新型稻壳基复合材料的制备及其吸附、催化降解与吸波性能研究

发布时间：2018-04-23 17:29

本文选题：稻壳 + 电磁波吸收　；参考：《浙江大学》2017年博士论文

【摘要】：稻壳是一种产量巨大的农业废弃物,常被直接丢弃或焚烧处理,不仅占用土地、污染环境,更造成资源浪费。稻壳中含有丰富的二氧化硅、纤维素和木质素成分,是廉价又来源稳定的可再生生物资源。因此,对稻壳进行资源化利用、提高其附加值以及提高其综合利用率显得尤为重要。本文以稻壳及稻壳灰为基础,研究了其对染料废水的吸附性能。通过镁热还原开发制备了稻壳基吸波材料。利用原位复合技术,制备了稻壳铁氧体纳米复合材料,并协同微波诱导技术,研究了其对染料废水的处理。此外,考察了微波诱导技术对传统芬顿体系处理染料废水增强作用,拓宽了芬顿体系在废水处理中的应用。通过研究,得到了以下结论:(1)制得的稻壳灰的主要成分为碳和二氧化硅,具有低密度(0.4gcm-3)、低成本和介电损耗高等优势(见第二章)。其吸波机理主要是介电损耗,其中有效吸波成分为碳。煅烧温度和气氛均会对稻壳灰的吸波性能造成影响,700℃以上制备得到的稻壳灰吸波性能较好,原因是高温下无定形碳的石墨化和K2O等杂质引起的表面熔融,从而增大其复介电常数的实部和虚部。在2-18GHz测试频段范围内,最大反射率最大可达-21dB,RL-10dB处的频宽为5 GHz。与传统电损耗型吸波材料相比,具有相当的性价比优势和应用潜力。(2)通过镁热还原反应从稻壳灰中制备了稻壳基吸波材料(见第三章),吸波成分主要为碳和碳化硅,其机理为电损耗。因此,氮气气氛下煅烧所得的稻壳灰经镁热还原后制备的SiC/C复合物样品吸波性能更好,表现出较高的介电损耗和较宽的带宽。所得样品在RL-5 dB和-10 dB处的最大带宽随碳含量减少而减小,而最佳厚度随碳化硅含量增加而减小。样品的电磁波吸收最佳厚度为1.5-2.0mm,最大RL为-28.9-68.4dB,当RL-5 dB时带宽范围为 6.7-13 GHz,当RL-10 dB 时带宽为 3.2-6.2 GHz。(3)稻壳灰可作为廉价吸附剂处理染料废水(见第四章)。煅烧气氛和温度直接影响稻壳灰的成分形貌和孔隙结构等物性特征。在氮气中煅烧得到的稻壳(BRHA)具有更大的比表面积、微孔体积以及碳含量。空气中煅烧得到的稻壳(WRHA)则含有更高的中孔比例和二氧化硅含量。600℃下煅烧得到的BRHA比表面积最大,为347 m2g-1。中孔是吸附亚甲基蓝(MB)的有效结构类型,因此稻壳灰的吸附性能与其中孔体积成线性相关。其最大亚甲基蓝吸附量q0为50.51 mgg-1。吸附过程符合准二级动力学方程,吸附平衡符合langmuir等温线模型。(4)制备了具有高比表面积和孔体积的多孔稻壳铁氧体纳米复合材料:RHA/MnFe204(RMN)和RHA/CoFe204(RCN)(见第五章)。在微波辅助作用下能快速高效处理MB。MB脱除过程符合准二级动力动力学方程。其脱除效率与样品用量、微波功率以及初始pH值呈正比。对比反应前后pH值发现,反应后pH值趋于中性。MB的发色基团最先被RMN和RCN脱除。根据反应后MB溶液溶度、NO3-和SO42-离子浓度,可以计算出推算出反应后MB分子的最低矿化度:在RMN和RCN分别达到的最大MB去除率55.0%和99.7%的反应中,分别有超过22.1%和46.8%的MB分子被完全降解。(5)研究了将微波诱导技术与芬顿体系协同作用脱除MB(见第六章)。结果表明,微波的引入大大强化了芬顿体系的对MB的脱除效率。仅微波辐照1min,可达到93.0%的脱除率,高于传统芬顿体系65 min的脱除效果。羟基自由基的产生是脱除效率的关键,因此随Fe2+和H202浓度的增加,则MB去除率也相应增大。MB的脱除率在pH小于7时变化不大,当pH达到8时,脱除效率急剧下降,最佳pH为3左右。在微波辅助芬顿氧化过程中,664 nm处特征峰削弱较另两处肩峰更为明显,且产生蓝移现象,说明664nm对应的二甲氨基发色团被氧化分解。
[Abstract]:Rice husk is a kind of large agricultural waste, which is often discarded or burned directly. It not only occupies land, pollutes the environment, but also causes the waste of resources. The rice husk contains rich silica, cellulose and lignin, which is a cheap and stable renewable biological resource. Therefore, the utilization of rice husk is used to improve its attachment. It is particularly important to add value and improve its comprehensive utilization rate. In this paper, the adsorption properties of rice husk waste water are studied on the basis of rice husk and rice husk ash. The rice husk base absorbing material is prepared by the development of magnesium heat reduction. The nanocomposite material of rice husk ferrite is prepared by in situ composite technology, and the microwave induction technology is used to study its microwave induction technology. In addition to the treatment of dye wastewater, the enhancement of the traditional Fenton system on the treatment of dye wastewater by the traditional Fenton system was investigated, and the application of the Fenton system in the wastewater treatment was widened. The following conclusions were obtained: (1) the main components of the rice husk ash are carbon and two silicon oxide, with low density (0.4gcm-3), low cost and dielectric. The high loss advantage (see chapter second). Its absorption mechanism is mainly dielectric loss, in which the effective absorption component is carbon. The calcining temperature and atmosphere will affect the absorption properties of the rice husk ash. The performance of the rice husk ash is better than that of the amorphous carbon at high temperature. The reason is the surface melting caused by the impurities such as K2O and other impurities at high temperature. In the range of 2-18GHz test band, the maximum reflectivity is up to -21dB, and the width of RL-10dB is 5 GHz.. Compared with the traditional electric lossless wave absorbing material, it has a considerable price ratio and application potential. (2) the absorption of rice husk based on the MgO heat reduction reaction from rice husk ash The material (see Chapter third) is mainly carbon and silicon carbide, and its mechanism is electrical loss. Therefore, the SiC/C composite sample prepared by magnesium heat reduction under nitrogen atmosphere is better at absorbing wave performance, showing high dielectric loss and wider bandwidth. The maximum bandwidth of the samples at RL-5 dB and -10 dB is with carbon content. The optimum thickness decreases with the increase of SiC content. The optimum thickness of electromagnetic wave absorption is 1.5-2.0mm and the maximum RL is -28.9-68.4dB. When RL-5 dB is 6.7-13 GHz, when RL-10 dB is 3.2-6.2 GHz. (3), rice husk ash can be used as a cheap adsorbent to treat dyestuff wastewater (fourth chapter). Calcining atmosphere And the temperature directly affects the physical properties of the composition and pore structure of the rice husk ash. The rice husk (BRHA) calcined in nitrogen has a larger specific surface area, micropore volume and carbon content. The rice husk (WRHA) calcined in the air contains higher mesoporous ratio and the BRHA specific surface area of the calcined two silicon oxide content at.600 C. The maximum, 347 m2g-1. mesopore is an effective structure type for adsorbing methylene blue (MB), so the adsorption properties of the rice husk ash are linearly related to the pore volume. The maximum methylene blue adsorption capacity of Q0 is 50.51 mgg-1., which conforms to the quasi two kinetic equation, and the adsorption equilibrium conforms to the Langmuir isotherm model. (4) the high specific surface has been prepared. RHA/MnFe204 (RMN) and RHA/CoFe204 (RCN) (see fifth). The process of rapid and efficient treatment of MB.MB removal under microwave assisted action meets the quasi two stage dynamic dynamic equation. The removal efficiency is proportional to the sample dosage, microwave power and initial pH value. PH before and after the reaction is compared. It is found that the chromophore of neutral.MB after reaction pH is first removed by RMN and RCN. According to the solubility of MB solution, NO3- and SO42- ion concentration after reaction, the minimum mineralization degree of MB molecules can be calculated after the reaction: the MB with the maximum MB removal rate of 55% and 99.7% of RMN and RCN respectively, there are more than 22.1% and 46.8% MB, respectively. The molecules were completely degraded. (5) the synergistic effect of microwave induction and Fenton system was studied to remove MB (see sixth chapter). The results showed that the introduction of microwave greatly enhanced the removal efficiency of the Fenton system. The removal rate of 93% was achieved by only microwave irradiation of 1min, which was higher than that of the 65 min of the traditional Fenton system. With the increase of the concentration of Fe2+ and H202, the removal rate of MB also increases with the increase of the concentration of MB, and the removal efficiency of.MB is little changed when pH is less than 7. When pH reaches 8, the removal efficiency decreases sharply and the best pH is about 3. In the process of microwave assisted Fenton oxidation, the characteristic peak of 664 nm is more obvious than the other two acromion. The blue shift phenomenon indicates that the two methylamino chromophores corresponding to 664nm are oxidized and decomposed.

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TB332

【参考文献】