电容去离子法电极材料脱盐特性及处理提钒高盐废水研究

发布时间：2018-05-03 08:17

本文选题：电容去离子 + 高盐废水　；参考：《武汉理工大学》2014年博士论文

【摘要】：在石煤提钒焙烧过程中通常需要添加一定量的工业盐作为焙烧添加剂促进钒的提取，因此，提钒过程会产生大量的高盐度、高矿化度的废水，目前处理这种高盐废水常用的方法有热法和膜法，普遍存在能耗大、成本高等问题。为探索性能更为优异的高盐废水处理方法，本研究采用电容去离子技术处理高盐废水，研究电极材料对脱盐的影响，探讨不同材料的吸附动力学过程，并对比电极材料改性前后对石煤提钒废水的处理性能。通过比较不同活性炭电极的电容去离子脱盐能力，结合活性炭化学、物理、电化学特性分析，得出吸附性能好的电极材料所具备的一般特性，指导电容去离子电极材料的选取。研究表明：在相同条件下进行电容去离子脱盐，矿物质活性炭电极的吸附量约为木质活性炭电极吸附量的4倍，是椰壳活性炭电极吸附量的7.5倍。导致吸附能力差异的主要原因是矿物质活性炭杂质含量少，孔隙结构发达，含氧官能团丰富，且电容量高、电阻较低，因而电容去离子电极材料的选取应具有以上特性。电容去离子操作的最佳工艺参数是：操作电压为2.0V，流速为25mL/min，电极板间距为3mm时，矿物质活性炭电极的粘结剂含量为9%。处理不同浓度NaCl溶液的动力学研究表明，电容去离子吸附过程满足准一阶动力学吸附方程。电容去离子过程离子选择性吸附研究表明：离子浓度是影响电极吸附量的主要因素；当离子浓度相同时，荷电量越高的离子，吸附量越大；相同荷电量的离子，水合半径越小，吸附量越大。对不同单一电解质溶液的电容去离子过程吸附动力学研究表明：活性炭电极对不同离子的吸附速率大小顺序为：Fe3+Al3+ Ca2+ Mg2+ K+ Na+，说明电极对高价离子的吸附速度大于低价离子，相同价态的离子，水合半径越小，吸附速率越快。利用3级电容去离子串联处理石煤提钒高盐废水，操作电压为2.0V，流量为25mL/min，电极板间距为3mm，处理时间为每级1h，活性炭电极对离子总吸附量达到了87.03mg/g。为了进一步提高电极材料的吸附能力，对其进行表面改性，硝酸改性活性炭的吸附性能最好。动力学研究表明，硝酸改性可以提高活性炭的吸附速率常数。硝酸改性提高活性炭的含氧官能团含量，如羟基和羧基的含量，并产生了x新的官能团C-N，降低了活性炭电极的疏水性，提高了电极与溶液的接触面积，进而增加了电极对离子的吸附量，同时提高了电极的电容量，降低电极的电阻。考察硝酸改性对其他碳基电极材料的处理效果，对多壁碳纳米管进行改性，在相同的操作条件下，，改性多壁碳纳米管电极的吸附量比未处理的多壁碳纳米管高44.9%。说明硝酸改性方法不仅可以提高活性炭电极的性能，也适用于对多壁碳纳米管电极的改性。电容去离子处理石煤提钒废水的电耗分析表明：将废水含盐量从30388mg/L降至1500mg/L以下，硝酸改性活性炭电极比未处理活性炭电极可以节约22.4%的电耗。同时降低了电极材料的用量，缩短了处理时间。
[Abstract]:In the process of roasting stone coal for vanadium extraction, a certain amount of industrial salt is needed to be used as a roasting additive to promote the extraction of vanadium. Therefore, the process of vanadium extraction will produce a large amount of high salinity and high salinity wastewater. At present, the common methods for treating this high salinity waste water are hot and membrane methods, which have high energy consumption and high cost. The treatment of high salt wastewater is more excellent. This study uses capacitance deionization technology to treat high salt waste water, studies the effect of electrode materials on desalination, discusses the adsorption kinetics of different materials, and compares the treatment performance of the vanadium extraction wastewater before and after the modification of the electrode materials.
By comparing the deionization deionization capacity of different activated carbon electrodes, combining with the chemical, physical, and electrochemical properties of activated carbon, the general characteristics of the electrode materials with good adsorption properties are obtained, and the selection of the capacitance deionized electrode materials is instructed. The adsorption capacity of the electrode is about 4 times that of the wood active carbon electrode and 7.5 times the adsorption capacity of the coconut active carbon electrode. The main reason for the difference of the adsorption capacity is that the content of the mineral activated carbon is less, the pore structure is developed, the oxygen functional group is rich, the capacitance is high, and the resistance is low, so the selection of the capacitance deionized electrode material should be set up. There are above characteristics.
The optimum process parameters for the deionized operation are: the operating voltage is 2.0V, the flow rate is 25mL/min, and the spacing of the electrode plate is 3mm. The kinetic study of the content of the binder content of the mineral activated carbon electrode is 9%. for the treatment of different concentration NaCl solutions. The kinetic study shows that the process of capacitive deionized adsorption meets the first order kinetic adsorption equation.
The study of ion selective adsorption in the process of capacitive deionization shows that the concentration of ion is the main factor affecting the adsorption capacity of the electrode; when the ion concentration is the same, the higher the charged ion, the larger the adsorption capacity; the smaller the hydration radius, the larger the adsorption capacity. The kinetic study shows that the adsorption rate of activated carbon electrodes on different ions is: Fe3+Al3+ Ca2+ Mg2+ K+ Na+, indicating that the adsorption rate of high valence ions is greater than that of low valence ions, the same valence ions, the smaller the hydration radius, the faster the adsorption rate, the 3 stage electric capacitive deionization is used to process the high salt waste water from the stone coal to extract vanadium. The total adsorption capacity of the activated carbon electrode was 87.03mg/g., with a voltage of 2.0V, a flow rate of 25mL/min, an electrode plate spacing of 3mm, and a treatment time of 1H.
In order to further improve the adsorption capacity of electrode materials and surface modification, the adsorption performance of nitric acid modified activated carbon is the best. Kinetic study shows that nitric acid modification can improve the adsorption rate constant of activated carbon. Nitric acid modification improves the content of oxygen containing functional groups, such as hydroxyl and carboxyl groups, and produces a new x function. The group C-N reduces the hydrophobicity of the activated carbon electrode, increases the contact area between the electrode and the solution, and then increases the adsorption amount of the electrode to the ion, at the same time, the capacitance of the electrode is increased and the resistance of the electrode is reduced.
The treatment effect of nitric acid modification on other carbon based electrode materials was investigated. Under the same operating conditions, the adsorption capacity of the modified multi wall carbon nanotube electrode was higher than that of the untreated multi walled carbon nanotubes (44.9%.). The modified method not only improved the performance of the activated carbon electrode, but also applied to the multi wall carbon. Modification of nanotube electrodes.
The electricity consumption analysis of the removal of vanadium wastewater from the stone coal with capacitive deionization shows that the salt content of the wastewater is reduced to less than 1500mg/L from 30388mg/L, and the nitric acid modified activated carbon electrode can save 22.4% of the electricity consumption than that of the untreated activated carbon electrode. At the same time, the amount of electrode material is reduced and the treatment time is shortened.

【学位授予单位】：武汉理工大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TQ150.1;X703

【参考文献】