Synthetic dyes or colorants are key chemicals for various industries producing textiles, food, cosmetics, pharmaceutics, printer inks, leather, and plastics. Nowadays, the textile industry is the major consumer of dyes. The mass of synthetic colorants used by this industry is estimated at the level of 1 ÷ 3 × 105 tons, in comparison with the total annual consumption of around 7 × 105 tons worldwide. Synthetic dyes are relatively easy to detect but difficult to eliminate from wastewater and surface water ecosystems because of their aromatic chemical structure. It should be highlighted that the relatively high stability of synthetic dyes leads to health and ecological concerns due to their toxic, mutagenic, and carcinogenic nature. Currently, removal of such chemicals from wastewater involves various techniques, including flocculation/coagulation, precipitation, photocatalytic degradation, biological oxidation, ion exchange, adsorption, and membrane filtration. In this review, a number of classical and modern technologies for synthetic dye removal from industry-originated wastewater were summarized and discussed. There is an increasing interest in the application of waste organic materials (e.g., compounds extracted from orange bagasse, fungus biosorbent, or green algal biomasses) as effective, low-cost, and ecologically friendly sorbents. Moreover, a number of dye removal processes are based on newly discovered carbon nanomaterials (carbon nanotubes and graphene as well as their derivatives).

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In the latest literature search, the technology based on graphite oxide (GO) nanomaterials exhibits a great potential in many aspects of wastewater treatment involving adsorption, photocatalysis, disinfection and membrane process. In this study experimental data involving the carbon element in different forms such as active carbon (AC), graphite and graphene oxide (GO) applied as the active reagents in wastewater treatment are summarized and discussed. The first step was to characterize the aforementioned carbon materials and nanoparticles using various complementary techniques. These include optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Raman spectrophotometry and zeta potential measurements. The second issue was to design the relatively simple experiment enabling us to observe the physicochemical and biological effects of carbon nanoparticles in the presence of sewage water and/or active sludge. Obtained experimental data have been inspected using univariate and multivariate (principal component analysis, PCA) approaches confirming the complex interaction of GO nanoparticles with microorganisms that are present in activated sludge. This experiment enabled the collection of an initial data set to design different large scale investigations focusing on active nanoparticles affecting wastewater purification. PCA calculations clearly revealed that GO strongly affects the wastewater technological processes investigated. It is hoped that the described results will allow the design of smart environmental protection systems in the future.

We report the results of experimental work focusing on host-guest supramolecular complex creation between macrocyclic compound (β-cyclodextrin) and 1-acenaphthenol enantiomers (racemic mixture) in liquid phase composed of 35% acetonitrile in water (v/v) at different temperatures ranging from 0 to 90 °C. Experimental setup involved several analytical protocols based on classical non-forced flow planar chromatography (RP-18 TLC plates), micro-TLC (RP-18 W HPTLC plates), column chromatography (HPLC with C-18 and C-30 stationary phases), as well as UV-Vis spectrophotometry and optical microscopy. It has been found that under various planar chromatographic conditions (stationary plates type, chamber shape and volume, development mode, and saturation) non-typical retention properties (extremely high retention) of 1-acenaphthenol at subambient temperatures can be observed. To our knowledge, reported experimental results are in opposition to currently described retention models based on column chromatographic investigation of host-guest complexes (where in case of strong interaction of given analyte with macrocyclic mobile phases additive, which itself is non strongly retarded by stationary phase—close to the retention of dead volume marker, the retention of target compounds is shortened at low temperatures). To explain this TLC phenomenon that may have in our opinion a number of practical applications, especially for selective high throughput separation involving microchromatographic and/or microfluidic devices as well fractionation and extraction protocols (using, e.g., bar extraction systems), several experiments were conducted focusing on (i) acenaphthenol chromatography under different instrumental conditions, (ii) cyclodextrin retention measured as analyte or mobile phase additive, (iii) plate development time under different mobile phases and temperature settings, (iv) various column chromatographic conditions including C-30 and two C-18 stationary phases, (v) UV-Vis spectrophotometry, and (vi) microscopy inspection of precipitated CD-acenaphthenol crystals. Analysis of collected data has revealed that the most probable reasons for TLC retention behavior of 1-acenaphthenol under β-cyclodextrin additive conditions can be associated with (i) solubility changes of created host-guest complex, (ii) kinetics of solid complex precipitation, and (iii) differences in analysis time between planar and column chromatography. Because precipitation phenomenon may have a massive impact on analytes quantification involving macrocycles as the mobile phase additives, our previously reported data concerning a number of low-molecular compounds (mainly steroids and non steroidal endocrine disrupting chemicals) using HPLC methodology based on binary mobile phases without and with β-cyclodextrin and its hydroxypropyl derivative were re-examined and results discussed. Considering these data and the whole data set reported presently, the enhanced model of chromatographic retention driven by host-guest interaction was proposed.Electronic s...

There is great interest in the search for multifunctional waste-based materials that may be applied as environmentally friendly adsorbents. Iron-rich sludge from ground drinking-water treatment plants may be considered a potential adsorbent for various water contaminants. This material is generated during ground water purification because of the excess of metal ions in water (Fe, Mn). In practice, this sludge is frequently disposed of as waste material and, so far, is not commonly applied as the adsorption base. Our research aims to explore the adsorption potential of iron sludge for selected synthetic dyes, including malachite green, ponceau 4R, and brilliant blue FCF. Experimental data were performed using iron sludge collected from the Groundwater Treatment Plant in Koszalin, Poland, and comparing it with adsorption properties of commercial activated carbons (Norit SA Super and Norit CA 1). The kinetics, adsorption isotherms, and temperature influence on the removal of target dyes were investigated and discussed. Preliminary experimental data have revealed that iron sludge can be considered an adsorbent for the removal of cationic dyes.