Structure and Property of Alkylated Graphene Oxide Depending on the Chain Length: Grand Canonical Monte Carlo-Molecular Dynamics Approach

Herein, we present all-atomistic molecular dynamics (MD) simulations of alkylated graphene oxides (AGOs), which involve the following two key procedures: (1) the structures of AGOs were determined using ab initio and grand canonical Monte Carlo simulations and (2) the AGO sheets were assembled and simulated in a layered structure using MD simulation and the physical properties were calculated based on the results. To investigate the effects of the chain length of the alkyl groups on the structure and properties of AGO-based materials, we performed two-step simulations, involving (1) equilibration of layered AGOs and (2) tensile tests. The results showed that longer alkyl chains reduce the interlayer distance and increase the density of the layered structure. Young's moduli of the layered structures were evaluated using the developed method and were found to increase with increasing alkyl chain length.N

Removal of Algae, and Taste and Odor Compounds by a Combination of Plant-Mineral Composite (PMC) Coagulant with UV-AOPs: Laboratory and Pilot Scale Studies

The seasonal occurrence of algae blooms in surface waters remains a common problem, such as taste and odor (T&Os), the risk of disinfection by-products (DBPs), and disturbance to water treatment systems. The coagulation efficiency of plant-mineral composite (PMC) coagulant followed by UV-based advanced oxidation processes (UV-AOPs; UV/H2O2 and UV/Cl2) was evaluated for removal of algae, turbidity, dissolved organic matters, and taste and odor compounds in lab-scale and pilot-scale tests. In the lab-scale test, coagulation process with 20 mg/L of PMC shows high removal efficiency of turbidity (94%) and algae (99%) and moderate removal efficiency of UV254 (51%) and geosmin (46%). The pilot test results also show good removal efficiency of turbidity (64%), chlorophyll-a (96%). After PMC coagulation process, the major water factors, which affected the performance of UV-AOPs (i.e., UV transmittance (85–94%), and scavenging factor (64,998–28,516 s−1)), were notably improved, and further degradation of geosmin and 2-methylisoborneol (2-MIB) was achieved in both lab-and pilot-scale tests of the UV-AOPs. The UV/H2O2 process shows higher removal efficiency of geosmin and 2-MIB than the UV/Cl2 process because of the pH effect. The results confirmed that the PMC-based coagulation followed by UV/H2O2 process could be an effective process for the removal of algae, geosmin, and 2-MIB

Evaluation of the formation of oxidants and by-products using Pt/Ti, RuO₂/Ti, and IrO₂/Ti electrodes in the electrochemical process

<div><p>The aim of this study was to evaluate the formation of oxidants and by-products by using different electrode materials, such as Pt/Ti, RuO₂/Ti, and IrO₂/Ti, in the electrochemical process. The harmful by-products and were formed during the electrolysis of a Cl⁻ electrolyte solution, as well as active chlorine, which is the most common water disinfectant. With regard to drinking water treatment, the most efficient electrode was defined as that leading to a higher formation of active chlorine and a lower formation of hazardous by-products. Overall, it was found that the Pt/Ti electrode should not be used for drinking water treatment applications, while the IrO₂/Ti and RuO₂/Ti electrodes are ideal for use.</p></div