Kim,
Hyunkyung
Magnetic cored dendrimer (which can be called as MCDs) is a hyper-branched polymer of a core, branch repeating units and functional groups which are composed of amine groups. Dendrimers can increase their terminal groups by repeating Micheal addition and amidation reaction steps. These procedures increase the generation of MCDs one by one. The dendrimer branches can react with contaminants in aqueous and gas phases media. Increased generations result in increased number of dendrimer branches in each MCDs. Higher generations of MCDs possibly react with more contaminants. In this research, different generations of MCDs are synthesized, and study about the number of produced dendrimer branches and removal efficiencies of contaminants on each branch were experimented to ensure the effect of the number of dendrimer branches as environmental applications.
Lee,
Sanbin
Sediment quality can be affected with different contaminants: oil, grease, heavy metals, and so on. Advanced oxidation processes (AOP) can be used to mineralize organic compounds in the sediment into harmless materials. Gas transfer using nanobubble is more effective than larger sized bubbles. Nano-sized air bubbles can be generated by cavitation. Ultrasonic treatment can enhance desorption and destruction of organic molecules. Combination of cavitation-based nanobubble aeration and ultrasonic applications remains at the laboratory scale due to the limitations of short effective distance of ultrasound and the lack of understanding of complex processes. In this study, a pilot-scale hybrid reactor of 20cm \*20cm \* 120cm was introduced to check the economic and technical feasibility of the combination of ultrasonic treatment and hydrodynamic cavitation. The column reactor with ultrasonic vibrators of 28kh, 132khz, and 580kHz was connected to the nanobubble generator and used to find the key parameters in degradation of toluene, meta-cresol, and phenol in sediment slurry.
Nanotubes can be formed in stainless steel plate (NSSP) and mesh (NSSM) uniformly with anodization. The increased surface area brings high degradation performance. The component of the anodization stainless steel is Fe2O3 and Cr2O3which can act as semiconductors with Z-scheme effect. Collaboration of Z-scheme effect with an oxidizing reagent such as hydrogen peroxide or ozone performs oxidation radicals for easily degrading organic compounds. In this process, NSSP and NSSM expect great photocatalytic degradation effect in UVC irradiation (20W, 254nm). Also, the reusability of NSSP and NSSM is the same as the first-time of degradation trial.
Activated carbon (AC) is a porous material with high surface area and high adsorption capacity. It can adsorb a wide variety of contaminants. AC has excellent adsorption capacity for organic compounds, but the adsorption of heavy metals is less than organic compounds. Surface oxidation can be applied AC so that, both heavy metals and organic compounds can be adsorbed. Powder activated carbon (PAC) with higher surface area was used in the experiment. HNO₃ application on the surface of PAC can produce surface oxygen groups, and then can be neutralized with strong bases to expand non-surface and voids, leaving only strong ion exchange sites, such as carboxylic groups.
Desalination is a process of eliminating dissolved solids from feed water resources, such as seawater, brackish water, wastewater and so on. It can be done using several methods, such as reverse electrodialysis (RED), reverse osmosis (RO), nano filtration (NF), membrane distillation (MD), forward osmosis (FO), and etc. RED is an electrochemical technique to extract work by mixing aqueous solutions of different salinities. This objective is to desalinate using RED under the conditions of using a metal anode and air cathode. They consist of eleven pairs of reverse electrodialysis cells (RED) with the stipulated operation time.
Activated carbon adsorbs organic substances well but adsorbs heavy metals relatively poorly. Therefore, to improve the heavy metal adsorption, it is necessary to modify the activated carbon. It is largely divided into physical modification and chemical modification. Physical reforming requires a high temperature of 600 degrees or more. Therefore, chemical modification is more economical and suitable. Among them, oxidation showed excellent adsorption of heavy metals. Metal binding to the surface functional groups of chemically modified activated carbon is affected by pH, metal speciation, cationic complexes, and so on. The unpredictability of such modified activated carbon hinders the application of the modified activated carbon to the field. Few studies were conducted on whether the adsorption of organic contaminants can be maintained in the modified state. Also, toxicity of activated carbon with contaminants adsorbed were not well understood.