Adsorption Rules Of Biomass-templated Hierarchical Porous Oxides And Their Functions

Biomass-templated hierarchical porous oxide is the functional material combining the hierarchical porous structure derived from natural biomass with the oxide chemical component of artificial synthesis. The research on biomass-templated hierarchical porous oxide was mainly focused on the application of its functional property in the past, but the related mechanisms of this novel material have not been reported frequently. As a potential novel adsorbent, the hierarchical porous structure of biomass-templated hierarchical porous oxide has potentially strong adsorption function, so it could be applied to the field of dye removal and pathogenic bacterial removal in water. On the other hand, the research on the mechanism of this novel adsorbent could assist the development of novel adsorbent. However, the research on the adsorption mechanism of biomass-templated hierarchical porous oxide is still a gap. Because of the unique hierarchical porous structure of biomass-templated hierachical porous oxide, its adsorption rule would be different from other materials, and the research result on its adsorption mechanism will further promote the development of novel functional materials.In this paper, the biotemplates derived from rice husk and leaves were utilized to synthesize a series of biomass-templated hierarchical porous oxides, and then the adsorption rules and mechanisms of various products were studied systematically, finally the products were used for dye removal and bacterial removal in water. The research of this paper could effectively reveal the relationship between the adsorption rules of the prepared materials and the function of dye removal and bacterial removal, which could provide references for the synthesis of novel bacterial removal functional materials. In this paper, the main results are shown as follows:1. The adsorption mechanism and bacterial removal function of biotemplated hierarchical porous composite oxide derived from rice husk:(1) it expounded that the key point of multilayer adsorption phenomenon of biomass-templated hierarchical porous oxide was the prepared material should have enough suitable pores for second microstructure adsorption.(2) It proposed a proven method of inferring the bacterial physical removal function of prepared material based on the result of negatively charged dye adsorption, as the bacterial removal function of the prepared material was better when its negatively charged dye adsorption performance was better, the results were shown as follows: among the titan yellow dye adsorption results of the prepared materials, the adsorption rate of SiO2 was the slowest, for comparison, that of TiO2 was 2.74 times to that of SiO2, that of BH-TiO2/SiO2 was 5.53 times to that of SiO2, that of activated carbon derived from rice husk was 3.47 times to that of SiO2; among the bacterial removal results of the prepared materials, the function of SiO2 was the worst too, for comparison, that of TiO2 was 3.83 times to that of SiO2, that of BH-TiO2/SiO2 was 6.07 times to that of SiO2, that of activated carbon derived from rice husk was 4.45 times to that of SiO2. This method could be a useful reference for the rapid detection of bacterial physical remocal properties of novel functional materials.(3) It proposed a model of factors of enhanced bacterial removal property of the sample, the material with integrate advantages of chemical component and hierarchical porous had much better performance than that with only one advantage, the bacterial physical removal function of the former was 96% better than that of the latter, the sterilization function of the former was 2.16 times better than that of the latter, the bacterial chemical removal function under the visible light of the former was 90% better than that of the latter. This model could be helpful for the development of novel bacterial removal functional materials.2. The relationship between the adsorption effect of biotemplated hierarchical porous composite oxide derived from rice husk and its photocatalytic function:(1) the light-harvesting function of the prepared material didn’t change a lot when the selected 4 calcination temperature changed, the same as the catalytic function, adsorption function and photocatalytic function.(2) The prepared materials were then used for dye adsorption and dye photocatalytic degradation, the dye photocatalytic degradation effects of all samples were more prominent under the UV irradiation condition, but the dye adsorption effects of all samples were more prominent under the visible light irradiation condition, the results were shown as follows: the average dye removal efficiency after 1 hour adsorption of 40 mg BH-TiO2/SiO2 calcinated under different temperature was about 11.3%, and that of TiO2 was about 7.3%; the average dye removal efficiency after 1 hour adsorption of 100 mg BH-TiO2/SiO2 calcinated under different temperature was about 84.9%, and that of TiO2 was about 23.5%. The average dye removal efficiency after 1 hour photocatalytic effect under UV and visible light of 40 mg BH-TiO2/SiO2 calcinated under different temperature was about 94.9%, and that of TiO2 was about 81.7%; the average dye removal efficiency after 1 hour photocatalytic effect only under visible light of 100 mg BH-TiO2/SiO2 calcinated under different temperature was about 58.8%, and that of TiO2 was about 14.1%.3. The isoelectric-point(IEP)-modified biotemplated hierarchical porous composite oxide derived from rice husk and its adsorption mechanism:(1) it used the high IEP MgO chemical component to modify the low IEP SiO2 chemical component to synthesize the composite BH-MgO/SiO2 which was positively charged in water, the sample without IEP-modified was negatively charged in water. The sample without IEP-modified sample did better in the adsorption of negatively charged methylene blue dye, but the IEP-modified sample did better in the adsorption of negatively charged titan yellow dye. It could be found in the dye adsorption experiment: the different concentrations of methylene blue dye removal efficiency after 1 hour adsorption effect of BH-MgO/SiO2 was about 36.3%, and that of SiO2 was about 86%; the different concentrations of titan yellow dye removal efficiency after 1 hour adsorption effect of BH-MgO/SiO2 was about 93.1%, and that of SiO2 was about 9.5%.(2) The adsorption mechanisms to 2 kinds of dyes of BH-MgO/SiO2 were better fit to long-acting pseudo-second-order adsorption kinetic, which were both fit to the monolayer adsorption mechanism. When the adsorbent had different charge to the adsorbate, the adsorption performance of the adsorbent could be significantly enhanced, so that the adsorption mechanism could be the much more effective Langmuir monolayer adsorption rather than the less effective Freundlich adsorption.4. The adsorption mechanism and bacterial removal function of biotemplated hierarchical porous oxide derived from camphor tree leaves:(1) the adsorption performances of all prepared samples were worse when the calcination temperature during synthesis process increased.(2) For negatively charged titan yellow dye adsorption, MgO with leaf tamplate was Flory-Huggins multilayer adsorption mechanism, which was different from MgO without template and activated carbon originating from leaf, the former was Langmuir and the latter was Freundlich monolayer adsorption mechanism, because MgO with leaf template was fit to the necessary condition of multilayer adsorption phenomenon of biomass-templated hierarchical porous oxide, as the material had enough suitable pores in a wide range.(3) The bacterial removal performance of the prepared material was better when its negatively charged dye adsorption performance was better. Among the titan yellow dye adsorption results of the prepared materials, the adsorption rate of activated carbon originating from leaf was the slowest, for comparison, that of MgO with leaf template was 12.94 times to that of activated carbon originating from leaf, that of MgO with leaf template was 3.55 times to that of activated carbon originating from leaf; among the bacterial removal results of the prepared materials, the perfomance of activated carbon originating from leaf was the worst too, for comparison, that of MgO with leaf template was 2.7 times to that of activated carbon originating from leaf, that of MgO with leaf template was 2.26 times to that of activated carbon originating from leaf.The research of this paper plays important guiding role for the development of novel bacterial removal functional materials, at the same time, it has improved the adsorption rules of biomass-templated hierarchical porous oxides.