Initial Molar Ratio Research Articles

Development of Co3O4/TiO2/rGO photocatalyst for efficient degradation of pharmaceutical pollutants with effective charge carrier recombination suppression

Pharmaceutical contaminations in the water resources becomes very serious global environmental issue. Therefore, these pharmaceutical molecules should be removed from the water resources. In the current work, 3D/3D/2D-Co3O4/TiO2/rGO nanostructures were synthesized through a facile self-assembly-assisted solvothermal method for an effective removal of pharmaceutical contaminations. The nanocomposite was finely optimized through the response surface methodology (RSM) technique with different initial reaction parameters and different molar ratios. Various characterization techniques were used to understand the physical and chemical properties of 3D/3D/2D heterojunction and its photocatalytic performance. The degradation performance of ternary nanostructure was rapidly increased owing formation of 3D/3D/2D heterojunction nanochannels. The 2D-rGO nanosheets play an essential role in trapping photoexcited charge carriers to reduce the recombination process rapidly as confirmed by photoluminescence analysis. Tetracycline and ibuprofen were used as model carcinogen molecules to examine the degradation efficiency of Co3O4/TiO2/rGO under visible light irradiation using halogen lamp. The intermediates produced during the degradation process were studied using LC-TOF/MS analysis. The pharmaceutical molecules tetracycline and ibuprofen follows pseudo first order kinetics model. The photodegradation results show that the 6:4 M ratio of Co3O4:TiO2 with 5% rGO exhibits 12.4 times and 12.3 higher degradation ability than pristine Co3O4 nanostructures against tetracycline and ibuprofen, respectively. These results shows high efficiency of Co3O4/TiO2/rGO composite against the degradation of tetracycline and ibuprofen.

Synthesis of isoamyl acetate using protein-coated microcrystals of different lipases

Abstract The goal of this study was the immobilization of different lipases as protein-coated microcrystals on K2SO4 and their uses in the synthesis of isoamyl acetate in n-hexane medium. The optimum conditions, such as lipase variety, temperature, the initial molar ratio of vinyl acetate/isoamyl alcohol, immobilized lipase amount, and reaction time were determined. The highest conversion was obtained when protein-coated microcrystals of Thermomyces lanuginosus lipase (TLL-PCMCs) was used for the synthesis of isoamyl acetate. The optimum temperature, the initial molar ratio of vinyl acetate/isoamyl alcohol, immobilized lipase amount, and reaction time were determined to be 50 °C, 3.0, 30 mg, and 360 min, respectively. Under the optimized conditions, isoamyl acetate yield was obtained as 95%. TLL-PCMCs retained 90% of their initial activity after five repeat use in the isoamyl acetate synthesis. TLL-PCMCs may be used in the preparation of industrially important aroma compounds due its ease of preparation and efficiency.

Regulating the multifactor during wet chemical synthesis to obtain calcium phosphate powders with controllable phase purity for bone repair

Calcium phosphate ceramics are widely used as bone repair materials owing to their excellent biocompatibility, bone conductivity, bone induction, and degradability. Although there are many methods for synthesizing calcium phosphate and controlling its phase composition, it is necessary to explore effective preparation methods by understanding the formation of calcium phosphate and its influencing factors. In this study, calcium phosphate powders with controllable phase compositions were synthesized using a wet chemical precipitation method by adjusting the process parameters (aging time, bipolar solution, initial Ca-P molar ratio, capping agent concentration, and system concentration). Subsequently, a certain biphasic proportion of (biphasic calcium phosphate, BCP) products was prepared, and pure (β-tricalcium phosphate, β-TCP) can be obtained according to the customer's requirements. BCP ceramics with desired phase compositions were obtained by pressing and sintering different calcium-deficient powders. Specifically, β-TCP powder with a purity of 99.83 wt% was obtained when the aging time, bipolar solution, initial Ca-P molar ratio, capping agent concentration, and system concentration were 0 h, 50% ethanol, 1, 0.27 M, and 0.0135 M, respectively. The BCP synthesized in this study shows great application potential in the field of bone tissue repair materials.

A comparative study on graft copolymerization of MMA onto wood fiber under microwave and conventional heating

Wood polymer composites (WPC) are gaining popularity and widespread usage due to an increased awareness of human population towards the importance of environmental effects and green eco-friendly materials. Mechanical properties of WPC could be improved through graft copolymerization of monomer onto wood fiber to improve interfacial bonding. In this study, a comparison of free radical graft copolymerization using microwave-assisted and conventional heating method was performed. Methyl methacrylate (MMA) monomer is used in graft copolymerization of Meranti wood using a free radical initiator system consisting of ferrous sulfate and hydrogen peroxide. Grafting reaction time was varied while other graft parameters were kept constant including monomer concentration, initiator molar ratio, reaction temperature and solvent volume. Maximum graft yield of 11.75% and 10.17% were obtained for water bath heated and microwave-assisted method respectively. The presence of grafted monomer was proven by FTIR spectra analysis. Thermogravimetric analysis performed on grafted wood fibers showed improved thermal resistance compared to ungrafted wood fiber.

Structural incorporation of iron influences biomethylation potential of mercury sulfide

Mercury and ferrous iron commonly co-exist in anaerobic environments, the hotspots of microbial mercury methylation that leads to formation of neurotoxic methylmercury. However, the influence of ferrous iron on mercury bioavailability and methylation remains unclear. Here, we discover that microbial methylmercury production is inhibited by iron addition in a non-monotonical manner, reaching the minimal level at the initial molar ratio of dissolved Fe/Hg as 1/3, when highly aggregated Hg–S–Fe nanoparticles occur and prevent the nanoparticle–bacteria interactions. The dominant mercury species formed upon Hg–S–Fe co-precipitation is iron-incorporated nano-metacinnabar with short-range structural disorder. The methylation potential of this mercury species is inversely correlated with the aggregation state of nanoparticles. The non-monotonical trends of the aggregation state and subsequent methylation of nano-metacinnabar are due to the opposite effects of ferrous iron on the nucleation and particle attachment that determine the formation of nanoparticle aggregates. Increased Fe/Hg ratio hinders particle nucleation and thus decreases the density of particle monomers for aggregation. However, Fe substitution of sub-surface Hg weakens the inner-sphere coordination of surface Hg with natural thiol ligands and consequently enhances nano-metacinnabar aggregation. This new mechanistic insight is important for assessing and minimizing the risks of mercury methylation, and informs how intertwined iron and sulfur cycling may influence metal bioavailability in the changing environment.

In-situ 1H NMR measurements of reactivity ratios and thermal properties for copolymerization of N-vinylpyrrolidone and 1-vinyl-3-butylimidazolium bromide

In-situ 1H NMR was used to obtain the copolymerization reactivity ratios of n-vinylpyrrolidone (VP) and 3-butyl-1-vinylimidazolium bromide (BVIM[Br]) using D2O and V50 as solvent and initiator, respectively. The influence of the VP-BVIM[Br] monomer ratios was studied at 45, 50, and 55 °C using initial molar ratios of (30−70), (50−50), and (70−30), respectively. According to the monomer conversions, it was determined that electrostatic and thermodynamic effects controlled the reactions. As the reaction temperature increased, higher conversions were obtained, and in the VP-BVIM[Br] (70−30) ratio, the conversions were higher and close to 100 % at 50 and 55 °C. This result was attributed to the lower ionic strength in the initial reaction system (0.46 mol/L). The monomer reactivities were calculated using the Mao-Huglin method and it was found that for the (70−30) VP-BVIM[Br] molar ratio at 45, 50, and 55 °C, rVP=rBVIM[Br]=1, obtaining random copolymers. For the VP-BVIM[Br] (30−70) molar ratio at 45 °C, the reactivity of VP was higher than that of BVIM[Br], rVP= 2.1 > rBVIM[Br]= 0.7, and for the VP-BVIM[Br] (50−50) molar ratio at 50 and 55 °C, the reactivity of VP was lower than that of BVIM[Br], rVP= 0.5 < rBVIM[Br]= 1.1 and rVP= 1 < rBVIM[Br]= 1.5, respectively, obtaining a spontaneous gradient copolymer. The decomposition temperature of the copolymers depended on the initial molar ratio of the reaction mixture, finding that the higher the VP molar ratio, the higher the initial decomposition temperature (279 °C). Random copolymers reached higher Tg (174 °C) in comparison with those that featured a spontaneous gradient microstructure (152 °C).

Preparation of novel diperylene-cored polyimide photocatalyst with broad-spectra response and high stability

A novel polyimide (PI) with broad-spectra response, high photocatalytic activity and stability under super acidic conditions (pH = 0) was synthesized via polymerizing method. Two types of perylene-cored materials (PDIAN and PTCDA) with anhydride and diamine respectively, were applied as precursors for PI polymerization. The as-prepared PI was optimized at 1:1 initial molar ratio of PDIAN to PTCDA. Using common PI (synthesized from melamine and pyromellitic dianhydride) as comparison, the Cr(VI) reduction rate was boosted from 25.4% to 96.6% within 120 min light irradiation. The corresponding rate constant by PI(PDIAN/PTCDA) was estimated to be ca. 11.7 times relative to that by common PI. The boosted performance was ascribed to the strong π-π conjugation from diperylene cores, which can decrease the photoluminescence intensity and electrochemical impedance, so as to promote the separation and transfer of photogenerated electron-hole pairs. In addition, the optimized PI(PDIAN/PTCDA) displayed wide-spectra response, which can still work under 730 nm light. The influencing factors toward Cr(VI) reduction were also clarified to be beneficial at lower pH and increased concentration of hole scavenger. After five cycles at pH 0, the PI still maintained excellent redox activity and structural stability.

The Formation and Transformation of Manganese Oxide Minerals on the Surface of Kaolinite

AbstractThe formation of manganese (Mn) oxides is influenced by environmental conditions and, in some red soils, Mn oxides occur as coatings on the surface of kaolinite particles in the form of colloidal films or fine particles. The present study aimed to explore the types of formation mechanisms of Mn oxide minerals on the surface of kaolinite. Mn oxide minerals synthesized by reducing the Mn in KMnO4 with a divalent Mn salt (MnSO4) were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of various initial molar ratios of Mn2+/Mn7+ (R = 1:0.67, 1:1, 1:2, and 1:4), cationic species (Na+ or Mg2+), synthesis temperatures (30, 60, and 110°C), and amount of added kaolinite (0.25, 0.5, 1.0, 2.0, and 5.0 g) on the formation of Mn oxides were studied. The results showed that Mn oxide mineral types were affected by the initial R value and the background cation. With decreases in the initial R value, the synthesized minerals transformed from cryptomelane to birnessite. The relative mass ratios of kaolinite to Mn oxide were calculated as 1:0.92, 1:0.63, 1:1.15, and 1:1.63. The sodium cation (Na+) had a greater role than Mg2+ in promoting the dissolution–recrystallization of birnessite to cryptomelane. The synthesis temperature had no effect on mineral types, but Mn content increased as temperature increased. When the amount of added kaolinite was increased from 0.25 to 5.0 g, Mn oxide minerals formed gradually and transformed from birnessite to cryptomelane. This work revealed a possible formation process and reaction mechanism on the surface of kaolinite particles in some red soils.

One-Pot Synthesis and Characterization of CuCrS2/ZnS Core/Shell Quantum Dots as New Blue-Emitting Sources.

In this paper, we introduce a new blue-emitting material, CuCrS2/ZnS QDs (CCS QDs). To obtain bright and stable photoluminescent probes, we prepared a core/shell structure; the synthesis was conducted in a one-pot system, using 1-dodecanethiol as a sulfur source and co-ligand. The CCS QDs exhibited a semi-spherical colloidal nanocrystalline shape with an average diameter of 9.0 nm and ZnS shell thickness of 1.6 nm. A maximum photoluminescence emission peak (PL max) was observed at 465 nm with an excitation wavelength of 400 nm and PLQY was 5% at an initial [Cr3+]/[Cu+] molar ratio of one in the core synthesis. With an off-stoichiometric modification for band gap engineering, the CCS QDs exhibited slightly blue-shifted PL emission spectra and PLQY was 10% with an increase in initial molar ratio of 2.0 (462 nm PL max). However, when the initial molar ratio exceeded two, the CCS QDs exhibited a lower photoluminescence quantum yield of 4.5% with 461 nm of PL max at the initial molar ratio of four due to the formation of non-emissive Cr2S3 nanoflakes.

Catalytic synthesis of methyl ethyl ketone from N-Butane

In the article, in order to evaluate the effect of various factors on the oxidation process of n-butane, a series of experiments were conducted at a temperature of 170 ℃ for 58 hours with the mixing of reactants in a reactor at a speed of 0.05 m amplitude 2s-1. Infrared spectroscopy, transmission electron microscopy, and powder X-ray diffraction data were reported. According to infrared spectroscopy, when the ratio of tetra-Npropylammonium hydroxide/tetraethoxysilane is less than 0.085, it is proved that the main product is a mixture of amorphous titanium(IV) oxide and the amorphous form of titanium(IV) oxide is amorphous silicon(IV) oxide. Powder X-ray diffraction of the samples also showed the X-ray appearance of amorphous titanium(IV) oxide peaks. According to electron microscopy, a change in the size of the catalyst particles is observed as the initial molar ratio of tetra-N-propylammonium hydroxide/tetraethylorthosilicate increases. As a result of the study of the effect of temperature on the reaction rate, it was proved that the productivity of butanone-2 increased from 13.65% to 30.85% and the conversion rate of potassium permanganate solution increased from 37.5 to 97.2% with an increase in temperature from 50 ℃ to 90 ℃. It should be noted that the initial tetra butyl titanatetetraethylorthosilicate molar ratio is xTiO2•(1-x)SiO2 (x=0.0001-0.04) with 33% porosity obtained by reaction in aqueous solutions at temperatures above 100 ℃ and pressures above 1 atmosphere. ) has a significant effect on the obtained samples of the catalyst.

Synthesis of functional polyacrylamide (co)polymers by organocatalyzed post-polymerization modification of non-activated esters.

The broad application of polyacrylamides (PAMs) has greatly promoted the development of new synthetic methods to prepare PAM-based functional (co)polymers regarding their traditional preparation via the direct polymerization of various acrylamide monomers. Herein, we have explored the post-polymerization modification of the poly(2,2,2-trifluoroethyl acrylate) (PTFEA) homopolymer, a typical non-activated ester, and various amines using the organo-catalytic system involving 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and 1,2,4-triazole (TA). The reaction kinetics (e.g., the optimized reaction solvent, temperature, time, initial molar ratio of amines to esters and the molar ratio of DBU to TA) were carefully studied with the modulus substrate of iso-propylamine as the formed poly(iso-propyl acrylamide) (PNIPAM) representing the most investigated PAM. The full and partial amidation of the esters in PTFEA could be precisely regulated just by controlling the kinetic conditions to give (co)polymers with designable compositions and structures. We have demonstrated that the poly(N-acryloyl pyrrolidine) obtained by the post-polymerization modification of non-activated ester and pyrrolidine exhibited a noticeable phase transition, which confirmed the robustness and versatility of the post-polymerization modification. The described method paves the way for the synthesis of various (co)polymers with amide side chains from readily available polymer precursors.

Raman spectroscopic study of dehydration reactions between boric acid and aliphatic dihydric alcohols in solution

Boric acid (B(OH)3) esters in dihydric alcohol (R(OH)2) solutions were analyzed using Raman spectroscopy to investigate the sequential reactions between B(OH)3 and the lower dihydric alcohol molecules. The dihydric alcohols used in this study were ethane-1,2-diol, propane-1,2-diol, butane-1,2-diol, butane-2,3-diol, propane-1,3-diol, and butane-1,3-diol, which are classified into two types: alkyl-n,(n+1)-diol and alkyl-n,(n+2)-diol (n = 1 or 2). The Raman spectral changes caused by adding B(OH)3 or H2O were analyzed in terms of the formation of boric acid esters in the alcohol solutions. Multiple Raman bands were observed in the frequency range 900–700 cm−1 for each alcohol solution and most of the band intensities depended on the initial molar ratios of B(OH)3/R(OH)2 and B(OH)3/R(OH)2/H2O. The difference spectra, obtained using the difference spectrum method, suggested the formation of cyclic boric acid esters with a 5- or 6-membered ring for all the dihydric alcohol solution systems used in this study. Based on the Raman spectral changes, we examined the boric acid esters formed in the dihydric alcoholic solutions.

Study on the epoxidation of olefins with H2O2 catalyzed by biquaternary ammonium phosphotungstic acid

Selective epoxidation of olefins is an important field in chemical industry. In this work, we developed a new phosphotungstic acid catalyst {[(C8H17)(CH3)2N]2(CH2)3}1.5{PO4[WO(O2)2]4} with long carbon chain and biquaternary ammonium cation. Cyclohexene could be epoxidized to cyclohexene oxide in 96.3% conversion and 98.2% selectivity. The catalyst type, solvent type, catalyst loading, initial molar ratio, temperature, cycle performance and substrate extensibility were studied and optimized, the kinetic parameters about overall reaction and unit reaction were also calculated. Dynamic light scattering analysis was carried out to explain the different catalytic performance between catalysts with different carbon chain length. This novel catalyst and the corresponding dynamics and mechanism study could probably help the industrial application on the epoxidation of cyclohexene with H2O2.

Development of high-strength geopolymers from red mud and blast furnace slag

The worldwide growing interest in green construction urges for innovation of building materials by reusing the existing waste resources, especially industrial by-products like red mud, which has been an environmental concern in the last few decades. This paper presents a study that investigated the potential use of red mud as a raw material in the development of high-strength geopolymers. A Sodium hydroxide (NaOH) and Sodium silicate (Na2SiO3) solution were used as the activation reagent for red mud, and blast furnace slag-derived geopolymers. This study adopted two different mixing procedures while activating the raw ingredients. Additionally, Ten percent (10%) by weight silica fume was introduced as an additive to assess its impact on the formed geopolymers. The mechanical and microstructural properties of the geopolymers were characterized based on two types of preparation processes. The synthesized geopolymers achieved extraordinary early compressive strength as high as 68.8 MPa. A high proportion of red mud, 50 percent by weight, could be utilized as a raw ingredient achieving a high strength of 66 MPa. The optimum initial molar ratios were reported based on the geopolymer products' compressive strength and microstructural performances. Silica fume was found to be an efficient additive that enhanced overall performance, ensuring higher proportional use of red mud as a raw material.

2-Methylimidazole-modifi ed Iron Metal-organic Framework as an Effi cient Methylene Blue Adsorbent

Metal organic frameworks have a wide range of applications in the fi eld of environmental remediation. In this study, Fe-BDC/Fe-2MI composites were synthesized by one-pot solvothermal method. By studying the adsorption performance of methylene blue (MB) in wastewater, it was confi rmed that Fe-BDC/Fe-2MI has excellent adsorption properties. When the initial molar ratio of FeCl3 .6H2O: H2BDC: 2-MI is 1:1.5:10, the adsorbent has the best adsorption performance. At the same time, the effects of different pH (2-10), temperature (303-323K) and initial concentration of adsorbate (30-90mg/L) on the adsorption capacity were further explored. It was found that when pH=6.0, T=303K was favorable for Fe-BDC/Fe-2MI to adsorb MB. The adsorption process conformed to the Langmuir isotherm adsorption model, indicating that it was a monolayer adsorption which was a good adsorption process. Thermodynamic parameters show that the adsorption process is a spontaneous exothermic reaction. These results demonstrated that Fe-BDC/Fe-2MI composites possess potential practical application value.

Characterization of ferrochrome ash and blast furnace slag based alkali-activated paste and mortar

Ferrochrome ash (FCA) is an industrial waste material which when disposed causes environmental pollution and health hazard. Therefore, in this paper, FCA replaced up to 30 % of blast furnace slag (BFS) to investigate its possible utilization by producing alkali-activated material. The effect of FCA content and varying Na2O dosage on fresh, physicomechanical and microstructural properties was discussed. The addition of FCA improved the rheological properties of mixes by reducing plastic viscosity from 47.3 to 22.9 Pa.s and from 129.2 to 71.1 Pa.s and yield stress from 87.5 to 40.7 Pa and from 89.8 to 44.0 Pa for Na2O dosage of 6 and 10 %, respectively. This allowed reduction of water content, which in turn resulted in similar or superior physicomechanical properties compared to the control mixtures. The setting time was prolonged with an increase in Na2O dosage and FCA addition and was mainly governed by the initial molar ratio of SiO2/Al2O3. The increase in FCA ratios consistently decreased semi-adiabatic peak temperature and time to reach the peak temperature. FCA addition decreased compressive strength and drying shrinkage of mortar mixes, whereas increase in Na2O dosage significantly enhanced strength. The microstructural investigations revealed that the major reaction products of paste mixes were CSH, C-ASH, and/or MSH gels, along with minor phases such as forsterite, natrolite, brownmillerite, and spinel. The formation of MSH type gels was observed with an increased replacement ratio of FCA. In addition, the polymerization of main reaction products is found to be controlled by the Ca/Si and Si/Al ratios as revealed by microstructural analysis. The findings of this research point out the viability of producing BFSand FCA-based alkali-activated materialwith reasonable properties and their efficient utilization which may ensure sustainability.

Formation of the structure-II gas hydrate from low-concentration propane mixed with methane

It has been recognized that a small amount of propane mixed with methane can change greatly in not only the thermodynamics but also the structural properties of gas hydrate. However, its mechanism is still not well understood yet. In this research, structure-II (sII) hydrate is synthesized using a methane-propane gas mixture with an initial mole ratio of 99:1, and it is found that large (51264) cages are co-occupied by multiple gases based on the rigid structure analysis of neutron diffraction data. The first principles calculation and molecular dynamics simulation are conducted to uncover the molecular mechanism for sII methane-propane hydrate formation, revealing that the presence of propane inhibits the formation of structure-I (sI) hydrate but promotes sII hydrate formation. The results help to understand the accumulation mechanism of natural gas hydrate and benefit to optimize the condition for gas storage and transportation in hydrate form.

Experimental Evaluation of Quantum Dots and Antibodies Conjugation by Surface Plasmon Resonance Spectroscopy.

The application of antibody-functionalized quantum dots (QDs) in different areas has been widely described in the literature. However, a standard routine method for obtaining information on the conjugation efficiency of QDs with antibodies in terms of the interaction of the functionalized QDs with a specific antigen is still lacking. Herein, surface plasmon resonance (SPR) spectroscopy is proposed for this purpose. Gold-coated SPR sensor disks were modified with a self-assembled monolayer of 11-mercaptoundecanoic acid, and carbodiimide cross-linker chemistry was used to covalently immobilize the CD44 biomarker on the premodified surface (Au/CD44). Meanwhile, QDs functionalized with amine-derivatized polyethylene glycol (PEG) (QDs-NH2) were chosen for conjugation with antibodies because of their low non-specific adsorption on the Au/CD44 surface. Prior to conjugation, the surface binding capacity (Bmax) and equilibrium dissociation constant (KD) of the specific antibodies against CD44 (anti-CD44) were found to be 263.32 ± 2.44 m° and 1.00 × 10−7 ± 2.29 × 10−9 M, respectively. QDs-NH2 and anti-CD44 were conjugated at their initial molar ratios of 1:3, 1:5, 1:10 and 1:12. SPR measurements showed that the conjugates (QDs-anti-CD44) prepared using 1:10 and 1:12 molar ratios interacted comparably with immobilized CD44 biomarkers. The equilibrium angles in the case of 10- and 12-fold concentrations of anti-CD44 were calculated to be 60.43 ± 4.51 and 61.36 ± 4.40 m°, respectively. This could be explained by the QDs-NH2 and anti-CD44 having a similar surface loading (about four molecules per QDs-NH2) and similar hydrodynamic diameters, which were 46.63 ± 3.86 and 42.42 ± 0.80 nm for the 1:10 and 1:12 ratios, respectively. An initial QDs-NH2: anti-CD44 molar ratio of 1:10 was chosen as being optimal. SPR spectroscopy proved to be the right choice for QDs-anti-CD44 conjugation optimization, and can be used for the evaluation of conjugation efficiency for other nanostructures with various bio-recognition molecules.

Synthesis of keto-biomacromolecule derivatives by oxidation of carboxymethyl cellulose using alkaline hexacyanoferrate (III) for alternative applications in biotechnology

The oxidation kinetics of polysaccharides involving carboxymethyl cellulose (CMC) by several oxidizing agent have been investigated in more detail with shedding some light on the synthesis of their respective keto-derivatives as oxidation precursor products. However, the literature survey indicated that no reports have appeared on the oxidation kinetics of CMC or the synthesis of keto-CMC using hexacyanoferrate (III) ion. Therefore, a lack of information on the transfer of electron process in the rate-determining stage as well as the nature of such keto-derivatives obtained as a result of polysaccharides oxidation using various oxidants in aqueous solutions.Accordingly, the present study presents synthesis of diketo CMC as a biomacromolecule derivative using potassium ferricyanide in alkaline media. The experimental results revealed the formation of either monoketo or diketo-derivatives of CMC based on initial molar ratio between the two reactants. The formation of such keto derivatives was confirmed by the reaction of the oxidation products with both 2,4-dinitrophenyl hydrazine and hydroxyl amine as well as FTIR spectra. The reaction kinetics of oxidation showed unity order in [Fe(CN)63−] and fractional first-orders with respect to both [CMC] and [OH−].The obedience of the reaction behavior to the Michael-Menten kinetics was indicative to the formation of 1:1 intermediate complex prior to the rate-determining step as a pathway route for oxidation.

Multicomponent Low Initial Molar Ratio of SiO2/Al2O3 Geopolymer Mortars: Pilot Research.

Alkali-activated binders have the potential to consume various types of waste materials. Low initial molar ratios of SiO2/Al2O3 geopolymer mortars were considered in this article. Here we studied alkali-activated binders produced with photovoltaic glass powder in 5%; kaolin clay in 15%; ground granulated blast furnace slag in 30%; alumina-lime cement in 30%; and, interchangeably, fly ash from coal combustion in 5%, fly ash from biomass combustion in 5%, or granulated autoclaved cellular concrete in 5%. The influence of clay dehydroxylation, curing conditions, glass presence, and a kind of waste material was investigated. According to the experimental results, strength (compressive and tensile) gradually increased with increasing time and with the use of calcined clay. Significant improvement in compressive strength was seen with the additional 3 days curing time in 105 °C when non-sintered clay was used. The presence of photovoltaic glass in alkali-activated mortars immobilised mercury and arsenic but released zinc, chromium, and sulphates. The microscopic observations confirmed the greater densification of the microstructure of the binder made of calcined clay due to its greater surface development and dehydroxylation. The binder of non-calcined clay was granular, and the interfacial transitional zone was more porous. The C–A–S–H gel seemed to be the main phase. XRD examination confirmed the presence of C–A–S–H, C–S–H, zeolites, and many other phases in minor amount. The presented research was a pilot study, and its main goal was to develop it further.