Adsorption kinetics and mechanism analysis of cyan printing dye on polyethylene microplastics

Printing on polymer materials might result with generation of coloured wastewater, enriched with a certain amount of microplastics in a form of polyethylene or polypropylene. In that way, microplastics may acquire the function of carriers of synthetic dyes, heavy metals and other polluting substances. In this paper, kinetics and adsorption mechanism of printing Cyan dye on polyethylene (powdered and granulated), as one of the most common types of microplastics, were investigated. The experiments were performed in a batch mode, in laboratory conditions. Based on the obtained results, a similar adsorption rate degree of selected printing dye was determined on granulated (adsorbed amount was 48.04 µg/g) and powdered material (adsorbed amount was 44.32 µg/g). The adsorption data were fitted well by pseudo-second-order kinetics, while isotherm studies were evaluated using two models: Langmuir and Freundlich. Freundlich and Langmuir equations showed similar performances to fit the solid/liquid distribution of Cyan dye on powdered polyethylene (R2 = 0.987), whereas Langmuir equation showed slightly better performances for granulated polyethylene than Freundlich equation

Application of green technology to extract clean and safe bioactive compounds from tetradesmus obliquus biomass grown in poultry wastewater

Microalgae are capable of assimilating nutrients from wastewater (WW), producing clean water and biomass rich in bioactive compounds that need to be recovered from inside the microalgal cell. This work investigated subcritical water (SW) extraction to collect high-value compounds from the microalga Tetradesmus obliquus after treating poultry WW. The treatment efficiency was evaluated in terms of total Kjeldahl nitrogen (TKN), phosphate, chemical oxygen demand (COD) and metals. T. obliquus was able to remove 77% TKN, 50% phosphate, 84% COD, and metals (48-89%) within legislation values. SW extraction was performed at 170 degrees C and 30 bar for 10 min. SW allowed the extraction of total phenols (1.073 mg GAE/mL extract) and total flavonoids (0.111 mg CAT/mL extract) with high antioxidant activity (IC50 value, 7.18 mu g/mL). The microalga was shown to be a source of organic compounds of commercial value (e.g., squalene). Finally, the SW conditions allowed the removal of pathogens and metals in the extracts and residues to values in accordance with legislation, assuring their safety for feed or agriculture applications.Serbia 142-451-2576/2019-02; 337-00-00227/2019-09/72 (Serbia); project ALGAVALOR—Lisboa-01-0247-FEDER-035234; LISBOA-01-0145-FEDER-022059; Red CYTED P319RT0025—RENUWAL;info:eu-repo/semantics/publishedVersio

Uticaj doze ozona i UV zračenja na potencijalnu toksičnost podzemne vode nakon O3/UV unapređenog oksidacionog procesa

In this study the impact of ozonation and advanced O3/UV oxidation process on the general toxicity of the groundwater was examined by using the Allium anaphase-telophase test. Investigated oxidation treatments lead to increasing the toxicity of groundwater in comparison to raw water. Ozonation process lead to increasing of toxicity mostly as a consequence of bromate formation. On the other hand O3/UV process lead to increasing of toxicity as a result of formation of brominated organic by-products.U ovom radu ispitivan je uticaj tretmana vode ozonom i primene unapređenog O3/UV procesa na opštu toksičnost podzemne vode primenom Allium anafazno-telofaznog testa. Ispitivani oksidacioni tretmani dovode do povećanja toksičnosti podzemne vode u odnosu na sirovu vodu. Proces ozonizacije dovodi do povećanja toksičnosti vode najvećim delom kao rezultat formiranja bromata. S druge strane, primena O3/UV procesa dovodi do povećanja toksičnosti vode kao rezultat formiranja bromovanih organskih nusproizvoda

Sorption-desorption behaviour of hydrophobic organic compounds on Danube sediment

The sorption-desorption hysteresis of naphthalene and phenanthrene onto Danube sediment was investigated. Hysteresis indices (HI) are calculated for three equilibrium concentration (Ce=1%, 5% i 50% of the solubility in water). The results of sorption-desorption hysteresis indicated that it exists for both investigated sorbates on the Danube sediment. For more hydrophobic compound, phenanthrene (logKOW< 4.55) hysteresis is less pronounced in comparison with naphthalene (logKOW< 3.36). In the case of naphthalene, the existence of hysteresis may be due to irreversible pore deformation of the sorbent which causes the formation of meta-stable states in the sorbate mesopores

Enhanced coagulation with pre-oxidation for the removal of arsenic from groundwater

One of the most wide-spread problems with current drinking water resources globally is the natural presence of arsenic in groundwaters. The aim of this work was to investigate the removal of arsenic by a variety of combined oxidation/coagulation processes, in order to identify and optimise the most critical process parameters. The most significant gains made by both preoxidation steps were observed in the techniques which combined aluminum and ferric chloride based coagulation. The most efficient coagulation treatment investigated involved application of preozonation at a dose of 7.5 mg O3/l with subsequent combined coagulation with PACl–FeCl3 (30 mg Al/l and 10 mg FeCl3/l)

Photochemical degradation of alachlor in water

This study investigates the photochemical degradation of alachlor, a chloroacetanilide herbicide. All experiments were conducted in ultra-pure deionized water (ASTM Type I quality) using direct ultraviolet (UV) photolysis and the UV/H2O2 advanced oxidation process. The direct UV photolysis and UV/H2O2 experiments were conducted in a commercial photochemical reactor with a quartz reaction vessel equipped with a 253.7 nm UV low pressure mercury lamp (Philips TUV 16 W). The experimental results demonstrate that UV photolysis was very effective for alachlor degradation (up to 97% removal using a high UV fluence of 4200 mJ/cm2). The UV/H2O2 process promoted alachlor degradation compared to UV photolysis alone, with a high degree of decomposition (97%) achieved at a significantly lower UV fluence of 600 mJ/cm2 when combined with 1 mg H2O2/L. The application of UV photolysis alone with a UV fluence of 600 mJ/cm2 gave a negligible 4% alachlor degradation. The photo degradation of alachlor, in both direct UV photolysis and the UV/H2O2 process, followed pseudo first-order kinetics. The degradation rate constant was about 6 times higher for the UV/H2O2 process than for UV photolysis alone

Sorption Behavior of Organic Pollutants on Biodegradable and Nondegradable Microplastics: pH Effects

Microplastics (MPs), chlorinated phenols (CPs), polycyclic aromatic hydrocarbons (PAHs) and halogenated benzenes (HBs) are pollutants that are widely present in freshwater systems. As alternatives to conventional plastics, bioplastics are receiving a lot of attention, but there are limited data on their impact on pollutant behavior. This work therefore investigated the impact of pH on the sorption of CPs, PAHs and HBs, as some of the toxic and highly persistent pollutants, on seven different plastics using kinetic and isotherm studies. The pH of the water matrix impacted the adsorption behavior of CPs on all selected MPs, with the highest degree of adsorption occurring at pH 7 for the majority of the selected CPs. The highest adsorption affinity of CPs on the MPs, at pH 7, was obtained for 4-chlorophenol and 2,4-dichlorophenol on powdered polyethylene standard (qt = 221 μg/g), while the lowest was obtained for the adsorption of pentachlorophenol on polyethylene terephthalate (qt = 25 μg/g). On the other hand, the pH value of the water matrix did not affect the adsorption of halogenated benzenes and PAHs on MPs. The pseudo-second-order rate model fit the adsorption kinetics data of all experiments. The results obtained for the adsorption of CPs on MPs indicated a lower sorption affinity of CPs with MPs at pH 4 and pH 10 compared to pH 7. The Langmuir isotherm, at pH 7, implied that 4-chlorophenol’s adsorption affinity was not significantly influenced by the type of MPs. On the other hand, at pH 7, the adsorption of 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol varied greatly, with powdered MP types showing the highest affinity for CP adsorption. Furthermore, the obtained adsorption isotherm results imply that electrostatic attraction, hydrogen bonds, π-π interactions and van der Waals interactions, are an integral part of adsorption mechanisms of the CPs on the MPs

Impact of Microplastics on the Fate and Behaviour of Arsenic in the Environment and Their Significance for Drinking Water Supply

The ubiquitous presence of microplastics (MPs) is a topic of great concern. Not only do MPs themselves represent potential toxicants for human health, they are never found alone in the environment and interact with and adsorb a variety of toxicologically significant pollutants. This review summarises recent work on interactions between MPs and heavy metals in the environment, with a special focus on arsenic, one of the most widespread and problematic water contaminants. Evidence for the adsorption of arsenic onto MP surfaces is given and the recent research into the consequences of this phenomenon for freshwater, marine, and soil environments presented. Finally, the lack of research into the significance of interactions between arsenic and MPs during drinking water treatment is highlighted. The performance of arsenic removal technologies is governed by a multitude of different factors, and with MPs detected in water sources all over the world, data on how these MPs impact the removal of arsenic and, indeed, other major water contaminants are urgently needed

Spectrophotometric determination of bifonazole in pharmaceutical formulations using bromphenol blue

A sensitive spectrophotometric method for the determination of bifonazole is described. Bifonazole was treated with bromphenol blue (BPB) in the presence of citrate buffer (pH 2.5; μ = 0.23). The formed ion-pair complex was extracted with chloroform. By using spectrophotometric measurements, Job's and Bent-French's methods, it was found that bifonazole and BPB formed an ion-pair complex with the absorption maximum at 414 nm (molecular ratio of bifonazole BPB = 1:2) and molar absorptivity 2.23 x 104 L mol-1 cm-1. Beer's law was obeyed up to 2.5 μg ml-1. The proposed method was applied for determination of bifonazole in pharmaceutical formulations. Statistical analysis of the results obtained showed that the proposed method has good reproducibility and precision