Low-carbon steel (LCS) in 0.5 M sulphuric acid is used to check the corrosion resistance performance of Pfaffia paniculata ( P. paniculata ) root extract. Notably, P. paniculata showed 91% corrosion resistance efficiency at 600 mg/L concentration. The adsorption of this inhibitor follows the Langmuir adsorption isotherm suggesting its monolayer formation on the LCS surface. The potentiodynamic polarization experiments indicated its nature as mixed adsorption behaviour. P. paniculata shows 88.34%, 90.16%, and 91.59% inhibition efficiency by weight loss, polarization, and EIS technique respectively. The scanning electron microscopy and atomic force microscopy techniques were used for the verification of protective layer on the LCS surface. The protective film formation study was checked using the UV–Vis. spectroscopy. Computational investigations were consolidated as a valuable report. All acquired outcomes confirmed that P. paniculata root extract can develop an efficient protective layer and resist the corrosion procedure.
Magnesium ferrite is a visible light absorber, and when combined with multiwall carbon nanotubes (MWCNTs), it can lead to low electron–hole recombination rates, thus improving its photocatalytic activity. In this work, a novel MgFe2O4/CNTs nanocomposite catalyst has been synthesized via anchoring MgFe2O4 nanoparticles onto MWCNTs surface by a sol–gel and microwave-assisted route. The prepared catalyst was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning and transmission electron microscopy, energy-dispersive X-ray analysis and vibrating scanning magnetometry. MgFe2O4 nanoparticles showed a cubic inverse spinel ferrite structure, while MgFe2O4/CNTs nanohybrids showed combinations of both structures. Morphology studies including Brunauer–Emmett–Teller (BET) analysis confirmed a 40 m2 g−1 specific surface area with narrow mesoporous size distribution for the MgFe2O4/CNTs nanocomposite. The photocatalytic performance of the new catalyst was assessed by photodegradation of methylene blue (MB). The experimental results demonstrated that MgFe2O4/CNTs exhibited strong photocatalytic activity, catalysing the photooxidation of about 98% of MB in 25 min under sunlight.
Building insulators reducing the natural gas required for interior heating or heating load reduction, have a positive impact on energy saving. Paints containing nano-silica aerogel can be applied as façade coatings and building insulators. In this study, the heating load was assessed for a building in a Mediterranean climate. Acrylic paint containing nano-silica aerogel was used as façade coating. The purpose was obtaining the performance of nano-paint on the reduction of heating load for the building. A model was developed to evaluate the amount of building heating load with and without the nano-paint. Nano-coated façade showed reductions in heating load compared to that façade without nano-coating. In addition, a stable heating load requirement was obtained after applying nano-paint, despite changes in the climatic conditions. Thermal insulation and water repellent properties of the paint containing nano-silica aerogel were important to reduce heating load requirement. Therefore, nano-paint containing silica aerogel was a cost-effective modification for façade which introduced a promising passive method to reduce heating load requirement in the buildings.
Degradation of a Basic Blue 41 dye using Fenton reagent was examined at laboratory scale in batch experiments using Box–Behnken statistical experiment design. Dyestuff, hydrogen peroxide (H2O2) and ferrous ion (Fe2+) concentrations were selected as independent factors. On the other hand, color and chemical oxygen demand (COD) removal were considered as the response functions. The value of coefficient of determination (R2) for both color and chemical oxygen demand removal with values 0.98 and 0.99 shows the best agreement between predicted value and experimental values. Perturbation plots indicated that iron dosage has the most effect on both color and COD removal. Normalized plot of residuals also indicated that the models were adequate to predict for both responses. Color and COD removal increased with increasing H2O2 and Fe2+ concentrations up to a certain level. High concentrations of H2O2 and Fe2+ did not result in better removal of color and COD due to hydroxyl radical being gradually consumed by both oxidant and catalyst. Percent color removal was higher than COD removal indicating the production of colorless compounds. The second-order polynomial model revealed optimal process factor ratio. The ratio of H2O2/Fe2+/dyestuff which gives a complete color removal and 95% COD removal was found to be 1195 mg/L/90 mg/L/255 mg/L.
The adsorption mechanism and inhibitive action of the Eucalyptus plant leaf extract (Eu) on the corrosion of mild steel in 0.5 M H2SO4 and 0.5 M H3PO4 solutions were investigated by potentiodynamic polarization curves measurements and electrochemical impedance spectroscopy technique. Potentiodynamic polarization curves revealed that the Eucalyptus leaf extract acts as a mixed type inhibitor in both acidic solutions. The impedance responses indicated that the corrosion process occurs under activation control. Fourier transform infrared spectroscopy has been used to predict the possible major chemical constituent of the leaf extract. Four adsorption isotherms including Langmuir, kinetic–thermodynamic, Flory–Huggins and Temkin model were used to investigate the mode of inhibition of Eucalyptus leaf extract. The free energy of adsorption showed that the corrosion inhibition takes place by spontaneous physical adsorption of Eucalyptus leaf extract molecules on the mild steel surface. The obtained data indicated that Eucalyptus leaf extract is a more efficient inhibitor of mild steel corrosion in 0.5 M H2SO4 than in 0.5 M H3PO4 solutions. Thermodynamics activation parameters were also calculated and discussed.
In contrast to physical failure of process systems, quantification of inherent system energy resilience has been carried out considering performance failure of process systems under this work. The inherent energy resilience for process systems can be conceptualized from the perspectives of material resilience (Guha, Environ Prog Sustain Energy, e13308, 2019). Correlations have been used to assess inherent energy resilience properties of constituent process systems pertaining to a gas sweetening unit (GSU) as a case study [1]. A steady state condition has been considered and system stress and system strain equations have been used to quantify the inherent system energy resilience [1]. It is assessed that absorber column and regenerator column systems under study possess inherent energy resilience of around 5% (absorber column) and 15% (regenerator column) with regard to variation in upstream feed sour gas flow rate beyond 100% design flow rate, i.e., 27,814 kg/h. It is also established that the lean-rich exchanger system under study possesses inherent energy resilience of around 10% with regard to variation in upstream feed sour gas flow rate beyond 100% design flow rate. Results also indicate that similar to a material, all the process systems under study (i.e., absorber, regenerator, lean-rich exchanger) of a gas sweetening unit (GSU) demonstrate inverse relationship of modulus of energy resilience (Ur) with modulus of elasticity (E-sys) in all applicable operating variable deviation regimes. Computer simulation using a process simulator SIMULATION SCIENCES INC, Pro/II (Version 9.2) has been utilized for this study. Finally, one example is given regarding design procedure in relation to incorporation of 50% over capacity factor or inherent energy resiliency in the absorber column by augmentation of number of column trays.
Oil-absorbing resins containing cross-linked poly(butyl acrylate) (PBA) were synthesized via precipitation polymerization in an environment-friendly route using supercritical carbon dioxide as the reaction media. The PBA resins were then regenerated through subcritical CO2 extraction process. The PBA resins with macroporous structures, prepared at pressures ranging from 17.5 to 24.5 MPa, were characterized by field emission scanning electron microscopy and mercury porosimetry. These structures are beneficial to oil absorption. Thermogravimetric analysis results showed that the PBA resin has good thermal stability. The effect of reaction pressure, initiator ratio, cross-linker content, and absorption time on yield and oil absorption was also investigated. The results revealed a slight decrease in yield with increasing pressure, within a pressure range of 17.5–24.5 MPa. The high initiator concentrations did lead to the decrease in the oil absorption capacity of the PBA resin. A higher product yield of 55% is acquired in the presence of the higher cross-linker content of 20 wt%. The highest absorption capacity of diesel oil onto the PBA resin was 7.5 g/g with oil retention capacity of 95.2%. Moreover, oil desorption of oil-saturated PBA resin was conducted with carbon dioxide instead of the traditional extraction solvents. After 10 repetitions, PBA resin exhibited good recyclability.
In this investigation, attempts have been made to study the corrosion inhibition properties of three new triazepine carboxylate compounds for mild steel in 1.0 M hydrochloric acid medium. The evaluation was carried out using mass loss, electrochemical impedance spectroscopy and polarization curves measurement. Impedance diagrams and Bode plots for uninhibited and inhibited systems were analyzed using Zview program. The fitted data observed trails in nearly the same pattern as the experimental results. It is showed that triazepine carboxylate compounds are very good inhibitors for mild steel corrosion in 1.0 M hydrochloric acid medium which act as mixed-type inhibitors. So, the inhibition efficiency was increased with inhibitor concentration in the order Cl–Me–CN > Me–CN > Cl–Me–CO 2 Et which depended on their molecular structures. Electrochemical impedance spectroscopy showed that all compounds act by the formation of a protective film at the metal surface. Surface analyses via SEM and Optical 3D profilometry were used to investigate the morphology of the steels before and after immersion in 1.0 M HCl solution containing inhibitors. The correspondence between inhibition property and molecular structure of the triazepine carboxylate compounds was investigated, using density functional theory (DFT). Experimental and DFT study was further supported by molecular dynamic simulations study.
The anatase TiO2-supported Ni–Cu bimetallic catalyst was prepared by Co-impregnation method and after shaping by three binders (bentonite, polyethylene glycol and poly vinyl alcohol) into extrudes, the effect of calcining temperature (200 °C, 400 °C, 600 °C and 800 °C) and calcining time (1, 3, 5 and 7 h) on the extrudes were investigated. According to the obtained results, the catalyst prepared at calcining temperature of 600 °C and calcining time of 5 h was selected as the optimal catalyst due to its anatase pure phase, high crystallinity and relatively high surface area. The as-prepared shape catalyst was evaluated as a Claus catalyst for conversion of H2S, CS2 and SO2 into elemental sulfur and provides high conversion of H2S 72.67%, CS2 69.77% and SO2 84.78%. The results indicated that the shaped catalyst with 75.50% of gas conversion efficiency is more active than the commercial Claus catalyst with 62.05% of conversion efficiency.
Fe-doped Bi2WO6/CeO2 nanocomposite materials were prepared by co-precipitation and hydrothermal methods. The physicochemical properties and photocatalytic activities of Bi2WO6/CeO2 nanocomposites after doping with Fe3+ ions were systematically investigated. The 0.2Fe-doped Bi2WO6/CeO2 nanocomposites exhibited the optimal photocatalytic activity in the degradation of rhodamine B (RhB), reaching to 62% degradation after 120 min irradiation, which was 10.3 and 2.7 times higher than CeO2 and Bi2WO6, respectively. The improved photocatalytic activity was mainly ascribed to the enhanced charge carrier separation efficiency of the direct Z-scheme heterojunction system. Moreover, the effective trapping of photogenerated electrons and holes by iron ions inhibits the electron–hole recombination. By a trapping experiment, the main radicals (O2·−) in the photocatalysis experiment were further ascertained. Finally, we proposed the photocatalytic mechanism of Fe-doped Bi2WO6/CeO2 nanocomposite for RhB degradation.
Novel blue pigments were prepared from copper, magnesium, aluminum nitrate solutions and phosphoric acid with pH adjustments (pH 5, 7, 9). The obtained precipitates were heated at 300, 500, and 700 °C for 1 h. The precipitates and their thermal products were estimated with X-ray diffraction (XRD), infrared (IR) spectra, ultraviolet–visible (UV–Vis) reflectance spectra, and L*a*b* color space. Sample without heating is light blue powder. By heating at 300 °C, the blueness of samples decreased. The hue of samples became darker by heating. The best condition for the unheated sample was pH 7, and for the heated sample was pH 5 at 300 °C. Samples prepared at Cu/Mg = 1/1 showed a* and b* values closer to zero than samples prepared with Cu/Mg = 1/0. These materials have potential as new inorganic blue pigments for inks and paints.
A terpolymer resin derived from Resorcinol, Formaldehyde and Salicylic acid was synthesized through condensation reaction. Transition metal ions namely Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) were incorporated into the resin forming polymer-metal complexes. Both the resin and the complexes were characterized by FTIR, UV–Vis., XRD, 1H NMR, TGA and SEM/EDX. Elemental analysis was carried out to determine the percentage of different elements present in the resin and its complexes. Conductivity measurement data showed higher conductivity of the metal complexes as compared to its precursor resin. The terpolymer resin and its metal complexes were tested against five strains of gram positive bacteria namely; S. aureus, S. mutans, S. pyrogenes, C. xerosis, C. diphtheria, and three strains of gram negative bacteria namely; E. coli, K. pneuomoniae and P. aeruginosa. All the metal complexes exhibited enhanced antibacterial properties as compared to its terpolymer resin. The Mn(II) and Co(II) demonstrated strong antibacterial activity.
Hexadecylamine-capped PbS nanoparticles were prepared from lead(II) complexes of dibenzyl dithiocarbamate (Dibzydtc) [PbS 1], imidazolyl dithiocarbamate (Imdtc) [PbS 2], 2-oxo-pyrrolidine dithiocarbamate (Pydtc) [PbS 3], diallyl dithiocarbamate (Diallyldtc) [PbS 4], and dihexyl dithiocarbamate (Dihexdtc) [PbS 5], at 120 °C. Powder X-ray diffraction patterns of the PbS nanoparticles are indexed to the face-centered cubic phase. The average particle sizes obtained from the TEM images are 19.04 ± 5.85 nm for PbS 1, 6.94 ± 1.71 nm PbS 2, 18.77 ± 3.37 nm PbS 3, 2.93 ± 2.20 nm PbS 4 and 22.02 ± 6.68 nm for PbS 5. The PbS nanoparticles are spherical in shape except for PbS 1 and PbS 3 with cubic shapes. The bandgap energies range from 3.0 to 3.8 eV and PbS 1 has the lowest bandgap of 3.0 eV while PbS 3 has the highest bandgap of 3.8 eV. The bandgaps are blue-shifted in comparison to the absorption band edges due to quantum size effect. The photocatalytic degradation of bromothymol blue by the as-prepared PbS nanoparticles showed highest degradation efficiency of 66% for PbS 3.
This work deals with the preparation of polyacetal (PAC)/graphene nano-platelets (GNP) and/or polypyrrole (PPY) in the presence of cobalt acetate-based composites. These materials were simply prepared via in situ emulsion in combination with sonication strategy technique. The resulting composites were characterized via Fourier transform infrared spectroscopy, thermogravimetric analysis, transmitting electron microscope, and particle size distribution analysis using dynamic light scattering technique. PAC was prepared through the reaction of cellulose with benzaldehyde. The results indicated that GNP could be successfully suspended in PAC in the presence of epichlorohydrin as a crosslinker and/or PPY as a conducting polymer. PAC/GNP-based composites had a particle size around 298 nm. However, the size was increased to 984–1338 nm after the addition of polypyrrole. The prepared composites were analyzed via the dielectric constants (ε′), dielectric losses (ε″), and AC conductivities. The composite samples containing GNP, polyacetal/GNP, and polyacetal/GNP/polypyrrole showed superior conductivities about, 0.6 and 0.022 S/cm, respectively, relative to the other ones they can be used for electrical energy storage devices.
ZnMnO3/Fe3O4 magnetic nanocomposites were fabricated via facile co-precipitation route and were calcined at 400 °C for 3 h. Synthesis of ZnMnO3/Fe3O4 magnetic nanocomposites were optimized by different weight percentages. Then, the as-synthesized sample was characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR), photoluminescence(PL), vibrating Sample Magnetometer (VSM), EDAX (Energy dispersive X-ray analysis), diffuse reflectance UV–Vis spectroscopy (DRS),ultraviolet–visible (UV–Vis) spectrometry, Bruner-Emmett-Teller (BET), transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM). Based on the results, elemental analyses of the samples were similar to those expected from the initial concentrations of the solutions used during synthesis. The x-ray diffraction pattern revealed that ZnMnO3/Fe3O4 has a cubic structure and average particle size of the catalyst was found 27.43 nm. In addition, Fourier transform infrared spectra could confirm the presence of hydroxyl group and Fe–O bond vibration in the catalyst. Further, the superparamagnetic behavior of the synthesized nanocomposite at room temperature was confirmed by VSM studies. Furthermore, the photocatalytic performance of ZnMnO3/Fe3O4 samples were evaluated based on the removal of Congo red (CR) in aqueous solution in 60 min of under visible light irradiation. The experiment demonstrated that 0.10 g of ZnMnO3/Fe3O4 nanocomposites can degrade (98.17%) 50 mg l−1 of Congo red (CR) solution. The mechanistic study using scavengers propose that the superoxide (O2·−) is the most reactive species involved in the photodegradation of organic dyes. The photocatalytic degradation of Congo red conformed the pseudo-first-order kinetic model and the rate constant achieved for 0.10 g l−1 of ZnMnO3/Fe3O4 was (k = 0.0384 min−1). Finally, the effect of reaction time, pH, and loading of ZnMnO3/Fe3O4 on degrading Congo red was studied. The synthesized ZnMnO3/Fe3O4 nanocomposite can be potentially applied as a magnetically separable photocatalyst to deal with water pollution problems.
The standard method (ISO 4264) for determining the cetane index of hydrogenated gas oil is time-consuming and expensive for routine laboratory tests. Conversely, near infrared (NIR) and Raman spectroscopies are high-speed and cost-effective techniques. In this study, these tools were used to create two models for the determination of the hydrogenated gas oil cetane index. First, ISO 4264 was used to measure the cetane index for 45 real samples used as calibration standards. Then, to create the models, the same samples were measured using NIR and Raman spectroscopies. The model values were then correlated against the ISO values. The Raman model predicted cetane index values with a maximum absolute difference of 1.2 from the ISO, while the NIR model showed a difference of 0.3. Finally, 10 additional real samples were used as validation standards to compare the models. The NIR model predicted values with better cross-validation error and lower absolute differences (NIR 0.334, Raman 0.654) from the ISO values compared to the Raman model. Thus, the NIR model is a fast and accurate method that can partially substitute for ISO 4264 when performing routine laboratory tasks.
The commercially available bleach activator, N , N , N ′, N ′-tetraacetylethylenediamine (TAED), has been widely used in laundry detergents to enable efficient low-temperature bleaching. However, the competitive hydrolysis of TAED limits its use in liquid detergents. Herein we report the synthesis of two TAED derivatives, N , N , N ′, N ′-tetracetylpropylene-1,2-diamine (TA(Me)ED) and N , N , N ′-triacetylpropylene-1,2-diamine (TriA(Me)ED), through the acetylation of propylene-1,2-diamine. The hydrolytic and perhydrolytic activity of the imide molecules were studied by HPLC to elucidate the structure–function relationship. Due to the increased steric hindrance imparted by the α-methyl group close to the imide, TA(Me)ED and TriA(Me)ED exhibited higher hydrolytic stability than TAED, with the hydrolytic rate constants ( k H ) at pH 8.0 decreased by 58% and 84% for TA(Me)ED and TriA(Me)ED, respectively. On the other hand, TA(Me)ED and TriA(Me)ED showed comparable perhydrolytic activity with TAED in the presence of peroxide, enabling similar bleaching effect of a model food dye at room temperature. These results suggest these TAED derivatives may have potential being used as improved bleach activators.
The oxidation of sulfide-based ores is industrially relevant as it facilitates the extraction of valuable metals and eliminates undesired elements from an ore. Even though oxidation can be done thermally (pyrometallurgy), solution-based (hydrometallurgical) methods are currently sought as they represent a more sustainable option. Here, the leaching of a sulfide ore (32% Fe, 2% Cu) is investigated using a mixture of sulfuric acid and hydrogen peroxide (0.15 M H2SO4 and 0.5 M H2O2), in proportions forming a slurry 10% w/w. The leaching process is found to occur in two stages, the first corresponding to an exothermic, peroxide-mediated dissolution, and the second corresponding to an acid-mediated reaction, which appears to be thermoneutral. Control experiments performed with only peroxide confirm that this oxidant is involved in the first stage of the dissolution process. The leaching process leads to copper and iron dissolution (15% and 5%, respectively), as determined using atomic absorption spectrometry (AAS). The mass of pyrite dissolved is estimated from AAS measurements and, from the stoichiometry of the peroxide-mediated dissolution reaction, it is found that ~ 80% of the peroxide participates in the dissolution, with the other 20% being decomposed, in a reaction catalyzed by ferric (Fe+3) ions produced during the first stage of the dissolution.
The method of micro bubbles is widely applied in the fields of water and soil treatment. A novel treatment method of NO in flue gas through a gas–liquid two-phase system formed by micro bubbles is proposed in this study. The system depends on the generation of hydroxyl radicals. The NO removal performance of the micro gas–liquid dispersion system induced by catalysts and O 3 was explored and the reaction pathways were elucidated. Micro bubbles, Fe 2+ , and Mn 2+ in solution improved NO removal performance significantly. Salinity and surfactants affected the removal performance of NO by altering micro bubbles. In the presence of Fe 2+ , the NO removal rate reached 65.2% at pH 5, 75.8% under 0.5 g/L NaCl and 82.1% under 6 mg/L sodium dodecyl sulfate. In the presence of Mn 2+ , the NO removal rate reached 69.2% at pH 5, 83.2% under 0.5 g/L NaCl and 92.3% under 6 mg/L sodium dodecyl sulfate. However, in the presence of both Mn 2+ and Fe 2+ , NO conversion rate was 93.2%. The NO removal rate in the presence of O 3 was further improved under the same conditions. The study provides the basis for the application and development of micro bubbles in flue gas treatments for NO removal. The results can help to solve the problems of high operating cost, large oxidant consumption, secondary pollution, and high energy consumption in traditional NO removal methods. Graphic abstract
