A Study to Enhance the Nitrate-Nitrogen Removal Rate without Dismantling the NF Module by Building a PFSA Ionomer-Coated NF Module

Abstract

Water resource pollution by nitrate-nitrogen, mainly caused by anthropogenic causes, induces eutrophication of water resources, and indicates the degree of organic pollution. Therefore, this study devised a method for coating PFSA ionomer with excellent chemical resistance without disassembling the module to improve the removal rate of nitrate-nitrogen in water by using a cyclic coating method on a commercially available nanofiltration membrane (NF membrane) module. Nafion was prepared as a supercritical fluid dispersion using a high-temperature and high-pressure reactor, and the particle size and the degree of dispersion of the dispersion were analyzed by DLS. The crystallinity was confirmed through XRD by drying the dispersion in the liquid state. After the dispersion was prepared as a membrane according to the heat treatment conditions, the characteristics according to the particle size were analyzed by tensile strength and TEM. The nitrate-nitrogen removal rate of the NF membrane module coated with the dispersion was increased by 93% compared to that before coating. Therefore, the result showed that the cycle coating method devised in this study could efficiently coat the already commercialized module and improve performance.

Dynamic Mechanical Fatigue Behavior of Polymer Electrolyte Membranes for Fuel Cell Electric Vehicles Using a Gas Pressure-Loaded Blister

“…In contrast to Nafion 211, the Nafion XL membrane has additional PTFE-support reinforcements and cerium-based radical scavengers to exhibit improved mechanical and chemical stability [ 32 ], which can be evidenced by SAXS results ( Figure 5 and Table 2 ). From the SAXS analysis, the size of the hydrophilic domains for the ion passway grew longer after hydrogen gas blistering from 3.10 nm to 3.22 nm for Nafion 211, and from 3.03 nm to 3.31 for Nafion XL, respectively [ 33 ]. Consequently, this trend was also consistent with the results of proton conductivity changes [ 34 ].…”

Nitrate Water Contamination from Industrial Activities and Complete Denitrification as a Remediation Option

“…Physical NO 3 − remediation from water includes the elimination and removal of NO 3 − , generally with a membrane that filters, repels, and in other applications binds to the NO 3 − ions [105]. Several of these membranes can be chemically charged with compounds that react to the NO 3 − , converting its state to a lesser oxidized form, hence referred to as physico-chemical remediation [106].…”

“…The IX method uses resins that are chemically charged with a strong base anion, allowing exchange of chloride or carbonates that exchange with NO 3 − ions on the resin [93]. In industrial wastewater remediation, application of IX removes SO 4 − prior to NO 3 − , which is a disadvantage when having both contaminants are present in high concentrations [106]. The method requires extensive maintenance, including washing and recharging the resins, and creates brine dumps of NO 3…”

Influence Law and Mechanism of Magnetic Field on Accumulation of Nitrite Nitrogen in Denitrification Process

“…While both NTR and NAR fluctuated and increased, the growth rate of NAR was lower than that of NTR, indicating that there was resistance in the denitrification reaction process in the system. Figure 5 shows the removal rate of under different magnetic field strengths of the four groups of reactors [17]. It can be seen from the figure that with the start-up process of the reactor, the removal rate of decreases, and the removal rate of nitrate nitrogen under the condition of an external magnetic field is lower than that of the reactor without a magnetic field, and the magnetic field strength of 50 mT with the highest accumulation of nitrous nitrogen is the magnetic reactor with the lowest nitrate removal rate.…”