In this study, the adsorption capacities of peanut shell activated carbon samples prepared using three types of peanut shell as raw material were compared. The effects of activation state, carbonization temperature, carbonization time, adsorption time during decolorization, and dosage on the performance of the peanut shell activated carbon samples were investigated. The performance of the modified peanut shell (activated carbon) on the decolorization of reactive brilliant blue X-BR and the adsorption kinetics were evaluated systematically. Among the three types of peanut shell activated carbon, the activated carbon that was first activated by phosphoric acid and then carbonized at 450 C for 3 h displayed the best performance, with an optimum dosage of 4 g l À1 and an optimum adsorption time of 2 h. The pseudo-second-order kinetics equation and the intraparticle diffusion equation could well describe the adsorption behavior of the activated carbon prepared by phosphoric acid activation. Intraparticle diffusion was not the only factor affecting the adsorption rate of the activated carbon on reactive brilliant blue X-BR.
System security monitoring has become more and more difficult with the ever-growing complexity and dynamicity of the Internet of Things (IoT). In this paper, we develop an Intelligent Maintenance and Lightweight Anomaly Detection System (IMLADS) for efficient security management of the IoT. Firstly, unlike the traditional system use static agents, we employ the mobile agent to perform data collection and analysis, which can automatically transfer to other nodes according to the pre-set monitoring task. The mobility is handled by the mobile agent running platform, which is irrelevant with the node or its operation system. Combined with this technology, we can greatly reduce the number of agents running in the system while increasing the system stability and scalability. Secondly, we design different methods for node level and system level security monitoring. For the node level security monitoring, we develop a lightweight data collection and analysis method which only occupy little local computing resources. For the system level security monitoring, we proposed a parameter calculation method based on sketch, whose computational complexity is constant and irrelevant with the system scale. Finally, we design agents to perform suitable response policies for system maintenance and abnormal behavior control based on the anomaly mining results. The experimental results based on the platform constructed show that the proposed method has lower computational complexity and higher detection accuracy. For the node level monitoring, the time complexity is reduced by 50% with high detection accuracy. For the system level monitoring, the time complexity is about 1 s for parameter calculation in a middle scale IoT network.
High-temperature calcination was used to modify garnet media. Brunauer–Emmett–Teller (BET) measurements, X-ray diffractometer (XRD), scanning electron microscopy (SEM), zeta potential analysis, and a static adsorption experiment on humic acid removal were carried out to compare unmodified garnet and traditional quartz sand. Fitting adsorption isotherm of the media before and after modification was conducted to determine the adsorption type, and a dynamic filtration experiment was performed to treat micro-polluted water. Results of the characterization analysis and the static adsorption experiment revealed that, compared with the smooth surface of unmodified garnet, the surface of modified garnet media was covered with Fe2O3, which showed a rough concave-convex structure with a specific area that was 2.44 times larger than that of unmodified garnet. The removal efficiency of organic matter after modification increased from 2.5–4.5% to 51.7–63.1%, and the adsorption capacity increased 11–24 times. The adsorption type of the modified garnet media belongs to the Langmuir and Freundlich adsorption mode, while that of the original media belongs to the Freundlich adsorption mode. Results of the dynamic filtration experiment revealed that the effect of modified garnet media on turbidity, CODMn, and UV254 removal was better than that of unmodified garnet and traditional quartz sand.
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