Degradation Of HCl Research Articles

S-doped rich-defect cobalt-based carbon catalyst derived from cobalt phthalocyanine as catalysts of peroxymonosulfate for degradation of tetracycline hydrochloride from water

Organic pollution is a serious problem in the water environment. Peroxymonosulfat (PMS)- based advanced oxidation processes (AOPs) is the optimal way to treat such pollution. To better activate PMS, the S-doped cobalt-based carbon catalysts are attracting considerable attention. In this work, a mixture of cobalt phthalocyanine (CoPc) and thiourea was used as precursor to prepare CoPc-S-800 under Ar atmosphere at 800℃. Subsequently, CoPc-S-800 was used to activate PMS for degrading tetracycline hydrochloride (TC• HCl). In addition, experiments and X-ray photoelectron spectroscopy (XPS) showed that the introduction of S can promote the redox cycle of CO (III)/CO (II). Electron paramagnetic resonance (EPR) suggested that •OH, SO4• −, O2• − and 1O2 played important roles in TC• HCl degradation. This study investigated the influence of pH, different sources of water, and anions/cations/halogen ions on TC• HCl degradation. The results showed the CoPc-S-800/PMS system maintained excellent performance. This study provides a new strategy for TC• HCl degradation using cobalt-based carbon catalysts with CoPc as precursor. This work also elucidates the reaction mechanism of PMS activation by the catalyst.

Synthesis of Bi4O5I2 coupled with Sb2WO6 boosts the photocatalytic degradation of tetracyclines under simulated sunlight

For this study, a Sb2WO6/Bi4O5I2 composite material was successfully prepared via a precipitation-calcination method. The Sb2WO6/Bi4O5I2 heterostructure enhanced the light absorption and facilitated the separation of charge carriers. Under simulated sunlight exposure, the removal rates of tetracycline (TC) and doxycycline hyclate (DOX·HCl) reached 88.2% and 83.9%, respectively, over an optimized SWB2 composite (theoretical mole ratio of Sb2WO6: BiOI was 1.5:10). Further, the total organic carbon (TOC) removal rates were 37.6% and 33.7%, respectively. The experiments explored various parameters including catalyst dosage, initial concentrations of TC and DOX·HCl, solution pH, and common inorganic ions. The TC and DOX·HCl degradation pathways were speculated. Furthermore, SWB2 demonstrated remarkable stability and cyclability under simulated sunlight. Trapping experiments and electron paramagnetic resonance (EPR) tests revealed that •O2- played a major role as a free radical in the photocatalytic process, while h+ and •OH also had significant contributions. Based on in-situ XPS, trapping experiments, EPR test, band bending analysis, and SPV tests, the formation of S-scheme heterojunction between Sb2WO6 and Bi4O5I2 was inferred. This study provides insights into the design strategy of S-scheme heterojunctions between Aurivillius-type compounds and bismuth-rich halide bismuth oxide, which is informative for the development of advanced environmental remediation concepts.

Defect- and nitrogen-rich porous carbon embedded with Co NPs derived from self-assembled Co-ZIF-8 @ anionic polyacrylamide network as PMS activator for highly efficient removal of tetracycline hydrochloride from water

The design of N-doped carbon-based nanomaterials for efficient heterogeneous activation of peroxymonosulfate (PMS) for environmental remediation has piqued the attention of many researchers. In this study, precise temperature control vaporized Zn to form defects, and N-doped porous carbon-encapsulated Co nanoparticles were successfully generated by pyrolyzing the zeolite imidazolium framework (Co-ZIF-8(CZ)) @ anionic polyacrylamide (APAM) network composite (Co-ZIF-8@APAM (CZA)). Benefiting from the defect structure and enhanced N content doped Co particles, the obtained nanomaterials exhibited excellent effect and stability on tetracycline hydrochloride (TC• HCl) breakdown by activated PMS. The separation efficiency of TC• HCl in the CZA-1000/PMS system was 99.8% within 30 min and was 2.43 times more than pure Co-ZIF-8/PMS. In addition, the study investigated potential factors including pH, the coexistence of anions/cations/halide ions, TC• HCl, Ciprofloxacin Hydrochloride (CPFX• HCl), and TC• HCl removal from natural water. CZA-1000/PMS system kept excellent performance. Through EPR, Raman spectroscopy, and XPS, the mechanism exploration revealed that the N-doped carbon modified with Co nanoparticles generated the oxygen defects and promoted the catalytic activity and stability. The radical and nonradical oxidation co-acted on TC• HCl degradation.

Heterostructure coal-bearing strata kaolinite/MnFe2O4 composite for activation of peroxydisulfate to efficiently degrade chlortetracycline hydrochloride

The excessive discharge of the antibiotic chlortetracycline hydrochloride (CTC·HCl) directly threatens human life and health. Different from previous studies on MnFe2O4 (MFO) combined with bulk BT or disc-shaped DE in the treatment of antibiotic wastewater, in this study, layered coal-bearing strata kaolinite (CK) was used as a carrier to prepare MnFe2O4/coal-bearing strata kaolinite (MFO/CK) catalyst, and used to evaluate the effect of activated peroxodisulfate (PDS) in the removal of CTC·HCl in wastewater under visible light. Compared with MFO and CK, the specific surface area of MnFe2O4/coal-bearing strata kaolinite-40% (MFO/CK-40%) was significantly increased, the reactive sites increased, and the PDS activation and CTC·HCl degradation were better. After 60 min of reaction under visible light, the removal rate of CTC·HCl can reach 85.1%. In addition, the influence of various factors on the degradation of CTC·HCl was investigated. It is concluded that the most effective removal of CTC·HCl occurs when there is an additional 25 mg of MFO/CK-40%, the concentration of CTC·HCl is 50 mg/L, pH= 4, and PDS is 1.5 mL. Then, through electron spin resonance and radical trapping experiments, it was determined that h+ and ·O2− were the main active species for removing CTC·HCl. The mechanism of CTC·HCl degradation by the MFO/CK-40%/PDS/Vis system was discussed. Finally, the stability and reusability of the MFO/CK-40% composite material were tested. After 3 cycles of experiments, the removal rate of CTC·HCl is still more than 70%, indicating that the MFO/CK-40% composite material has good stability and catalytic activity. Therefore, the MFO/CK catalyst can be used as a new and efficient PDS activator, which is widely used in the photocatalytic degradation of organic matter in wastewater. Data AvailabilityNot applicable.

BiVO4 ternary photocatalyst co-modified with N-doped graphene nanodots and Ag nanoparticles for improved photocatalytic oxidation: A significant enhancement in photoinduced carrier separation and broad-spectrum light absorption

The efficient removal of antibiotics in water is essential to protect aquatic environment as antibiotics are some of the most hazardous pollutants in water. Herein, we report the synthesis of a novel N-GNDs/Ag/BiVO4 ternary photocatalyst consisting of BiVO4 coupled with Ag nanoparticles (Ag-NPs) and nitrogen-doped graphene nanodots (N-GNDs) to degrade and mineralize tetracycline hydrochloride (TC•HCl) in water. The ternary photocatalyst shows higher photocatalytic degradation of TC•HCl under full spectrum light than pure BiVO4. Based on the morphology, crystalline structure, physicochemical properties, and photoelectrochemical behavior of the ternary photocatalyst, the enhanced photocatalytic performance is attributed to the upconversion effect of N-GNDs and the localized surface plasmon resonance (LSPR) effect of Ag-NPs. Thus, the synergetic effects expand the absorption range of light and significantly promotes the separation of photoexcited carriers. Further, a possible photocatalytic reaction mechanism of TC•HCl degradation over N-GNDs/Ag/BiVO4 is discussed via through investigation of the charge carrier migration, active species, and intermediates in the degradation processes.

Degradation of tetracycline hydrochloride by coupling of photocatalysis and peroxymonosulfate oxidation processes using CuO-BiVO4 heterogeneous catalyst

In this study, we synthesized CuO modified BiVO4 composite (CuO-BiVO4) and used it to construct a novel coupling system, in which two processes of photocatalysis and peroxymonosulfate (PMS) oxidation processes were integrated together to synergistic remove tetracycline hydrochloride (TC−HCl). XRD, XPS, FESEM, EDS, PL and UV–vis DRS techniques were applied for characterization of the catalyst features. CASTEP procedure of MS software was employed to calculate the electronic structure of the catalyst. The catalytic performance of CuO-BiVO4+ Vis + PMS system was investigated under impact of different variables such as CuO loading amount, pH, PMS dosage, catalyst dosage, temperature and co-existing ions. Compared with the individual photocatalysis or peroxymonosulfate oxidation process, the catalytic performance of the coupling system was significantly improved. Under visible light irradiation, 100 mL of 80 mg/L TC−HCl solution was completely degraded using 2 mM PMS activated by a CuO-BiVO4 composite in 50 min without adjust pH, and the system synergistic index reached 3.04. The improved catalytic activity is due to the effective separation of photogenerated electrons-holes and the availability of more activation PMS sites. After five cycling experiments, the degradation rates of TC−HCl were reduced slightly to 94 %, which indicated the catalysts exhibited excellent reusability and stability for its practical applications. Active species trapping experiments and ESR tests confirmed that SO4·−,·OH, hVB+, O2·− and 1O2 worked together for the TC−HCl degradation. Furthermore, the possible reaction mechanism of the coupling system was proposed, and the degradation intermediates of TC−HCl were identified by LCMS. In conclusion, integration of CuO-BiVO4, Vis and PMS exhibited an excellent performance for TC−HCl degradation within 50 min reaction, which could be introduced as an effective and promising method for the wastewater treatment.

UV/Vis Light Induced Degradation of Oxytetracycline Hydrochloride Mediated byCo-TiO2 Nanoparticles.

Pharmaceuticals, especially antibiotics, constitute an important group of aquatic contaminants given their environmental impact. Specifically, tetracycline antibiotics (TCs) are produced in great amounts for the treatment of bacterial infections in both human and veterinary medicine. Several studies have shown that, among all antibiotics, oxytetracycline hydrochloride (OTC HCl) is one of the most frequently detected TCs in soil and surface water. The results of the photocatalytic degradation of OTC HCL in aqueous suspensions (30 mg·L−1) of 0.5 wt.% cobalt-doped TiO2 catalysts are reported in this study. The heterogeneous Co-TiO2 photocatalysts were synthesized by two different solvothermal methods. Evonik Degussa Aevoxide P25 and self-prepared TiO2 modified by the same methods were used for comparison. The synthesized photocatalysts were characterized by X-ray powder diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), UV/vis diffuse reflectance spectroscopy (DRS), and N2 adsorption (BET) for specific surface area determination. The XRD and Raman results suggest that Ti4+ was substituted by Co2+ in the TiO2 crystal structure. Uv/visible spectroscopy of Co-TiO2-R showed a substantial redshift in comparison with bare TiO2-R. The photocatalytic performance of the prepared photocatalysts in OTC HCL degradation was investigated employing Uv/vis spectroscopy and high-performance liquid chromatography (HPLC). The observed initial reaction rate over Co-TiO2-R was higher compared with that of Co-TiO2-HT, self-prepared TiO2, and the commercial P25. The enhanced photocatalytic activity was attributed to the high surface area (153 m2·g−1) along with the impurity levels within the band gap (2.93 eV), promoting the charge separation and improving the charge transfer ability. From these experimental results, it can be concluded that Co-doping under reflux demonstrates better photocatalytic performances than with the hydrothermal treatment.

First report on clorprenaline HCl degradation products: identification and characterization by LC–MS/MS

Clorprenaline hydrochloride (CLOR), β2 adrenergic agonist, was used for the therapeutic treatment for bronchial asthma. It is important to know the stability behavior of the drug in various degradation conditions because the drug is incompatible with strong oxidizing agent and strong base. The main objective of the study was to identify and characterize degradation products of clorprenaline HCl by LC–MS/MS. The mass-compatible method was developed, validated and further used for LC–MS/MS. In reverse-phase high-performance liquid chromatography (RP-HPLC), the resolution was achieved using Phenomenex C18 (250 × 4.6 mm, 5 µ) column and ammonium acetate buffer (5 mM), 0.1% TEA, pH 6.5 with acetic acid/methanol (70:30, v/v) as mobile phase. The flow rate was 1 mL/min. The wavelength was selected for UV detection at 215 nm. Different forced degradation conditions such as hydrolytic (acidic and basic), oxidative, thermal and sunlight have been applied according to ICH Q1A (R2) guidelines to derive stability of the drug. Further, the method was validated as per ICH Q2 (R1) guidelines. The degradation product was characterized by LC–MS/MS using ESI in positive ion mode. Potential degradation product DP (36.87% of total degradation) was found in basic condition, while no degradation was observed in acidic, neutral, sunlight, oxidation and thermal conditions. The stability indicating analytical method was found to be novel, simple, specific, selective, sensitive, accurate, precise and robust for the determination of clorprenaline HCl.

Carbon nanotubes stabilize poly(vinyl chloride) against thermal degradation

In this study, multiwalled carbon nanotubes (CNT), ball-milled CNT (bmCNT), and acid-treated CNT (CNT-COOH) were assessed as thermal stabilizers in poly(vinyl chloride) (PVC). Films of pure PVC, CNT/PVC, bmCNT/PVC, and CNT-COOH/PVC cast from tetrahydrofuran were subjected to thermal aging in N2 in a test tube submerged in an oil bath maintained at 180 °C for a certain time. FTIR and UV-Vis spectra and discoloration of aged PVC composites were investigated on the formation of conjugated polyene structure in PVC. The results found that all three types of CNT of small amounts (0.1 or 0.3 phr) could stabilize PVC against thermal degradation by retarding the rate of formation of a conjugated polyene structure, with the stabilizing efficacy in the order of bmCNT > CNT > CNT-COOH. Moreover, Congo red and dehydrochlorination (pH measurement) tests were investigated on the degradation of PVC to HCl during the thermal aging as a function of time, CNT type and content. Thermal degradations of PVC to HCl were promoted by all three types of CNT in the initial 30 min of aging but were clearly stabilized against degradation over prolonged aging (for instance, 120 min) by bmCNT followed by CNT-COOH, both exhibiting the optimal stabilizing efficacy at 1 phr. The bmCNT was the most effective thermal stabilizer among the three types of nanotubes studied in PVC to resist both its discoloration and degradation of HCl. This newly-developed PVC composite with CNT as an additive provides an efficient route towards the development of highly thermal-stabilized PVC.

Validated simultaneous determination of antipyrine and benzocaine HCl in the presence of benzocaine HCl degradation product

Two validated, sensitive and highly selective stability-indicating methods were adopted for the simultaneous quantitative determination of antipyrine (ANT) and benzocaine HCl (BEN) in the presence of the degradation product of benzocaine HCl [p-aminobenzoic acid (PABA)].

Effect of Stabilization Temperature on the Degradation of Adriamycin Ik Albumin Microspheres

The effect of stabilization temperature on the degradation of adriamycin HCl during the preparation of albumin microspheres was investigated. The degradation of adriamycin HCl by heating at various temperature with different time interval in dried adriamycin HCl powder, adriamycin HCl aqueous solution, wetted Adriablastina (adriamycin HCl with lactose) powder and Adriablastina aqueous solution was also studied. In the presence of water the degradation of adriamycin HCl was found; whereas, in the absence of water no degradation occurred. The degradation of adriamycin HCl in solution and wetted powder showed a zero order reaction. An increase in temperature increased degradation rate. The rate constant for adriamycin HCl degradation in Adriablastina solution obtained was in good agreement with that in adriamycin HCl solution. It was suggested that the presence of lactose had no interference in the degradation of adriamycin HCl. The zero-order reaction of degradation was attributed to the drug behaved like a suspension. The degradation of adriamycin HCl at various stabilization temperature during the preparation of microspheres had the same tendency as those of the adriamycin HCl solution and the wetted adriamycin HCl powder that were heated by the DSC instrument with the condition similar to the preparation of microspheres.

Reactions of Cp 2M(CO) 2 and Cp 2M(CO)(PPh 3) (M = Zr, Hf) with acetylenes: Formation of some metallacyclopentadiene complexes of zirconocene and hafnocene

The photolysis of Cp 2Zr(CO) 2 with diphenylacetylene or 3-hexyne yields the respective zirconacyclopentadiene complexes Cp 2Z(C 4R 4) (R = Ph, Et). The thermolysis of Cp 2Z(CO) 2 with 3-hexyne or bis(pentafluorophenyl)acetylene also leads to the formation of Cp 2Z(C 4R 4) (R = Et, C 6F 5). HCl degradation of Cp 2Zr[C 6(C 6F 5) 4] yields 1,2,3,4-tetrakis(pentafluorophenyl)-1,3-butadiene and Cp 2ZrCl 2. When Cp 2Zr(CO) 2 is heated with diphenylacetylene in a closed vessel, tetraphenylcyclopentadienone is formed along with Cp 2Zr(C 4Ph 4). The hafnacyclopentadiene complexes Cp 2Hf(C 4R 4) (R = Ph, C 6F 5, Et) are obtained when Cp 2Hf(CO) 2 is thermolyzed with the respective acetylene in refluxing octane. Complexes Cp 2Hf(C 4R 4) (R = Ph, Et) are also formed when Cp 2Hf(CO) 2 is photolyzed with diphenylacetylene or 3-hexyne, respectively. The monocarbonyl-triphenylphosphine complexes Cp 2M(CO)(PPh 3) (M = Zr, Hf) can be prepared via the irradiation of hydrocarbon solutions of Cp 2M(CO) 2 and triphenylphosphine. These complexes react readily with diphenylacetylene and 3-hexyne at 55–60 °C to afford the corresponding metallacyclopentadiene complexes Cp 2M(C 4R 4) (M = Zr, Hf; R = Ph, Et). The metallocene dicarbonyls Cp 2M(CO) 2 (M = Zr, Hf) are readily prepared via the reduction of Cp 2MCl 2 (M = Zr, Hf) with amalgamated magnesium metal in THF solution under one atmosphere of carbon monoxide.

3] Purified human placental arylsulfatases: Their actions on slow-reacting substance of anaphylaxis and synthetic leukotrienes

This chapter explores a possible structure of slow-reacting substance of anaphylaxis (SRS-A) that can be hydrolyzed and inactivated by purified human placental arylsulfatase (AS) B. Arylsulfatase B is used for the analysis of degradation products from SRS-A. The amino acid composition of SRS-A is determined after hydrochloric acid (HCL) degradation. Analysis of the hydrazine degradation products by thin layer chromatography (TLC) revealed the presence of glycine and glutamic acid. Dinitrophenylglutamic acid was identified in the analysis of HCL degradation products of dinitrophenylated SRS-A by TLC. These data demonstrated that the substituent at C-6 eicosatetraenoic acid consisted of three amino acids, viz. cysteic acid or its derivative, glutamic acid as the N-terminal residue, and glycine as the C-terminal residue. In order to examine the substrate specificity of purified human placental arylsulfatase B, 500 units of SRS-A in 0.2 M acetate buffer at pH 5.7 was incubated with 750 units of ASA or 300 units of ASB at 37 ° for 90 min, and then the residual contractile activity of SRS-A was determined.

Structure of slow-reacting substance of anaphylaxis (SRS-A)

To elucidate the chemical structure of slow-reacting substance of anaphylaxis from rat (SRS-A rat), SRS-A rat were purified by the method of Orange with modification using DEAE-Sephadex A-25 chromatography. Ultraviolet absorption spectrum of purified SRS-A rat indicated the presence of conjugated triene. Arylsulfatase B degradation products and HCl degradation products were subjected to analysis by a gas chromatography and mass spectrometry and a thin layer chromatography. Products obtained by arylsulfatase B catalysis contained 5,6-dihydroxy-7,9,11,14-eicosatetraenoic acid. HCl degradation products showed the presence of glycine, glutamic acid and cysteic acid. Furthermore, the analysis of anhydrous hydrazine degradation products of SRS-A rat and of HCl hydrolyzed products of dinitrophenylated SRS-A rat revealed the presence of glycine at C-terminal and glutamic acid at N-terminal. The study of the substrate specificity of arylsulfatase B against various materials including SRS-A rat suggested the presence of sulfone in SRS-A rat. The molecular ion peak of SRS-A rat sodium salt was observed at m/e 680 in field desorption mass spectrum of SRS-A rat. On the basis of these data, we identified the structure of SRS-A rat as [γ-glutamyl-4(5-hydroxy-7,9,11,14-eicosatetraenoic acid-6-yl)-4,4-dioxocysteinyl] glycine.