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Textile dye effluents and textile waste disposal represent two significant environmental challenges. Here, we present possible combined solution for both. Urea-derived graphitic carbon nitride g-C3N4 is thermally exfoliated to nano n-C3N4. Both obtained materials are characterized in detail, and their photocatalytic efficacies in photodegradation of three textile azo dyes under simulated solar light irradiation are compared. n-C3N4 exhibited superior performance over g-C3N4 under given experimental conditions. Novelty of the work is the subsequent usage of the non-woven jute post-industrial waste as a photocatalyst support. It was shown that NW jute impregnated with n-C3N4 can be successfully used in three consecutive photocatalytic cycles, keeping high photodegradation efficacy (~ 90% in the case of Acid Orange 7, and 55% in the case of Acid Blue 113). Additionally, possibility of usage of NW jute post-industrial waste as textile dye sorbent is presented in the case of Basic Yellow 28.

Nickel-alumina composites with various content of nickel were synthetized by sol-gel method. The characterization of samples was performed by diffuse reflectance spectroscopy and electrochemical impedance spectroscopy using the Mott-Schottky analysis. Glassy carbon electrode modified by synthesized composites was investigated for reduction of 4-nitrophenol. Modification of glassy carbon electrode with composite sample led to the strong apparent electrocatalysis. Principal component analysis was used to establish correlation between structural, textural and electrochemical data of investigated composites.

The goal of this work was the synthesis of a montmorillonite based catalyst for advanced oxidative degradation of organic water pollutants. Montmorillonite (Mt) –rich bentonite was acid-activated (MtA), and impregnated with cobalt (II) solution using the incipient wetness impregnation method. The impregnation was followed by heat treatment. Cobalt(II) ions were added in the quantities corresponding to 0.5 and 1.0 of the cation exchange capacity value. All samples were characterized by using chemical analysis, X-ray powder diffraction (XRPD), Electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM) coupled with Energy-dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM) and low temperature N2 physisorption. The incorporation of the cobalt in the impregnated samples and the development of porous structure in the acid-activated ones were confirmed. The montmorillonite (Mt) was used as a catalyst support, while the cobalt in its oxide form was responsible for the generation of sulfo-radicals from Oxone®. Two aromatic N-compounds were tested as model pollutants: diazo dye - Acid Orange 10 (AO10) and nicotine. It was found that the synthesized catalysts could be used for the degradation of both pollutants, although more efficiently in AO10 degradation. The acid activation, higher cobalt loading, and temperature were found to be beneficial for the degradation of AO10.

Alumina powders, pure and doped with nickel, were synthetized by sol-gel method and calcined at 500, 900 and 1100oC in order to obtain mesoporous structures with a high specific surface area, well adapTab. to catalytic application. The characterization of samples was performed by XRD, EPR spectroscopy and electrochemical impedance spectroscopy (EIS). XRD analysis showed that the addition of Ni2+, as well as the annealing temperature, affects the structural properties of the obtained composites. EPR analysis revealed the traces of Fe3+ impurities, the presence of oxy defects in alumina and Ni2+ in tetrahedral position for samples calcined at 1100oC. The impedance of the Nafion/alumina modified GCE depended on combined effect of porous structure and surface properties of alumina samples. The electrochemical behavior of a glassy carbon electrode modified with Ni (II)-doped aluminas was studied in 0.5 M NaOH solution, with and without methanol. The electrochemical activity of nickel-doped alumina composites was dictated by the amount of present NiO impurity.

Aluminum pillared clay was synthesized and impregnated with Co2+ (CoAP), using incipient wetness impregnation method. The obtained CoAP was characterized by chemical analysis, XRPD, SEM with EDS, XPS and low temperature N2 physisorption. By these methods the incorporation of Co2+ was confirmed in both micro and mesoporous region. The synthesized material was investigated as a catalyst in catalytic oxidation of organic water pollutants – dyes – in the presence of Oxone® (peroxymonosulfate). Oxone® is a precursor of sulfate radicals. Tartrazine was chosen as a model dye pollutant. The influence of the mass of the catalyst, temperature and initial pH was investigated. Temperature increase was beneficial for dye degradation rate. The reaction rate was the highest for initial pH values around those corresponding to neutral conditions, somewhat slower for pH < 4 values, while for pH > 10 decolorization was significantly less expressed. Along with decolorization of tartrazine solution the formation and degradation of tartrazine catalytic oxidation products were monitored using UV–Vis spectroscopy. CoAP was found to be efficient catalyst in Oxone® induced catalytic degradation of both tartrazine and detected products of its degradation.

Series of alkylammonium modified smectites with different alkylammoinum/clay ratios was synthesized (H series). The obtained organoclays were used as precursors for carbon-clay composite materials (C series). Both set of materials were characterized by X-ray diffraction (XRD), point of zero charge (pHPZC), N2 adsorption-desorption isotherms, Raman spectroscopy and electron paramagnetic resonance (EPR) analysis. XRD analysis of organomodified clays confirmed incorporation of HDTMA+ into interlamellar space of smectite. Series of carbonized clays showed constant d001 value of 1.4 nm. The pHPZC of two series differed indicating that carbonization changed the profile of pH dependent sites on the clay surface. Textural properties of the H series decreased throughout the series, while in the C series the most developed porous structure was obtained for sample where HDTMA+ loading was equal to cation exchange capacity. Raman spectroscopy showed that amorphous carbon was formed during carbonization process. The obtained materials were used as modifiers of carbon paste electrode and investigated using electrochemical impedance spectroscopy, cyclic voltammetry and square wave voltammetry. The comparison of electrochemical behavior of H series and C series showed the importance of interlamellar species for charge transfer process. The investigation of influence of composition of carbon paste and form of added carbon showed that performance of carbon-clay based electrodes depended on synergy of different factors. © 2018 Elsevier Ltd

The external invertase isoform 1 (EINV1) was immobilised on eight differently modified beidellite nanoclays, Modifications were composed of organo-modification with different amounts of surfactant - hexadecyl trimethylammonium cation (HDTMA), pillaring with Al/Fe containing polyhydroxy cations and acid modification of Na-enriched and pillared clays. The modified nanoclays were characterised by XRD, N-2-physisorption, SEM and FT-IR spectroscopy. The amount of bound enzyme activity was significantly influenced by the modification of beidellite ranging from 50 to remarkable 2200 U/g. Biochemical characterization was performed for five modified nanoclays showing the highest enzyme activity after invertase immobilisation. The investigation demonstrated that after immobilisation the structure and the catalytic properties of invertase were preserved, while Km values were slightly increased from 26 to 37 mM. immobilisation significantly improved thermal and storage stability of EINV1. Results indicate that beidellite nanoclays obtained by low cost modifications can be applied as a suitable support for the immobilisation of invertase. The immobilizate can be efficiently engaged in sucrose hydrolysis in batch reactor.

The external invertase isoform 1 (EINV1) was immobilised on eight differently modified beidellite nanoclays, Modifications were composed of organo-modification with different amounts of surfactant - hexadecyl trimethylammonium cation (HDTMA), pillaring with Al/Fe containing polyhydroxy cations and acid modification of Na-enriched and pillared clays. The modified nanoclays were characterised by XRD, N-2-physisorption, SEM and FT-IR spectroscopy. The amount of bound enzyme activity was significantly influenced by the modification of beidellite ranging from 50 to remarkable 2200 U/g. Biochemical characterization was performed for five modified nanoclays showing the highest enzyme activity after invertase immobilisation. The investigation demonstrated that after immobilisation the structure and the catalytic properties of invertase were preserved, while Km values were slightly increased from 26 to 37 mM. immobilisation significantly improved thermal and storage stability of EINV1. Results indicate that beidellite nanoclays obtained by low cost modifications can be applied as a suitable support for the immobilisation of invertase. The immobilizate can be efficiently engaged in sucrose hydrolysis in batch reactor.

(99)Technetium is one of the largest components of nuclear waste material. In aqueous solutions Tc-99 is present as the pertechnetate oxoanion, (TcO4-)-Tc-99, which is highly soluble and mobile in groundwater under oxidizing conditions, thus posing a major environmental concern. In this study, a series of organo-modified bentonite clay samples was tested as adsorbents for the removal of radioactive (TcO4-)-Tc-99 from aqueous solution at room temperature. The influence of the hexadecyl trimethylammonium (HDTMA)/bentonite ratio on the adsorption ability of the organobentonites was investigated. It was found that the adsorbent in which the exchangeable cations were only partially substituted with HDTMA showed very low affinity toward pertechnetate. On the other hand, the adsorbents in which the HDTMA loading exceeded the cation exchange capacity (CEC) value had high efficiency. The behavior of such adsorbents was best described by a Freundlich isotherm, while for the sample in which the HDTMA loading was equal to the CEC, the linear adsorption isotherm was the most appropriate. The difference in adsorption performance of several adsorbents was discussed from the point of view of the interlayer arrangement of the HDTMA. The kinetics of pertechnetate adsorption on HDTMA-bentonites was tested and analyzed using different surface reaction- and diffusion-based kinetic models. For all the investigated adsorbents, the most appropriate kinetic model was the pseudo-second-order kinetics model. The obtained adsorption capacities were and HDTMA-bentonites with HDTMA loadings exceeding CEC value should be regarded as very promising adsorbents for the remediation of Tc-99 polluted waters. (C) 2014 Elsevier B.V. All rights reserved.

Two series of organobentonites (OBs) were synthesized from Na+-exchanged bentonite clay from Bogovina, Serbia. In the first series the starting material was modified using hexadecyltrimethylammonium (HDTMA(+)) ion in the amounts corresponding to 0.2, 0.5, 1.0 and 2.0 of the CEC value. The second series was obtained using quaternary alkyl ammonium cations (QAACs) with different alkyl chain lengths: hexadecyltrimethylammonium (HDTMA(+)), dodecyltrimethylammonium (DDTMA(+)) and tetramethylammonium (TMA(+)) ions. The synthesized OBs were characterized. The adsorption of anionic reactive dye Reactive Black 5 (RB5) and Pb2+ from single component solutions and their hi-component solution was investigated for both series of OBs. The adsorptive properties of the OBs were correlated to the amount and type of incorporated QAACs. The correlation was tested using different mathematical models and best fits were found. Experimental results showed that simultaneous adsorption of RB5 and Pb2+ exhibited synergic effect. The adsorption capacity for both RB5 and Pb2+ was higher in their hi-component solution than in single-component solutions. These results indicate the creation of new adsorption sites during the simultaneous adsorption.

Modification and characterization of bentonite from location Bogovina, Serbia was performed in order to obtain material applicable in wastewater purification. The lt 75 mu m bentonite fraction was used in organobentonite synthesis while the lt 2 mu m bentonite fraction, obtained by hydroseparation was used in pillaring procedure. Organo-modification of bentonite was performed with (1-hexadecyl)trimethylammonium bromide (HDTMA-Br). Pillared bentonite was obtained using standard procedure. Al3+ and Fe3+ were incorporated in pillars in 4:1 ratio and applied as catalyst in catalytic wet peroxide oxidation. Differences in structure of starting and modified bentonites were established by XRD analysis and nitrogen physisorption on -196 degrees C. The (001) smectite peak around 2 theta = 6 degrees shifts during the modification process. The Na-exchange process lowered d(001) from 1.53 nm (2 theta = 5.78 degrees) for starting clay to 1.28 nm (2 theta = 6.92 degrees), but the clay retained its swelling properties. The pillaring process increased and fixed the basal spacing to 1.74 nm. Intercalation of HDTMA ions into smectite structure increased d(001) to 2.00 nm for organobentonite. Specific surface area, S-BET, was affected by particle size and type of modification. The samples with finer bentonite fraction had higher S-BET due to increased smectite content. Na-exchanged bentonite samples had higher S-BET value than starting clay samples of same granulation. Organomodification caused dramatic decrease in S-BET value, while the pillaring process lead to an increase of S-BET value. Adsorptive and catalytic purification of wastewaters containing dyes was tested using Acid Yellow 99 as a model dye. Na-exchanged bentonite had greater adsorption affinity for dye adsorption than raw bentonite owing to higher S-BET. By organomodification this affinity was enhanced more than 70 times due to transition of bentonite surface from hydrophilic to organophilic. Al,Fe pillared bentonite wa, Izvršena je modifikacija i karakterizacija bentonita radi dobijanja materijala za prečišćavanje otpadnih voda. Organo-modifikacija bentonita izvedena je pomoću heksadeciltrimetilamonijum-bromida. Pilareni bentonit dobijen je standardnim postupkom uz ugradnju Al3+ i Fe3+ jona u odnosu 4:1, i korišćen je kao katalizator za oksidativnu razgradnju u prisustvu vodonik-peroksida. Razlike u strukturi polaznog i modifikovanih bentonita utvrđene su rendgeno-strukturnom analizom i fizisorpcijom azota na -196°C. Ispitivano je adsorpciono i katalitičko prečišćavanje otpadnih voda koje sadrže boje, korišćenjem Acid Yellow 99 kao model boje. Izvršeno je poređenje katalitičkih i adsorpiconih svojstava modifikovanih bentonita.

Partial substitution of the interlayer cations of a local bentonite (Bogovina) by hexadecyl trimethylammonium ions (HDTMA) was performed to prepare adsorbents able to simultaneously adsorb toxic metal cations and organic pollutants. Acid Orange 10 adsorption increased with increasing HDTMA addition, while the adsorption of Pb2+ decreased with increasing organophilicity. The adsorption of the dye and Pb2+ and their mixture onto Na-rich bentonite and HDTMA-bentonites, regardless of adsorbents' organophilicity, obeyed the pseudo-second-order kinetics model. (C) 2009 Elsevier B.V. All rights reserved.

Two types of aluminosilicate, zeolite type 13X and pillared smectite, were used as template for formation of metallic nanodispersions by method of impregnation/thermal degradation of acetilacetonate salts. The clusters of nickel, platinum, silver, and platinum/ruthenium mixture were incorporated in zeolite, while pillared smectite was impregnated only with silver. The optimal conditions (the temperature and the atmosphere) for thermal degradation of acetilacetonate salts were established by thermogravimetric analysis of these salts. The XRD analysis showed that incorporated metallic clusters were crystals only in low degree. It was also showed that impregnation/thermal degradation method does not destroy the aluminosilicate structure at lower content of incorporated metal. SEM and TEM analysis showed that part of metal was incorporated into the zeolite cages, while the other part formd metallic particles on the outer surface of the zeolite. The zeolite structre was partly colapsed during incorporation of nickel in amounts higher then 20 mass%. The specific surface area, micopore volume and total pore volume of original and modified aluminosilicates were evaluated by nitrogen adsorption-desorption isotherms. Textural properties parameteres decreased with the increase of the metal content in the sample. The electrocatalytic properties of modified zeolites were investigated in several reactions: oxygen reduction, the oxidation of hydroxil group, the oxidation of carbon monoxide and the oxidation of methanol. The electrochemical behavior of nickel modified zeolite is similar to the behavior of smooth nickel electrode: the characteristic Ni(OH)2 / NiOOH redox couple as well as good catalytic activity for oxygen reduction and evolution could be seen on cyclic voltammograms. The methanol oxidation occurs on nickel oxide. The rate od this reaction was higher on the sample with higher nickel content. The platinum impregnated zeolite showed discrepances in comparison to smoot

Nanodispersed metallic clusters of platinum and palladium were incorporated into NaX zeolite cavities by impregnation with acetone solution of corresponding acetylacetonates, solvent evaporation and acetylacetonate thermal decomposition. The acetylacetonate decomposition was followed by thermogravimetry. Modified zeolite samples were characterized by x-ray diffractommetry. In order to get a satisfactory electronic conductivity of modified zeolite, 10% wt of carbon black was added. This material was applied to a rotating glassy carbon disc electrode, and was used to study electrochemical water splitting in slightly acidic aqueous solutions. Noble metal modified zeolites exhibit significant reduction in water decomposition overvoltage as compared to smooth polycrystalline platinum.

Platinum was incorporated into the cavities of NaX zeolite by impregration/thermal decomposition technique, using Pt(II)-acetylacetonate in acetone as an impregnating solution. The platinum-to-zeolite weight ratio amounted to 0.092. The sample was characterized by thermogravimetry, X-ray diffraction and Na-23 MAS NMR methods. The mixture of modified zeolite and 10 wt. % of carbon black, in a form of thin layer, was pasted to a glassy carbon stance. With such an electrode material, the electrochemical decomposition of aqueous 2.5 mM H2SO4 + 1 M Na2SO4 solution with hydrogen and oxygen production has been kinetically studied. In comparison with smooth polycrystalline platinum, this electrode material provided an remarkable overvoltage drop,for water splitting, primarily due to the acceleration of oxygen evolution reaction.

Na X type zeolite was loaded with platinum, by the thermal decomposition of Pt(II) acetylacetonate, up to the Pt/NaX mass ratio of 0.174. The sample, dispersed on a glassy carbon rotating disc, was used in slightly acidic solution to observe the kinetics of the hydrogen evolution reaction. A comparison was Made With the rate of hydrogen evolution on smooth polycrystalline platinum, and both slower and faster evolution rates were observed, depending on the percentage of carbon black added to the zeolite sample.