Biogenic deterioration of concrete and its mitigation technologies

Concrete is used in great volumes for construction of buildings, roads, sewer systems, marine structures, bridges, and tunnels. Although chemical degradation is regarded as the major cause of their deterioration, recent research has revealed important role of biogenic deterioration. In particular, biogenic deterioration is a serious problem in sewer systems, subsea pipelines, bridge piers, oil and gas pipelines, and offshore platforms. Recently, nanomaterial-embedded concrete and nanomaterial-incorporated coatings with novel functionalities such as self-protection and anti-corrosion ability have been successfully developed for prevention and control of concrete deterioration. This paper presents an overview of both existing control measures and recent progress on development of nano-enabled approaches for protection of concrete structures against biogenic deterioration

Removal of Selected Micropollutants During Conventional and Advanced Water Treatment Processes

Micropollutants such as caffeine, carbamazepine, metoprolol (MTP), and sulfamethoxazole (SMZ), which are frequently detected in aquatic environments, were selected, and their removal and persistence using classical water treatment processes (coagulation, adsorption, and chlorination), and advanced oxidation processes (AOPs) (ozonation, UV photolysis, UV/H2O2, and UV/chlorine) were examined using liquid chromatographytandem mass spectrometry (LC-MS/MS). While SMZ was most effectively removed, MTP showed the lowest removal efficiency in all applied water treatments. During coagulation and adsorption processes, SMZ was effectively removed by electrostatic interaction. Chlorination was not effective for removal of the selected micropollutants. Among AOPs, UV/chlorine reaction showed the most effective removal (90-100%) for selected micropollutants, including MTP. Considering its persistence, MTP was proposed as an indicator micropollutant during water treatment.OAIID:RECH_ACHV_DSTSH_NO:T201721400RECH_ACHV_FG:RR00200001ADJUST_YN:EMP_ID:A072570CITE_RATE:1.547DEPT_NM:환경보건학과EMAIL:[email protected]_YN:YN

Characterization of fullerene C60 nanomaterials within commercial face cream byproducts

International audienceno abstrac

Enhancement of Physical Characteristics of Styrene–Acrylonitrile Nanofiber Membranes Using Various Post-Treatments for Membrane Distillation

Insufficient mechanical strength and wide pore size distribution of nanofibrous membranes are the key hindrances for their concrete applications in membrane distillation. In this work, various post-treatment methods such as dilute solvent welding, vapor welding, and cold-/hot-pressing processes were used to enhance the physical properties of styrene–acrylonitrile (SAN) nanofiber membranes fabricated by the modified electrospinning process. The effects of injection rate of welding solution and a working distance during the welding process with air-assisted spraying on characteristics of SAN nanofiber membranes were investigated. The welding process was made less time-consuming by optimizing system parameters of the electroblowing process to simultaneously exploit residual solvents of fibers and hot solvent vapor to reduce exposure time. As a result, the welded SAN membranes showed considerable enhancement in mechanical robustness and membrane integrity with a negligible reduction in surface hydrophobicity. The hot-pressed SAN membranes obtained the highest mechanical strength and smallest mean pore size. The modified SAN membranes were used for the desalination of synthetic seawater in a direct contact membrane distillation (DCMD). As a result, it was found that the modified SAN membranes performed well (>99.9% removal of salts) for desalination of synthetic seawater (35 g/L NaCl) during 30 h operation without membrane wetting. The cold-/hot-pressing processes were able to improve mechanical strength and boost liquid entry pressure (LEP) of water. In contrast, the welding processes were preferred to increase membrane flexibility and permeation

Efficient Phosphorus Recovery from Municipal Wastewater Using Enhanced Biological Phosphorus Removal in an Anaerobic/Anoxic/Aerobic Membrane Bioreactor and Magnesium-Based Pellets

Municipal wastewater has been identified as a potential source of natural phosphorus (P) that is projected to become depleted in a few decades based on current exploitation rates. This paper focuses on combining a bench-scale anaerobic/anoxic/aerobic membrane bioreactor (MBR) and magnesium carbonate (MgCO3)-based pellets to effectively recover P from municipal wastewater. Ethanol was introduced into the anoxic zone of the MBR system as an external carbon source to improve P release via the enhanced biological phosphorus removal (EBPR) mechanism, making it available for adsorption by the continuous-flow MgCO3 pellet column. An increase in the concentration of P in the MBR effluent led to an increase in the P adsorption capacity of the MgCO3 pellets. As a result, the anaerobic/anoxic/aerobic MBR system, combined with a MgCO3 pellet column and ethanol, achieved 91.6% P recovery from municipal wastewater, resulting in a maximum P adsorption capacity of 12.8 mg P/g MgCO3 through the continuous-flow MgCO3 pellet column. Although the introduction of ethanol into the anoxic zone was instrumental in releasing P through the EBPR, it could potentially increase membrane fouling by increasing the concentration of extracellular polymeric substances (EPSs) in the anoxic zone

Active Control of Irreversible Faradic Reactions to Enhance the Performance of Reverse Electrodialysis for Energy Production from Salinity Gradients

Irreversible faradic reactions in reverse electrodialysis (RED) are an emerging concern for scale-up, reducing the overall performance of RED and producing environmentally harmful chemical species. Capacitive RED (CRED) has the potential to generate electricity without the necessity of irreversible faradic reactions. However, there is a critical knowledge gap in the fundamental understanding of the effects of operational stack voltages of CRED on irreversible faradic reactions and the performance of CRED. This study aims to develop an active control strategy to avoid irreversible faradic reactions and pH change in CRED, focusing on the effects of a stack voltage (0.9-5.0 V) on irreversible faradic reactions and power generation. Results show that increasing the initial output voltage of CRED by increasing a stack voltage has an insignificant impact on irreversible faradic reactions, regardless of the stack voltage applied, but a cutoff output voltage of CRED is mainly responsible for controlling irreversible faradic reactions. The CRED system with eliminating irreversible faradic reactions achieved a maximum power density (1.6 W m-2) from synthetic seawater (0.513 M NaCl) and freshwater (0.004 M NaCl). This work suggests that the control of irreversible faradic reactions in CRED can provide stable power generation using salinity gradients in large-scale operations. Accepted Author ManuscriptChemE/Transport Phenomen

Physical-chemical characterization of residues from alteration of engineered nanomaterials: Commercialized sunscreens containing titanium dioxide nanoparticles

International audienceno abstrac

Long-Term Transformation and Fate of Manufactured Ag Nanoparticles in a Simulated Large Scale Freshwater Emergent Wetland

Transformations and long-term fate of engineered nanomaterials must be measured in realistic complex natural systems to accurately assess the risks that they may pose. Here, we determine the long-term behavior of poly­(vinylpyrrolidone)-coated silver nanoparticles (AgNPs) in freshwater mesocosms simulating an emergent wetland environment. AgNPs were either applied to the water column or to the terrestrial soils. The distribution of silver among water, solids, and biota, and Ag speciation in soils and sediment was determined 18 months after dosing. Most (70 wt %) of the added Ag resided in the soils and sediments, and largely remained in the compartment in which they were dosed. However, some movement between soil and sediment was observed. Movement of AgNPs from terrestrial soils to sediments was more facile than from sediments to soils, suggesting that erosion and runoff is a potential pathway for AgNPs to enter waterways. The AgNPs in terrestrial soils were transformed to Ag₂S (∼52%), whereas AgNPs in the subaquatic sediment were present as Ag₂S (55%) and Ag-sulfhydryl compounds (27%). Despite significant sulfidation of the AgNPs, a fraction of the added Ag resided in the terrestrial plant biomass (∼3 wt % for the terrestrially dosed mesocosm), and relatively high body burdens of Ag (0.5–3.3 μg Ag/g wet weight) were found in mosquito fish and chironomids in both mesocosms. Thus, Ag from the NPs remained bioavailable even after partial sulfidation and when water column total Ag concentrations are low (<0.002 mg/L)