Residual Solution Research Articles

Phase behavior of aqueous solutions of ethaline deep eutectic solvent

We have established a detailed phase diagram of a prototypical DES as a function of the hydration level. Two distinct thermal phase behaviors are observed depending on the water content with respect to a cross-over composition Wg’ = 30%. For W < Wg’, the formation of ice is not observed under the experimental conditions used in this study, and the solution falls in the category of glassforming systems. Fully vitreous states could also be obtained between 30% and 50%, but they are metastable with respect to water crystallization. For W > Wg’, ice crystallization occurs but the residual DES solution remains amorphous (liquid or glassy). In the latter case, whatever the initial water fraction, this transformation finally ends at the fixed composition Wg’ corresponding to 6 to 10 water molecules per choline ion for the two studied DESs. We infer that the residual liquid water molecules forming this maximally freeze-concentrated solution are strongly interacting with DES molecular units. This situation is also known as the “water-in-DES” case. Conversely, ice crystallization concerns free water molecules, provided that W > Wg’, also known as the “DES-in-water” case. This entire phase behavior is explained in the context of maximally freeze-concentrated solutions and attributed to the concomitant effects of ice freezing depression, glassforming ability of weakly hydrated DES (W < Wg’) and water structure distortion. This study also highlights the potential of DESs for their uses in freeze-drying processes and biopreservative applications.

Evaluation of ecotoxicity of contaminated water for validation of phytoremediation time

Phytoremediation has been used as an alternative for removal of heavy metals in aquatic environments, but plant residence time and toxicity reduction need to be studied. Ecotoxicological bioassays and root anatomic studies were conducted in order to validate the phytoremediation of Echinochloa crus-galli L. at three different ages. The experiment was conducted using E. crus-galli seeds with processing factorial experimental design (2x3) and four replicates. Cadmium presence and absence (0.8 and 0 mg L-1) at three times (20, 30, and 45 days after germination). Cd levels were quantified by flame atomic absorption spectroscopy on both aerial parts and roots. A bioassay was performed testing both acute and chronic effects using microcrustacean Daphnia similis with the purpose of evaluating phytoremediation efficiency. Regardless of biomass, E. crus-galli L. can be used for 16 to 19 days for 45 days after germination (DAG), tolerating the phytotoxicity of this metal. The residual solution after phytoremediation had chronic effect on D. similis, indicating that the time taken was not sufficient to reduce the toxicity of the solution. Thus, ecotoxicological essays are important tools in evaluating the efficiency of this type of process. While E. crus-galli L. is a valuable tool in Cd phytoremediation programs, exposure time must be higher than 19 days to reduce concentrations of this metal in the water to conform to the CONAMA 357/2005 e 430/2011 standards.

Determination of the Ratio of the Decantation Time and the Separation of Components in Lipoaspirate.

Thirty milliliters of fat were obtained from 11 healthy adults and decanted at room temperature for 0, 30, and 60 minutes. After decantation, the infiltration liquid and the remnant fat were measured with a volumetric pipette. Once the solution was removed, the remnant fat was centrifuged at 3000 rpm for 5 minutes to separate any residual solution, to measure the amount of actual fat obtained at that time point. Viability was determined with trypan blue staining for all the samples. After decantation, 9.4 ± 0.79 mL of fat was obtained at time 0, whereas 7.7 ± 1.56 mL was obtained at 30 minutes and 6.9 ± 0.92 mL at 60 minutes. Actual fat volume was 6.6 ± 1.56 mL, 5.5 ± 1.39, and 5.26 ± 1.3 mL, respectively. Viability at time 0 was 73.33 ± 0.06%, 72.57 ± 0.1% at 30 minutes, and 59.3 ± 0.09% at 60 minutes (P = 0.004). The fat grafting, processed by decantation, will have the best performance within a period of 30 minutes after harvesting, where the best rate of viability and separation of components will be achieved.

Kremeňovo-karbonátové žily s U-Mo-Cu mineralizáciou v permských intermediárnych až bázických vulkanitoch hronika na lokalite Kravany (Kozie chrbty, východné Slovensko)

Historical uranium ore deposit Kravany is located in the eastern part of Kozie Chrbty Mts., approximately 9 km SW of the district town Poprad. Stratiform, infiltration U-Cu-Pb mineralization is bound to the Upper Permian clastic sediments (Kravany Beds, member of Malužiná Formation, Hronicum Unit), which are enriched in fragments of carbonized flora. Vein U-Mo-Cu mineralization was found in the Upper Permian intermediate to basic volcanics intersecting the sediments of the Kravany Beds (also ore lenses). Vein filling originated in the following development stages: I.) Quartz-pyrite (quartz, pyrite, marcasite), II.) Dolomite-pyrite (dolomite, pyrite, marcasite, galena), III.) Copper (tetrahedrite, tennantite, chalcopyrite), IV.) Uranium-molybdenum (uraninite, Pb-Mo-S phase, coffinite, quartz), and V.) Calcite (calcite, chalcopyrite). The formation of mineralization can be explained by the geological position: random emplacement of the diorite porphyrite, resp. basalt-andesite dikes, directly in the preexisting U,Mo-bearing sediments. Vein U-Mo-Cu mineralization could thus most likely have formed according to the following scenario: I.) sedimentation of Kravany Beds in the Permian riftogenic basin: formation of beds of arkoses and arkosic sandstones with abundant fragments of charred flora, II.) formation of infiltration U mineralization: reduction and accumulation of U in sediments rich in organic matter, III.) emplacement of dikes of intermediate to basic volcanics: intersection of sediments with organics and with high U and Mo content, mobilization of formation fluids, assimilation of U and Mo into intermediate-basic magma, IV.) cooling of volcanic bodies → their contraction (formation of contraction cracks) → filling of contraction cracks with quartz, carbonates and ore minerals (crystallization from residual magmatic solutions mixed with formation waters). From this point of view it is syngenetic volcanogenic vein U-Mo-Cu mineralization, originally of the Permian age, with subsequent Alpine (most probably Cretaceous) reworking (this is evidenced by the variable composition of uraninite). It belongs to the Neohercynian late- to postorogenic metallogenetic stage. The possible younger, post-Permian age of mineralization from alpine hydrothermal solutions must also be assumed, but this consideration has several inconsistencies.

Multiple residual symmetries and soliton-cnoidal wave interaction solution of the $$(2+1)$$-dimensional negative-order modified Calogero–Bogoyavlenskii–Schiff equation

The residual symmetry for the \((2+1)\)-dimensional negative-order modified Calogero–Bogoyavlenskii–Schiff (nmCBS) equation is derived from the truncated Painleve expansion, and is extended to the multiple residual symmetries, which can be transformed to Lie point symmetries by introducing a suitable prolonged system. The nth Backlund transformation (BT) related to multiple residual symmetries is given in terms of determinant. More importantly, we obtain the explicit soliton-cnoidal wave interaction solution from a consistent differential equation.

Degradation of Spent Radioactive Ion Exchange Resins and Its Mechanisms by Fenton Process

Spent IERs are released during the operation and decommissioning of nuclear facilities. The safe and efficient treatment of spent IERs is an emergent problem in nuclear industry. IRN77 is a typical ion exchange resin widely used in many nuclear power plants. Fenton process can degrade organic resins and reduce the radioactive residues volume and the disposal cost significantly. In this work, the IRN77 resin was selected as a model ion exchange resin and its treatment via Fenton process was investigated. The influencing factors for resin degradation, including catalyst dosage, reaction time, initial pH, temperature and oxidant dosage were investigated and optimized via the single-factor experimental method. Under the reaction temperature of 100°C and reaction time of 120 min at initial pH of 2, more than 97% COD was removed with 1.66 g H2O2 and 32 mg FeSO4·7H2O added to per gram of wet resin. The catalyst dosage and H2O2 dosage can decrease 78% and 50% respectively compared to previous results. SEM, FT-IR and ion chromatograph were employed to characterize the resin beads, soluble organics and intermediates during the degradation reaction. Based on the characterization results, the resin degradation pathway was discussed in detail and it is proposed to three stages including beads dissociation, styrene and divinylbenzene decomposition and carboxylic acids mineralization. During the IERs degradation, formic acid, acetic acid, propionic acid and oxalic acid were quantitatively monitored as main intermediates, and oxalic acid accounted for over 90% of COD in the final residue solution. Fenton process is suggested as a promising resin degradation method.

Calorimetric and small-angle X-ray scattering studies on the memory effect in the tetra-n-butylammonium bromide semiclathrate hydrate system

Abstract The solution structures in the tetra-n-butylammonium bromide (TBAB) aqueous solution relate closely with the memory effect. In the present study, the behavior derived from the existence of the residual solution structures after TBAB semiclathrate hydrate (TBAB SCH) decomposition was investigated with two methods. One is a high-precision differential scanning calorimetry. The heat capacity of a TBAB aqueous solution with memory effect was slightly larger than that after the memory effect disappeared. The larger heat capacity implies the existence of solution structures. The other is a small-angle X-ray scattering (SAXS). In the first cooling process, strong scattering derived from rapid crystallization was observed at 263.6 K. In the second cooling process where the TBAB aqueous solution exhibited the memory effect, the scattering intensity gradually increased and became remarkably strong at a temperature (approximately 277 K) higher than 263.6 K. In the second cooling process, the invariant Q, which corresponds to electron density fluctuation, increased gradually until crystallization, whereas, in the first cooling process, the change of the invariant Q was quite small until crystallization. The increase of invariant Q implies the existence of 10–100 nm density fluctuation, which is consistent with the cluster size (10–20 nm) previously observed with electron microscopy in the same system.

Synthesis of LiNi0.6Co0.2Mn0.2O2 from mixed cathode materials of spent lithium-ion batteries

With the aggravation of resource shortage and environmental problems, the disposal of spent lithium-ion batteries becomes crucial. In this work, a sustainable closed-loop route to recycle mixed cathode materials from spent lithium-ion batteries is proposed. The sulfuric acid and H2O2 were used to leach mixed cathode powders, and parameters such as temperature, acid concentration, and time were investigated. The leaching efficiency of each metal was observed to be above 99%. The ternary cathode precursor was directly prepared from leachate. Li2CO3 was recovered from the residual solution by adding saturated Na2CO3. The mixture of precursor and Li2CO3 was roasted to resynthesize ternary cathode materials (LiNi0.6Co0.2Mn0.2O2). The characterization of LiNi0.6Co0.2Mn0.2O2, as well as its electrochemical performance was investigated. LiNi0.6Co0.2Mn0.2O2 possesses a layered structure and shows excellent cycling stability and rate capacity. The capacities at the first charge and discharge at 0.2C are 196.26 mA h·g−1 and 180.072 mA h·g−1, respectively. The coulombic efficiency after the second cycle is observed to be about 99%.

Investigation on the hot ductility of Q235 low-carbon steel with boron addition

We tested the mechanical properties of B-containing steel at 600–1300 °C using Gleeble 1500, and the hot ductility was investigated according to the reduction in area (RA). The fractured specimens were examined using scanning electron microscopy. The results indicate that boron strongly influences the hot ductility of B-containing steel in comparison with B-free Q235 steel. Boron could expand the low temperature embrittlement range from 750–850 °C to 700–1000 °C, and lead to a worse hot ductility at 1150 °C, related to its re-melting property. The reduction in area is as low as 18% at 1300 °C, and the high temperature embrittlement zone is inevitable given the existence of residual solute phase between dendrites.

Pilot-scale demonstration of nitrogen recovery in the form of ammonium phosphate (AP) from anaerobic digestate

Nitrogen in anaerobic digestate was recovered as ammonium phosphates (APs), a valuable fertilizer, in a pilot-scale system consisting of ammonia stripper, absorber and crystallizer. The dissolved ammonium concentration in the anaerobic digestate was stripped and then absorbed into the phosphoric acid (42.5 wt%) with 95% absorbing efficiency. As the NH3 stripping continued, both the N/P ratio and pH, key operating parameters in the absorber are optimized N/P = 0.6 and pH = 1.7. The residual AP solution after crystallization was reused to enhance the crystallization efficiency up to 88%. The overall recovery efficiency of APs was estimated at 72% of the input nitrogen mass. Analyses of SEM and XRD revealed that the recovered AP crystals were mainly composed of mono-ammonium phosphate (MAP). This pilot-scale study demonstrated that nitrogen load in anaerobic digestates could be effectively recovered as a valuable fertilizer source of AP crystals.

Sn isotope fractionation during volatilization of Sn(IV) chloride: Laboratory experiments and quantum mechanical calculations

Volatilization is an important pathway of element transport in nature, and this process may be associated with stable isotope fractionation, which could be used to understand the elemental volatilization mechanisms. In this study, we report that evaporation of Sn(IV) chloride solution under experimental conditions (96 °C, 1 atmospheric pressure) results in significant loss of aqueous Sn(IV) and Sn stable isotope fractionation. The δ122/116Sn of the residue solution can increase by up to 0.50‰ (or a 0.33‰ increase in δ122/118Sn) after repeated evaporation, indicating preferential partitioning of isotopically light Sn species into the vapor phase during evaporation. The observed Sn loss and associated Sn isotope fractionation during the evaporation experiments can be described using a Rayleigh fractionation function, with a best-fitting isotope fractionation factor of −0.36‰ in Δ122/116Snvapor-aq (or −0.24‰ in Δ122/118Snvapor-aq). We also performed quantum mechanical calculations to assess the stability of different potential Sn(IV) species in aqueous and vapor phases, and derived the equilibrium Sn isotope fractionation factors between these Sn(IV) species. The calculation results suggest that the dominant gaseous species of Sn(IV), SnCl4, is isotopically heavier than the aqueous Sn(IV) species by 1.24‰–0.35‰ in δ122/116Sn (or 0.82‰–0.19‰ in δ122/118Sn) under equilibrium at 96 °C, which is opposite to the experimental results. Such contrast in the direction of Sn isotope fractionation implies that kinetic isotope fractionation, rather than thermodynamic equilibrium isotope fractionation, took place for SnCl4 in the evaporation experiments at 96 °C. The observed experimental data can be explained by a kinetic isotope fractionation model involving backward reaction of SnCl4 vaporization at the solution-vapor boundary. This study, in combination with a recent report of positive Δ122/116Snvapor-aq (or Δ122/118Snvapor-aq) factor during evaporation of SnCl4 at 150 °C (Wang et al., 2019a), suggests that Sn(IV) volatilization mechanisms may be different with and without fluid boiling. Combined laboratory experiments and quantum mechanical calculations on the isotopic effects of Sn(IV) chloride solution evaporation provide important constraints for understanding the rapidly accumulating Sn isotopes data from studies on Sn ore-forming processes, bronze metallurgy and archeology, and volatile elements in planetary processes.

Flow-Induced Precipitation in Thin Capillaries Creates Helices, Lamellae, and Tubes.

Precipitation reactions under flow in confined media are relevant to the control of pathological biomineralization, processes affecting aquifers, and challenges in the petroleum industry. Here we show that for a simple geometry, such conditions create macroscopic structures including helices, tubes, lamellae, slugs, and disordered patterns. All structures emerge when salt solution is slowly injected into thin capillaries filled with hydroxide solution. For the helices, the pitch is proportional to the pump rate revealing a constant period of 0.63 s. Different morphologies of the insoluble metal hydroxide can co-exist causing random transitions along the capillary. On average, 15 % of the final system contains residual hydroxide solution. While mechanically stable for flow speeds above 25 mm min-1 , structures collapse and sediment for slower injection speeds. Some of the observed features share similarities with precipitate tubes in chemical gardens and the dynamics of liquid-liquid pipe flow.

Synthesis of MgFe Layered Double Hydroxide from Iron-Containing Acidic Residual Solution and Its Adsorption Performance

The paper presents a new method of layered double hydroxide (LDH) synthesis starting from secondary sources, namely acidic residual solutions. The iron content of the acidic solution resulting from the pickling step of the hot-dip galvanizing process make it suitable to be used as an iron precursor in LDH synthesis. Here, Mg4Fe–LDH synthesized through the newly proposed method presented structural and morphological characteristics similar to the properties of layered double hydroxides synthesized from analytical-grade reagents. Moreover, the as-synthesized LDH and its calcined product presented efficient adsorption properties in the removal process of Mo(VI) from aqueous solutions. The adsorption studies are discussed from the equilibrium, kinetic, and thermodynamic points of view. The proposed novel technologies present both economic and environmental protection benefits.

Hydrothermal liquefaction of microalgae for biofuel production: the recycling of nutrients from an aqueous solution after HTL

Microalgae are an alternative source for the renewable biofuels production. One of the promising technologies of microalgae fuel production is the hydrothermal liquefaction (HTL) with obtaining bio-oil as the target product. We have carried out a number of experiments on the hydrothermal liquefaction the biomass of blue-green microalgae Arthrospira platensis rsemsu 1/02-P (collection of Renewable Source Energy Laboratory at Lomonosov Moscow State University). For the HTL of arthrospira biomass the reactor of the Institute of High Temperatures RAS have been used. The outputs of bio-oil, gaseous products, solid residue and aqueous solution were 34-46%, 12-18%, 26-30%, 10-24% respectively. The aqueous solution hydrothermal liquefaction is a by-product, it has a limited energy value and needs to be recycled. Aqueous solution contains the nutrients necessary for growing algae but in quantities that are orders of magnitude higher than the standard ones. Studies growth of different algae species in aqueous solution after HTL have shown that in order to prevent the growth inhibitors toxic effect intensive its dilution is necessary. Microalgae strains, which can be cultivated in 500-fold diluted aqueous solution (Galdieria sulphuraria rsemsu G-1, Chlorella vulgaris rsemsu Chv-20/11-Ps), have been experimentally selected. It allows partially recycling the by-product of bio-oil from microalgae

A new insight into solar paint concept: regeneration of CuS nanoparticles for paintable counter electrodes in QDSSCs

Copper sulfide (CuS) counter electrodes (CEs) fabricated by chemical bath deposition (CBD) are commonly employed CEs in quantum-dot-sensitized solar cells (QDSSCs). This article focuses on regenerating crystalline CuS nanoparticles (NPs) from residual solution of CBD and then utilizing them for paintable CEs. Our strategy eliminates the underuse of CuS NPs in conventional CBD and provides a simplistic and economically viable approach to develop efficient CEs from regenerated CuS NPs. Affirmatively, we transformed regenerated CuS NPs into paint with and without binder to make CEs having substantial electrochemical performance. Such paintable CEs revitalize the concept of a solar paint that was previously limited to photoanodes only. While demonstrating the feasibility of paintable CEs, we also prepared CEs via spin coating and drop casting using the same regenerated CuS NPs to draw a comparison with originally produced CE from CBD. The higher surface roughness, homogeneous porosity, and hydrophilicity offered by the CE prepared by paint without binder made it electrochemically more active with least charge transfer resistance (Rct), and hence, a significant power conversion efficiency of ~ 0.7% was obtained for a QDSSC having painted photoanode as well as CE.

A Novel and Efficient Hybrid RSILU Preconditioner for the Parallel GMRES Solution of the Coarse Mesh Finite Difference Equations for Practical Reactor Simulations

The solution of the large, nonsymmetric, sparse linear system resulting from the discretization of the Boltzmann transport equation can be computationally intensive, even when innovative coarse mesh finite difference (CMFD) acceleration methods are applied on a high-performance computer. The research reported here describes the development and implementation of an innovative hybrid Reduced Symmetric Successive Over-Relaxation (RSOR) and Incomplete Lower Upper (ILU) (RSILU) preconditioner for the preconditioned Generalized Minimal RESidual (GMRES) solution of the three-dimensional, whole-core, pin-resolved transport calculation of a nuclear reactor core. The preconditioner was designed specifically to improve parallel computing capability and minimize the computational burden for solution of the CMFD method on a high-end computing platform. The hybrid RSILU preconditioner is applied to the preconditioned GMRES method without multicolor reordering by utilizing the ILU preconditioner for internal elements on each processor and the RSOR preconditioner for boundary elements that would require interprocessor communication. The construction of the RSILU preconditioner requires only that the diagonal elements be modified, factorized, and stored, which is identical to serial ILU. The computational cost of RSILU is minimized since the factorized diagonal block requires minimal data preparation time for interprocessor communication and exchanges information only once in parallel computation. This paper reports first the serial performance of RSOR, and numerical results show that the new proposed RSOR is an effective preconditioner even for serial computing applications. The parallel performance of RSILU is then assessed and compared to conventional multicolor ILU preconditioners. The results show that RSILU provides comparable convergence rates to the Standard Incomplete Lower Upper (SILU) preconditioners, but it is easier to implement since it does not require multicolor ordering. Although the required iterations of RSILU preconditioned GMRES increase as the number of processors increases, only slightly more iterations are required than the SILU preconditioner for a practical nuclear reactor application. The number of iterations required by the RSILU preconditioner increases only slightly and significantly less than the increased number of iterations required when using conventional Block-Jacobi Incomplete Lower Upper or Symmetric Successive Over-Relaxation preconditioners. Overall, the RSILU is shown to be an efficient and practical preconditioner for the GMRES method for improving the parallel computing performance for large-scale applications.

Nitrogen-Doped Hollow Copolymer Tube via Template-Free Asynchronous Polymerization with Highly Selective Separation of Hydrophilic Dipeptide for Enhancing Inhibitory Activity of Angiotensin Converting Enzyme.

A N-doped hollow copolymer tube (NHCT) was fabricated via template-free one-pot asynchronous polymerization strategy. Discrepancies of monomer polymerization speed and their hydrophilic-hydrophobic interaction resulted in the assembly of a hollow tube having inner diameter and double wall thickness of ∼230 and 40 nm, respectively. The formation and growth mechanism of NHCT analyzed via advanced characterization revealed that the unique growth processes tuned a demarcating surface layer between inner (hydrophilic) and outer (hydrophobic) layers. The screening and recognition ability of NHCT were determined for two specific dipeptides (WW and RR) possessing great discrepancies in hydrophilicity and angiotensin converting enzyme inhibitory (ACE-I) activity. NHCT realized high adsorption capacity (1.57 mmol/g) and selectivity (∼1274) for hydrophilic dipeptide RR (low ACE-I activity) from the mixture of RR/WW. As a result, ACE-I activity for residual solution were enhanced about 4.1 times as compared to original solution from natural silkworm pupae protein hydrolysate. Awarding to these results and its facile and discerning ability, NHCT can be envisioned to be of great value for the separation of small functional peptides from a natural edible source.

Recovery of Gallium from Bauxite Residue Using Combined Oxalic Acid Leaching with Adsorption onto Zeolite HY

Bauxite residue, the byproduct of alumina production, may potentially be a valuable source of strategically important metals, e.g. Gallium. Ga is considered critical element for the EU. To ensure adequate supply of Ga for the future, secondary sources such as bauxite residue should be exploited with efficient extraction methods. Therefore, in this study, mineral acids (H2SO4, HCl, and HNO3) and an organic acid (H2C2O4—oxalic acid), were evaluated for their efficiencies to extract Ga from bauxite residue. Using H2C2O4, the highest Ga leaching efficiencies were achieved, compared to other acids. The achieved leaching experimental results were considered for the construction of a design of experiment (DOE) model to achieve optimal conditions for Ga extraction using H2C2O4. These values were validated by experiments which resulted in ~ 94% accuracy. In the second part of the study, using pure Ga solution, the adsorption of Ga onto zeolite HY was studied. The effects of adsorbent dosage, temperature, and contact time on the adsorption of Ga from solution by zeolite HY were studied. The obtained adsorption experimental results were used to construct a DOE model to achieve optimal conditions for Ga adsorption on to zeolite HY. The DOE-achieved optimal conditions were evaluated by experiments in pure Ga solution, which resulted in an efficiency of ~ 99.4 %. In the third stage, the bauxite residue was leached in H2C2O4 under the optimal DOE conditions which resulted in 71% efficiency; thus the resulting bauxite residue solution was subjected to adsorption using zeolite HY under the optimal DOE conditions achieved. The Ga adsorption onto the zeolite was only 16% compared to the Ga adsorption of 99.4 % under the pure Ga solution, thus, representing the influences of the other leachates in the solution, which are minimizing the Ga adsorption onto the zeolite HY and providing an opportunity for future studies on the different mechanisms involved.

Effectively remediating spiramycin from production wastewater through hydrolyzing its functional groups using solid superacid TiO2/SO4

Breaking down the structural bonds and eliminating the functional groups are more efficient than destroying the whole molecule in antibiotic production wastewater (APW) pretreatment before further biotreatment. Two sulfated titania (TiO2/SO4) solid superacids, SSA1 and SSA2 were synthesized, characterized and used for hydrolytic pretreatment of spiramycin in APW. Spiramycin removal followed an order of SSA2>SSA1>TiO2≈pH = 3>control. The hydrolytic efficiencies increased at elevated temperature from 25 °C to 65 °C. The hydrolytic kinetics followed a first-order model and SSA2 performed the fastest. The performances were positively correlated with both the total acidity determined by n-butylamine titration and the strength of acid sites measured by NH3-temperature-programmed desorption (TPD). The residual solution for SSA2 presented the least antibacterial potency and anaerobic inhibition among all treatments. The hydrolyzed product was identified as the m/z 699.4321 fragment using UPLC-Q/TOF-MS, which was formed after losing a functional mycarose moiety from the parent molecular. The solid superacids were effective in selectively eliminating 433 mg/L of spiramycin and the antibacterial potencies of the spiramycin production wastewater, which contained very high concentrations of COD (33,000 mg/L). This hydrolytic method avoids using and handling hazardous and corrosive mineral acids on site. It is attractive as a selective catalytic pretreatment method to cleave antibiotics’ functional groups and to reduce its inhibitory effects before sequential biotreatments.

Antioxidant activity of crude ethanolic extract and fractions of Ziziphus mauritiana Lam. (Rhamnaceae) leaves from Burkina Faso.

Background Ziziphus mauritiana Lam. is a plant used in traditional medicine in Burkina Faso in the treatment of several diseases, of which diabetes is characterized by oxidative stress. The aim of this study was to evaluate the in vitro antioxidant potential of the extracts of leaves of this plant. Methods The crude hydroethanolic extract (HEE) of the leaves of Z. mauritiana and their partitionates in n-hexane, dichloromethane, and ethyl acetate, and in the residual aqueous solution (the F1, F2, F3, and F4 fractions, respectively) were first prepared. The content of polyphenols was determined and the antioxidant effects of the extracts were evaluated by their 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity, inhibition of lipid peroxidation (TBARS), and the ferric reducing antioxidant power (FRAP). Results The HEE as well as the F3 and F4 fractions were rich in polyphenols with contents between 58 and 84 mg equivalent gallic acid per 100 mg. The flavonoid content was 4 mg quercetin equivalents in the HEE and the F4 fraction. Except for the F1 fraction, the HEE and the other fractions showed significant DPPH scavenging activity (IC50 between 8 and 12 μg/mL). The IC50 of TBARS by different extracts was in the range 1-5 μg/mL, and the FRAP activity was 7-85 mg ascorbic acid equivalent per 100 mg. Total polyphenol content was highly correlated with the antioxidant activities. Conclusions The HEE, F3, and F4 fractions were found to be the richest in polyphenols and had the best antioxidant activity. The antioxidant activity of the extracts of the leaves of Z. mauritiana is due to these polyphenolic compounds.