Weak Acidic Medium Research Articles

Preparation of catalyst for CO2 hydrogenation reaction based on the idea of element sharing and preliminary exploration of catalytic mechanism.

Under the background of the continuous rise of CO2 annual emissions, the development of CO2 capture and utilization technology is urgent. This study focuses on improving the catalytic capacity of the catalyst for CO2 hydrogenation, improving the efficiency of CO2 conversion to methanol, and converting H2 into chemical substances to avoid the danger of H2 storage. Based on the concept of element sharing, the ASMZ (Aluminum Shares Metal Zeolite catalysts) series catalyst was prepared by combining the CuO-ZnO-Al2O3 catalyst with the ZSM-5 zeolite using the amphoteric metal properties of the Al element. The basic structural properties of ASMZ catalysts were compared by XRD, FTIR, and BET characterization. Catalytic properties of samples were measured on a micro fixed-bed reactor. The catalytic mechanism of the catalyst was further analyzed by SEM, TEM, XPS, H2-TPR, and NH3-TPD. The results show that the ASMZ3 catalyst had the highest CO2 conversion rate (26.4%), the highest methanol selectivity (76.0%), and the lowest CO selectivity (15.3%) in this study. This is mainly due to the fact that the preparation method in this study promotes the exposure of effective weakly acidic sites and medium strength acidic sites (facilitating the hydrogenation of CO2 to methanol). At the same time, the close binding of Cu-ZnO-Al2O3 (CZA) and ZSM-5 zeolite also ensures the timely transfer of catalytic products and ensures the timely play of various catalytic active centers. The preparation method of the catalyst in this study also provides ideas for the preparation of other catalysts.

Curcumin-loaded pH-sensitive carboxymethyl chitosan nanoparticles for the treatment of liver cancer

In this study, the pH-responsive API-CMCS-SA (ACS) polymeric nanoparticles (NPs) based on 1-(3-amino-propyl) imidazole (API), stearic acid (SA), and carboxymethyl chitosan (CMCS) were fabricated for the effective transport of curcumin (CUR) in liver cancer. CUR-ACS-NPs with various degrees of substitution (DS) were employed to prepare through ultrasonic dispersion method. The effect of different DS on NPs formation was discussed. The obtained CUR-ACS-NPs (DSSA=12.4%) had high encapsulation rate (more than 85%) and uniform particle size (186.2 ± 1.42 nm). The CUR-ACS-NPs showed better stability than the other groups. Drug release from the CUR-ACS-NPs was pH-dependent, and more than 90% or 65% of CUR was released in 48 h in weakly acid medium (pH 5.0 or 6.0, respectively). Additionally, the CUR-ACS-NPs increased the intracellular accumulation of CUR and demonstrated high anticancer effect on HepG2 cells compared with the other groups. CUR-ACS-NPs prolonged the retention time of the drug, and the area under the curve (AUC) increased significantly in vivo. The in vivo antitumor study further revealed that the CUR-ACS-NPs exhibited the capability of inhibiting tumor growth and lower systemic toxicity. Meanwhile, CUR, CUR-CS-NPs, and CUR-ACS-NPs could be detected in the evaluated organs, including tumor, liver, spleen, lung, heart, and kidney in distribution studies. Among them, CUR-ACS-NPs reached the maximum concentration at the tumor site, indicating the tumor-targeting properties. In short, the results suggested that CUR-ACS-NPs could act a prospective drug transport system for effective delivery of CUR in cancer treatment.

Carboxymethyl-hexanoyl chitosan: A promising candidate for hydrophobic and hydrophilic drug delivery

Biodegradable polymers are versatile materials that are used in a plethora of biomedical applications owing to their biocompatible nature, degradability, non-toxicity, and low cost. Among the available biodegradable polymers, chitosan is found highly utilized in various pharmaceutical applications. Chitosan is soluble in weak acidic medium, which hinders further utility in higher concentrations for biological applications. However, derivatives of chitosan could be explored for biomedical applications by considering their aqueous solubility followed by hydrophobic and hydrophilic drug encapsulation efficiency. One among them, carboxymethyl-hexanoyl chitosan (CHC) has demonstrated promising footprints in ocular drug delivery, cancer therapeutics, insulin delivery, tissue engineering, multimodal imaging, antimicrobial activity, and wound healing applications. Furthermore, biocompatibility, water retention and uptake ability, and biodegradability are attributed to the presence of both amino and carboxylic functional groups present in CHC. In the present review, we have given a consolidated overview of CHC-based systems used so far in biomedical applications including global trends and future perspective. We believe that the review will help to understand CHC-based systems and the need for further innovations in the biomedical sciences.

Preparation of water-soluble chitosan oligosaccharides by oxidative hydrolysis of chitosan powder with hydrogen peroxide

Chitosan (CS) is only soluble in weak acid medium, thereby limiting its wide utilisation in the field of biomedicine, food, and agriculture. In this report, we present a method for preparing water-soluble CS oligosaccharides (COSs) at high concentration (∼10%, w/v) via the oxidative hydrolysis of CS powder with molecular weight (Mw) ∼90,000 g/mol) in 2% H2O2 solution at ambient temperature by a two-step process, namely, the heterogeneous hydrolysis step and homogeneous hydrolysis step. The resultant COSs were characterised by gel permeation chromatography (GPC), fourier transforms infrared spectroscopy (FT-IR), ultraviolet–visible spectroscopy (UV–Vis), proton nuclear magnetic resonance spectroscopy (1H NMR) and X-ray diffraction (XRD) spectroscopy. The resulting products were composed of COSs (Mw of 2000−6600 g/mol) that were completely soluble in water. The results also indicated that the structure of COSs was almost unchanged compared with the original CS unless Mw was low. Accordingly, COSs with low Mw (∼2000 g/mol) and high concentration (10%, w/v) could be effectively prepared by the oxidative hydrolysis of CS powder using hydrogen peroxide under ambient conditions.

Removal of Formaldehyde and Its Analogues Using a Hybrid Assembly of Pyrene-Modified Hydrazide and rGO: A Negative Carbon Emission and Green Chemical Decomposition Method.

Indoor gaseous formaldehyde is the main environmental pollutant that can cause fatal threats to human health. A number of physical and chemical methods have been developed to tackle this issue. However, the existing methods are still unsatisfactory to meet the requirement of sustainable development owing to the flaws of low efficiency and reversible or second pollution. Herein, a chemical method based on a nucleophilic reaction between hydrazine and aldehyde that generates the only by-product of H2O is designed for the removal of formaldehyde. 1-Pyrenebutyric hydrazide was synthesized by a simple esterification reaction and then self-assembled on reduced graphene oxide (rGO) with a large surface area by forming π-π stacking to obtain a composite for chemical removal of gaseous formaldehyde under ambient conditions. In a practical test, the formaldehyde removal rate could reach 91% of the theoretical value, which meets the requirement for commercial formaldehyde removal applications. After 10 times recycling, the formaldehyde removal rate still remains as high as 85%. Moreover, the composite could be regenerated in weak acidic media, which greatly reduce the manufacturing cost in practical applications.

Thermal Fabrication of Magnetic Fe3O4 (Nanoparticle)@Carbon Sheets from Waste Resources for the Adsorption of Dyes: Kinetic, Equilibrium, and UV–Visible Spectroscopy Investigations

Thermal treatment is applied for the direct conversion of palm stalk waste to Fe3O4 (np)@carbon sheets (Fe3O4 (np)@CSs). The effect of conversion temperature was investigated. The TEM examination of the prepared magnetic Fe3O4 (np)@CSs showed the formation of Fe3O4 (np) in a matrix of carbon sheets as a coated layer with surface functional groups including carbonyl and hydroxyl groups. Removal of dyes such as methyl orange, methylene blue, and neutral red was achieved using fabricated Fe3O4 (np)@CSs which were prepared at 250 °C, 400 °C, and 700 °C in a weak acidic medium. By studying the contact time effect for the adsorption of methylene blue, neutral red, and methyl orange, using the fabricated Fe3O4 (np)@CSs which were prepared at 250 °C and 400 °C, equilibrium occurred between 120 min and 180 min. In addition, the first-order and second-order kinetic models were applied to the adsorption data. The results revealed that the adsorption data fit better with the second-order kinetic model. Furthermore, the Freundlich model was found to be more suitable for describing the process of the separation of the dyes onto Fe3O4 (np)@CSs which were prepared at 250 °C and 400 °C, suggesting heterogenous surfaces and multi-layer adsorption.

GSH-depleting metal-polyphenol-network nanoparticles with dual enzyme activities induce enhanced ferroptosis.

Ferroptosis is a non-apoptotic form of regulated cell death. The efficiency of ferroptosis is restrained in the tumor microenvironment (TME) by overexpression of glutathione (GSH) and insufficient production of hydrogen peroxide (H2O2). In this work, theranostic nanoparticles Ce-aMOFs@Fe3+-EGCG, termed MEFs, are developed by coating uniform Ce-based amorphous metal-organic frameworks (Ce-aMOFs) with epigallocatechin gallate (EGCG) and Fe3+. Fe3+ is chelated by the adjacent phenol hydroxyl groups in EGCG. In the tumor cell interior, overexpressed GSH and weak acidic medium degrade the coating to release Fe3+ and EGCG accompanied by exposure of Ce-aMOFs. Fe3+ and EGCG consume GSH along with turning Fe3+ into Fe2+. Ce-aMOFs act as a nanozyme possessing dual-enzymatic activities, i.e. superoxide dismutase (SOD)- and phosphatase-like activities. In the TME, Ce-aMOFs catalyze the conversion of endogenous superoxide (O2˙-) into H2O2, and Fe2+ catalyzes H2O2 to generate toxic hydroxyl radicals (˙OH), which may further induce tumor cell death through ferroptosis. In addition, the phosphatase-like activity of Ce-aMOFs may sustainably dephosphorylate NADPH and effectively inhibit intracellular biosynthesis of GSH. Therefore, MEFs ensure down-regulation of intracellular GSH levels and up-regulation of oxidative pressure, which enhance the ferroptosis effect.

The impact of pH value in the Phenolic content and Antioxidant potential of Medicinal plant extract

In this research, the aim was to investigate the influence of pH value in the extraction medium on the phytochemical composition and antioxidant activity of Artemisia herba-alba species used in traditional medicine. For this reason, two analytical methods were used (UV-visible spectroscopy, HPLC). Antioxidant properties of the extracts at different pH were estimated by two tests: total antioxidant capacity (TAC) and DPPH free radical scavenging capacity. The results of the evaluation of phenolic compounds showed that the aqueous extracts in a weak acid medium had a high percentage of phenol content, and the highest value for total phenol content was 90.759±1.267mg GAE/g. Whereas, the HPLC analysis indicated the presence of most of the standard phenolic compounds in the majority of the extracts. For antioxidant activity, the best antioxidants reported in extract at pH=6, with a semi-maximal inhibitory concentration (0.151±0,032mg/ml) and a total antioxidant capacity (TAC) of 66.840±0.241mg EAA/g, which indicates that it is effective antioxidant for therapeutic applications.

Redox-Responsive Crosslinked Mixed Micelles for Controllable Release of Caffeic Acid Phenethyl Ester.

We report the elaboration of redox-responsive functional micellar nanocarriers designed for triggered release of caffeic acid phenethyl ester (CAPE) in cancer therapy. Three-layered micelles, comprising a poly(ε-caprolactone) (PCL) core, a middle poly(acrylic acid)/poly(ethylene oxide) (PAA/PEO) layer and a PEO outer corona, were prepared by co-assembly of PEO113-b-PCL35-b-PEO113 and PAA13-b-PCL35-b-PAA13 amphiphilic triblock copolymers in aqueous media. The preformed micelles were loaded with CAPE via hydrophobic interactions between the drug molecules and PCL core, and subsequently crosslinked by reaction of carboxyl groups from PAA and a disulfide crosslinking agent. The reaction of crosslinking took place in the middle layer of the nanocarriers without changing the encapsulation efficiency (EE~90%) of the system. The crosslinked polymeric micelles (CPMs) exhibited superior structural stability and did not release CAPE in phosphate buffer (pH 7.4). However, in weak acidic media and in the presence of 10 mM reducing agent (dithiothreitol, DTT), the payload was released at a high rate from CPMs due to the breakup of disulfide linkages. The physicochemical properties of the nanocarriers were investigated by dynamic and electrophoretic light scattering (DLS and ELS) and atomic force microscopy (AFM). The rapid release of CAPE under intracellular-like conditions and the lack of premature drug release in media resembling the blood stream (neutral pH) make the developed CPMs a promising candidate for controllable drug release in the microenvironment of tumors.

Photodegradation of humic acid from the surrounding soils of a sub-alpine Lake Tiancai

溶解性有机质（DOM）是湖泊生态系统的物质循环和能量流动的基础.典型亚高山湖泊DOM的主要来源为流域土壤腐殖酸（外源DOM），其具有较强的光吸收特性，光降解是其重要的转化过程，从而改变碳、氮、磷等物质的存在形式.在气候变暖的背景下，亚高山湖泊中DOM的浓度、pH、溶解氧及太阳辐射都可能发生变化；但这些环境变化对亚高山湖泊DOM光降解过程的影响尚不够清楚.由此本文研究了亚高山湖泊——天才湖（树线下200 m）周边土壤提取的腐殖酸（THA）的光降解过程：首先考察在光源为500 W汞灯、不通气以及pH=8.0条件下THA的降解过程中DOC浓度、有色溶解性有机质（CDOM，以a₂₈₀表征）和荧光溶解性有机质（FDOM）的变化，其后定性比较、定量分析不同光降解条件（pH、载气和光照波段）对THA的光降解过程的影响.结果表明，THA含有4种荧光组分，其中C1~C3均为类腐殖质，占总荧光强度83.64%，C4占比16.36%，为类蛋白质物质.在500 W汞灯的照射下，THA分子量逐渐降低，10 h后DOC浓度降低44.5%，a₂₈₀随光照时间的增加逐渐减少，CDOM含量较初始大幅度下降；而FDOM （以荧光组分强度表示）总体趋势表现为先增加后下降.相对于弱碱性的环境（pH=8.0），弱酸性环境（pH=6.0）更有利于THA的光化学过程.氧气的存在很大程度上促进了DOM光化学转化过程，通入空气的条件下a₂₈₀的降解速率是氮气条件下的3.25倍.在不同光波段的实验下表明，可见光和紫外光对THA降解的贡献差异较大，紫外光波段的表观光子降解率（η）约为可见光的5~11倍.结果表明在气候变化背景下，亚高山湖泊中DOM的光化学降解将可能加快，亚高山湖泊在碳循环中的作用可能增强.;Dissolved organic matter (DOM) in lakes is ubiquitous and plays an important role in the aqueous ecosystem. DOM in sub-alpine lakes is dominated by the terrestrially-derived humic acid in the soil. Photodegradation is an important transformation process of DOM because of its strong light absorption, changing the form of carbon, nitrogen, phosphorus. Under the scenario of climate warming, DOM concentration, pH, dissolved oxygen and solar radiation in subalpine lakes may change. However, the effects of these environmental changes on DOM photodegradation in sub-alpine lakes are still unclear. In this paper, the photodegradation of allochthonous DOM in a sub-alpine lake-Lake Tiancai (located 200 m below the tree line) were studied. Firstly, the humic acid (THA) was extracted from the soil around Lake Tiancai. Then the photodegradation of THA was investigated at different light bands (ultraviolet or visible light) and different pH conditions. The results showed that four components were identified by excitation-emission matrix fluorescence coupled with parallel factor analysis (EEM-PARAFAC), including C1-C3 were humic-like fluorescence, accounting for 83.64% of the total fluorescence intensity, and C4 was protein-like substance, accounting for 16.36%. Under the irradiation of 500 W mercury lamp, the molecular weight of THA decreased gradually and DOC concentration decreased by 44.5% after 10 h. The value of a₂₈₀ (a proxy for colored dissolved organic matter (CDOM)) decreased gradually with the irradiation time; while the fluorescent dissolved organic matter (FDOM) showed an overall trend of increasing at first and then decreasing. Compared with the weakly alkaline media (pH=8.0), the weakly acidic media (pH=6.0) facilitated for the photochemical process of THA and acidification may further promote DOM degradation. Oxygen played a crucial role in DOM photochemical reaction as the pseudo-first-order kinetic constant of a₂₈₀ in the presence of oxygen was 3.25 times that in the absence of oxygen. The ultraviolet light was much more efficient for THA degradation than visible light. The apparent quantum degradation ratios (η) of ultraviolet light were about 5-11 times that of visible light. This result of this study suggested that under the scenario of climate change, the photodegradation of DOM in sub-alpine lakes might accelerate, enhancing the role of sub-alpine lakes in the carbon cycle.

Thermochemical study of the structural stability of low-silicate CHA zeolite crystals

In this study, the effect of synthesis method on the structural stability of low-silica CHA zeolite crystals were investigated. For this purpose, template-free CHA crystals with similar chemical compositions were synthesized using seeded secondary growth and inter-zeolite transformation approaches. The stability performance of as-synthesized crystals was studied at temperatures, steam flow in a closed system, and acidic media. The results were analyzed using XRD, FTIR, DLS and FESEM. It was found both methods have similar structural stability behavior. The thermal stability investigation proved they have maintained their crystalline structure against heating, up to 800 °C, and at higher temperatures, the amorphous phase prevailed. The CHA crystals synthesized via both methods are stable in terms of hydrothermal stability up to 200 °C. Moreover, the results of chemical resistance showed CHA crystals exhibit excellent resistance to weak acidic medium, but against stronger acids, it has completely lost its crystallinity after 72 h.

Glutathione-responsive prodrug conjugates for image-guided combination in cancer therapy.

Theranostic prodrug was highly desirable for precise diagnosis and anti-cancer therapy to decrease side effects. However, it is difficult to conjugate chemo-drug and molecular probe for combined therapy due to the complex pharmacokinetics of different molecules. Here, a novel anticancer theranostic prodrug (BTMP-SS-PTX) had been designed and synthesized by conjugating paclitaxel (PTX) with 2-(benzo[d]thiazol-2-yl)-4-methoxyphenol (BTMP) through a disulphide (-S-S-) linkage, which was redox-sensitive to the high concentration of glutathione in tumors. Upon activation with glutathione in weakly acid media, the BTMP-SS-PTX can be dissociated to release free PTX and visible BTMP, which realized the visual tracking of free drug. The cytotoxicity study demonstrated that soluble prodrug BTMP-SS-PTX displayed more outstanding anticancer activity in HepG2, MCF-7 and HeLa cells, lower toxicity to non-cancer cells (293T) than free drugs. Furthermore, BTMP-SS-PTX was still able to induce apoptosis of HeLa cells and significantly inhibited tumor growth in HeLa-xenograft mouse model. On the basis of these findings, BTMP-SS-PTX could play a potential role in cancer diagnosis and therapy.

Design of High-Relaxivity Polyelectrolyte Nanocapsules Based on Citrate Complexes of Gadolinium(III) of Unusual Composition.

Through nuclear magnetic relaxation and pH-metry, the details of the complexation of gadolinium(III) ions with citric acid (H4L) in water and aqueous solutions of cationic polyelectrolytes are established. It is shown that the presence of poly(ethylene imine) (PEI) in solution affects magnetic relaxation behavior of gadolinium(III) complexes with citric acid (Cit) to a greater extent than polydiallyldimethylammonium chloride (PDDC). A large increase in relaxivity (up to 50 mM−1s−1) in the broad pH range (4–8) is revealed for the gadolinium(III)–citric acid–PEI system, which is particularly strong in the case of PEI with the molecular weight of 25 and 60 kDa. In weakly acidic medium (pH 3–7), the presence of PEI results in the formation of two tris-ligand associates [Gd(H2L)3]3− and [Gd(H2L)2(HL)]4−, which do not exist in aqueous medium. In weakly alkaline medium (pH 7–10), formation of ternary complexes Gd(III)–Cit–PEI with the Gd(III)–to–Cit ratio of 1:2 is evidenced. Using transmission electron microscopy (TEM) and dynamic light scattering techniques (DLS), the formation of the particles with the size of 50–100 nm possessing narrow molecular-mass distribution (PDI 0.08) is determined in the solution containing associate of PEI with tris-ligand complex [Gd(H2L)2(HL)]4−.

Silanol-functionalized tetranuclear copper complex and its nanoscale-heterogenization by immobilization on glass surface from solution

3-Formylsalicylic acid (3-FSA) was treated in a weak acid medium with 1,3-bis(2-aminoethylaminomethyl)tetramethyldisiloxane to form a salen-type ligand, followed by the addition of copper(II) chloride to build the corresponding coordination compound in a one-pot procedure. Along with the CH=N bond formation, Si-O-Si bond was also broken down to form the Si-OH ones tailing the remained monoamine. As single crystal X-ray diffraction revealed, when the copper salt is added, a tetranuclear complex, [Cu4(L1)2(L2)2Cl2(H2O)2], is formed consisting in two asymmetric dinuclear units, [Cu2L1L2Cl(H2O)], in which a molecule of 3-FSA (H2L1) and one of derived azomethine (H2L2), both doubly deprotonated and tridentate, participate in the coordination of oxo-bridged {Cu4} core. The coordination sphere is completed by chlorine atoms and water molecules. In the tetranuclear structure, the azomethine groups and implicitly the silanol arms are located in trans-position. The thermal behavior of the complex was studied by TGA and DSC. Besides the intrinsic properties induced by the presence of the metal ion (magnetic, biological, etc.), the free reactive silanol group may allow post-functionalization of the complex or, as found herein, its chemical binding to a suitable substrate. The attachment of the complex to the glass surface was proven by XPS but also highlighted by MFM due to its intrinsic magnetism.

Adsorption behavior and adsorption mechanism of glyphosate in water by amino-MIL-101(Fe)

Glyphosate is a highly-efficient herbicide used in agriculture. With the massive use of glyphosate, many rivers and lakes have become seriously polluted. Therefore, an effective adsorbent is needed to adsorb glyphosate from eutrophic water. In this work, two metal-organic framework (MOF) materials, MIL-101(Fe) and amine-modified MIL-101(Fe), have been synthesized by a hydrothermal method, and the adsorption kinetics, isotherms, and solution matrix effects (e.g., solution pH, coexisting ions, and ionic strength) of glyphosate binding there on have been measured. Their selectivities, adsorption properties, and adsorption mechanisms have thereby been evaluated. The results show that appending NH2 groups effectively improves the properties of MIL-101(Fe). The adsorption amount and partition coefficient (PC) of NH2-MIL-101(Fe) are 431.13 mg g−1 and 2.96 mg g−1 μM−1 at pH 4.0, respectively. In weakly acidic media, the electrostatic interaction between glyphosate and NH2-MIL-101(Fe) increases due to protonation of the NH2 groups. The terminal hydroxyl group of NH2-MIL-101(Fe) is the main substitution site of the phosphate group of glyphosate at pH 4.0 and pH 8.0. However, the terminal hydroxyl group of MIL-101(Fe) is substituted by the carboxyl group of glyphosate at pH 8.0, indicating that the NH2 groups improve the adsorptive selectivity of MIL-101(Fe) for the phosphate group. Fourier-transform infrared (FTIR) spectra and zeta potential measurements have been used to determine the main adsorption process, and a possible adsorption mechanism on MIL-101(Fe) is proposed.

Newly Designed Mesoporous Silica and Organosilica Nanostructures Based on Pentablock Copolymer Templates in Weakly Acidic Media.

We developed a new category of porous silica and organosilicas nanostructures in a facile method based on weakly acidic aqueous-ethanol media by utilizing two different pentablock copolymer templates of type PLGA-PEO-PPO-PEO-PLGA. Pluronic block templates were used mainly to prepare these pentablock copolymers with different molecular weights and volume ratios. Silica precursor tetraethyl orthosilicate and organosilicas precursor 1,4-bis(triethoxysilyl)benzene have been used as main source for synthesizing the silica and organosilicas samples. Weak Lewis acids iron(III) chloride hexahydrate, aluminum(III) chloride hexahydrate, and boric acid were utilized as catalyst instead of any strong inorganic acids and the molar ratio of catalyst/precursor has been optimized to 1–2 for preparation of ordered mesostructures. Reaction temperatures have been optimized to 25 °C for pure silica and both 25 °C as well as 40 °C for organosilicas to get the best result for mesostructures. A detailed analysis by using various analytical techniques like synchrotron small angle X-ray scattering, nitrogen sorption, transmission electron microscopy, scanning electron microscope, solid-state 29Si CP-MAS nuclear magnetic resonance (NMR), and so on has revealed well developed mesostructures with surface area of 388–836 m2/g for silica and 210–691 m2/g for organosilica samples, respectively. Furthermore, bimodal typepores have been observed from pore size distribution plot of the samples. Thermal stability of the materials was up to 400 °C as analyzed by thermogravimetric analysis.

The flotation separation of sphalerite from pyrite through a novel flotation reagent system of FeCl3-CuSO4-aminotriazolethione

To reduce the consumption of lime in mineral processing means reducing CO2 emission. Herein, a novel FeCl3-CuSO4-APTT (4-amino-5-pentyl-1,2,4-triazole-3-thione) approach was first developed to replace the common CaO-CuSO4-xanthate technology during flotation separation of sphalerite from pyrite. APTT exhibited a stronger collecting power towards pyrite than sphalerite, while the attendance of ferric chloride significantly depressed the floatability of pyrite and sphalerite, and its inhibition against pyrite was stronger than that to sphalerite. The addition of cupric sulfate not only removed the inhibition of ferric chloride against sphalerite, but also promoted its floatability. Nevertheless, the floatability of the FeCl3-depressed pyrite was hardly recovered by cupric sulfate. Using FeCl3 as the depressor against pyrite and CuSO4 as the activator for sphalerite, APTT realized a selective and efficient flotation recovery of sphalerite from pyrite in the weakly-acidic medium. FTIR (Fourier Transform Infrared Spectroscopy) and contact angle indicated that the pretreatment with FeCl3 and CuSO4 in sequence significantly weakened APTT adsorption on pyrite, while benefited sphalerite adsorption towards APTT, resulting in creating a dramatical difference of surface hydrophobicity and flotation recovery between the two minerals. XPS (X-ray photoelectron spectroscopy) elucidated that after modifying sphalerite surface successively through FeCl3, CuSO4 and APTT, the Cu-APTT complexes were detected on sphalerite, which were of significance to hydrophobizing its flotation.

Preparation of Al(OH)3-based layered structural material by shear alignment from aqueous dispersion of colloidal gibbsite platelets

Development of the technological and industrial capabilities to obtain hexagonal gibbsite nanoplatelets with a regularly well-defined configuration is an ongoing consideration that has not yet covered a required level of feasible architecture. Here we present a convenient method to synthesize the colloidal gibbsite particles based on a simple hydrothermal process from aluminum alkoxides in weak acid media. These colloids are near-regularly shaped and fairly monodisperse hexagons with an average diameter of 185 nm and a thickness of ~5.3 nm. The aqueous dispersion of gibbsite platelets can be shear-aligned to form highly ordered, continuous films on a substrate by an industrially adaptable method for producing large-area membranes. Overall, the modified synthesis method exhibits an excellent potential for scalable-up production with high quality in various practical applications. The aligned films also have outstanding properties due to the self-assemblies and interfacial physical interactions between adjacent gibbsite platelets and the possibility of industrial fabrication from those layered structural materials. Moreover, we prepare this shear-aligned membrane by the in-plane shearing method to introduce the great promise of disk-like-derived gibbsite as new gas-barrier material or surface-protective materials.

ВЛИЯНИЕ НЕФТЯНОГО ЗАГРЯЗНЕНИЯ СЕРОЙ ЛЕСНОЙ ПОЧВЫ НА УРОЖАЙНОСТЬ ЯРОВОГО РАПСА

The purpose of the research is increasing the yield of spring rape in the Tatarstan pre-Kama zone. Soil pollution affects food safety both by reducing plant performance and yield class. Oil and petrochemicals are common con-tamination sources of environment. The work is devoted to the assessment of the impact of oil pollution of the soil on the yield of spring rapeseed. The study was conducted on the experimental field of the Department of «Agro-chemistry and Soil Science» of the Kazan State Agrarian University, located in the pre-Kama zone of Tatarstan. The experimental site is presented by gray forest medium loamy soil, which is the predominant difference for this zone. The area unpolluted soil was characterized by a low content of humus and a weak acidic medium, high con-centration of phosphorus and potassium active forms. The soil was purposely contaminated with commercial crude oil by spreading over the surface at the rate of 10, 20 and 40 l/m2. These levels of soil pollution, as shown by previ-ous studies, were estimated, respectively, as low, medium and high. A close positive correlation was established between the yield of spring rapeseed and the limitation of soil contamination (R2=0.763÷0.940). Mechanical soil treatment, liming, application of mineral fertilizers and Baikal EM-1 biologics was tested for recultivation. The yield of oilseeds of spring rapeseed was closely correlated with the level of single contamination of gray forest soil with commercial crude oil for at least 15 years. Obtaining the maximum yield of spring rapeseed on oil-polluted gray forest soil was provided by comprehensive application of soil loosening, liming and application of full mineral ferti-lizer.

Iranian Qara Qat fruit (redcurrant) in Arasbaran forests as the resource of anthocyanin pigments in formation of [ACN-Mg2+/Al3+/Ga3+/ Sn2+/Cr3+/Fe3+] chelation clusters

Clusters of metallic cations (Mg2+, Al3+, Ga3+, Sn2+, Cr3+ and Fe3+) jointed to anthocyanins in water media were studied for unraveling the color shifting of different complexes of these structures in the low ranges of pH. Anthocyanin jointed to metallic cation progresses the color expression range of anthocyanin in more different range of pH. In this verdict, it has been studied the metallic cations diffusing of deprotonating for the anthocyanin (B)-ring of cyanidin (Cy), delphinidin (Dp) and petunidin (Pt) in two media of gas and water, transforming flavylium cations to the blue quinonoidal bases at lower range of pH applying the infrared method by approaching Beer Lambert law for getting the physico-chemical parameters of frequency, intensity, and absorbance of the compounds, respectively. In previous investigation, it has been indicated that the important factor for enhancing the absorbance in a positive non-linear fashion due to deviating from the Beer Lambert law is the self-association of anthocyanins of cyanidin, delphinidin and petunidin of anthocyanin structures. The difference of heat of formation (∆HR) among clusters of metallic cations jointed to anthocyanins has been illustrated toward the double bonds and carbonyl groups by the chelation of (B)-ring for cyanidin, delphinidin and petunidin anthocyanins in two media of gas and water that explains the stability and color of [anthocyanin-metallic cations] cluster chelation of cyanidin (Cy), delphinidin (Dp) and petunidin (Pt) colorful pigments in a weak acidic medium. By this work we exhibited that the color of the anthocyanin chelates is an important factor for estimating the efficiency of these types of food colorants.