微波辐射法制备活性氧化镁除氟剂的实验研究

采用微波辐射法制备饮用水除氟用粉末吸附剂.以碱式碳酸镁为原料,在原料中掺加活性炭以强化微波加热效率,制备条件为:掺加活性炭与碱式碳酸镁的质量比为(5～7):8,煅烧温度高于450 ℃,微波功率在0.5～2.0 kW,煅烧时间在20 min以上.在原水pH为5～9时,含活性炭的活性氧化镁粉末除氟剂的静态除氟容量为13.11～13.29 mg/g.产物的XRD和SEM分析结果表明,碱式碳酸镁分解完全,活性氧化镁为松散片状结构.     

赤泥原料及其对吸附剂吸附性能的影响

赤泥的堆放会对环境造成污染,但其具有较高的吸附性能,因此研究制备赤泥吸附剂能达到以废治废的目的。实验分别采用平果和德保赤泥制备吸附剂,研究了赤泥原料及赤泥吸附剂的物相组成,采用除氟及除铜实验研究了赤泥产地及赤泥堆放时间对吸附剂吸附性能的影响。结果表明,以平果、德保赤泥制备的吸附剂,在焙烧温度500℃、焙烧2 h、溶液p H值为6的条件下,氟浓度可分别从19 mg/L降低到0.21、0.19 mg/L;铜浓度可分别从64 mg/L降低到0.32、0.51 mg/L。对氟的吸附容量均可达0.94 mg/g;对铜吸附容量分别可达3.18、3.17 mg/g;对氟、铜的去除率分别在99%、98%以上。     

锆掺杂镁铝水滑石去除水中氟离子的研究

采用共沉淀法制备出锆掺杂镁铝水滑石,将焙烧产物作为吸附剂用于去除水中氟离子的研究。结果表明,不同镁铝比吸附剂除氟效果有明显差异,其中以镁铝比为3:1除氟效果最好;掺杂锆后吸附剂除氟效率明显提高,除氟率可达到98.7%。详细考察了水滑石焙烧温度、吸附温度、时间、溶液pH及吸附剂用量等因素对吸附剂除氟效果的影响。在室温及空速45h-1条件下,锆掺杂镁铝水滑石成型吸附剂的动态除氟容量达到47.6 mg/g,表明其具有较高的吸氟容量和较快的除氟速率,在饮用水除氟方面具有较好的应用前景。     

改性粘土对氟的吸附研究

为了提高粘土对氟的吸附能力,采用PAC对天然粘土进行改性,并探讨了PAC投加量、煅烧时间,吸附时间、pH等因素对除氟效果的影响.结果表明,在PAC投加质量分数为1%、300℃下煅烧45 min条件下,制备的改性粘土对舍氟水中的氟具有高吸附容量;对氟初始质量浓度为20mg·L-1的废水,PAC改性后的粘土吸附性能增加了62.61%;当吸附时间为5h,含氟废液pH=6～7时,饱和吸附量达到1.67g·kg-1,吸附行为符合Langmuir吸附等温模型和Lagergren2级吸附速率方程,相关系数R2分别为0.9991和0.9996.改性后的粘土吸附剂对pH具有强的适应性.     

含膦多孔有机聚合物负载氧化镁的制备及其CO2吸附性能

MgO吸附剂因其成本低廉、来源广泛、再生能耗低等优势在CO₂吸附领域应用广泛,但比表面积低限制了其吸附性能。以高表面积、多级孔结构的含膦多孔有机聚合物POL-PPH₃为载体,采用浸渍煅烧法和超声煅烧法制备得到POL-PPH₃负载的MgO吸附剂(MgO/POL-PPH₃),用于CO₂捕集。探究制备方法、煅烧温度、煅烧时间等制备条件对MgO/POL-PPH₃吸附剂上CO₂吸附性能的影响。研究发现,浸渍煅烧法优于超声煅烧法,且随着煅烧温度和煅烧时间增加,MgO/POL-PPH₃样品上CO₂吸附容量逐渐降低。采用浸渍煅烧法,煅烧温度300℃,煅烧时间1 h时,MgO/POL-PPH₃-300-1吸附剂上获得最优CO₂吸附量,达0.55 mmol/g。在组成为12%CO₂,其余为氮气的模拟烟道气中,MgO/POL-PPH₃     

Mg-Al-Zr金属复合氧化物除氟影响因素

采用共沉淀-煅烧法制备Mg-Al-Zr金属复合物,并用扫描电镜和X射线衍射对其进行表征,考察了吸附剂质量浓度、吸附时间、pH、初始氟质量浓度和共存阴离子对除氟影响。结果表明,在初始溶液pH=4~10,吸附剂质量浓度为3 g/L,氟初始质量浓度为40 mg/L时,对溶液中的氟去除效果最佳,吸附平衡时间为300 min。等温吸附数据分析显示其等温吸附特征可用Langmuir等温吸附方程描述,由其计算饱和吸附量为48.90 mg/g。共存阴离子对吸附材料除氟效率影响力大小为:PO_4~(2-)CO_3~(2-)SO_4~(2-)NO_3~-。吸附剂再生循环3次后,除氟效率仍在70%以上。     

硅胶载体除氟剂的性能研究

以层析硅胶为载体,以活性氧化铝和活性氧化镁为吸附质制备出了两种载体型除氟剂。在相似条件下,前人研究活化沸石除氟剂的动态除氟容量为0.98 mg/g,本实验制备的两种除氟剂的动态除氟容量分别为1.00 mg/g和1.72 mg/g,明显高于文献值。对实验室制备的硅胶/活性氧化铝和硅胶/活性氧化镁除氟剂的除氟性能进行了测试,测试分析了高氟水溶液中的常规离子SO42-、Cl-、Ca2 和Mg2 等对自制除氟剂的除氟容量的影响,表明这两种除氟剂有较好的抗干扰性。对比了高氟矿泉水的除氟数据,制备的除氟剂具有良好的除氟效果,为进一步制备除氟容量更高、抗干扰能力更强的除氟剂,提供了依据。     

国内除氟吸附剂的研究进展

吸附法除氟是处理含氟水的众多方法中应用非常广泛的一种,因此除氟吸附剂的研究一直是一个重要课题。国内对除氟吸附剂的研究经过了寻找简单除氟吸附剂、对简单除氟吸附剂进行改性、开发新型高效除氟吸附剂以及使用电吸附除氟四个阶段。概述了每个阶段的研究情况,对今后的研究提出了建议,认为今后应该以实现除氟吸附剂制备与应用的产业化为最终目标,贯彻绿色环保原则,提升研究的理论高度,实现吸附剂除氟综合效果最优化。     

普鲁兰复合吸附剂对As的去除研究

以重金属砷为主要研究对象,将普鲁兰和氧化镁用溶胶凝胶法制得普鲁兰复合吸附剂,探究了普鲁兰复合吸附剂的最佳制备条件,并研究了其对As的吸附去除性能。试验表明:在氧化镁与普鲁兰的质量配比为3∶2,搅拌时间为12 h,烘干温度为65℃,煅烧温度为400℃和煅烧时间为1 h的条件下,可以得到具有良好除砷性能的复合吸附剂。同时考察了初始砷浓度、初始pH、吸附温度及吸附时间等因素对该吸附剂吸附砷的影响。结果表明:普鲁兰复合吸附剂能较好的处理As质量浓度为50～200 mg/L,pH为3～11的含砷废水,且在室温下吸附反应5 h吸附剂达到饱和,其吸附量可达到136. 190mg/g。     

磁性羟基磷灰石的制备及其除氟性能研究

氟离子在饮用水中浓度超过1.0mg/L,将对人体健康造成极大危害.通过原位共沉淀法将具有磁性的四氧化三铁掺入羟基磷灰石(HAP)中制备磁性HAP.磁性HAP可通过普通磁体将其吸附并分离回收.实验结果表明,最佳的制备条件为反应温度和时间为60℃和1h,陈化温度和陈化时间为25℃和12h,四氧化三铁用量为0.08g.比较了HAP和磁性HAP对水溶液中氟离子的去除效果.Langmuir模型更适合于该体系,拟合得到最大吸附容量为13.70mg/g,说明磁性HAP对氟离子的吸附属于单层吸附.ΔG0<0和ΔH0>0表明该吸附过程为自发的吸热过程.吸附过程符合拟二级动力学.磁性HAP循环再生使用4次以上,仍能保持85％以上的除氟效率.高吸附容量和优异的循环使用性能表明磁性HAP是一种有效的、可重复使用的除氟吸附剂.     

Fluoride ions adsorption from water by CaCO3 enhanced Mn–Fe mixed metal oxides

Novel CaCO₃-enhanced Mn–Fe mixed metal oxides (CMFC) were successfully prepared for the first time by a simple-green hydrothermal strategy without any surfactant or template combined with calcination process. These oxides were then employed as an adsorbent for adsorptive removal of excess fluoride ions. The adsorbent was characterized by SEM, XPS, XRD, FTIR, and BET analysis techniques. The adsorption property of CMFC toward fluoride ion was analyzed by batch experiments. In fact, CMFC exhibited adsorption capacity of 227.3 mg∙g^‒1 toward fluoride ion. Results showed that ion exchange, electrostatic attraction and chemical adsorption were the main mechanism for the adhesion of large amount of fluoride ion on the CMFC surface, and the high adsorption capacity responded to the low pH of the adsorption system. When the fluoride ion concentration was increased from 20 to 200 mg∙L^‒1, Langmuir model was more in line with experimental results. The change of fluoride ion adsorption with respect to time was accurately described by pseudo-second-order kinetics. After five cycles of use, the adsorbent still maintains a performance of 70.6% of efficiency, compared to the fresh adsorbent. Therefore, this material may act as a potential candidate for adsorbent with broad range of application prospects.     

利用凹凸棒土制备废水氨氮吸附剂的研究

以凹凸棒土为主要原料,制备废水氨氮吸附剂,采用正交实验设计,考察了添加剂含量、焙烧温度、焙烧时间等因素对氨氮去除率的影响。结果表明,添加剂含量10%,焙烧温度500℃,焙烧时间1 h时,所制备的吸附剂性能指标最好,对废水中氨氮的去除率可达85%。     

The defluoridation of water by acidic alumina

Fluoride is considered as a major inorganic pollutant present in drinking water. To remove this excess fluoride, defluoridation was done by alumina. In the present study, alumina used was acidic in nature and hence considered as a good fluoride removing adsorbent. Characterization of the adsorbent was done by XRD, SEM, BET and FTIR with BET surface area of 144.27 m²/g. Systematic adsorption experiments were carried out with different process parameters such as contact time, adsorbent mass, pH, temperature and stirring speed. Fluoride adsorption by alumina was highly pH dependent. Maximum fluoride was removed from water at pH 4.4. At very low and very high pH, fluoride removal efficiency was affected. The study of thermodynamic parameters inferred that physical adsorption was dominant with activation energy of 95.13 kJ/mol and endothermic behavior of the process. The kinetics study concluded that pseudo second order kinetics was followed by the adsorption process. Adsorption equilibrium was studied with Langmuir and Freundlich isotherm models. The adsorption process followed Langmuir isotherm with an adsorption capacity of 8.4 mg/g. A regeneration study was proposed in order to reuse the adsorbent for better economy of the process. Finally, a process design calculation was reported to know the amount of adsorbent required for efficient removal of fluoride from aqueous medium.     

Adsorptive removal of fluoride from water samples using <Emphasis Type="Italic">Azospirillum</Emphasis> biofertilizer and lignite

The present study involves a comparison of Azospirillum biofertilizer and lignite for removal of fluoride from aqueous solution. Batch experiments were performed to remove fluoride by the use of Azospirillum biofertilizer and lignite. Fluoride adsorption capacity was found by varying different parameters such as adsorbent dose, pH, initial concentration, temperature and contact time. The adsorption capacity for fluoride by using Azospirillum biofertilizer was 0.456 mg/g and for lignite 0.16 mg/g. Pseudo-second-order kinetic model best fit the experimental data. Field water samples were tested for fluoride removal by Azospirillum biofertilizer and lignite. The fluoride concentration was reduced to the permissible limit.     

Defluoridation of Water Using Zirconium Impregnated Coconut Fiber Carbon

Abstract

In this study the applicability of Zirconium ion impregnated coconut fiber carbon (ZICFC) as an adsorbent for fluoride removal from water was investigated. The dependence of fluoride adsorption on the physicochemical properties includes pH, agitation time, adsorbent dosage, temperature, and the initial concentration of the adsorbate. Maximum defluoridation was obtained at an original pH value of 4.0 with a rapid 93% adsorption being achieved within 10 min of contact with ZICFC. Adsorption data for fluoride onto ZICFC were better correlated to the Langmuir isotherm and pseudo-second order chemical reaction provided the best fit for the experimental data as obtained from kinetic studies. A combination of chemisorption and physisorption processes in hand with intraparticle diffusion, account for the high defluoridation ability of ZICFC, with the thermodynamic parameters indicating an endothermic phenomenon. The fluoride adsorption capacity of ZICFC when compared with those of other commonly used fluoride adsorbents highlights the substantial improvement in fluoride adsorption capacity of coconut fiber carbon on zirconium impregnation.     

Defluoridation of Water by Graphene Oxide Supported Needle-Like Complex Adsorbents

The dicarboxylic acids like oxalic acid, malonic acid and succinic acid mediated graphene oxide–zirconium needle like complexes were synthesized and used to remove fluoride from simulated fluoride contaminated water. The adsorption of fluoride by dicarboxylic acids mediated graphene oxide–zirconium complexes were by both electrostatic interaction at acidic pH and ion-exchange mechanism at neutral pH. The maximum defluoridation capacity observed was 9.70 mg/g at the minimum contact time of 18 min at room temperature. Various batch equilibrium parameters like pH studies, contact time, common ion interference and temperature studies were optimized. The synthesized graphene oxide and graphene oxide supported complexes were characterized using UV–vis, FTIR, XRD and SEM with EDAX analysis to establish the mechanism of fluoride adsorption. The removal of fluoride was described by the pseudo-second-order reaction kinetics, Freundlich isotherm model and thermodynamic studies which indicates the nature of adsorption was endothermic and spontaneous. Regeneration studies depict that the dicarboxylic acid mediated graphene oxide–zirconium complex can be used as an effective adsorbent for the removal of fluoride ions from wastewater. Also, the field applicability of the material has been verified with field samples collected from nearby fluoride endemic villages.     

基于Box-Behnken响应面法的钠离子吸附剂的制备工艺条件优化

赤泥中含有一定量的钠离子,这对赤泥应用性能影响很大。本研究通过制备吸附剂来分离钠离子,应用Design-Expert软件响应面法中的Box-Behnken程序,对吸附剂的制备工艺条件进行优化研究。通过单因素试验,以钠离子去除率为评价指标,确定了煅烧温度、煅烧时间和Al掺量三因素的适宜范围。在此基础上,利用Box-Behnken中心组合试验,以钠离子去除率为响应值进行响应面分析,对制备工艺条件进行优化。结果表明,最佳制备条件为煅烧温度400 ℃,煅烧时间5 h,Al掺量40%。在此条件下,钠离子去除率为95.30%,这为赤泥中钠离子的分离提供了一种方法。     

Adsorption behavior of fluoride ions using a titanium hydroxide-derived adsorbent

The removal behavior of fluoride ions was examined in aqueous sodium fluoride solutions using a titanium hydroxide-derived adsorbent. The adsorbent was prepared from titanium oxysulfate (TiOSO₄·xH₂O) solution, and was characterized by X-ray diffraction, scanning electron microscopy, thermogravimetry-differential thermal analysis, Fourier transform infrared spectrum and specific surface area. Batchwise adsorption test of prepared adsorbent was carried out in aqueous sodium fluoride solutions and real wastewater containing fluoride ion. The absorbent was the amorphous material, which had different morphology to the raw material, titanium oxysulfate, and the specific surface area of the adsorbent (96.8 m²/g) was 200 times higher than that of raw material (0.5 m²/g). Adsorption of fluoride on the adsorbent was saturated within 30 min in the solution with 200 mg/L of fluoride ions, together with increasing pH of the solution, due to ion exchange between fluoride ions in the solution and hydroxide ions in the adsorbent. Fluoride ions were adsorbed even in at a low fluoride concentration of 5 mg/L; and were selectively adsorbed in the solution containing a high concentration of chloride, nitrate and sulfate ions. The adsorbent can remove fluoride below permitted level (< 0.8 mg/L) from real wastewaters containing various substances. The maximum adsorption of fluoride on the adsorbent could be obtained in the solution at about pH 3. After fluoride adsorption, fluoride ions were easily desorbed using a high pH solution, completely regenerating for further removal process at acidic pH. The capacity for fluoride ion adsorption was almost unchanged three times after repeat adsorption and desorption. The equilibrium adsorption capacity of the adsorbent used for fluoride ion at pH 3 was measured, extrapolated using Langmuir and Freundlich isotherm models, and experimental data are found to fit Freundlich than Langmuir. The prepared adsorbent is expected to be a new inorganic ion exchanger for the removal and recovery of fluoride ions from wastewater.     

改性骨炭去除饮用水中氟离子的研究

文章旨在研究改性骨炭对饮用水中氟离子的去除效果。用AlCl3对常见的骨炭进行改性,并考察了pH、氟溶液初始浓度、温度及吸附剂用量对氟离子吸附去除的影响。结果表明:经AlCl3溶液改性的骨炭,用量为0.2 g/L时,其在24 h内对10 mg/L氟离子的去除率达97%以上。该吸附剂比未改性效果好,具有一定的应用前景。     

Optimization of a Fe-Al-Ce nano-adsorbent granulation process that used spray coating in a fluidized bed for fluoride removal from drinking water

A coating granulation technology comprising the spraying of a Fe-Al-Ce nano-adsorbent suspension onto glass beads in a fluidized bed was developed. An acrylic-styrene copolymer latex was used as a binder. The granulated adsorbent was used in a packed bed for fluoride removal from drinking water. The effects of coating temperature, latex/Fe-Al-Ce ratio, and coating amount on granule compressive strength and adsorption capacity were investigated. With increased coating temperature, cross linking in the polymer in the coated layer increased, which resulted in increased granule strength but decreased adsorption capacity. With increased latex/Fe-Al-Ce ratio, more active sites were covered by the polymer, which also resulted in increased granule strength but decreased adsorption capacity. The optimal parameters for making high performance adsorbent granules were for the granules to be coated at 65 °C using a latex/Fe-Al-Ce ratio of 0.5:1 and a coating amount of 27.8%. These granules had a fluoride adsorption capacity of 2.77 mg/g (coated granules) for water with an initial fluoride concentration of 0.001 M that was treated at pH 7.