Halogenated By-Products in Chlorinated Indoor Swimming Pools: A Long-Term Monitoring and Empirical Modeling Study.

Monitoring the disinfection process and swimming pool water quality is essential for the prevention of microbial infections and associated diseases. However, carcinogenic and chronic-toxic disinfection by-products (DBPs) are formed with reactions between disinfectants and organic/inorganic matters. DBP precursors in swimming pools originate from anthropogenic sources (body secretions, personal care products, pharmaceuticals, etc.) or chemicals used in pools. Temporal (48 weeks) water quality trends of trihalomethanes (THMs), haloacetic acids (HAAs), haloacetonitriles (HANs), and halonitromethanes (HNMs) in two swimming pools (SP-A and SP-B) and precursor-DBP relationships were investigated in this study. Weekly samples were taken from swimming pools, and several physical/chemical water quality parameters, absorbable organic halides (AOX), and DBPs were determined. THMs and HAAs were the most detected DBP groups in pool water. While chloroform was determined to be the dominant THM compound, dichloroacetic acid and trichloroacetic acid were the dominant HAA compounds. The average AOX concentrations were measured to be 304 and 746 µg/L as Cl- in SP-A and SP-B, respectively. Although the amount of AOX from unknown chlorinated by-products in SP-A did not vary temporally, a significant increase in unknown DBP concentrations in SP-B was observed over time. AOX concentrations of chlorinated pool waters were determined to be an important parameter that can be used to estimate DBP concentrations.

Copper recovery by cementation process from polymeric membrane concentrate flows and sensor integration.

In this study, copper recovery and sensor integration for concentrate flows of membrane processes were studied. In the first phase, cementation tests for copper recovery were carried out with various different Fe/Cu stoichiometric ratios, copper concentrations, temperatures, and stirring speeds. The effects of the parameters which were stirring speed, temperature, stoichiometric ratio, and concentration in the solution on the cementation process were determined. In the second phase, a novel electroanalytical sensor was applied to concentrate flow. The application of cementation within the scope of precious metal recovery from concentrate streams by integrating a sensor to the process as an innovative online-sensing-approach is conducted. Four different copper concentrations (64, 128, 512, 1280 mg/L) and 5 different Fe/Cu stoichiometric ratios for these concentrations were studied. For concentrations of 64 mg/L and 128 mg/L, 1/1, 2/1, 5/1, 7/1, 10/1 Fe/Cu ratios and for both 512 mg/L and 1280 mg/L concentrations, 1/1, 1.25/1, 1.5/1, 1.75/1, 2/1 Fe/Cu ratios were applied. The cumulative average of ICP-MS linearity of developed electroanalytical sensor was 94.9%. The efficient recovery of copper from the concentrate flows with the sensor integrated-cementation process has a strong potential for "Industry 4.0" applications with enhanced automation levels.

Preparation and analytical application of the novel Hg(II)-selective membrane electrodes based on oxime compounds.

Novel Hg(II)-selective poly(vinyl) chloride (PVC) membrane electrodes based on oxime compounds of (4-(4-methylphenylaminoisonitrosoacetyl)biphenyl, I1; 4-(4-clorophenylaminoisonitrosoacetyl)biphenyl, I2; N,N-bis[1-(4-phenylphenyl)-2-hydroxyimino-2-(4-chloroaniline)-1-ethylidene]-diethylenetriamine, I3 and N,N-bis[1-(4-phenylphenyl)-2-hydroxyimino-2-(4-chloroaniline)-1-ethylidene]- 1,3-propanediamine), I4 were developed. Effects of the species and ratios of ionophore, plasticizer, PVC and lipophilic additive on the potentiometric response of electrodes were investigated in order to determine the electrode specifications. Overall results revealed that the optimum membrane composition was: 4% ionophore, 64% plasticizer (o-NPOE), 31% PVC, and 1% lipophilic additive (NaTPB). Obtained results showed that the electrodes have detection limit of 1.76×10(-6), 1.68×10(-6), 2.35×10(-6) and 2.44×10(-6) and have linear responses of 34.2, 33.4, 35.9 and 37.6 mV/pHg(2+) for a wide concentration range of Hg(II) ions. According to durability studies, the electrodes can be used for approximately 1 month without any considerable divergence in potential values. Analytical applications of the electrodes were performed and it was found that developed electrodes can successfully be used as indicator electrodes for the potentiometric titration of Hg(II) ion with EDTA solution.