Presence Of Tert-butyl Alcohol Research Articles

Kinetic Study of Manganese Oxidative Precipitation Reaction by Using SO2/Air Gas Mixture

Removing manganese from zinc electrolytes is necessary to pave the way for replacing lead-based anodes with mixed metal oxide (MMO) anodes. MMO anodes offer significantly lower overpotential towards oxygen evolution reactions, thus are attractive from an energy consumption viewpoint. Previous studies had shown that, thanks to the catalytic effect of cobalt, manganese can be removed successfully from the zinc purification solution through the oxidative precipitation method using a simulated roasting off-gas plant. This study focuses on understanding the primary mechanism behind manganese oxidation precipitation and investigating the influence of various operating parameters such as temperature, dissolved oxygen (DO), and solution potential on the reaction kinetics. The results revealed that the kinetics of the reaction was highly dependent on the temperature and catalyst activity rather than on the reactant concentration. Additives, with radical scavenging effects, were added to identify the radicals responsible for the oxidation of Mn. The manganese oxidation reaction was dramatically suppressed when methanol was added. However, in the presence of tert-butyl alcohol (TBA), a sensible reduction in manganese removal was not observed, suggesting sulfate radical as the predominant species for oxidizing manganese. The physical and chemical characteristics of the sediments were also presented.

Degradation of dibutyl phthalate by ozonation in the ultrasonic cavitation-rotational flow interaction coupled-field: performance and mechanism.

Dibutyl phthalate (DBP) is present in hydraulic fracturing flowback and produced water. Degradation of DBP in aqueous by means of ozonation in ultrasonic cavitation-rotational flow interaction coupled-field (UC-RF coupled-field) was studied. The effect of ozone dosage, ozone intake flow, operating temperature, initial pH, DBP initial concentration, liquid flow rate, and ultrasonic power on the DBP removal was investigated. Results indicated that the DBP degradation rate was strongly influenced by the liquid flow rate and the ultrasonic power over the range investigated. HCO3- and Cl- revealed an inhibitory effect on the DBP removal. SO42- seemed to have no effect on DBP removal. The ozone utilization efficiencies in the UC-RF coupled-field were 2.77 and 1.13 times higher than those in the conventional microporous aeration (CMA) and rotating-flow microbubble aeration (RFMA), respectively. The DBP degradation rate was diminished in the presence of tert-butyl alcohol. Cavitation bubbles are considered as innumerable microreactors. Degradation of DBP by direct ozonation, hydroxyl radical (·OH) oxidation, high pressure, and high-temperature pyrolysis was demonstrated. Finally, a possible degradation pathway of DBP is obtained on the basis of the main reaction intermediates.

Facile synthesis of MnO2 nanorods and ZnMn2O4 nanohexagons: a comparison of microwave-assisted catalytic activity against 4-nitrophenol degradation

The present preliminary research work reports the synthesis of MnO2 nanorods and ZnMn2O4 spinel via co-precipitation method. The synthesized nanomaterials were characterized via scanning electron microscopy coupled energy-dispersive X-ray spectroscopy (SEM-EDX) with elemental mapping, transmission electron microscopy(TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) techniques. The chemical composition and purity were established via XRD and XPS studies. Formation of MnO2 nanorods and hexagonal shaped ZnMn2O4 nanostructures was confirmed via SEM and TEM studies. The TGA studies confirmed high thermal stability of MnO2 as compared to ZnMn2O4. Microwave-assisted catalytic activity was assessed by degrading 50ppm of 4-nitrophenol solution in presence of MnO2 and ZnMn2O4 under microwave irradiation for 30min. almost 85% degradation within 30min was achieved using ZnMn2O4 as catalyst. The degradation followed first order kinetics in both cases and the rate constant (k) values were found to be 0.02075 in presence of MnO2 min−1 and 0.05912min−1 in presence of ZnMn2O4. The effect of addition of hydrogen peroxide was also investigated and the increase in catalyst dosage from 50mg to 250mg increased the degradation efficiency from 71% to 94% using ZnMn2O4 as catalyst. Likewise, upon increasing the microwave power from 200W to 1000W, the degradation efficiency increased from 71% to 94%. The radicals responsible for degradation were confirmed by the scavenging experiments using tert-butyl alcohol (TBA) and 1,4-Benzoquinone (BQ) as radical scavengers. The degradation efficiency decreased to almost 50% in presence of TBA as compared to BQ which revealed 75% degradation of 4-nitrophenol solution under microwave irradiation for 30min. A plausible mechanism of microwave-assisted catalytic degradation was proposed.

Apparent kinetics of the ozone oxidation of nitrobenzene in aqueous solution enhanced by high gravity technology

This study investigated the apparent reaction kinetics and degradation pathways of nitrobenzene by ozone enhanced by high gravity technology in the presence of tert-butyl alcohol, a radical scavenger. A promoted effect of ozone and high gravity technology was observed in the degradation of nitrobenzene due to the enhanced mass transfer of ozone into water by unique characteristics of high gravity technology. The second order rate constant was obtained varied from 0.732 L/(mol·s) to 5.267L/(mol·s) at different operation parameters (temperature, initial pH value, high-gravity factor, initial nitrobenzene concentration and ozone dosage). A kinetic empirical model was established to reflect the effects of different operating parameters on the apparent rate constants of ozone and nitrobenzene, which showed that rate constants varied strongly with initial nitrobenzene concentration and high-gravity factor. The reaction was proved in the slow kinetics of gas-liquid reaction. Furthermore, the results of Gas Chromatography-Mass Spectrometer showed that nitrobenzene could only be degraded into intermediate products with unopened benzene ring (p-benzoquinone, phenol, catechol and hydroquinone) by ozone alone.

Sonocatalytic degradation of tetracycline antibiotic using zinc oxide nanostructures loaded on nano-cellulose from waste straw as nanosonocatalyst

The aim of the present investigation was the combination of ZnO nanostructures with nano-cellulose (NC) for the efficient degradation of tetracycline (TC) antibiotic under ultrasonic irradiation. The removal efficiency of 12.8% was obtained by the sole use of ultrasound (US), while the removal efficiency increased up to 70% by the US/ZnO treatment process. Due to the integration of ZnO nanostructures with NC, the removal efficiency of 87.6% was obtained within 45 min. The removal efficiency substantially decreased in the presence of tert-butyl alcohol (more than 25% reduction), indicating that radOH-mediation oxidation is responsible for the degradation of TC molecules. Peroxymonosulfate (PMS) led to the most enhancing effect on the removal of TC among percarbonate, persulfate and periodate ions. The addition of PMS caused the degradation efficiency of 96.4% within the short contact time of 15 min. The bio-toxicity examination on the basis of inhibition test conducted on activated sludge revealed diminishing the oxygen consumption inhibition percent [IOUR (%)] from 33.6 to 22.1% during the US/ZnO/NC process. Consequently, the utilization of the US/ZnO/NC process can convert TC molecules to less toxic compounds. However, longer reaction time is required for complete conversion into non-toxic substances.

Combination of solar disinfection (SODIS) with H2O2 for enhanced disinfection of marine aquaculture effluents

Technologically advanced recirculation aquaculture systems (RAS), developed for intensive farming, allows to recycle about 90–99% of water. As a result, accumulation of pathogenic bacteria in water often occurs and possesses threat of infectious fish diseases. The goal of this study was to evaluate feasibility of solar disinfection in combination with hydrogen peroxide for seawater and real marine aquaculture effluent. Specific roles of solar disinfection (SODIS), hydrogen peroxide and highly reactive oxidizing species (experiments conducted in presence of tert-butyl alcohol), generated in combined SODIS/H2O2 process were investigated. Natural consortia of Vibrio spp., known as highly resistant pathogen, present in seawater and real marine aquaculture effluent were chosen as target microorganisms. The SODIS/H2O2 process significantly enhances inactivation of natural Vibrio consortia (Vibrio harveyi, Vibrio owensii and Vibrio alfacsensis) in seawater in comparison with individual SODIS and H2O2 treatment. The best results in terms of Vibrio spp. inactivation efficiency was obtained with SODIS/H2O2 conducted using open channel raceway reactor. The efficiency of Vibrio spp. inactivation by SODIS/H2O2 in raceway and compound parabolic collector (CPC) reactors was found to be similar, requiring the dose of 28–29 Wh m−2 for complete inactivation of Vibrio spp. present in seawater. Absence of toxic effect of residual H2O2 for Nannochloropsis gaditana, as well as absence of Vibrio spp. regrowth (48 h) indicate suitability of SODIS/H2O2 process for inactivation of pathogenic bacteria in aquaculture effluent and following nutrients removal by microalgae. Moreover, feasibility of SODIS/H2O2 performed in raceway reactor for disinfection of real aquaculture effluent, containing more than 5⋅103 CFU mL−1 of Vibrio harveyi, was demonstrated requiring the dose of 34.4 Wh m−2 for complete Vibrio spp. inactivation. The annual operation and maintenance cost of aquaculture effluent disinfection using CPC and raceway reactors were evaluated.

Effects of tert-Butyl Alcohol on Water at the Liquid–Vapor Interface: Structurally Bulk-like but Dynamically Slow Interfacial Water

We have investigated the effects of tert-butyl alcohol (TBA) on the structure and dynamics of water at the liquid–vapor interface. The structure of interfacial water has been studied by calculating the structural correlations and vibrational sum frequency generation (VSFG) spectrum from molecular dynamics simulations. It is found that the dangling peak of the VSFG spectrum of the air–water interface near ∼3700 cm–1 almost disappears in presence of TBA at the chosen concentration which means that the interfacial region is covered by the solute molecules. The hydrogen-bonded peak in the VSFG spectrum is found to be red-shifted by ∼100 cm–1 as compared to that of pure the air–water interface despite the fact that the strength of hydrogen bonds in the interfacial region is found to be similar to that of the bulk. This red shift in the VSFG spectrum is found to be a consequence of the cancellation of the nonlinear responses from “up-” and “down”-oriented O–H modes of water in that region. The local structure a...

Evaluation of different parameters on the acetamiprid degradation by bimetallic Fe/Ni nanoparticles

Abstract This work investigates the effect of different variables on acetamiprid degradation in aqueous systems by Fe/Ni nanoparticles. The variables studied were pH (2.0–5.0), temperature (283–313 K), and nanoparticles dosage (0.200 the 0.500 g L−1). The reactions monitoring was made by HPLC. The degradation was greater than 90% in only 5 reaction minutes. The results showed that occurs the formation of hydroxyl radicals in the system because in the presence of tert-butyl alcohol, used as scavenger of these radicals, there was a significant reduction in the degradation rate of approximately 100–10%. Kinetic studies were performed and the results showed that the reaction kinetics followed a pseudo-first order. The degradation rate (kobs) was increased when dosage of the nanoparticles and temperature were increased. Regarding pH, the degradation rate increased with decreasing pH of the medium. Finally, the reuse of the nanoparticles was evaluated yielding a 70% of efficiency in acetamiprid degradation.

Removal of aqueous metazachlor, tembotrione, tritosulfuron and ethofumesate by heterogeneous monopersulfate decomposition on lanthanum-cobalt perovskites

This study reports LaCoO3 perovskite oxide activity in the removal of aqueous herbicides (metazachlor, tembotrione, tritosufuron and ethofumesate) by means of potassium monopersulfate (MPS) decomposition. The influence of initial MPS concentration and catalyst load have been assessed. MPS is instantaneously absorbed onto the perovskite surface where this species decomposes. Thus, MPS breakage leads to the formation of powerful oxidizing radicals which react with herbicides in solution. Tritosulfuron was the most recalcitrant compound towards this technology. Catalyst stability was tested by means of consecutive reuse cycles. No appreciable loss of activity was experienced. Experiments in the presence of tert-butyl alcohol, methanol and carbonate outlined the importance of radicals in herbicides degradation. Finally, synthetized LaCoO3 was characterized. Scanning and transmission electron microscopy showed the presence of nanosized material, mostly spherical shaped, with 15.20m2g−1 of BET area. LaCoO3 perovskite structure was corroborated by diverse techniques such as X-ray fluorescence (La:Co atomic ratio of 1:1), X-ray photoelectron spectroscopy (surface Co(III) and La(III)), and X-ray diffraction (rhombohedral LaCoO3 phase).

Visible-light-absorbing Evonik P-25 nanoparticles modified with tungstophosphoric acid and their photocatalytic activity on different wavelengths

For the first time, Evonik P-25 nanoparticles were impregnated with tungstophosphoric acid (TPA) (30% w/w) and annealed at two different temperatures, 200°C (P25-TPA-200) and 500°C (P25-TPA-500) for 1h. Samples were characterized by different analytical techniques. Their photocatalytic activity was evaluated in the degradation of malachite green (MG) solutions at pH 5.0 upon three different irradiations: λ1>320nm, λ2>450nm and λ3>590nm. Only sample P25-TPA-500 showed visible-light absorption. This absorption could be related to the formation of a surface complex TPA Keggin anion-TiO2. P25-TPA-500 and P25-TPA-200 samples showed an important dark adsorption of MG dye (⿼30%); however, sample P25-TPA-500 exhibited the highest photocatalytic activity either under irradiation λ1 or λ2. The presence of tert-butyl alcohol (TBA), an OH scavenger affected the photocatalytic reaction upon irradiation λ1, but just slightly upon irradiation λ2. Finally, P25-TPA-200 exhibited a higher leaching of TPA than P25-TPA-500 samples.

Sonochemical degradation of basic fuchsin in water

Basic fuchsin (BF) is an important dye used in textile and in biological and chemical assays, suspected of being carcinogenic. The environmental and occupational issues related to it are very important. This study aimed at investigating the sonochemical degradation of BF in water using high-frequency ultrasound waves (600 kHz). The effects of several operating parameters, namely initial substrate concentration, ultrasonic power, and liquid temperature (25–45°C), on the efficiency of ultrasonic process were investigated. Additionally, experiments were conducted in the presence of salts (NaCl and Na2SO4) as well as tert-butyl alcohol as a radical scavenger. The viability of ultrasound to degrade BF in natural water was also examined. The obtained results showed that ultrasound (600 kHz) is an efficient technique for removing BF. It was found that the initial degradation rate of BF increased with increasing initial dye concentration in the range 1–15 mg L−1 and liquid temperature in the interval 25–35°C. The initial degradation rate increased by factor of 2.8 when the delivered power increased from 30 to 90 W. Excepting the salting out effect, the presence of salts, even at high concentration, has practically no significant effect on the efficiency of BF removal, making ultrasonic treatment as a promising technique for removing organic pollutants from industrial and natural waters. The presence of tert-butyl alcohol in a mass ratio of 1:1 (BF:alcohol) drastically inhibited the degradation rate of BF, making sure that hydroxyl radical was the main species involved in the degradation of this compound.

One-pot synthesis of polysubstituted 1,2,3,4-tetrahydropyridines

Mono- and bicyclic 1,2,3,4-tetrahydropyridine derivatives have been synthesized in up to 98% yield by one-pot three-component condensation of ethyl acetoacetate with methoxymethanol and primary amines (diamines) in methanol in the presence of tert-butyl alcohol.

Partial degradation of carbofuran by natural pyrite

This work provides new insight into the degradation of 2,2-dimethyl-2,3-dihydrobenzofuran-7-yl-methylcarbamate (hereafter carbofuran) by natural pyrite as a function of pH and adsorbent loading. In the presence of tert-butyl alcohol i.e., OH scavenger, the degradation efficiency of carbofuran was almost stopped. In acidic solutions (pH<5) the degradation kinetics was pseudo first order in carbofuran as −d[carbofuran]dt=−kobserved×[carbofuran]. The dependence of kobserved on [FeS2] was given as kobserved=k0+[FeS2]×k1 where k0=1.16×10−7h−1 and k1=0.137h−1. The elucidation of precise steps of carbofuran degradation by pyrite has yet to be solved.

Gene mdpC plays a regulatory role in the methyl-tert-butyl ether degradation pathway of Methylibium petroleiphilum strain PM1.

Among the few bacteria known to utilize methyl tert-butyl ether (MTBE) as a sole carbon source, Methylibium petroleiphilum PM1 is a well-characterized organism with a sequenced genome; however, knowledge of the genetic regulation of its MTBE degradation pathway is limited. We investigated the role of a putative transcriptional activator gene, mdpC, in the induction of MTBE-degradation genes mdpA (encoding MTBE monooxygenase) and mdpJ (encoding tert-butyl alcohol hydroxylase) of strain PM1 in a gene-knockout mutant mdpC(-). We also utilized quantitative reverse transcriptase PCR assays targeting genes mdpA, mdpJ and mdpC to determine the effects of the mutation on transcription of these genes. Our results indicate that gene mdpC is involved in the induction of both mdpA and mdpJ in response to MTBE and tert-butyl alcohol (TBA) exposure in PM1. An additional independent mechanism may be involved in the induction of mdpJ in the presence of TBA.

Hydrophobic Hydration in Water-tert-Butyl Alcohol Solutions by Extended Depolarized Light Scattering.

Molecular dynamics and structural properties of water-tert-butyl alcohol (TBA) mixtures are studied as a function of concentration by extended depolarized light scattering (EDLS) experiments. The wide frequency range, going from fraction to several thousand GHz, explored by EDLS allows distinguishing TBA rotational dynamics from structural relaxation of water and intermolecular vibrational and librational modes of the solution. Contributions to the water relaxation originating from two distinct populations, i.e. hydration and bulk water, are clearly identified. The dynamic retardation factor of hydration water with respect to the bulk, ξ ≈ 4, almost concentration independent, is one of the smallest found by EDLS among a variety of systems of different nature and complexity. This result, together with the small number of water molecules perturbed by the presence of TBA, supports the idea that hydrophobic simple molecules are less effective than hydrophilic and more complex molecules in perturbing the H-bond network of liquid water. At increasing TBA concentrations the average number of perturbed water molecules shows a pronounced decrease and the characteristic frequency of librational motions reduces significantly, both of which are results consistent with the occurrence of self-aggregation of TBA molecules.

N-Nitrosodimethylamine Formation from Hydrazine Compounds on Ozonation

N-Nitrosodimethylamine formation from six hydrazine compounds on ozonation was investigated. N-Nitrosodimethylamine formation yields in groundwater (pH 7) were 7.5%–89%. Results in the presence of tert-butyl alcohol indicated that N-nitrosodimethylamine was formed by reaction with molecular ozone, except for tetramethyltetrazene. From the results of effects of pH, tert-butyl alcohol and water matrix (groundwater and river water), it was suggested that reactions of tetramethyltetrazene with ozone, hydroxyl radicals, etc., were associated with N-nitrosodimethylamine formation. Some reactions restricted N-nitrosodimethylamine formation. Because N-nitrosodimethylamine formation of hydraxine compounds on chloramination was low, they are more important N-nitrosodimethylamine precursors on ozonation in actual water treatment.

Stereochemistry of Disilanylene-Containing Cyclic Compounds. Thermal Reactions of cis- and trans-3,4-Benzo-1,2-diisopropyl-1,2-dimethyl-1,2-disilacyclobut-3-ene

The thermal reaction of cis-3,4-benzo-1,2-diisopropyl-1,2-dimethyl-1,2-disilacyclobut-3-ene (1a) with tert-butyl alcohol at 300 °C for 24 h proceeded with high stereospecificity to give erythro-1-(...

Ring-opening polymerization of propylene oxide by double metal cyanide catalysts prepared by reacting CoCl2 with various metal cyanide salts

Polymerization of propylene oxide (PO) has been carried out by using a series of double metal cyanide (DMC) catalysts prepared by reacting dicationic CoCl2 with dianionic K2Ni(CN)4, K4Fe(CN)6, trianionic K3Fe(CN)6, or K3Co(CN)6 in the presence of tert-butyl alcohol as the complexing agent and poly(tetramethylene ether) glycol as the co-complexing agent. The resulting DMC catalysts are characterized by elemental analysis, X-ray photoelectron spectroscopy, infrared spectroscopy, and X-ray diffractometry. Screening the catalytic activity in PO polymerization shows that it is dependent on the type of catalyst, relative ratio of cationic cobalt and anionic metal salts, and polymerization conditions. Thus, the DMC catalyst prepared by reacting CoCl2 with K2Ni(CN)4 yielded the highest activity. The polyols produced by DMC catalysts had a very low level of unsaturation. The molecular weight and particularly the polydispersity of the resulting polyols are sensitive to the type of anionic metal salts.

Synergism of oxygen vacancy and carbonaceous species on enhanced photocatalytic activity of electrospun ZnO-carbon nanofibers: Charge carrier scavengers mechanism

Novel ZnO-carbon and ZnO nanofibers were fabricated by electrospinning of polymer precursor followed by subsequent annealing in nitrogen and air, respectively. Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) indicated the smooth and beadless nanofibers with wurtzite crystal structure. X-ray photoelectron spectroscopy (XPS) showed the presence of oxygen vacancies (VO) and chemisorbed O2 on the surface of the samples. Band gap narrowing of the ZnO-carbon nanofibers in comparison to ZnO were measured by diffuse reflectance spectroscopy (DRS). Photo-degradation of azo dye under the UV and visible light was evaluated and ZnO-carbon showed an enhancement in photocatalytic activity due to the presence of carbonaceous species and oxygen vacancies. Formation of hydroxyl radical during the photocatalytic process was verified by the formation of carbon using photoluminescence (PL) analysis. The photocatalytic mechanism was investigated by measuring the degradation rate in the presence of tert-butyl alcohol (t-BuOH) and I− anion as OH radical and hole (h+) scavenger. The results indicated photo-generated electrons are the main photo-oxidation pathway.

Removal of sulfamethoxazole from aqueous solution by sono-ozonation in the presence of a magnetic catalyst

The degradation of sulfamethoxazole (SMX) was investigated under the sono-catalytic ozonation process over magnetic suspension. The effects of various operating conditions were investigated, including initial pH value, catalyst dosage, and power density. The results indicated that the degradation of SMX followed a pseudo-first-order kinetic model under different operating conditions. The removal rate increased with the increase of pH, but it decreased when the catalyst dosage or power density exceeded a certain value. The removal rate was inhibited in the presence of tert-butyl alcohol, isopropanol or NaF. After 20min treatment, the COD removal reached 57.5%, the acute toxicity to Daphnia magna largely decreased, and the biodegradability (BOD5/COD ratio) increased from 0.02 to 0.41. COD was almost completely removed when the reaction time was extended to 120min.