1, LLD-2 and LLD-3. According to correlation coefficient, the fluoride adsorption onto these 3 ad- sorbents was correlated well with pseudo-second-order kinetic model. From thermodynamic study, the spontaneous nature and feasibility of the adsorption process with negative enthalpy (ΔH0) value also supported the exothermic nature were shown. The rate of fluoride adsorption was mathematically described as a function of experimental parameters and was modeled through Box-Behnken (Response surface methodology). The results showed that the responses of fluoride adsorption were significantly affected by the quadratic term of pH, initial concentration, contact time and temperature and the statistical analysis was performed by ANOVA which indicated good correlation of experimental parameters.

关键词： Lemon Leaf Fluoride Adsorption Langmuir Isotherm pseudo-second-order Kinetic Model Thermodynamic Study Response Surface Methodology

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Al(OH)3改性羟基磷灰石的制备及其对氟离子的吸附性能研究

Al(OH)3改性羟基磷灰石的制备及其对氟离子的吸附性能研究

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作者：张灿中国矿业大学

学位级别：硕士

氟是人体必需的微量元素之一,然而,摄取过量的氟会导致各种疾病的发生。羟基磷灰石(HAP)具有出色的稳定性、生物相容性且无二次污染,常被用于去除水中的氟离子(F)。然而,HAP比表面积较小、活性位点较少,导致其除氟容量较低,限制了HAP在... 详细信息

氟是人体必需的微量元素之一,然而,摄取过量的氟会导致各种疾病的发生。羟基磷灰石(HAP)具有出色的稳定性、生物相容性且无二次污染,常被用于去除水中的氟离子(F)。然而,HAP比表面积较小、活性位点较少,导致其除氟容量较低,限制了HAP在水处理方面的应用。针对上述问题,本研究采用EDTA辅助水热法制备出颗粒均匀、分散性好的纳米级羟基磷灰石(nHAP),通过共沉淀法使用Al(OH)改性nHAP,以获得比表面积大、表面活性位点多、除氟容量大的新型除氟材料—Al(OH)-nHAP。以nHAP、Al(OH)-nHAP对F的吸附性能为指标,优化制备条件和反应条件;对最优制备条件下得到的Al(OH)-nHAP进行表征分析;考察Al(OH)-nHAP对F的吸附性能和吸附动力学、热力学规律,并与nHAP进行对比;进而探索Al(OH)-nHAP对F的吸附机理,主要的结论如下:采用Al(OH)改性nHAP成功合成比表面积大、活性位点多且纯度较高的介孔材料—Al(OH)-nHAP。通过XRD、TEM、FTIR和BET等手段对其进行表征分析,结果表明:与nHAP相比,经Al(OH)改性后的Al(OH)-nHAP,其平均孔径由23nm减小到16nm,比表面积由71.29m/g增加到112.39m/g,且表面羟基含量相应增多,这为吸附F提供更多的活性位点。考察吸附剂用量、溶液pH值、共存阴离子(Cl、NO、SO、CO、PO)等变量因子对Al(OH)-nHAP除氟性能的影响机制,结果表明:在F初始浓度为5mg/L的条件下,当F的去除率到达90%以上时,Al(OH)-nHAP用量仅为nHAP用量的1/5;随着溶液pH值的增大,Al(OH)-nHAP的除氟性能逐渐下降,在pH值小于9时,Al(OH)-nHAP对F的吸附效果稳定,吸附容量保持在11.08mg/g以上;Cl、NO和SO对nHAP、Al(OH)-nHAP除氟容量的影响均不明显,但CO和PO因在水溶液中易发生水解,使溶液中产生大量的OH与F竞争吸附位点,导致除氟容量下降。Al(OH)-nHAP有良好的再生循环能力,且稳定性高、安全性高、不会产生二次污染。选择pH为12的NaOH溶液作为解吸液,经过4次再生循环,与nHAP相比,Al(OH)-nHAP对F的吸附效率由68.32%增大为81.32%。Al、Ca溶出实验表明,出水溶液中Al、Ca和F的浓度分别为0.01mg/L、2.11mg/L、0.56mg/L,均远低于国家标准。在温度为318K、溶液pH为7、F初始浓度为200mg/L的条件下,Al(OH)-nHAP的最大吸附容量达194.20mg/g,是同等条件下nHAP最大吸附容量的6.6倍;同时Al(OH)-nHAP相比于nHAP到达吸附平衡所需要的时间由150min缩短到60min。pseudo-second-order与Freundlich模型能更好的描述Al(OH)-nHAP对F的吸附过程,这说明Al(OH)-nHAP对F的吸附过程主要由化学吸附控制,且是在Al(OH)-nHAP异质表面上发生的多层吸附,是一种自发的吸热反应。Al(OH)-nHAP对F的吸附主要包括静电吸引、离子交换两种作用。经Al(OH)修饰后,Al(OH)-nHAP表面活性羟基基团的含量增多,具有较强的离子交换作用。此外,在pH值为3时,Al(OH)-nHAP表面被质子化、正电性增强,与带负电的F之间产生了较强的静电吸引作用,联合离子交换作用使其除氟性能较好。而pH值为92时,Al(OH)-nHAP表面被去质子化,同时,由于溶液中存在大量电荷和离子半径与F的相似性的OH,与F竞争活性位点,导致F的去除率降低。pH值为5时,Al(OH)-nHAP对F的静电吸引作用降低,离子交换起到主导作用。在溶液pH值为7时,Al(OH)-nHAP除氟容量达到11.37mg/g,是未改性nHAP的4.9倍,说明Al(OH)-nHAP是一种性能良好的除氟剂。

关键词： Al(OH)2-nHAP F- pseudo-second-order Freundlich 静电吸引和离子交换

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