The use of carbonaceous adsorbents for the extraction of silver ions from solutions and slurries

The adsorption of silver(I) ions from aqueous solutions on carbonaceous adsorbents synthesized from hard coals was studied. Adsorption isotherms were measured under static and dynamic conditions at various temperatures. Adsorption was shown to be maximum in alkaline media. The isotherms obtained at low silver concentrations were described by the Freundlich equation. A decrease in adsorption as the temperature increased was evidence that the process was exothermic. The kinetics of the process was studied and the thermodynamic parameters of adsorption determined.     

Evaluation of the working conditions of light adsorbents and their use as sampling material for the GC analysis of organic air pollutants in work areas

Summary The use of traps containing graphitized carbon black for the collection and pre-analysis of atmospheric pollutants in industrial areas is presented. The working conditions, in terms of trapping capability and effectiveness of release by thermal desorption are discussed. Some practical applications are also given.     

New catalytic methods for obtaining cellulose and other chemical products from vegetable biomass

Experimental data concerning the effects of catalysts are discussed for the oxidative destruction of wood lignin in the acetic acid-hydrogen peroxide-water medium, for lignin oxidation with oxygen into aromatic aldehydes in aqueous alkali, for the acid-catalyzed conversion of carbohydrates into esters of levulinic acid and 5-hydroxymethylfurfural in the two-phase system butanol-water, and for α-angelicalactone polymerization into biodegradable polymers.     

Chitosan-based adsorbents for analytical sample preparation and removal of pollutants from aqueous media: Progress,challenges and outlook

The development of greener and more efficient materials for extracting environmental contaminants from various matrices is a growing area of research. Materials that do not cause secondary pollution are highly desirable in such applications. Chitosan (CS) is a non-toxic biopolymer enriched with amino and hydroxyl groups, used not only for extracting pollutants but also for crosslinking and functionalizing CS with other materials. The composites of CS with carbon, metal-organic frameworks, metal and metal oxide nanoparticles, and magnetic materials have been used to extract various inorganic and organic analytes in aqueous samples. CS-based sorbents have been evaluated across multiple extraction techniques, such as dispersive solid phase extraction, magnetic solid phase extraction, solid phase microextraction, syringe solid phase extraction, membrane-protected solid phase extraction, and others. This review offers an overview of the CS-based sorbents in analytical extractions, highlighting their strengths, weaknesses, and potential solutions. At the end, a brief overview of the CS-based adsorbents in water treatment applications is also provided.     

Charting the trends in nuclear techniques for analysis of inorganic environmental pollutants

Publications in analytical abstracts in the period 1975-1984 and papers presented at the Modern Trends in Activation Analysis international conferences series in the period 1961-1986 have been used as an empirical basis for assessing general trends in research and publication activity. Some ebbs and flows in the specialty of instrumental techniques for analysis of environmental trace pollutants are revealed by a statistical analysis of the publications.     

The use of microwave ovens for rapid organic synthesis

Four different types of organic reactions have been studied and seven different organic compounds have been prepared, under pressure in a microwave oven. Considerable rate increases have been observed.     

Methods for obtaining solid dispersions of drugs and their properties

The possibility of improving the solubility of drugs by obtaining solid dispersions (SDs) with polymers is demonstrated. The solubility of these SDs is dependent both on the nature of drug and polymer and on the conditions of their preparation. IR spectroscopy of the obtained SDs and the analysis of results found in literature indicate that inclusion complexes are formed within them.

     

Synthesis of polyfunctional polyconjugated oligomers of 4-aminophenol and their use in obtaining of antistatic composite materials

Polyconjugated oligomers containing aromatic links with hydroxyl and amino functional groups were synthesized by oxidative polycondensation of 4-aminophenol. They exhibit solubility and fusibility, heat resistant, paramagnetic and semiconductor properties, and also high reactivity in reactions characteristic for aromatic hydroxyl groups. These oligomers were used as supplements to industrial polymers. Composite materials were obtained including a rubber with high physico-mechanical, thermal, and electrical properties.     

Smart modification of inorganic fibers and flammability mechanical and radiation shielding properties of their rubber composites

Facile and smart method for the modification of inorganic fibers has been developed. The polyaniline was synthesized on basalt fiber surface presenting an organic polymer shell to the inorganic fibers. The modified basalt fibers were dispersed in rubber-producing well-dispersed rubber composites. Various mass loadings of modified basalt fibers were dispersed and optimized. The effect of radiation on the properties of developed rubber composites was investigated by exposure to different gamma radiation doses. The flammability, thermal and mechanical properties were studied. The flammability of developed composites was improved achieving 62 and 16% reduction in the peak heat release rate compared to blank rubber and unmodified basalt fiber-based rubber composite, respectively. This is in addition to significant reduction in emission of CO and CO₂ gases by 65 and 58%, respectively. Also, the tensile strength property was enhanced by 38 and 53% compared to blank and unmodified basalt composite, respectively. The role of polyaniline layer on inorganic fiber surface and their effect on the properties of the produced composites was studied. The organic polymer shell achieved good compatibility and interfacial adhesion of basalt fibers with rubber matrix and radiation protection effect for the developed composites.     

Non-hydrolytic synthesis of titanosilicate xerogels by acetamide elimination and their use as epoxidation catalysts

Novel non-hydrolytic syntheses of titanosilicate xerogels by polycondensation of silicon acetate, Si(OAc)₄, with titanium (IV) dimethylamide or diethylamide, Ti(NR₂)₄ (R?=?Me, Et), are presented. The reactions are based on acetamide elimination and yield gels with a high content of Si?CO?Ti bonds in comparison with the ester elimination route. Although a ligand exchange was observed, it was interestingly not followed by homo-condensation and during the synthesis the phase separation to SiO₂ and TiO₂ was avoided. The degree of condensation reached up to 68?%. The xerogels prepared for a comparison by ester elimination from Si(OAc)₄ and titanium (IV) isopropoxide featured a significantly lower content of the Si?CO?CTi bonds. The initial tests in the epoxidation of cyclohexene by cumyl hydroperoxide (CHP) indicated a high selectivity and moderate activity of the xerogels. The catalytic properties were significantly improved by combining non-hydrolytic and hydrolytic methods yielding mesoporous and homogeneous Si/Ti mixed oxides. The catalysts prepared by these methods provided a complete epoxidation of cyclohexene in 2?h at?65?°C.     

Effectiveness of radiation processing in elimination of Campylobacter from poultry meat

Campylobacter, a common poultry intestine commensal, is a well known cause of human gastric illnesses across the globe. Consumption of contaminated poultry meat is a major cause of Campylobacter related infections. In the present study, radiation sensitivity of indigenous strains of C. jejuni and C. coli isolated from poultry was evaluated. The decimal reduction dose (D₁₀) values of different Campylobacter isolates at 0-4 °C in saline and blood broth were in the range of 0.120-0.210 kGy and 0.170-0.234 kGy, respectively. D₁₀ values in chicken meat homogenate for Campylobacter were in the range of 0.110-0.190 kGy. Chicken meat samples were inoculated with C. jejuni and exposed to gamma radiation to study the effectiveness of radiation treatment in elimination of Campylobacter. Radiation treatment with a dose of 1 kGy could achieve complete elimination of 10⁵ CFU of Campylobacter/g in poultry meat samples. No recovery of Campylobacter was observed, even after enrichment and selective plating in 1 kGy treated chicken meat samples stored at 4 °C up to 7 days. Present study shows that irradiation of poultry meat with 1 kGy can ensure safety of poultry meat.     

Recent advances in the use of graphene-family nanoadsorbents for removal of toxic pollutants from wastewater

Adsorption technology is widely considered as the most promising and robust method of purifying water at low cost and with high-efficiency. Carbon-based materials have been extensively explored for adsorption applications because of their good chemical stability, structural diversity, low density, and suitability for large scale production. Graphene – a single atomic layer of graphite – is the newest member in the family of carbon allotropes and has emerged as the “celeb” material of the 21st century. Since its discovery in 2004 by Novoselov, Geim and co-workers, graphene has attracted increased attention in a wide range of applications due to its unprecedented electrical, mechanical, thermal, optical and transport properties. Graphene's infinitely high surface-to-volume ratio has resulted in a large number of investigations to study its application as a potential adsorbent for water purification. More recently, other graphene related materials such as graphene oxide, reduced graphene oxide, and few-layered graphene oxide sheets, as well as nanocomposites of graphene materials have also emerged as a promising group of adsorbent for the removal of various environmental pollutants from waste effluents. In this review article, we present a synthesis of the current knowledge available on this broad and versatile family of graphene nanomaterials for removal of dyes, potentially toxic elements, phenolic compounds and other organic chemicals from aquatic systems. The challenges involved in the development of these novel nanoadsorbents for decontamination of wastewaters have also been examined to help identify future directions for this emerging field to continue to grow.     

Advances in organic–inorganic hybrid sorbents for the extraction of organic and inorganic pollutants in different types of food and environmental samples

The efficiency of the extraction and removal of pollutants from food and the environment has been an important issue in analytical science. By incorporating inorganic species into an organic matrix, a new material known as an organic–inorganic hybrid material is formed. As it possesses high selectivity, permeability, and mechanical and chemical stabilities, organic–inorganic hybrid materials constitute an emerging research field and have become popular to serve as sorbents in various separaton science methods. Here, we review recent significant advances in analytical solid‐phase extraction employing organic–inorganic composite/nanocomposite sorbents for the extraction of organic and inorganic pollutants from various types of food and environmental matrices. The physicochemical characteristics, extraction properties, and analytical performances of sorbents are discussed; including morphology and surface characteristics, types of functional groups, interaction mechanism, selectivity and sensitivity, accuracy, and regeneration abilities. Organic–inorganic hybrid sorbents combined with extraction techniques are highly promising for sample preparation of various food and environmental matrixes with analytes at trace levels.