The main aim of this study is to investigate the feasibility of utilising novel hydrotalcite-like-compounds as ion-exchangers for the removal of anionic impurities from aqueous solution. Hydrotalcite ...is naturally occurring, rarely found anionic clay. It has a positively charged layered structure consisting of two metal oxide layers and an interlayer of carbonate anions. Hydrotalcites can, therefore, be used as ion-exchangers. However, the carbonate anion is highly selected by natural hydrotalcite, making the ion-exchange capacity for other anions very low. In this study, several synthetic hydrotalcite-like compounds and a magnetic hydrotalcite-like compound samples were prepared in order to remove anionic impurities from waters. The physical structure and chemical properties of these anionic clays were characterised using standard characterisation techniques. The removal capacities of the synthetic products obtained were then investigated. Magnetic hydrotalcite-like-compound, namely, CaII-FeII-FeIII, was proved to be a good ion-exchanger.
To assess climate change impact on the hydrology of Izmit Bay, a coupled model chain using the results of four combinations of Global Climate Models (GCMs) and Regional Climate Models (RCMs) and ...consisting two hydrological models (mGROWA and PROMET) and one hydrodynamic model (MIKE 3HD) was established. Climate model data of the 4 GCM-RCM combinations were applied to both hydrological models. The resulting 8 streamflow data of the hydrological models were then applied to the MIKE 3HD to assess possible hydrodynamic situations in Izmit Bay. Related model results indicate a range of possible future streamflow regimes suitable for the analysis of climate change impact on Izmit Bay. In order to evaluate the effects of the hydrological changes only on the bay, the bay was considered as closed in terms of hydrodynamics. There is a clear indication that the climate change induced impacts on streamflow may influence the sea level in the Bay to a minor extent. However, climate change induced water exchange processes in the Bay may have a much bigger influence. Hence, it is suggested that further simulations should be run once the hydrologic regime of the Marmara Sea has been assessed in a broader macro-scale study.
The bacterial communication through signaling molecules termed quorum sensing has gained a lot of attention due to its applicability to different fields of study. Quorum sensing regulates several ...bacterial activities such as biofilm formation, antibiotic resistance, bioluminescence and bacterial virulence. These coordinated activities are only realized when the bacterial population reaches a high population density. The signaling molecules used in quorum sensing occur at very low concentrations which call for very sensitive methods for their identification and characterization. Many studies have been performed on the use of inhibitors in attempt to disrupt quorum sensing and consequently alleviate its negative effects. This article gives a description of the types of auto-inducers involved in quorum sensing and the fields of study they greatly affect especially the environmental one. It also covers types of analytical sample preparation and detection methods, and different types of inhibitors used for quorum quenching.
•Auto-inducers used in quorum sensing for bacterial communication.•Impact of quorum sensing on environmental and biological systems.•Sensitive analytical methods for accurate and precise determination of auto-inducers.•Prospects of inhibitors for quorum quenching.
This study utilized switchable solvent liquid-phase microextraction (SS-LPME) to enrich eleven nervous system active pharmaceutical ingredients (APIs) from aqueous samples for their determination at ...trace levels by gas chromatography mass spectrometry. The analytes selected for the study included APIs utilized in antidepressant, antipsychotic, antiepileptic, and anti-dementia drugs. Parameters of the microextraction method including switchable solvent volume, concentration and volume of the trigger agent (sodium hydroxide), and sample agitation period were optimized univariately to boost extraction efficiency. Under the optimum conditions, the detection limits calculated for the analytes were in the range of 0.20–8.0 ng/mL, and repeatability for six replicate measurements as indicated by percent relative standard deviation values were below 10%. Matrix matching calibration strategy was used to enhance quantification accuracy for the analytes. The percent recovery results calculated for the eleven analytes ranged between 86 and 117%.
A magnetic Fe3O4/reduced graphene oxide composite was synthesized by a one-step chemical coprecipitation method and characterized by different methods. The synthesized magnetic composite was used as ...magnetic sorbent in dispersive solid phase extraction process for preconcentration of 4-tert octylphenol and atrazine. The experimental variables in dispersive solid phase extraction were optimized based on two strategies: one-factor-at-a-time for mixing type and buffer pH; Box Behnken design for sorbent amount, mixing period, eluent volume and buffer volume. Analysis of variance study for proposed model resulted to high determination coefficient (R2) of 0.957 and adjusted-R2 of 0.929 indicating a good adjustment of regression model with observed values. Under the optimum extraction conditions, the determination of analytes was carried out by a gas chromatography–mass spectrometry system. The limits of detection and quantification values under the optimum conditions were found to be 1.23 and 4.10 ng mL−1 for 4-tert octylphenol and 6.81 and 22.71 ng mL−1 for atrazine, respectively. The low relative standard deviation (≤ 6.2%) indicated good repeatability and satisfactory percent recovery values (96.3–112.6%) demonstrated the applicability of proposed method to tap water, river water and waste water samples.
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•A three factor Box-Behnken experimental design was used to optimize microextraction method for the analyes.•The detection limits were found to be 1.23 and 6.81 ng mL−1 for 4-tert octylphenol and atrazine, respectively.•Appreciable recovery values were obtained for tap water, river water and waste water samples.
•Electro-Fenton (EF) process is used for the first time as a new method for shale gas wastewater treatment.•RSM was used to determine optimum operating conditions for EF process.•Analysis of variance ...(ANOVA) was found to be significant for all the responses.•The operational cost of the EF process at optimum conditions was determined.
Shale gas is an alternative natural source of energy resulting from the anaerobic degradation of organics within shale formations. However, shale gas exploration is accompanied by shale gas wastewater production constituting a new source of pollution threatening the environment. Electro-Fenton process (EF) is used for the first time in this study as a new method for shale gas wastewater treatment where the optimum operating parameters of the the responses including COD, color, total phenol removal efficiencies and waste sludge volume were determined using a response surface methodology (RSM). Based on the analysis of variance (ANOVA), the coefficient of determination (R2) was calculated and found to be above 0.94 for all the responses. The maximum removal efficiencies were found to be around 87.35%, 89.15%, and 91.75% for COD, color, and total phenol removal under the optimum conditions, respectively. The operational cost of the EF process applied to shale gas wastewater for COD removal at optimum conditions was determined to be 4.13 €/m3. The results indicated that the electro-Fenton seems to be an efficient treatment method for shale gas wastewater.
In this study, seven compounds of environmental and health concern were treated by electrooxidation to determine their removal efficiencies from domestic wastewater. A batch type lab-scale reactor ...was used for the treatment process, and the analytes studied included two obsolete pesticides, two alkylphenols, two hormones, and bisphenol A. Titanium oxide and graphite electrodes were used as anode and cathode, respectively. Parameters of the electrooxidation process including pH of wastewater, ionic strength, applied current and treatment period were optimized by the univariate approach to maximize the removal efficiency of the analytes from wastewater. The optimum conditions were determined as nonadjusted pH of wastewater, 1.5 A current, 15 min treatment period and 5.0 g/L sodium chloride. Dispersive liquid-liquid microextraction was used to preconcentrate analytes before and after treatment in order to calculate the removal efficiency of analytes. The removal efficiency obtained under the optimum conditions was satisfactory for all seven analytes at different influent concentrations.
Atrazine is a triazine herbicide widely used for the control of weeds. Physico-chemical characteristics of atrazine such as long half-life, low vapor pressure, low pKa, and high mobility have led to ...its persistence in the environment. Thus, atrazine may accumulate and exceed acceptable levels in terrestrial ecosystems, groundwater, and surface water bodies. Several studies related to atrazine determination have been performed as the first step to monitor its presence in the environment. In addition, various treatment strategies have been developed for the efficient removal of atrazine from wastewater. This review summarizes the primary methods for atrazine determination, focusing upon selective and sensitive methods that achieve low detection limits (ng/L). In addition, several treatment strategies that recorded removal efficiencies from 7.0 to 99.70% for atrazine are discussed.
A large amount of water is used in the textile industry during the finishing and dyeing processes leading to the production of what is known as textile wastewaters. Textile wastewater is highly rich ...in COD and color and is characterized by relatively low biodegradability. This study aimed to investigate the treatability of reactive red dye-rich textile wastewater with the application of an airlift internal circulation membrane bioreactor (AIC-MBR). Experimental results demonstrated that high removal efficiencies of COD, NH3-N, and reactive red up to 99.70%, 97.83%, and 97.23%, respectively, can be achieved using the AIC-MBR system. Besides, EPS and SMP analyses reflected an SMP polysaccharide (PS) and protein (PN) membrane rejection that reached 88% and 72.6%, respectively. Finally, the capillary suction time measurement highlighted a good dewatering capacity of the sludge with a low membrane fouling tendency at the end of the operating period.
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