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In this study, porous ceramics, based on available and cost-effective raw materials natural zeolite and kaolin clay, were synthesized and examined as an adsorbent for removing ammonium (NH4 + ) ions from aqueous solutions. The synthesis was carried out using the foaming method with the addition of sodium dodecyl sulfate as the foaming agent, polyvinyl alcohol as an organic binder, and hydrogen peroxide as the blowing agent. The obtained green and sintered samples were characterized by thermogravimetric analysis, scanning electron microscopy, X-Ray diffraction, and Fourier transform infrared spectroscopy. After sintering, the porosity was 79.49%. The NH4 + adsorption kinetics and isotherms fit the pseudo-second-order and Langmuir models, confirming chemisorption. The maximum adsorption capacity obtained using the Langmuir model was approximately 7.66 mg g -1 . The thermodynamic parameters showed that adsorption is a spontaneous and exothermic process. Based on the obtained results, it was demonstrated that the synthesis of porous ceramics based on natural zeolite and kaolin clay is a practical way to increase the adsorption performance of natural zeolite for NH4+ removal from water solutions.

Municipal wastewater, as well as wastewater from arable land drainage, is a major source of organic pollutants such as insecticides. Intensive research is aimed at finding efficient, economically profitable, as well as environmentally acceptable adsorbents for their removal [1]. Zeolites are microporous crystalline aluminosilicates that show good adsorption properties in water purification processes [2]. The crystal lattice of zeolite is negatively charged and it does not have the ability to adsorb anions and nonpolar organic molecules. However, the zeolite surface can be adapted for the adsorption of organic molecules in different ways. The aim of this work was the preparation of an adsorbent based on surfactant-modified natural zeolite and calcium hydroxyapatite (HAp) and an investigation of its potential application for the removal of acetamiprid (AC) from aqueous solution. The resulting powder was characterized before and after adsorption by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG/DTG) and scanning electron microscopy (SEM). The concentration of acetamiprid in the solution was determined by liquid chromatography-tandem mass spectrometry (LC-MS) technique. TG/DTG and FTIR analyses confirmed the binding of the surfactant to the zeolite surface, while SEM microscopy confirmed the presence of needle-like crystals of HAp. During the adsorption experiment, 0.6 mg AC per g (30%) was removed, while the equilibrium state was established after 90 min. The pseudo-secondorder Lagergren model best described the kinetics of acetamiprid binding to the adsorbent surface.

Natural zeolites (NZ) have found numerous applications in the life science such as medicine, agriculture, and environmental protection, in practical applications, and in basic research. Various ways in which natural zeolites are used in microbiology, where they are desirable due to their non-toxicity and ion exchange capacity, are presented here. Natural zeolites of the clinoptilolite type are excellent bacterial carriers with potential applications in biotechnology. When modified with heavy metals, the zeolites could fill biofilters and be used in wastewater treatment. Since zeolites facilitate biofilm growth, they can be used as an excellent support and model material that enables biofilm formation in porous media and subsequent visualization of biofilm in 3D by using X-ray microtomography.

Municipal wastewater, as well as agricultural drainage wastewater, is the main source of organic pollutants such as drugs and pesticides. Efficient, economically profitable and environmentally acceptable adsorbents for their removal are the subject of intensive research. In this work, a composite based on surfactant-modified zeolite and hydroxyapatite was synthesized. It was in detail characterized and examined as an adsorbent of two organic pollutants: one of the most commonly used antibiotics, ciprofloxacin, and an insecticide necessary in agricultural production, acetamiprid. The results showed that the obtained adsorbent removed 5.3 mg ciprofloxacin g-1 and 0.6 mg acetamiprid g-1 from the aqueous solution.

Municipal wastewater, as well as agricultural drainage wastewater, is the main source of organic pollutants such as drugs and pesticides. Efficient, economically profitable and environmentally acceptable adsorbents for their removal are the subject of intensive research. In this work, a composite based on surfactant-modified zeolite and hydroxyapatite was synthesized. It was in detail characterized and examined as an adsorbent of two organic pollutants: one of the most commonly used antibiotics, ciprofloxacin, and an insecticide necessary in agricultural production, acetamiprid. The results showed that the obtained adsorbent removed 5.3 mg ciprofloxacin g-1 and 0.6 mg acetamiprid g-1 from the aqueous solution.

Natural zeolite is a good sorbent for many cations due to its specific porous structure. The degree of sorption efficiency depends on the cation type and the availability of exchange positions in the zeolite lattice. The aim of this work is to examine the synthesis possibility of a new adsorbent based on natural zeolite and hydroxyapatite. The adsorbent was prepared mechanochemically by using clinoptilolite-rich zeolite tuff from the Slanci deposit (Serbia) and hydroxyapatite obtained by the hydrothermal process. The milling process was performed in a ball mill and optimized regarding contact time and milling speed. For the synthesis of zeolite/hydroxyapatite adsorbent (ZHAp), optimal values for these two parameters were 10 min and 250 rpm, respectively. The resulting sample ZHAp was characterized by X-ray powder diffraction, thermal analysis and scanning electron microscopy. Diffraction analysis of the ZHAp confirmed the presence of the most abundant mineral in zeolite tuff - clinoptilolite and hydroxyapatite. Needle-like crystals of hydroxyapatite on the clinoptilolite surface are observed in SEM images. Zeolite/hydroxyapatite sample is thermally stable at 800 °C. Adsorption properties of ZHAp were examined for nickel and chromium ions, towards which natural zeolite shows a low affinity. The presence of hydroxyapatite on the zeolite surface led to an increase in the adsorption capacity more than two times for both tested ions compared to the initial zeolite tuff.

Clinoptilolite, due to its specific porous structure, is good sorbent for many cations, however, the degree of efficiency depends on the type of cations and the availability of a zeolite lattice for exchange. Therefore, the aim of this work is to investigate the possibility of improving the sorption efficiency of clinoptilolite towards nickel (II) and chromium (III) ions from aqueous solutions using composites prepared by synthesis of hydroxyapatite on the clinoptilolite surface. Clinoptilolite/hydroxyapatite composites were obtained by hydrothermal crystallization of calcium-hydroxyapatite in the presence of clinoptilolite at 160°C for 4 hours. The sorbents were prepared in two ways: in the first one, ion exchange was previously performed in order to enrich clinoptilolite with calcium ions (CH1), while in the second, calcium ion was introduced with other reactants into the reaction mixture from which hydroxyapatite crystallized (CH2). Phosphorus, necessary for the crystallization of hydroxyapatite, was introduced as a solution of ammonium hydrogen phosphate. The resulting powders were characterized in detail by X-ray powder diffraction (XRPD), thermal TG-DTG analysis, specific surface area and pore distribution (BET) analysis, as well as by scanning electron microscopy (SEM). XRPD analysis of composites showed that the most abundant mineral in zeolite tuff is clinoptilolite, while the presence of hydroxyapatite was identified in the samples obtained by hydrothermal synthesis. Needle-like crystals of hydroxyapatite on the clinoptilolite surface can be observed at SEM photos and it was concluded that the amount of crystallized hydroxyapatite was greater in sample CH2. The results of thermal analysis showed that zeolite/hydroxyapatite composites CH1 and CH2 are thermally stable at 800 °C and that the total mass loss is a consequence of dehydration due to water leaving the clinoptilolite structure and dehydroxylation of hydroxyapatite. The presence of hydroxyapatite in

Zeolites have different interactions with bacteria, depending on the type of zeolitic material (natural zeolitized tuffs (NZ), modified NZ or synthetic zeolites) and bacterial species to be affected (e.g. useful or pathogenic bacteria). In this work, the review of bacteriazeolites interactions is given. As a model useful bacterium Acinetobacter junii, which is used in the tertiary-stage wastewater treatment, is chosen. An emerging hospital pathogen Acinetobacter baumannii is chosen as a model pathogenic bacterium. Clinoptilolite rich NZ is a promising material for the immobilization of bacteria in both nutrient-poor and nutrient-rich water. Both A. junii and A. baumannii, with hydrophilic or hydrophobic cell surface, could be immobilized onto NZ in the form of biofilm within 24h of contact. The extent of bacterial immobilization increases with the decrease of particle size of NZ. The extent of bacterial immobilization on single NZ cannot be predicted by mineralogical and chemical analysis of NZ, its cation exchange capacity or zeta potential [1]. The NZ modified with Cu(II) or benzalkonium cations act bactericidal against A. baumannii within 1h of contact. The Ni(II) or Zn(II) modified NZ act slightly antibacterial [2]. The surfactant-modified NZ with monolayer, partial bilayer or bilayer hexadecyltrimethylammonium coverage have the bactericidal effect. In the case of partial monolayer hexadecyltrimethylammonium coverage bacteria are not affected [3]. The addition of 1 wt% of Cu(II) modified NZ shortens the survival of A. baumannii in soils. The addition of 0.1 wt% of Ag(I) modified NZ to slightly acidic or alkaline soil completely removes viable A. baumannii within 1 h of contact, with negligible impact on native soil bacteria [4]. Commercial synthetic zeolites of Linde Type A (LTA) in water show the antibacterial effect in the concentration range 0.1-1 wt%. The mechanism of LTA toxicity is explained by the hydrolysis of LTA in water and leaching of aluminosilicate

Natural zeolite is a good sorbent for many cations due to its specific porous structure. The degree of sorption efficiency depends on the cation type and the availability of exchange positions in the zeolite lattice. The aim of this work is to examine the synthesis possibility of a new adsorbent based on natural zeolite and hydroxyapatite. The adsorbent was prepared mechanochemically by using clinoptilolite-rich zeolite tuff from the Slanci deposit (Serbia) and hydroxyapatite obtained by the hydrothermal process. The milling process was performed in a ball mill and optimized regarding contact time and milling speed. For the synthesis of zeolite/hydroxyapatite adsorbent (ZHAp), optimal values for these two parameters were 10 min and 250 rpm, respectively. The resulting sample ZHAp was characterized by X-ray powder diffraction, thermal analysis and scanning electron microscopy. Diffraction analysis of the ZHAp confirmed the presence of the most abundant mineral in zeolite tuff - clinoptilolite and hydroxyapatite. Needle-like crystals of hydroxyapatite on the clinoptilolite surface are observed in SEM images. Zeolite/hydroxyapatite sample is thermally stable at 800 °C. Adsorption properties of ZHAp were examined for nickel and chromium ions, towards which natural zeolite shows a low affinity. The presence of hydroxyapatite on the zeolite surface led to an increase in the adsorption capacity more than two times for both tested ions compared to the initial zeolite tuff.

Clinoptilolite, due to its specific porous structure, is good sorbent for many cations, however, the degree of efficiency depends on the type of cations and the availability of a zeolite lattice for exchange. Therefore, the aim of this work is to investigate the possibility of improving the sorption efficiency of clinoptilolite towards nickel (II) and chromium (III) ions from aqueous solutions using composites prepared by synthesis of hydroxyapatite on the clinoptilolite surface. Clinoptilolite/hydroxyapatite composites were obtained by hydrothermal crystallization of calcium-hydroxyapatite in the presence of clinoptilolite at 160°C for 4 hours. The sorbents were prepared in two ways: in the first one, ion exchange was previously performed in order to enrich clinoptilolite with calcium ions (CH1), while in the second, calcium ion was introduced with other reactants into the reaction mixture from which hydroxyapatite crystallized (CH2). Phosphorus, necessary for the crystallization of hydroxyapatite, was introduced as a solution of ammonium hydrogen phosphate. The resulting powders were characterized in detail by X-ray powder diffraction (XRPD), thermal TG-DTG analysis, specific surface area and pore distribution (BET) analysis, as well as by scanning electron microscopy (SEM). XRPD analysis of composites showed that the most abundant mineral in zeolite tuff is clinoptilolite, while the presence of hydroxyapatite was identified in the samples obtained by hydrothermal synthesis. Needle-like crystals of hydroxyapatite on the clinoptilolite surface can be observed at SEM photos and it was concluded that the amount of crystallized hydroxyapatite was greater in sample CH2. The results of thermal analysis showed that zeolite/hydroxyapatite composites CH1 and CH2 are thermally stable at 800 °C and that the total mass loss is a consequence of dehydration due to water leaving the clinoptilolite structure and dehydroxylation of hydroxyapatite. The presence of hydroxyapatite in

Zeolites have different interactions with bacteria, depending on the type of zeolitic material (natural zeolitized tuffs (NZ), modified NZ or synthetic zeolites) and bacterial species to be affected (e.g. useful or pathogenic bacteria). In this work, the review of bacteriazeolites interactions is given. As a model useful bacterium Acinetobacter junii, which is used in the tertiary-stage wastewater treatment, is chosen. An emerging hospital pathogen Acinetobacter baumannii is chosen as a model pathogenic bacterium. Clinoptilolite rich NZ is a promising material for the immobilization of bacteria in both nutrient-poor and nutrient-rich water. Both A. junii and A. baumannii, with hydrophilic or hydrophobic cell surface, could be immobilized onto NZ in the form of biofilm within 24h of contact. The extent of bacterial immobilization increases with the decrease of particle size of NZ. The extent of bacterial immobilization on single NZ cannot be predicted by mineralogical and chemical analysis of NZ, its cation exchange capacity or zeta potential [1]. The NZ modified with Cu(II) or benzalkonium cations act bactericidal against A. baumannii within 1h of contact. The Ni(II) or Zn(II) modified NZ act slightly antibacterial [2]. The surfactant-modified NZ with monolayer, partial bilayer or bilayer hexadecyltrimethylammonium coverage have the bactericidal effect. In the case of partial monolayer hexadecyltrimethylammonium coverage bacteria are not affected [3]. The addition of 1 wt% of Cu(II) modified NZ shortens the survival of A. baumannii in soils. The addition of 0.1 wt% of Ag(I) modified NZ to slightly acidic or alkaline soil completely removes viable A. baumannii within 1 h of contact, with negligible impact on native soil bacteria [4]. Commercial synthetic zeolites of Linde Type A (LTA) in water show the antibacterial effect in the concentration range 0.1-1 wt%. The mechanism of LTA toxicity is explained by the hydrolysis of LTA in water and leaching of aluminosilicate

Low-cost and easily available natural zeolite is a promising adsorbent for metal ions removal in wastewater treatment. The possibility of using zeolitic tuff from Serbia in the form of Na-enriched natural zeolite (Na-Z) for the adsorption of Pb2+, Zn2+, Cu2+, and Ni2+ions from wastewater was investigated in the presented paper. The research included Na-Z characterization and determination of adsorption kinetics in individual ion adsorption tests using Weber-Morris intraparticle diffusion model, non-linear pseudo-first-order (PFO), pseudo-second-order (PSO) and mixed-order (MO) kinetic models. The results indicate that the adsorption processes of metal ions on Na-Z are complex processes dominated by multiple rate-limiting mechanisms and best defined by the MO model. The mechanisms of ion diffusion and adsorption to active sites are equally represented in the Pb2+adsorption process. The mechanism of ion adsorption on the active sites is the rate-limiting step in the Zn2+adsorption process, while in the case of the Cu2+and Ni2+adsorption ion diffusion is the rate-limiting kinetic mechanism. Within the MO model, the PFO rate (external/internal diffusion) and the PSO rate (adsorption on active sites) were calculated and results wereapplied to a multicomponent wastewater sample in order to determine and explain the adsorption efficiency in wastewater treatment. The results show that the rate of adsorption of individual metal ions and the efficiency of ion removal from a multicomponent wastewater sample are influenced by several factors including the radius of the hydrated ion and the free energy of hydration. The achieved removal of metal ions by Na-Z is Pb2+(89%) > Cu2+(72%) > Zn2+(61%) > Ni2+(58%) and defines Na-enriched naturalzeolite as an effective adsorbent in wastewater treatment.

Low-cost and easily available natural zeolite is a promising adsorbent for metal ions removal in wastewater treatment. The possibility of using zeolitic tuff from Serbia in the form of Na-enriched natural zeolite (Na-Z) for the adsorption of Pb2+, Zn2+, Cu2+, and Ni2+ ions from wastewater was investigated in the presented paper. The research included Na-Z characterization and determination of adsorption kinetics in individual ion adsorption tests using Weber-Morris intraparticle diffusion model, non-linear pseudo-first-order (PFO), pseudo-second-order (PSO) and mixed-order (MO) kinetic models. The results indicate that the adsorption processes of metal ions on Na-Z are complex processes dominated by multiple rate-limiting mechanisms and best defined by the MO model. The mechanisms of ion diffusion and adsorption to active sites are equally represented in the Pb2+ adsorption process. The mechanism of ion adsorption on the active sites is the rate-limiting step in the Zn2+ adsorption process, while in the case of the Cu2+ and Ni2+ adsorption ion diffusion is the rate-limiting kinetic mechanism. Within the MO model, the PFO rate (external/internal diffusion) and the PSO rate (adsorption on active sites) were calculated and results were applied to a multicomponent wastewater sample in order to determine and explain the adsorption efficiency in wastewater treatment. The results show that the rate of adsorption of individual metal ions and the efficiency of ion removal from a multicomponent wastewater sample are influenced by several factors including the radius of the hydrated ion and the free energy of hydration. The achieved removal of metal ions by Na-Z is Pb2+ (89%) > Cu2+ (72%) > Zn2+ (61%) > Ni2+ (58%) and defines Na-enriched natural zeolite as an effective adsorbent in wastewater treatment.

Natural zeolite is a good sorbent for many cations due to its specific porous structure. The degree of sorption efficiency depends on the cation type and the availability of exchange positions in the zeolite lattice. The aim of this work is to examine the synthesis possibility of a new adsorbent based on natural zeolite and hydroxyapatite. The adsorbent was prepared mechanochemically by using clinoptilolite-rich zeolite tuff from the Slanci deposit (Serbia) and hydroxyapatite obtained by the hydrothermal process. The milling process was performed in a ball mill and optimized regarding contact time and milling speed. For the synthesis of zeolite/hydroxyapatite adsorbent (ZHAp), optimal values for these two parameters were 10 min and 250 rpm, respectively. The resulting sample ZHAp was characterized by X-ray powder diffraction, thermal analysis and scanning electron microscopy. Diffraction analysis of the ZHAp confirmed the presence of the most abundant mineral in zeolite tuff - clinoptilolite and hydroxyapatite. Needle-like crystals of hydroxyapatite on the clinoptilolite surface are observed in SEM images. Zeolite/hydroxyapatite sample is thermally stable at 800 °C. Adsorption properties of ZHAp were examined for nickel and chromium ions, towards which natural zeolite shows a low affinity. The presence of hydroxyapatite on the zeolite surface led to an increase in the adsorption capacity more than two times for both tested ions compared to the initial zeolite tuff.

Low-cost and easily available natural zeolite is a promising adsorbent for metal ions removal in wastewater treatment. The possibility of using zeolitic tuff from Serbia in the form of Na-enriched natural zeolite (Na-Z) for the adsorption of Pb2+, Zn2+, Cu2+, and Ni2+ions from wastewater was investigated in the presented paper. The research included Na-Z characterization and determination of adsorption kinetics in individual ion adsorption tests using Weber-Morris intraparticle diffusion model, non-linear pseudo-first-order (PFO), pseudo-second-order (PSO) and mixed-order (MO) kinetic models. The results indicate that the adsorption processes of metal ions on Na-Z are complex processes dominated by multiple rate-limiting mechanisms and best defined by the MO model. The mechanisms of ion diffusion and adsorption to active sites are equally represented in the Pb2+adsorption process. The mechanism of ion adsorption on the active sites is the rate-limiting step in the Zn2+adsorption process, while in the case of the Cu2+and Ni2+adsorption ion diffusion is the rate-limiting kinetic mechanism. Within the MO model, the PFO rate (external/internal diffusion) and the PSO rate (adsorption on active sites) were calculated and results wereapplied to a multicomponent wastewater sample in order to determine and explain the adsorption efficiency in wastewater treatment. The results show that the rate of adsorption of individual metal ions and the efficiency of ion removal from a multicomponent wastewater sample are influenced by several factors including the radius of the hydrated ion and the free energy of hydration. The achieved removal of metal ions by Na-Z is Pb2+(89%) > Cu2+(72%) > Zn2+(61%) > Ni2+(58%) and defines Na-enriched naturalzeolite as an effective adsorbent in wastewater treatment.

Hydroxyapatite/zeolite composite (Hap/NZ) was obtained by hydrothermal synthesis from a reaction mixture containing Ca-enriched natural zeolite (NZ, Slanci deposit, Serbia) and aqueous ammoniumhydrogen phosphate solution. Calcium ions, necessary for the crystallization of hydroxyapatite on the zeolite surface, are released from the crystalline structure of NZ by ion exchange with ammonium ion. XRD analysis revealed the presence of hydroxyapatite, while SEM micrography showed unevenly distributed needle crystals corresponding to hydroxyapatite. Thermal analysis showed that synthetized composite was stable at 800 °C. Further, composite was investigated as the adsorbent of the Ni (II) and Cr (III) ions and the results were compared with adsorption capacity of the natural zeolite. Less than 10 wt.% of hydroxyapatite on the zeolite surface significantly increase the adsorption capacity. After 24 h, 100% of Cr (III) and 79% of Ni (II) ions were removed from the solution using Hap/NZ composites compared to natural zeolite which can remove 30% of Cr (III) and 23% of Ni (II). The kinetics of metal cation binding to Hap/NZ and NZ can be described by the Lagergren pseudo-second order model. The possibility of regeneration of Hap/NZ and NZ adsorbents was investigated in NaCl and EDTA solutions, after which the adsorbents were reused in the process of sorption of toxic cations.

Natural zeolite-clinoptilolite (from Vranjska Banja deposit in Serbia) and synthetic Beta zeolite, were amin-functionalized using (3-aminopropyl)-triethoxysilane (APTES). The results of the Fourier transform infrared spectroscopy and thermogravimetric analysis confirmed the presence of amino groups derived from APTES onto the modified zeolite surface. APTES-enriched zeolite was further used as an adsorbent of silver ions from aqueous solutions. Natural zeolite-clinoptilolite showed a higher adsorption capacity (96 mg Ag/g), compared to beta zeolite (54 mg Ag/g) which is attributed to the presence of exchangeable cations in the structure of clinoptilolite. The kinetic data follows the pseudo-second-order model which indicates a chemical interaction between silver ions and functional amino groups on the surface of the zeolite. Ag-APTES and APTES-enriched zeolites further were studied as antibacterial agents toward the pathogenic bacteria Gram-negative Escherichia coli DSM 498 and Gram-positive Staphylococcus aureus ATCC 25923. Based on the results, it was concluded that the APTES-zeolites do not exhibit antibacterial activity while AgAPTES enriched zeolites shows antibacterial effect toward both examined bacterial strains. Antibacterial activity is attributed to the presence of silver ions.

Poli(mlečna kiselina), PLA, je jedan od najistaknutijih predstavnika biodegradabilnih sintetskih polimera. Ovaj polimer ima i dodatnu prednost u tome što se dobija iz obnovljivih izvora. Radi povećanja upotrebne vrednosti PLA, svojstva joj se mogu modifikovati i poboljšati različitim puniocima mikro i nano dimenzija. U okviru ovog rada pripremljena je serija kompozita sa PLA kao matricom i puniocem prirodnog porekla, zeolitom (1, 3, 5 mas.%) modifikovanim benzalkonijum-hloridom. TG analizom je ispitana termooksidativna stabilnost kompozita koja se nije umanjila dodatkom punioca. DSC analizom je određen stepen kristaliničnosti PLA matrice koji pokazuje nešto veće vrednosti pri najvećem sadržaju zeolita, uz skoro nepromenjenu temperaturu topljenja. Dinamičko- mehaničkim merenjima je pokazano da je dodatak punioca uticao na poboljšanje mehaničkih svojstava matrice, posebno u gumolikom stanju. U testovima alkalne hidrolize je utvrđeno da se degradabilnost kompozita povećava sa povećanjem sadržaja modifikovanog zeolita., Poly(lactic acid), PLA, is one of the most prominent member of biodegradable synthetic polymers. PLA is obtained from renewable sources, which is an additional advantage of this polyester. In order to expand its application window, properties of PLA could be further improved by composite preparation. In this work, composites of PLA with benzalkonium chloride-modified zeolite (1, 3, 5 wt%), as a filler of natural origin, were prepared by solution casting. Thermal stability of PLA was preserved after the addition of zeolite, as determined by TG analysis. DSC measurements showed that degree of crystallinity was slightly higher for the composite with the highest amount of zeolite, with unaltered melting temperature. Mechanical properties were improved, especially in the rubbery state, evidenced from dynamic mechanical analysis. In alkaline hydrolysis tests composites showed trend of increased degradability with higher amount of zeolite.

Hydroxyapatite/zeolite composite (Hap/NZ) was obtained by hydrothermal synthesis from a reaction mixture containing Ca-enriched natural zeolite (NZ, Slanci deposit, Serbia) and aqueous ammoniumhydrogen phosphate solution. Calcium ions, necessary for the crystallization of hydroxyapatite on the zeolite surface, are released from the crystalline structure of NZ by ion exchange with ammonium ion. XRD analysis revealed the presence of hydroxyapatite, while SEM micrography showed unevenly distributed needle crystals corresponding to hydroxyapatite. Thermal analysis showed that synthetized composite was stable at 800 °C. Further, composite was investigated as the adsorbent of the Ni (II) and Cr (III) ions and the results were compared with adsorption capacity of the natural zeolite. Less than 10 wt.% of hydroxyapatite on the zeolite surface significantly increase the adsorption capacity. After 24 h, 100% of Cr (III) and 79% of Ni (II) ions were removed from the solution using Hap/NZ composites compared to natural zeolite which can remove 30% of Cr (III) and 23% of Ni (II). The kinetics of metal cation binding to Hap/NZ and NZ can be described by the Lagergren pseudo-second order model. The possibility of regeneration of Hap/NZ and NZ adsorbents was investigated in NaCl and EDTA solutions, after which the adsorbents were reused in the process of sorption of toxic cations.

Natural zeolite-clinoptilolite (from Vranjska Banja deposit in Serbia) and synthetic Beta zeolite, were amin-functionalized using (3-aminopropyl)-triethoxysilane (APTES). The results of the Fourier transform infrared spectroscopy and thermogravimetric analysis confirmed the presence of amino groups derived from APTES onto the modified zeolite surface. APTES-enriched zeolite was further used as an adsorbent of silver ions from aqueous solutions. Natural zeolite-clinoptilolite showed a higher adsorption capacity (96 mg Ag/g), compared to beta zeolite (54 mg Ag/g) which is attributed to the presence of exchangeable cations in the structure of clinoptilolite. The kinetic data follows the pseudo-second-order model which indicates a chemical interaction between silver ions and functional amino groups on the surface of the zeolite. Ag-APTES and APTES-enriched zeolites further were studied as antibacterial agents toward the pathogenic bacteria Gram-negative Escherichia coli DSM 498 and Gram-positive Staphylococcus aureus ATCC 25923. Based on the results, it was concluded that the APTES-zeolites do not exhibit antibacterial activity while AgAPTES enriched zeolites shows antibacterial effect toward both examined bacterial strains. Antibacterial activity is attributed to the presence of silver ions.

Regarding enormous expansion of bacterial contamination as well as their increase resistivity to commonly used disinfectants, there is a great demand for antibacterial material, which will not be based on organic compounds. Among various inorganic substances, environmentally friendly, low-cost and chemically stable ZnO and TiO2 demonstrate considerable antibacterial activity.This work primarily focuses on idea of developing novel disinfectant based on both, ZnO and TiO2, which would integrate all the worthy properties of both oxides. For that matter, titanium(IV) butoxide was dissolved in a solution of zinc acetate following with the ammonia addition until pH value was 8.5. Half of the initial solution was hydrothermally treated, dried and calcined at 500 (H-ZnTi-500) and 800°C (H-ZnTi-800). Two other samples (ZnTi-500 and ZnTi-800) were obtained from the other half of the initial solution which was directly dried and calcined under the same conditions. The samples were characterized by XRD including Rietveld refinement, FESEMand TG/DTA. Antibacterial activity was examined towards Gram-positive S. aureus and Gram-negative E. coli .The results showed that only ZnTi-800 consisted of pure Zn2TiO4 (Fd-3m) while Zn TiO was the major phase in three other samples. In the case of samples calcined at 500 °C, traces of ZnO were found. H-ZnTi-800 contained three phases: Zn2TiO4, ZnO and Zn2Ti3O8 (P4332). Cubic Zn2TiO4 contains two cation sites: tetrahedrally coordinated Zn at 0,0,0 and octahedral site at 5/8,5/8,5/8 shared between Zn and Ti. The calculated a-parameters of all obtained Zn2TiO4 as well as Zn–O and Zn/Ti–O bond distances were independent of synthesis. At 500 °C nanocrystalline Zn2TiO4 were obtained with the crystallite sizes 26 and 71 nm for H-ZnTi-500 and ZnTi-500, respectively, while microcrystalline phases were obtained at 800 °C with the crystallite sizes larger than 110 nm. The soft agglomerates consisted of smaller particles were obtained at 500 °C comparin

Regarding enormous expansion of bacterial contamination as well as their increase resistivity to commonly used disinfectants, there is a great demand for antibacterial material, which will not be based on organic compounds. Among various inorganic substances, environmentally friendly, low-cost and chemically stable ZnO and TiO2 demonstrate considerable antibacterial activity. This work primarily focuses on idea of developing novel disinfectant based on both, ZnO and TiO2, which would integrate all the worthy properties of both oxides. For that matter, titanium(IV) butoxide was dissolved in a solution of zinc acetate following with the ammonia addition until pH value was 8.5. Half of the initial solution was hydrothermally treated, dried and calcined at 500 (H-ZnTi-500) and 800°C (H-ZnTi-800). Two other samples (ZnTi-500 and ZnTi-800) were obtained from the other half of the initial solution which was directly dried and calcined under the same conditions. The samples were characterized by XRD including Rietveld refinement, FESEM and TG/DTA. Antibacterial activity was examined towards Gram-positive S. aureus and Gram-negative E. coli . The results showed that only ZnTi-800 consisted of pure Zn2TiO4 (Fd-3m) while Zn TiO was the major phase in three other samples. In the case of samples calcined at 500 °C, traces of ZnO were found. H-ZnTi-800 contained three phases: Zn2TiO4, ZnO and Zn2Ti3O8 (P4332). Cubic Zn2TiO4 contains two cation sites: tetrahedrally coordinated Zn at 0,0,0 and octahedral site at 5/8,5/8,5/8 shared between Zn and Ti. The calculated a-parameters of all obtained Zn2TiO4 as well as Zn–O and Zn/Ti–O bond distances were independent of synthesis. At 500 °C nanocrystalline Zn2TiO4 were obtained with the crystallite sizes 26 and 71 nm for H-ZnTi-500 and ZnTi-500, respectively, while microcrystalline phases were obtained at 800 °C with the crystallite sizes larger than 110 nm. The soft agglomerates consisted of smaller particles were obtained at 500 °C compa

Regarding enormous expansion of bacterial contamination as well as their increase resistivity to commonly used disinfectants, there is a great demand for antibacterial material, which will not be based on organic compounds. Among various inorganic substances, environmentally friendly, low-cost and chemically stable ZnO and TiO2 demonstrate considerable antibacterial activity.This work primarily focuses on idea of developing novel disinfectant based on both, ZnO and TiO2, which would integrate all the worthy properties of both oxides. For that matter, titanium(IV) butoxide was dissolved in a solution of zinc acetate following with the ammonia addition until pH value was 8.5. Half of the initial solution was hydrothermally treated, dried and calcined at 500 (H-ZnTi-500) and 800°C (H-ZnTi-800). Two other samples (ZnTi-500 and ZnTi-800) were obtained from the other half of the initial solution which was directly dried and calcined under the same conditions. The samples were characterized by XRD including Rietveld refinement, FESEMand TG/DTA. Antibacterial activity was examined towards Gram-positive S. aureus and Gram-negative E. coli .The results showed that only ZnTi-800 consisted of pure Zn2TiO4 (Fd-3m) while Zn TiO was the major phase in three other samples. In the case of samples calcined at 500 °C, traces of ZnO were found. H-ZnTi-800 contained three phases: Zn2TiO4, ZnO and Zn2Ti3O8 (P4332). Cubic Zn2TiO4 contains two cation sites: tetrahedrally coordinated Zn at 0,0,0 and octahedral site at 5/8,5/8,5/8 shared between Zn and Ti. The calculated a-parameters of all obtained Zn2TiO4 as well as Zn–O and Zn/Ti–O bond distances were independent of synthesis. At 500 °C nanocrystalline Zn2TiO4 were obtained with the crystallite sizes 26 and 71 nm for H-ZnTi-500 and ZnTi-500, respectively, while microcrystalline phases were obtained at 800 °C with the crystallite sizes larger than 110 nm. The soft agglomerates consisted of smaller particles were obtained at 500 °C comparin

Chitosan/gelatin and chitosan/gelatin/zeolite films prepared by solvent casting method were impregnated with a mixture of thymol and carvacrol using a green solvent, supercritical carbon dioxide at 35 °C and 30 MPa, during 18 h. Proposed method enabled preparation of biocompatible and biodegradable blends with strong antioxidant and antibacterial activity, whereby amounts of loaded thymol/carvacrol mixture were in the range from 3.3-6%. After initial burst release, both types of films exhibited gradual release of bioactive compounds, with around 72 and 96% of impregnated thymol/carvacrol mixture released in water and PBS (pH 7.4) during tested period of 10 days, respectively. Results of water vapor transmission rate (> 76 gm-2 day-1) confirmed that prepared composites are suitable for wound dressing application. Thermal analysis showed superior properties of prepared thymol/carvacrol loaded films compared to control samples. In addition, mechanical and structural properties, as well as solubility and swelling behavior of the obtained films were investigated in detail.

Chitosan/gelatin and chitosan/gelatin/zeolite films prepared by solvent casting method were impregnated with a mixture of thymol and carvacrol using a green solvent, supercritical carbon dioxide at 35 °C and 30 MPa, during 18 h. Proposed method enabled preparation of biocompatible and biodegradable blends with strong antioxidant and antibacterial activity, whereby amounts of loaded thymol/carvacrol mixture were in the range from 3.3-6%. After initial burst release, both types of films exhibited gradual release of bioactive compounds, with around 72 and 96% of impregnated thymol/carvacrol mixture released in water and PBS (pH 7.4) during tested period of 10 days, respectively. Results of water vapor transmission rate (> 76 gm-2 day-1) confirmed that prepared composites are suitable for wound dressing application. Thermal analysis showed superior properties of prepared thymol/carvacrol loaded films compared to control samples. In addition, mechanical and structural properties, as well as solubility and swelling behavior of the obtained films were investigated in detail.

Natural zeolite-clinoptilolite (from Vranjska Banja deposit in Serbia) and synthetic Beta zeolite, were amin-functionalized using (3-aminopropyl)-triethoxysilane (APTES). The results of the Fourier transform infrared spectroscopy and thermogravimetric analysis confirmed the presence of amino groups derived from APTES onto the modified zeolite surface. APTES-enriched zeolite was further used as an adsorbent of silver ions from aqueous solutions. Natural zeolite-clinoptilolite showed a higher adsorption capacity (96 mg Ag/g), compared to beta zeolite (54 mg Ag/g) which is attributed to the presence of exchangeable cations in the structure of clinoptilolite. The kinetic data follows the pseudo-second-order model which indicates a chemical interaction between silver ions and functional amino groups on the surface of the zeolite. Ag-APTES and APTES-enriched zeolites further were studied as antibacterial agents toward the pathogenic bacteria Gram-negative Escherichia coli DSM 498 and Gram-positive Staphylococcus aureus ATCC 25923. Based on the results, it was concluded that the APTES-zeolites do not exhibit antibacterial activity while Ag- APTES enriched zeolites shows antibacterial effect toward both examined bacterial strains. Antibacterial activity is attributed to the presence of silver ions.

Zeolites are inorganic, crystalline aluminosilicates that nowadays has been used as adsorbents, catalysts and carriers of catalytically activated substances, due to the small size of their pores, large internal surface, and well-defined chemical composition. In this paper, the modification of beta zeolite using (3-aminopropyl)-triethoxysilane (APTES) was investigated. The results of the Fourier transform infrared spectroscopy and thermogravimetric analysis confirmed the presence of amino groups derived from APTES onto the modified zeolite surface. APTES-enriched zeolite was further used as an adsorbent of silver ions from aqueous solutions. The obtained results reveal that a zeolite after modification exhibited significantly better adsorption efficiency (97%) in comparison to the unmodified (37%). The kinetic data follows the pseudo-second-order model which indicates a chemical interaction between silver ions and functional amino groups on the surface of the silanizedbeta zeolite. Ag-APTES enriched beta zeolite also was studied as anantibacterial agent toward the pathogenic bacteria Gram-negative Escherichia coliDSM 498 and Gram-positive Staphylococcus aureus ATCC 25923.

Chitosan/gelatin and chitosan/gelatin/zeolite films prepared by solvent casting method were impregnated with a mixture of thymol and carvacrol using a green solvent, supercritical carbon dioxide at 35 °C and 30 MPa, during 18 h. Proposed method enabled preparation of biocompatible and biodegradable blends with strong antioxidant and antibacterial activity, whereby amounts of loaded thymol/carvacrol mixture were in the range from 3.3-6%. After initial burst release, both types of films exhibited gradual release of bioactive compounds, with around 72 and 96% of impregnated thymol/carvacrol mixture released in water and PBS (pH 7.4) during tested period of 10 days, respectively. Results of water vapor transmission rate (> 76 gm-2 day-1) confirmed that prepared composites are suitable for wound dressing application. Thermal analysis showed superior properties of prepared thymol/carvacrol loaded films compared to control samples. In addition, mechanical and structural properties, as well as solubility and swelling behavior of the obtained films were investigated in detail.

Chitosan/gelatin and chitosan/gelatin/zeolite films prepared by solvent casting method were impregnated with a mixture of thymol and carvacrol using a green solvent, supercritical carbon dioxide at 35 °C and 30 MPa, during 18 h. Proposed method enabled preparation of biocompatible and biodegradable blends with strong antioxidant and antibacterial activity, whereby amounts of loaded thymol/carvacrol mixture were in the range from 3.3-6%. After initial burst release, both types of films exhibited gradual release of bioactive compounds, with around 72 and 96% of impregnated thymol/carvacrol mixture released in water and PBS (pH 7.4) during tested period of 10 days, respectively. Results of water vapor transmission rate (> 76 gm-2 day-1) confirmed that prepared composites are suitable for wound dressing application. Thermal analysis showed superior properties of prepared thymol/carvacrol loaded films compared to control samples. In addition, mechanical and structural properties, as well as solubility and swelling behavior of the obtained films were investigated in detail.

Chitosan/gelatin and chitosan/gelatin/zeolite films prepared by solvent casting method were impregnated with a mixture of thymol and carvacrol using a green solvent, supercritical carbon dioxide at 35 °C and 30 MPa, during 18 h. Proposed method enabled preparation of biocompatible and biodegradable blends with strong antioxidant and antibacterial activity, whereby amounts of loaded thymol/carvacrol mixture were in the range from 3.3-6%. After initial burst release, both types of films exhibited gradual release of bioactive compounds, with around 72 and 96% of impregnated thymol/carvacrol mixture released in water and PBS (pH 7.4) during tested period of 10 days, respectively. Results of water vapor transmission rate (> 76 gm-2 day-1) confirmed that prepared composites are suitable for wound dressing application. Thermal analysis showed superior properties of prepared thymol/carvacrol loaded films compared to control samples. In addition, mechanical and structural properties, as well as solubility and swelling behavior of the obtained films were investigated in detail.

Chitosan/gelatin and chitosan/gelatin/zeolite films prepared by solvent casting method were impregnated with a mixture of thymol and carvacrol using a green solvent, supercritical carbon dioxide at 35 °C and 30 MPa, during 18 h. Proposed method enabled preparation of biocompatible and biodegradable blends with strong antioxidant and antibacterial activity, whereby amounts of loaded thymol/carvacrol mixture were in the range from 3.3-6%. After initial burst release, both types of films exhibited gradual release of bioactive compounds, with around 72 and 96% of impregnated thymol/carvacrol mixture released in water and PBS (pH 7.4) during tested period of 10 days, respectively. Results of water vapor transmission rate (> 76 gm-2 day-1) confirmed that prepared composites are suitable for wound dressing application. Thermal analysis showed superior properties of prepared thymol/carvacrol loaded films compared to control samples. In addition, mechanical and structural properties, as well as solubility and swelling behavior of the obtained films were investigated in detail.

Kontaminacija bakterijama je poslednjih godina postala problem na globalnom nivou zbog čega se javila potreba za novim antibakterijskim agensima. Stabilni titan- -dioksid i cink-oksid pokazuju antibakterijsku aktivnost te se smatraju pogodnim materijalima i zbog njihove netoksičnosti i niske cene [1, 2]. Cilj ovog rada bio je dobijanje novog materijala na bazi ZnO i TiO2 sa antibakterijskim svojstvima. U tu svrhu, titan(IV)-butoksid (25 mol.%) rastvoren je u vodenom rastvoru cink-acetata (75 mol.%), nakon čega je dodavan amonijak dok vrednost pH nije iznosila 8,5. Polovina dobijenog rastvora je hidrotermalno tretirana 12 h na 120 °C, zatim sušena 20 h na 100 °C i kalcinisana 1 h na 500 (uzorak H-ZnTi-500) i 800 °C (uzorak H-ZnTi-800). Druga polovina dobijenog rastvora bila je direktno sušena i kalcinisana pod istim uslovima (uzorci ZnTi-500 i ZnTi-800). Na osnovu XRD rezultata, fazni sastav i veličina kristalita izračunati su u Powder Cell programu, dok su parametri jedinične ćelije i dužine veza dobijeni Ritveldovim utačnjavanjem pomoću FullProf/Winplotr programskog paketa. Termogravimetrijskom analizom nekalcinisanih uzoraka određena je temperatura kalcinacije. Antibakterijska aktivnost dobijenih prahova ispitana je prema dva soja bakterija: Gram-pozitivnoj S. aureus ATCC 25923 i Gram-negativnoj E. coli DSM 498. Jednofazni kubni Zn2TiO4 (ICSD#162392, prostorna grupa ) dobijen je jedino u slučaju ZnTi-800, dok je u ostale tri sinteze Zn2TiO4 bio većinska faza. Pored Zn2TiO4, uzorci H-ZnTi-500 i ZnTi-500 sadržali su 22 i 4 mas.% ZnO (ICSD#26170) redno, dok je u uzorku H-ZnTi-800 pronađeno 7 mas.% ZnO i 5 mas.% Zn2Ti3O8 (ICSD#083525). Parametar a svih dobijenih Zn2TiO4 pokazao se nezavisnim od samog procesa sinteze, a dobijene vrednosti su približno iste: 8,4465(3) za H-ZnTi-500, 8,4604(2) za ZnTi-500, 8,4564(2) za H-ZnTi-800 i 8,4565(2) Å za ZnTi-800. U strukturi kubnog Zn2TiO4 postoje dva katjonska mesta: tetraedarski koordinirani Zn u 0,0,0, i oktaedarski koordini, In recent years bacterial contamination has become a significant problem of the global environment causing the necessity for novel antibacterial agents. Stable, non-toxic and low cost zinc oxide and titanium dioxide are considered as suitable antibacterial materials [1, 2]. The aim of this work was to find a new antibacterial material based on both, ZnO and TiO2. Therefore, titanium(IV) butoxide (25 mole%) was dissolved in a water solution of zinc acetate (75 mole%) after which the ammonia was added until pH was adjusted to 8.5. Half of the obtained solution was hydrothermally treated for 12 h at 120 °C, dried for 20 h at 100 °C and then calcined at 500 (sample H-ZnTi-500) and 800 °C (sample H-ZnTi-800) for 1 h. The other half of obtained solution was directly dried and calcined under the same conditions (samples ZnTi-500 and ZnTi-800). Base on XRD data for obtained powders, the phase composition and crystallite size were calculated in Powder Cell software while unit cell parameters and bond distances were obtained by Rietveld refinement using FullProf software in Winplotr environment. TG analysis of uncalcined samples was used to determine temperature of calcination. Antibacterial properties of obtained powders were examined towards Gram-positive S. aureus ATCC 25923 and Gram-negative E. coli DSM 498 bacteria. The single-phase cubic Zn2TiO4 phase (ICSD#162392, space group ) was obtained in the case of ZnTi-800 while, for three other samples, the Zn2TiO4 is found to be a predominant phase. Beside Zn2TiO4 samples H-ZnTi-500 and ZnTi-500 contained 22 and 4 wt.% of ZnO (ICSD#26170) respectively, while H-ZnTi-800 had 7 wt.% of ZnO and 5 wt.% of Zn2Ti3O8 (ICSD#083525). The a-parameter of all obtained Zn2TiO4 was independent of synthetic procedure having following values: 8.4465(3) for H-ZnTi-500, 8.4604(2) for ZnTi-500, 8.4564(2) for H-ZnTi-800 and 8.4565(2) Å for ZnTi-800. Two cation sites can be found in cubic Zn2TiO4: tetrahedrally coordinated Zn at 0,0,0 and octahedr

The aim of this study was to investigate the possibilities and to optimize the conditions for the synthesis of hydroxyapatite (HAP) on calcium-enriched natural and synthetic zeolites as carriers. Two synthetic zeolites were used in the paper: zeolite 4A (Na-form) and zeolite 5A (Ca-form) as well as natural zeolite - clinoptilolite from Slanci deposit in Serbia. Clinoptilolite and zeolite 4A were enriched with calcium ions by ion exchange treatmentin order to enable the source of Ca 2+ in the crystallization of hydroxyapatite. Phosphorus, necessary for the crystallization of hydroxyapatite, was introduced through a solution of ammonium-hydrogenphosphate. The influence of the concentration of hydrogen phosphate ions, temperature and crystallization time of hydroxyapatite on the morphology of the zeolite surface as well as the degree of its coverage with newly formed hydroxyapatite particles was monitored in the experiments. The obtained powders were characterized by X-ray powder diffraction (XRD), thermal TG-DTG analysis, infrared spectroscopy with Fourier transformation (FTIR) and scanning electron microscopy (SEM). Based on the structural analysis, it was shown that the synthesis of hydroxyapatite did not affect on the structure of the zeolite, except in the case when a very concentrated hydrogen-phosphate solution was used. Thermal analysis showed that all obtained zeolite and HAP samples were stable up to 800 °C. Optimization of the hydrothermal crystallization process showed that temperature and time do not have a crucial influence on the synthesis of the materials (similar results were obtained at 120 °C for 20 hours and at 160 °C for 4 hours). When the concentration of the solution of ammonium hydrogen phosphate was higher, larger crystals of hydroxyapatite were obtained, but the crystal lattice of the zeolite was collapsed. SEM micrography showed that unevenly distributed hydroxyapatite crystals were formed on natural zeolite due to the presence of various imp

Adsorption of the antibiotic ciprofloxacin (CIP) from an aqueous solution by calciumrich clinoptilolite (CLI) was investigated. Obtained results showed that natural CLI possesses a high adsorption efficiency in the removal of CIP at 283, 288 and 293 K and at pH= 5. Adsorption kinetics studied for the initial CIP concentrations of 15–75 mg dm–3 follow Lagergren’s pseudo-second order equation and the adsorption is best represented by the Langmuir model. The adsorption mechanism involves strong electrostatic interactions between aluminosilicate lattice of CLI and the cationic form of CIP accompanied by an ion-exchange reaction. The CIP saturated CLI was successfully regenerated by a cold atmospheric pressure plasma treatment.

Composites based on clinoptilolite and monoterpene phenols - thymol and carvacrol were prepared by supercritical solvent impregnation (SSI) at 30 MPa and 35 ºC during 18 h in supercritical carbon dioxide (scCO2). The composites were characterized in detail and their antibacterial activity was tested towards two potentially pathogenic bacteria; Escherichia coli and Staphylococcus aureus.

Nowadays, all categories of fresh water, surface water, groundwater and atmospheric water, are exposed to various types of pollution. The most troublesome polluting compounds classified as persistent pollutants cannot be completely removed by using conventional water processing methods [1]. Antibiotics fall into this pollutant category due to their very stable molecule structures and a long-life persistence in the environment [2]. One of the effective approaches for treatment of water polluted by antibiotics is adsorption. Zeolite-based adsorbents have recently proved to have excellent performance in antibiotics removal [3]; together with their advantage of having a relatively simple design and cost effectiveness, they appear to be exceptional adsorbents for this purpose. However, the cost of the treatment process, apart from the cost of the adsorbent material, also depends on its recyclability. In case of zeolites, the adsorption of antibiotics was found to be irreversible preventing the reuse of the spent adsorbent material. In this study, the use of non-equilibrium plasma processing for regeneration of spent natural zeolite-clinoptilolite adsorbent was investigated in order to recover its adsorption properties. The antibiotic ciprofloxacin was used as a model persistent pollutant. Treatments of the spent clinoptilolite were performed in a surface dielectric barrier discharge operating in air. Highvoltage sine signal was supplied to the square-shaped segmented upper electrode separated by 2 mm from the lower electrode, which served as a sample holder. The simple geometry of the plasma source design allowed scaling up the device in order to study the effect of the electrode surface in the zeolite treatment. Recovery of the adsorption potential of up to 70% was achieved after 20 minutes of treatment in the first regeneration cycle. High recovery rates were also obtained in subsequent cycles showing that non-equilibrium plasma is a prospective method for recycling us

A novel adsorbent based on natural zeolite-clinoptilolite and nano-oxide particles of magnetite was prepared for removal of the antibiotic ciprofloxacin (CIP) from water media. The adsorbent efficiently removes CIP for initial concentration 15-75 mg dm-3 at 283-293 K at pH=5 following the Lagergren's pseudo-second-order equation. For all studied temperatures and initial concentrations more than 80% of CIP is removed within the first 10 min. The adsorption mechanism includes electrostatic interactions between negatively charged aluminosilicate lattice and cationic form of CIP accompanied by an ion-exchange reaction. The leaching test showed that less than 5% of the adsorbed CIP is desorbed during 24 h suggesting strong interactions between CIP and the adsorbent not only due to electrostatic interactions between CIP and the clinoptilolite lattice but also due to interaction of the carboxylic groups of the CIP and magnetite nano particles. It seems that magnetite coverage not only induces magnetism to the zeolite but also protects the CIP from desorption. The CIP-containing adsorbent exhibits a strong antibacterial activity towards pathogenic bacteria suggesting its applicability in a tertiary stage of a water treatment.

Poly(lactic acid), PLA, as a polyester obtained from renewable resources and with biodegradable properties, is seen as a promising alternative to conventional commodity plastics. In the field of packaging application it would be of great importance to improve some functional properties of PLA, such as antibacterial activity. Within the framework of this study, PLA composites with antibacterial activity were obtained by incorporation of silver-enriched zeolite (Ag-Z) in polymer matrix. Composites with 1, 3 and 5 wt.% of Ag-Z were obtained by solution casting from chloroform. Thermal and thermo-oxidative properties were not altered in grate extent by the introduction of zeolite, which could be beneficial for future melt processing. Degrees of crystallinity of the samples were calculated from melting enthalpy obtained from DSC analysis. Slight decrease of crystallinity degree of polymer matrix was observed with increase in Ag-Z content. Dynamic-mechanical analysis was used to evaluate mechanical properties and transition temperatures. Reinforcement effect of Ag-Z is observed, as judged from storage modulus increase with introduction of Ag-Z filler in polymer matrix. Glass transition temperature of composites was not affected by the presence of the filler. Antibacterial activity of all synthetized composites was investigated toward two bacterial strains, Gram-negative Escherichia coli DSM 498 and Gram-positive bacteria Staphylococcus aureus ATCC 25923. Composites showed good antibacterial activity toward examined strains which is slightly pronounced toward E.coli. In order to investigate the mechanism of antibacterial activity, the leached amount of silver from composites after the investigation of antibacterial activity was measured. The results show slow release of silver, indicating that the mechanism of antibacterial effect can be connected to the metal itself. According to the present results, PLA/Ag-Z composites are promising materials for food packaging.

Composites based on clinoptilolite and monoterpene phenols - thymol and carvacrol were prepared by supercritical solvent impregnation (SSI) at 30 MPa and 35 ºC during 18 h in supercritical carbon dioxide (scCO2). The composites were characterized in detail and their antibacterial activity was tested towards two potentially pathogenic bacteria; Escherichia coli and Staphylococcus aureus.

Poly(lactic acid), PLA, as a polyester obtained from renewable resources and with biodegradable properties, is seen as a promising alternative to conventional commodity plastics. In the field of packaging application it would be of great importance to improve some functional properties of PLA, such as antibacterial activity. Within the framework of this study, PLA composites with antibacterial activity were obtained by incorporation of silver-enriched zeolite (Ag-Z) in polymer matrix. Composites with 1, 3 and 5 wt.% of Ag-Z were obtained by solution casting from chloroform. Thermal and thermo-oxidative properties were not altered in grate extent by the introduction of zeolite, which could be beneficial for future melt processing. Degrees of crystallinity of the samples were calculated from melting enthalpy obtained from DSC analysis. Slight decrease of crystallinity degree of polymer matrix was observed with increase in Ag-Z content. Dynamic-mechanical analysis was used to evaluate mechanical properties and transition temperatures. Reinforcement effect of Ag-Z is observed, as judged from storage modulus increase with introduction of Ag-Z filler in polymer matrix. Glass transition temperature of composites was not affected by the presence of the filler. Antibacterial activity of all synthetized composites was investigated toward two bacterial strains, Gram-negative Escherichia coli DSM 498 and Gram-positive bacteria Staphylococcus aureus ATCC 25923. Composites showed good antibacterial activity toward examined strains which is slightly pronounced toward E.coli. In order to investigate the mechanism of antibacterial activity, the leached amount of silver from composites after the investigation of antibacterial activity was measured. The results show slow release of silver, indicating that the mechanism of antibacterial effect can be connected to the metal itself. According to the present results, PLA/Ag-Z composites are promising materials for food packaging.

Adsorption of the antibiotic ciprofloxacin (CIP) from an aqueous solution by calciumrich clinoptilolite (CLI) was investigated. Obtained results showed that natural CLI possesses a high adsorption efficiency in the removal of CIP at 283, 288 and 293 K and at pH= 5. Adsorption kinetics studied for the initial CIP concentrations of 15–75 mg dm–3 follow Lagergren’s pseudo-second order equation and the adsorption is best represented by the Langmuir model. The adsorption mechanism involves strong electrostatic interactions between aluminosilicate lattice of CLI and the cationic form of CIP accompanied by an ion-exchange reaction. The CIP saturated CLI was successfully regenerated by a cold atmospheric pressure plasma treatment.

Kontaminacija bakterijama je poslednjih godina postala problem na globalnom nivou zbog čega se javila potreba za novim antibakterijskim agensima. Stabilni titan- -dioksid i cink-oksid pokazuju antibakterijsku aktivnost te se smatraju pogodnim materijalima i zbog njihove netoksičnosti i niske cene [1, 2]. Cilj ovog rada bio je dobijanje novog materijala na bazi ZnO i TiO2 sa antibakterijskim svojstvima. U tu svrhu, titan(IV)-butoksid (25 mol.%) rastvoren je u vodenom rastvoru cink-acetata (75 mol.%), nakon čega je dodavan amonijak dok vrednost pH nije iznosila 8,5. Polovina dobijenog rastvora je hidrotermalno tretirana 12 h na 120 °C, zatim sušena 20 h na 100 °C i kalcinisana 1 h na 500 (uzorak H-ZnTi-500) i 800 °C (uzorak H-ZnTi-800). Druga polovina dobijenog rastvora bila je direktno sušena i kalcinisana pod istim uslovima (uzorci ZnTi-500 i ZnTi-800). Na osnovu XRD rezultata, fazni sastav i veličina kristalita izračunati su u Powder Cell programu, dok su parametri jedinične ćelije i dužine veza dobijeni Ritveldovim utačnjavanjem pomoću FullProf/Winplotr programskog paketa. Termogravimetrijskom analizom nekalcinisanih uzoraka određena je temperatura kalcinacije. Antibakterijska aktivnost dobijenih prahova ispitana je prema dva soja bakterija: Gram-pozitivnoj S. aureus ATCC 25923 i Gram-negativnoj E. coli DSM 498. Jednofazni kubni Zn2TiO4 (ICSD#162392, prostorna grupa ) dobijen je jedino u slučaju ZnTi-800, dok je u ostale tri sinteze Zn2TiO4 bio većinska faza. Pored Zn2TiO4, uzorci H-ZnTi-500 i ZnTi-500 sadržali su 22 i 4 mas.% ZnO (ICSD#26170) redno, dok je u uzorku H-ZnTi-800 pronađeno 7 mas.% ZnO i 5 mas.% Zn2Ti3O8 (ICSD#083525). Parametar a svih dobijenih Zn2TiO4 pokazao se nezavisnim od samog procesa sinteze, a dobijene vrednosti su približno iste: 8,4465(3) za H-ZnTi-500, 8,4604(2) za ZnTi-500, 8,4564(2) za H-ZnTi-800 i 8,4565(2) Å za ZnTi-800. U strukturi kubnog Zn2TiO4 postoje dva katjonska mesta: tetraedarski koordinirani Zn u 0,0,0, i oktaedarski koordini, In recent years bacterial contamination has become a significant problem of the global environment causing the necessity for novel antibacterial agents. Stable, non-toxic and low cost zinc oxide and titanium dioxide are considered as suitable antibacterial materials [1, 2]. The aim of this work was to find a new antibacterial material based on both, ZnO and TiO2. Therefore, titanium(IV) butoxide (25 mole%) was dissolved in a water solution of zinc acetate (75 mole%) after which the ammonia was added until pH was adjusted to 8.5. Half of the obtained solution was hydrothermally treated for 12 h at 120 °C, dried for 20 h at 100 °C and then calcined at 500 (sample H-ZnTi-500) and 800 °C (sample H-ZnTi-800) for 1 h. The other half of obtained solution was directly dried and calcined under the same conditions (samples ZnTi-500 and ZnTi-800). Base on XRD data for obtained powders, the phase composition and crystallite size were calculated in Powder Cell software while unit cell parameters and bond distances were obtained by Rietveld refinement using FullProf software in Winplotr environment. TG analysis of uncalcined samples was used to determine temperature of calcination. Antibacterial properties of obtained powders were examined towards Gram-positive S. aureus ATCC 25923 and Gram-negative E. coli DSM 498 bacteria. The single-phase cubic Zn2TiO4 phase (ICSD#162392, space group ) was obtained in the case of ZnTi-800 while, for three other samples, the Zn2TiO4 is found to be a predominant phase. Beside Zn2TiO4 samples H-ZnTi-500 and ZnTi-500 contained 22 and 4 wt.% of ZnO (ICSD#26170) respectively, while H-ZnTi-800 had 7 wt.% of ZnO and 5 wt.% of Zn2Ti3O8 (ICSD#083525). The a-parameter of all obtained Zn2TiO4 was independent of synthetic procedure having following values: 8.4465(3) for H-ZnTi-500, 8.4604(2) for ZnTi-500, 8.4564(2) for H-ZnTi-800 and 8.4565(2) Å for ZnTi-800. Two cation sites can be found in cubic Zn2TiO4: tetrahedrally coordinated Zn at 0,0,0 and octahedr

The aim of this study was to investigate the possibilities and to optimize the conditions for the synthesis of hydroxyapatite (HAP) on calcium-enriched natural and synthetic zeolites as carriers. Two synthetic zeolites were used in the paper: zeolite 4A (Na-form) and zeolite 5A (Ca-form) as well as natural zeolite - clinoptilolite from Slanci deposit in Serbia. Clinoptilolite and zeolite 4A were enriched with calcium ions by ion exchange treatmentin order to enable the source of Ca 2+ in the crystallization of hydroxyapatite. Phosphorus, necessary for the crystallization of hydroxyapatite, was introduced through a solution of ammonium-hydrogenphosphate. The influence of the concentration of hydrogen phosphate ions, temperature and crystallization time of hydroxyapatite on the morphology of the zeolite surface as well as the degree of its coverage with newly formed hydroxyapatite particles was monitored in the experiments. The obtained powders were characterized by X-ray powder diffraction (XRD), thermal TG-DTG analysis, infrared spectroscopy with Fourier transformation (FTIR) and scanning electron microscopy (SEM). Based on the structural analysis, it was shown that the synthesis of hydroxyapatite did not affect on the structure of the zeolite, except in the case when a very concentrated hydrogen-phosphate solution was used. Thermal analysis showed that all obtained zeolite and HAP samples were stable up to 800 °C. Optimization of the hydrothermal crystallization process showed that temperature and time do not have a crucial influence on the synthesis of the materials (similar results were obtained at 120 °C for 20 hours and at 160 °C for 4 hours). When the concentration of the solution of ammonium hydrogen phosphate was higher, larger crystals of hydroxyapatite were obtained, but the crystal lattice of the zeolite was collapsed. SEM micrography showed that unevenly distributed hydroxyapatite crystals were formed on natural zeolite due to the presence of various imp

A novel adsorbent based on natural zeolite-clinoptilolite and nano-oxide particles of magnetite was prepared for removal of the antibiotic ciprofloxacin (CIP) from water media. The adsorbent efficiently removes CIP for initial concentration 15-75 mg dm-3 at 283-293 K at pH=5 following the Lagergren's pseudo-second-order equation. For all studied temperatures and initial concentrations more than 80% of CIP is removed within the first 10 min. The adsorption mechanism includes electrostatic interactions between negatively charged aluminosilicate lattice and cationic form of CIP accompanied by an ion-exchange reaction. The leaching test showed that less than 5% of the adsorbed CIP is desorbed during 24 h suggesting strong interactions between CIP and the adsorbent not only due to electrostatic interactions between CIP and the clinoptilolite lattice but also due to interaction of the carboxylic groups of the CIP and magnetite nano particles. It seems that magnetite coverage not only induces magnetism to the zeolite but also protects the CIP from desorption. The CIP-containing adsorbent exhibits a strong antibacterial activity towards pathogenic bacteria suggesting its applicability in a tertiary stage of a water treatment.