开题报告内容:(包括拟研究或解决的问题、采用的研究手段及文献综述,不少于2000字)
1. Introduction
1.1 Nuclear power and its fussion product
Nuclear energy or nuclear power appears to be one of the best options to implement this consideration. It originates from the splitting of uranium atoms which is a process called fission. This generates heat then produce steam that can be used to generate electricity by using a turbine generator. Nowadays nuclear energy provides over 10% of the worldrsquo;s electricity and 18% of electricity in OECD countries. The operation of nuclear power plants do not produce any greenhouse gas emmisions such as carbondioxide, which mainly occupy air polution that was announced as present largest enviromental risk by World Health Organization (WHO). However, the fission product of uranium that regarded as dangerous radioactive waste pollution until now is iodine. It can spread easily through air and water that causing serious problems, for example the 2011 Fukushima Daiichi nuclear disaster.
1.2 Radioactive iodine as main disposal problem
The radioactive waste called radionuclides 129I and 131I are the two main components of waste stream. The both radioidonine contaminates the life of humans and animals across ecosystem within air and water as mediator. Because of its short half-life, 8 days (t1/2 of 131I), 131I levels usually fall below detection in environments contaminated by nuclear event shortly after release, but 129I which has long half-life can sustain in the environment for 1.57 X 107 year (t1/2 of 129I) or about 16 million years. They are capable of eliciting a serious cytotoxic effects which can cause serious health problems, such as thyroid cancer. 4,5,15
1.3 Outline of reviewing methods for iodine capture
To date, capturing radioactive waste iodine has been divided into many large methods which include using inorganic porous materials, organic-inorganic porous materials, and organic porous materials, etc. Inorganic materials e.g. synthetic silver-containing zeolites have the weakness of low iodine adsorption capacity, non economic-effeciency, and bad reutilization in practical application. These urge further studies toward another types of porous materials.
Metal-organic frameworks (MOFs) are classified as organic-inorganic porous materials. They are built by coordinative bonds between metal nodes (metal ions or clusters) and organic linkers, so included as organic-inorganic hybrid porous materials. Owing to their fascinating structural chemistry which can be achieved by altering their connectivity or changing the identity of either metal or ligand themselves, and great industrial applications, MOFs have drawn tremendous attention. The crystalline MOFs that we will show in this review, divided into Cu-BTS@PES composite beads5, PPS-ZIF-8 and PPS-ZIF-8-BSA composite membranes6, GDUT-712, and Co sites with C-I covalent bond11. All of them posses their own advantages. For example, PPS-ZIF-8-BSA with rapid preparation through novel biomimetic mineralization, high uptake capacity up to 2.51 g/g, flexible properties (fire resistance, corrosion resistance) fitted for nuclear power plants application.
Porous organic polymers (POPs) are classified as organic porous materials. These materials have many advantages such as light-weight, superior inherent porosity, high thermal and chemical stability, designable, tunable structures and functions. Nowadays, they have received increasing intention and interest in a rising research of porous materials, especially for their tremendous potential in gas capture and storage. The POPs we will show in this review, include triazine-based CalCOPs1, indole-based PTIBBL4, CMPs-LS-782, mulberry-like CSU-CPOPs-127, TatPOP-2 and MelPOP-214, and free free standing HCP NSs and HCP NTs10. All of them posses their own advantages. For example, CMP-LS-8 with pi-conjugated networks and rich heterocycle interaction, high uptake capacity of 5.29 g/g for iodine capture in vapor phase.
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