Leticia S. ContieriVitor L SanchesLeonardo M. de Souza Mesquita
18页
查看更多>>摘要：Propolis is a functional food ingredient classified by its physical-chemical characteristics, vegetal source, bee species, and geographical origin. Due to its complex nature and variable composition, the massive use of propolis extracts would require standardization. Several techniques for recovering bioactive compounds from propolis have been reported, varying according to their complexity, degree of automation, and energy dependence. The recovery of propolis target compounds must be carried out using the most appropriate extraction process and the optimized conditions, guaranteeing a better use of the raw material, lower process costs, and good extraction selectivity. This work presents and discusses conventional and alternative techniques developed in the last 20 years. The extraction efficiency, selectivity, the type and amount of solvent, and the conditions to optimize and guarantee safe products (e.g., toxicity and bio compatibility) were reviewed. The current trends were reported, and the technological advances, future perspectives, and applications of the natural bioactive compounds obtained from propolis were discussed. A comprehensive determination of the main advantages and disadvantages of the extraction techniques and the impact of operational conditions on the processes' performance was assessed. Based on the available evidence, some future strategies will be scrutinized, not only regarding the future of using propolis and its products but also considering the impact of a propolis-business model crossing the concept of a circular economy and combining it with the idea of resource efficiency.
查看更多>>摘要：Owing to the excellent adsorption capacity and high selectivity, aerogel have attracted considerable attention recently as promising sorbent materials for oil-water separation. Although many preparation methods for aerogel have been reported, green, facile, and low-cost fabrication is still a challenge. Herein, we reported the preparation of superhydrophobic and superoleophilic aerogel for oil and organic solvents collection from water. The crushed corn stover was treated with sodium hydroxide and hypochlorous acid to obtain the biomass cellulose fibers. The aerogels were produced using polyvinyl alcohol binder, followed by a freeze-drying method. It showed high porosity (98.26-99.01%) and low density (15.15-24.95 mg/cm~3). After modified with hexadecyltrimethoxysilane by chemical vapor deposition, the aerogel exhibited superior superhydrophobicity and showed excellent adsorption capacity (75 g/g). The adsorbed oil and organic solvents can be recovered by extrusion or centrifugation, and the aerogel showed stable performance and excellent reusability. Besides, the aerogel can separate various water-in-oil emulsions with separation efficiencies up to 99.94% and flux as high as 5529 L·m~(-2)·h~(-1). Taken together, the results illustrate that the aerogel hold promise for the fields of oil recovery and environmental protection.
查看更多>>摘要：The expeditious advancement of solar-driven interfacial steam generation by utilizing renewable and free solar energy is a promising strategy for remedying the water crisis. However, salt accumulation on solar evaporators and organic pollutants increases in the remaining bulk water block its commercial potential for practical applications. Herein, a Janus solar evaporator was designed by using a commercialized melamine sponge as the matrix, followed by PDMS modification and deposition of Chinese ink, and TiO2 nanoparticles. The Janus photothermal melamine sponge (JPMS) was designed with containing a hydrophobic salt resistance layer, and a composite photothermal and photocatalysis layer from top to bottom. The applicability of the developed JPMS was systematically investigated for water evaporation, photocatalytic degradation, desalination as well as wastewater treatment. The JPMS exhibits an evaporation rate of 1.49 kg m~(-2)h~(-1) with a corresponding efficiency of 93.54% under 1 sun illumination. Notably, the JPMS also exhibits the high efficiency of synergic photocatalysis for organic pollutants and acquires an excellent salt rejection capability. Integration of SISG, photocatalytic, and salt resistance may be viewed as a prospective avenue for water purifying.
查看更多>>摘要：A novel porous MOF [In_(0.5)(dcpia)_(0.5)·2H2O ·2DMF·(Me2NH2)_(0.5)]n (1)was successfully built by utilizing flexible 4-(3',5'-dicarboxylphenoxy)isophthalic acid (H4dcpia) and In~(3+) ion, which shows a 3D porous structure with 2D perforating pore, and the unique polar pore environment result in high C2H2, CO2 and vapor uptakes together with high gas affinity and CH4 separation performances, which was further certified by IAST calculation, breakthrough curves and theoretical simulations. Moreover, GCMC simulations pointed out that different interactions between framework and gas are the reason for dissimilarity in adsorption process.
查看更多>>摘要：The hydrophobic membrane dominates in the membrane-based gas absorption processes, but sometimes the hydrophilic membrane can show advantages in diluted gas absorption. In order to further study the effect of wettability on absorption performance and select suitable membrane absorption modes, a mass transfer model based on the interfacial partition coefficient (K) was proposed. K simply described the gas-liquid interface relationship and could make a link among various absorption systems for easy comparison. Based on the K, two extreme wetting modes of hydrophobic and hydrophilic ceramic membranes were used to investigate and compare the absorption performances between them, and combining K with the actual interfacial equilibrium relationship to select a suitable absorption mode. The results showed that the hydrophilic membrane is indeed suitable for the absorption of diluted gases, and the K introduced into the model helped to quickly determine the appropriate membrane contactor according to the absorption requirements.
查看更多>>摘要：Nanofiltration with precise separation ability demonstrates the increasing importance in water treatment and high-value substance recycling compared with traditional energy-intensive separation technologies. Nevertheless, nanofiltration membranes still suffer from the permeance-selectivity "trade-off" issue. Herein, we designed the de novo nanofiltration membrane with enhanced separation performance by adopting deprotonated tannic acid (TA) as intermediate layer to tune pyrrole polymerization for forming the polypyrrole selective layer. TA were coated followed by in-situ polymerization of pyrrole and they assembled based on the strong electrostatic and hydrogen bonding interaction. The deprotonation of phenolic hydroxyl groups in TA effectively regulated the polymerization process of pyrrole to obtain the synthesized nanofiltration membrane with the average pore diameter of 0.45 nm. The optimized nanofiltration membrane exhibited a 3.7-fold increase in permeance and almost complete rejection for various dyes with different molecular weights and charges, which breaks the permance-selectivity "trade-off". In addition, the synthesized membrane possessed the excellent structural stability even in polar organic solvent of tetrahydrofuran. Our new strategy for constructing high-performance nanofiltration membrane via intermediate-layer-tuned formation/polymerization of the selective layer can provide an alternative potential avenue to fabricate next-generation molecular separation membranes towards environmental remediation and resource recovery.
查看更多>>摘要：Although nanofiltration (NF) has been widely reported for removing long-chain per-and polyfluoroalkyl substances (PFAS) from water, little is known about the correlations between removal efficacy and PFAS/membrane characteristics, especially for emerging PFAS with shorter polyfluoroalkyl chain or containing fluoroether moieties. A systematic study of treatment of structurally diverse PFAS by NF can help predict the behavior of more unknown compounds during NF process. In this study, we conducted filtration experiments with five commercial NF membranes. Results show that seven legacy PFAS, three emerging perfluoroalkyl ether acids (PFEA) and two fluorotelomer sulfonates (FTS) can be removed simultaneously during the NF process, with rejection ranging from 66.0% to > 99.9%. The removal efficiency of five membranes decreased successively as DK > NF90 > XN45 > NF270 > DL. Rejection of FTS and PFEA by DK membranes were 88.3% to 97.1% and 81.7% to > 99.9%, respectively. Correlation analysis revealed that PFAS molecular structure and membrane characteristics significantly affect PFAS rejection. PFAS molecular weight (MW) and hydrophobicity (logK_(ow)) and membrane intrinsic structural characteristics (e.g., molecular weight cut-off (MWCO), water permeability, and salt selectivity) are among the most significant parameters impacting PFAS removal. The findings imply that both steric hindrance and hydrophobic interactions contribute to PFAS rejection. Moreover, the mass of PFAS adsorbed on the membrane was positively correlated with their molecular parameters (i.e., MW and logK_(ow) and weakly correlated with membrane properties, suggesting that the adsorption and rejection of PFAS have similar driving forces. This study provides critical insights into the application of NF for emerging PFAS removal for both the scientific community and private industry, concerning water purification processes and remediation of thousands of PFAS-impacted sites.
Mariia E. DmitrenkoAnna I. KuzminovaAndrey A. Zolotarev
14页
查看更多>>摘要：Solution-processable polyelectrolyte complex (PEC) modified with various water-soluble fullerene derivatives (fullerenol, carboxyfullerene, fullerene derivative with L-arginine) were synthesized by using sodium carboxymethyl cellulose (CMC) and poly(diallyldimethylammonium chloride) (PDADMAC) for the creation of novel supported mixed matrix membranes for enhanced pervaporation and nanofiltration. The optimal preparation conditions and membrane composition were found. The structural characteristics and physicochemical properties of PEC-based membranes were analysed by Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron (SEM) and atomic force (AFM) microscopies, thermogravimetric analysis (TGA), contact angle measurements and swelling experiments. The developed membranes were tested in pervaporation dehydration of isopropanol (12-50 wt% water) and, for the first time, in nanofiltration of heavy metals (model solutions and wastewater from galvanic production). Optimal transport characteristics were possessed by a supported membrane with a selective layer based on PEC-fullerenol (4%) composite: improved permeation flux of 0.28-1.62 kg/(m~2h) and 99.99-79.30 wt% water in permeate in pervaporation dehydration of isopropanol (12-50 wt% water) at 22 °C, and 2.5 times improved permeability at a high rejection coefficients in nanofiltration of heavy metals compared to the pristine CMC membrane, which indicated its promise industrial application for water purification.
Vijay Mohan NagulapatiHafiz Muhammad Raza Ur RehmanJunaid Haider
15页
查看更多>>摘要：Deep eutectic solvents (DES) are used as a green sustainable alternative to room temperature ionic liquids (RTILs), given their low cost and environmentally friendly nature. In this work, solubilities of CO2, CO, CH4, H2 and N2 gases in choline chloride/urea (ChCl/Urea) based DES is investigated. Experimental solubility data from literature is used to train machine learning models to predict the solubilities of different gases in ChCl/Urea at temperatures ranging from 298.15 K to 372.15 K and pressure ranging from 0.01 to 5 MPa. In this context, a Support Vector Machine and Long Short-term Memory Auto Encoder-based hybrid machine learning model is proposed. The hybrid model exhibited excellent prediction accuracy with low root mean square error values of 0.000985, 0.00055, 0.00037, 0.000583 and 0.000164 for CO2, CO, CH4, H2 and N2, respectively. The predicted solubility data is regressed in commercial software Aspen Plus V11 for process design of H2 separation from gaseous feed mixture. Complex feed mixture consisting of CO2, CH4, H2, CO, and N2 is absorbed in ChCl/Urea. As a result, hydrogen is recovered and purified from complex feed mixture at specific energy consumption of 6.03 kWh/kg_(H2). Furthermore, carbon removal is observed as > 99% from feed gas at the expense of 3.02 MJ/kgCO2.
查看更多>>摘要：Abating the common indoor pollutants by adsorption is profoundly governed by the properties of adsorbent and the presence of water. We carried out Monte Carlo simulations of adsorption of five common indoor pollutants (benzene, hydrogen sulfide, sulfur dioxide, formaldehyde and ammonia) on functionalized graphitic pores at 298 K with and without the presence of water to investigate the effects of concentration and type of functional groups (FGs) and pore size. The simulation results for the isotherm, the isosteric heat at zero loading, and the spatial distribution of water and pollutant were analyzed to evaluate the effectiveness of remediation of these pollutants. It is found that adsorption of the pollutants at typical indoor concentrations (sub-ppm) occurs in the Henry's law region where the interaction between pollutant and adsorbent dominates the intermolecular interaction of pollutant. Regardless of the pollutants water is always strongly attracted to the FGs in forms of clusters, and the abatement of the pollutant rests on its electrostatic interactions with water molecules in the clusters and van der Waals interactions with the graphitic surface. The relative interplay of these interactions depends on the properties of the pollutant, and this gives rise to two distinct phenomena: competition and cooperation. For ammonia and formaldehyde whose electrostatic interactions with water (in the cluster on the FGs) are strong, their capture is enhanced. On the other hand, the abatement of benzene and hydrogen sulfide is negatively affected because of their weaker interactions with water. Given the inevitable occupation over the FGs by water, more attention should be paid on the interactions between adsorbed water and the pollutants.
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