Improvement Of Sorption Properties Research Articles

Magnetic amino-sulfonic dual sorbent for uranyl sorption from aqueous solutions – Influence of light irradiation on sorption properties

The association of magnetite microparticles with bi-functional amino-sulfonate polymer (obtained by condensation of guanidine and amino hydroxynaphthalene sulfonic acid, mediated by formaldehyde) allows synthesizing a magnetic composite sorbent (M−GANS). The sorbent bearing both amine and sulfonate groups is efficient for uranyl sorption at pH 4–5. The sorption isotherms are successfully fitted by the Temkin equation, while kinetics is controlled by the pseudo-first order rate equation. The sorption properties are increased by UV irradiation in terms of both sorption capacity (by 25 %, up to 1.25 mmol U g−1) and kinetics. The sorption occurs on both amine and sulfonate groups; the improvement in sorption properties under UV irradiation is tentatively assigned to the photo-reduction of uranyl species (mediated by magnetite particles and amine groups from polymer layer). The UV irradiation improves the selectivity of M−GANS for uranium against other metal ions, tested on both synthetic and real solutions. This improvement can be correlated to the higher propensity of uranyl to be photo-reduced compared with investigated competitor ions. The recycling of the sorbent was successfully tested for five successive cycles of sorption and desorption (stably complete): the loss in sorption performances is slightly reduced (less than 1.5 % at the fifth cycle) under UV irradiation compared with experiments performed under dark conditions (loss close to 4.2 %). The uranium peroxide precipitate obtained at the end of the treatment of acid leachate of ore shows higher purity when UV irradiation was applied.

Antimicrobial Activity and Barrier Properties against UV Radiation of Alkaline and Enzymatically Treated Linen Woven Fabrics Coated with Inorganic Hybrid Material.

One of the directions of development in the textiles industry is the search for new technologies for producing modern multifunctional products. New solutions are sought to obtain materials that will protect humans against the harmful effects of the environment, including such factors as the activity of microorganisms and UV radiation. Products made of natural cellulose fibers are often used. In the case of this type of material, it is very important to perform appropriate pretreatment before subsequent technological processes. This treatment has the aim of removing impurities from the surface of the fibers, which results in the improvement of sorption properties and adhesion, leading directly to the better penetration of dyes and chemical modifiers into the structure of the materials. In this work, linen fabrics were subjected to a new, innovative treatment being a combination of bio-pretreatment using laccase from Cerrena unicolor and modification with CuO-SiO2 hybrid oxide microparticles by a dip-coating method. To compare the effect of alkaline or enzymatic pretreatment on the microstructure of the linen woven fabrics, SEM analysis was performed. The new textile products obtained after this combined process exhibit very good antimicrobial activity against Candida albicans, significant antibacterial activity against the Gram-negative Escherichia coli and the Gram-positive Staphylococcus aureus, as well as very good UV protection properties (ultraviolet protection factor (UPF) > 40). These innovative materials can be used especially for clothing or outdoor textiles for which resistance to microorganisms is required, as well as to protect people who are exposed to long-term, harmful effects of UV radiation.

Potential of Biochar to Alternate Soil Properties and Crop Yields 3 and 4 Years after the Application

Several studies have reported that biochar can improve soil properties which are linked with higher crop yields and this effect is long-term. This paper aimed to study the effects of biochar (0, 10 and 20 t ha−1) and its combinations with N-fertilization (zero, first and second level of N-fertilization) after 3 and 4 years of its application on improving soil characteristics of loamy Haplic Luvisol and crop yields (Dolná Malanta, Slovakia). The results indicated an increase in soil pH (+7%), improvement in sorption properties (hydrolytic acidity decreased by 11%, sum of basic cations and base saturation increased by 20% and 5%, respectively) and soil organic carbon rose by 27% with increasing biochar rate in the soil. N-fertilization applied to biochar treatments was a stabilizing moment in C sequestration even in the case of its labile forms. Overall, humus stability and quality were not significantly changed, however in biochar treatments without N-fertilization, the humus stability and quality decreased 3 and 4 years after biochar application. Yield parameters differed with relation to climate conditions during both vegetation crop seasons, however the combination of 20 t ha−1 of biochar with the first and second level of N-fertilization had the highest potential to increase the grain yield.

Chemical modification of Byrsonima crassifolia with citric acid for the competitive sorption of heavy metals from water

This study reports the chemical modification of the Byrsonima crassifolia biomass with citric acid to improve its sorption properties for the removal of cadmium and nickel ions from aqueous solutions under competitive sorption conditions (i.e., multicomponent solutions). The best operating conditions of the chemical modification process were identified using the signal-to-noise ratio to enhance the metal uptakes and to reduce the competitive sorption effects during the simultaneous removal of these metals using the modified biomass. Results indicated that both the sorption capacity and selectivity for heavy metal removal can be improved in multicomponent metal solutions. This improvement in sorption properties of B. crassifolia biomass is mainly related to an increment of the acidic functional groups on the biomass surface caused by the chemical reaction between citric acid and this lignocellulosic material. The methodology reported in this study can be used to increase the sorption properties of other biomasses for the effective removal of toxic pollutants from multicomponent solutions and for the synthesis of sorbents with tailored sorption properties.

2Mg-Fe Alloy Processed by Hot Extrusion: Influence of Particle Size and Extrusion Reduction Ratio on Hydrogenation Properties

Samples of a 2Mg-Fe (at.%) mixture were produced by high energy ball-milling (HEBM) with ball to powder ratio = 20:1, in an argon gas atmosphere, in 190 ml vials (sample-1) to produce powders and in 300 ml vials (sample-2) to produce plates. Both samples were cold-pressed into preforms. The preforms were then extruded at 300°C at a ram speed of 1mm/min., with the following extrusion ratios: sample-1 at 3/1 to ensure porosity and sample-2 at 5/1 to increase the adhesion of the plates. The resulting bulks from samples 1 and 2 were hydrogenated for 24h in a reactor under 15 bar of H2to produce the Mg2FeH6complex hydride, and at 11 bar of H2to produce both the complex hydride and MgH2hydride. In addition, sample-1 was severely temperature-hydrogen cycled to verify its microstructural stability and the influence of grain size on the sorption properties. XRD patterns showed Mg(hc), Fe(ccc) and Mg2FeH6in both samples, and sample-2 also contained MgH2and MgO (attributed to processing contamination). DSC results demonstrated that the initial desorption temperature of sample-1 was lower than that of sample-2. However, sample-2 showed faster desorption kinetics, presenting a desorption peak about 73°C below that of sample-1. This could be attributed to the activation/catalyst effect of the MgH2hydride. The improvement in sorption properties was attributed mainly to porosity and to the type of employed catalysts.