Effect of Sodium Benzenesulfonate on SO42− Removal from Water by Polypyrrole-Modified Activated Carbon

Sodium benzenesulfonate was doped into polypyrrole-modified granular activated carbon (pyrrole-FeCl3·(6H2O)-sodium benzenesulfonate-granular activated carbon; PFB-GAC) with the goal of improving the modified GAC’s ability to adsorb sulfate from aqueous solutions. At a GAC dosage of 2.5 g and a pyrrole concentration of 1 mol L−1, the adsorption capacity of PFB-GAC prepared using a pyrrole:FeCl3·(6H2O):sodium benzenesulfonate ratio of 1000 : 1500 : 1 reached 23.05 mg g−1, which was eight times higher than that for GAC and two times higher than that for polypyrrole-modified GAC without sodium benzenesulfonate. Adsorption was favored under acidic conditions and high initial sulfate concentrations. Doping with sodium benzenesulfonate facilitated polymerization to give polypyrrole. Sodium benzenesulfonate introduced more imino groups to the polypyrrole coating, and the N+ sites improved ion exchange of Cl− and SO42− and increased the adsorption capacity of sulfate. Adsorption to the PFB-GAC followed pseudo-second-order kinetics. The adsorption isotherm conformed to the Langmuir model, and adsorption was exothermic. Regeneration using a weak alkali (NH3·H2O), which released OH− slowly, caused less damage to the polypyrrole than using a strong alkali (NaOH) as the regeneration reagent. NH3·H2O at a concentration of 12 mol L−1 (with the same OH− concentration as 2 mol L−1 NaOH) released 85% of the sorbed sulfate in the first adsorption-desorption cycle, and the adsorption capacity remained >6 mg g−1after five adsorption-desorption cycles.

Water-soluble polymeric particle embedded cryogels: Synthesis, characterisation and adsorption of haemoglobin

Making cryogels, which are among today’s accepted adsorbents, more functional with different methods, has been one of the subjects spent overtime. In this study, water-soluble poly(maleic anhydride-alt-acrylic acid) polymer embedded in poly(2-hydroxyethyl methacrylate) cryogels. Copper ions were then immobilised to this structure, and this polymer was used for adsorption of haemoglobin from aqueous systems. Adsorption interaction was carried out on an electrostatic basis, and approximately 448.62 mg haemoglobin/g polymer adsorption capacity value was obtained. It was found that the same material has managed to maintain its adsorption ability by 90.3% even after the use of it five times in the adsorption/desorption cycle. The adsorption interaction was determined to be appropriate for the Langmuir model by isotherm studies. The change in Gibbs free energy value was calculated as −2.168 kJ/mol.

Short-cut Method for Assessing Solvents for Gas Cleaning by Reactive Absorption

A new short-cut method (NoVa) for assessing solvents for gas cleaning by reactive absorption is presented. It considers the absorption / desorption cycle using the assumption of infinite number of stages in both columns. For a given feed and removal rate, the method yields an estimate for the specific regeneration energy q as a function of the solvent circulation rate L/G. The sole solvent-dependent input consists of two correlations describing the gas solubility at absorber and desorber conditions and estimates of caloric properties. Furthermore, a simple equation (SolSOFT) for correlating the gas solubility as a function of the gas loading of the solvent is presented. A theoretical analysis of the process reveals general properties of the dependency of q on L/G. The NoVa method is described and tested using amine-based solvents for post combustion carbon capture as examples.

Synthesis of Ethylenediaminetetraacetic Acid Disodium Salt Functionalized Magnetite/Chitosan Nanospheres for the Highly Efficient Removal of Methylene Blue

In this paper, novel Ethylenediaminetetraacetic acid disodium salt (EDTA) functionalized magnetite/ chitosan nanospheres (Fe3O4/CS-EDTA) are synthesized by combining solvothermal method and chemical modification, and they are further applied as a kind of adsorbent to eliminate dye of methylene blue (MB) from wastewater. The properties as well as structure exhibited by the fabricated adsorbent are characterized through FTIR, XRD, TG and TEM, together with VSM. The impact exerted by sorption parameters (time of contact, initial dye concentration, temperature, etc.) on the adsorptions were evaluated in batch system. These results demonstrated that our magnetic materials held the adsorption capacity for MB of 256 mg g−1 (pH = 11), and the kinetic model of pseudo-second-order and the Langmuir model could make an effective simulation regarding the adsorption kinetics and isotherm, respectively. Besides, the external magnetic field can assist in easily separating dye adsorbed Fe3O4/CS-EDTA from solution for regeneration. The removal efficiency of recycled adsorbents remained above 92% in the 5th adsorption/desorption cycle. These superioritiesmake Fe3O4/CS-EDTA a high-efficientmultifunctional adsorbent for removing dyes from wastewater.

Dynamic molecular pockets on diffusion channel for efficient production of polymer-grade propylene

Size-based molecular sieving works well for rigid molecules with complete exclusion of larger ones, yet interaction-induced molecular sieving may offer unusual separation capability for molecules with matching physicochemical properties. Here we report a MOF material (XXU-3) featuring one-dimension channels with embedded molecular pockets opening to C3H6 and C3H8 at substantially different pressures. The dynamic nature of the pockets is revealed by single-crystal-to-single-crystal transformation upon exposure of the activated XXU-3 to C3H6 or C3H8 atmosphere. Breakthrough experiments demonstrate that XXU-3 is not only capable of separating C3H6 from C3H8 with record-high C3H6 productivity, but also the first MOF material realizing polymer-grade C3H6 production in a single adsorption-desorption cycle from an equimolar C3H6/C3H8 mixture. The underlying separation mechanism, namely orthogonal-array dynamic molecular sieving, is an exemplary strategy for both large separation capacity and fast adsorption-desorption kinetics. This work presents an ideal design for next-generation sieving materials and it holds great potential for applications in adsorptive separation.

Simultaneous Adsorption of Cation and Anion by Thermosensitive Hydrogels

Simultaneous usage of cationic and anionic thermosensitive hydrogels was shown to positively contribute to adsorption of heavy metal ions. The potential capacity for recovering heavy metal ions from an aqueous solution was enhanced by incorporating relatively hydrophobic moiety to the hydrogels, which was ascribed to the increase in the desorption on elevating the temperature over the lower critical swelling temperature (LCST). N-tert-butylacrilamide was added into the hydrogels to increase its desorption potential. The addition of N-tert-butylacrylamide does not significantly affect hydrogels’ adsorption ability. Moreover, the adsorption-desorption cycle was not diminished by repeating the temperature swing above the critical temperature at which the volume phase transition was induced.

Hydrating the Respiratory Tract: An Alternative Explanation Why Masks Lower Severity of COVID-19 Disease

Seasonality of respiratory diseases has been linked, among other factors, to low outdoor absolute humidity and low relative humidity in indoor environments, which increase evaporation of water in the mucosal layer lining the respiratory tract. We demonstrate that normal breathing results in an absorption-desorption cycle inside facemasks, where super-saturated air is absorbed by the mask fibers during expiration, followed by evaporation during inspiration of dry environmental air. For double-layered cotton masks, which have considerable heat capacity, the temperature of inspired air rises above room temperature, and the effective increase in relative humidity can exceed 100%. We propose that the recently reported, disease-attenuating effect of generic facemasks is dominated by the strong humidity increase of inspired air.SIGNIFICANCE STATEMENTFacemasks are the most widely used tool for mitigating the spread of the COVID-19 pandemic. Decreased disease severity by the wearer has also been linked to the use of cloth facemasks. This well-documented finding is surprising considering that such masks are poor at filtering the smallest aerosol particles, which can reach the lower respiratory tract and have been associated with severe disease. We show that facemasks strongly increase the effective humidity of inhaled air, thereby promoting hydration of the respiratory epithelium which is known to be beneficial to the immune system. Increased humidity of inspired air could be an alternate explanation for the now well-established link between mask wearing and lower disease severity.