Enhanced photocatalytic degradation of sulfadiazine by Fe^(3+) in aqueous TiO_2 suspension

In order to explore the reaction mechanism of Fe^3＋ and the mineralization effect of the micropollutant, Fe^3＋ assisted photocatalytic oxidation of sulfadiazine （SD） in the TiO2 suspended solution is investigated. The effect of Fe^3＋ participation, the degradation kinetics of SD, the effect of SD mineralization and the possible mechanism of Fe^3＋ participation in TiO2 suspension are analyzed by adding FeCl3, taking samples at a given time and determining the SD concentration. Results indicate that the degradation of SD catalyzed by TiO2/ Fe^3＋ is faster than that catalyzed by TiO2 or Fe^3＋ separately. The photocatalytic degradation of SD follows the pseudo-first- order kinetics model in a range of 20 to 80 mg/L of initial concentration. The mineralization rate of SD can be enhanced by the addition of Fe^3＋ in the TiO2 suspended solution. The mechanism of the rapid degradation of SD is proposed, which indicates that Fe^3＋ adsorbed on the surface of TiO2 particles acts as an electron acceptor. The amount of recombining electronhole pairs decreases, and the amount of hydroxyl radicals increases. The increased hydroxyl radical strengthens the degradation of SD in the TiO2/Fe^3＋ suspended solution.

Optimization strategies for separation of sulfadiazines using Box-Behnken design by liquid chromatography and capillary electrophoresis

Development of effective chromatographic or electrophoretic separation involves judicious deciding of selection of optimal experimental conditions that can provide an adequate resolution at a reasonable run time for the separation of interested components. Box-Behnken factorial design was effectively applied for the separation optimization of eight structurally related sulfonamides using capillary zone electrophorosis and reverse high performance liquid chromatography. Optimum values for volume ratio of THF to H2O in eluent, column temperature and flow rate of eluent are found as 12 to 88, 35℃ and 1.0 mL/min, respectively. Box-Behnken modified optimization model is extended to separation by capillary electrophoresis (CE). While using CE, a satisfactory separation is achieved with a minimum resolution larger than 1.0 for a separation time less than 10 min.

Determination of Sulfadiazine Based on Its Derivatization with Fluorescamine by Self-Ordered Ring Fluorescence Microscopic Imaging Technique

A self-ordered ring(SOR) fluorescence microscopic imaging technique has been developed for the determination of trace amounts of sulfadiazine based on its derivatization with fluorescamine.In the presence of HAc-NaAc buffer solution(pH 3.12) and polyvinyl alcohol-124(PVA-124),the droplet containing fluorescamine derivatized sulfadiazine can form a SOR on the solid support after solvent evaporation with the diameter of 1.86mm and its ring belt width of 54.9 μ m.The quantitative analysis of sulfadiazine is achieved with the linear range of 7.8×10-14 ～1.8×10-12 mol·ring-1(3.9×10-7 ～9.0×10-6 mol·L-1) and detection limit of 7.8×10-15 mol·ring-1(3.9×10-8 mol·L-1) when 0.2 μ L droplet was spotted.The technique has been satisfactorily applied to the determination of sulfadiazine in the tablet,synthetic sample and residues in six different milk samples with the recoveries of 91.0%～105.8%,respectively,and RSDs less than 4.4%.

Synthesis, Characterization and Antimicrobial Activities of Sulfadiazine Schiff Base and Phenyl Dithiocarbamate Mixed Ligand Metal Complexes

Sulfadiazine Schiff base and Phenyl dithiocarbamate mixed ligand metal complexes have been synthesized and characterized. The characterization of metal complexes is based on the results of the solubility, colour, melting points and elemental analysis as well as the spectroscopic studies. The results obtained from the spectroscopic spectra revealed from the UV-visible showed the presence of chromophoric groups while the FTIR results confirmed that the metals coordinated through the two nitrogen atoms of Sulfadiazine Schiff base and sulphur atom of the N-phenyl dithiocarbamate. Also the antimicrobial activities of the metal complexes proved that the metal complexes are more active than the parent ligands.

Comparative study of raw and HNO_(3)-modified porous carbon from waste printed circuit boards for sulfadiazine adsorption: Experiment and DFT study

A huge amount of waste printed circuit boards(WPCBs) was produced while the electronic manufacturing industry developed rapidly. WPCBs mainly consist of organic compounds, which makes it possible to prepare them into porous carbon as valuable adsorbent. However, WPCBs are also rich in valuable metals.Cu makes up the most of these metals. It is worth studying whether the residual metal will affect the application of carbon materials. In this study, the porous active carbon(AC) was prepared from WPCBs as an adsorbent. Sulfadiazine(SD), a widely detected antibiotic contaminant, was used as a target pollutant.Nitric acid(HNO_(3)) was used to modify AC(AC-HNO_(3)) to remove the residual Cu. The experiment results showed that the adsorption kinetics of SD by AC(k = 0.0025) and AC-HNO_(3)(k = 0.0029) can be described better using a pseudo-second-order kinetic equation. The adsorption isotherms of AC and AC-HNO_(3) on SD could be fitted by the Langmuir model. AC had a larger adsorption capacity than AC-HNO_(3). Density functional theory(DFT) calculation results suggested that the-OH group and Cu on the surface of AC could be the adsorption sites and promote the SD adsorption. This work provides practical methods to recycle WPCBs into wealth and realized waste control by waste.

Simultaneous degradation of sulfadiazine and dissolved organic matter based on low-impact development facilities

Sulfadiazine(SD)is a common antibiotic administered to treat bacterial infections in livestock,and its fate andmigration are greatly affected by dissolved organicmatter(DOM).The soil infiltration system[a typical low-impact development(LID)facility]can significantly alterDOMproperties during runoff pollution,thus affecting the complexation of SDwithDOM.Here,the binding characteristics of different DOM components and SD in the soil infiltration system were explored using spectroscopic techniques(excitation–emission matrices,parallel factor analysis,and synchronous fluorescence spectroscopy).Combined with the weakening of DOM fluorescence intensity and 78.63%reduction in mean SD concentration following treatment,synchronous degradation may have occurred.The binding sequence of SD and DOM fluorophores was further explored using two-dimensional correlation spectroscopy.Effluent DOM showed greater sensitivity to SD and more binding sites than influent DOM.Moreover,hydrophobic protein-like substances exhibited higher log K_(M) values than other fluorescent components,indicating that protein-like components play significant roles in SD complexation.The soil percolation system improved the complexation stability and binding sequence of fulvic-like substances.Thus,SD–DOM can be intercepted and degraded using LID facilities to reduce the risk of SD in aquatic environments.

Impacts of temperatures and phosphoric-acid modification to the physicochemical properties of biochar for excellent sulfadiazine adsorption

The textural properties and surface chemistry of phosphoric acid-modified biochars(PABCs)prepared at different pyrolysis temperatures(500-700℃)were studied based on the results obtained from XRD,SEM,BET,FT-IR,Raman,XPS and elements analyses.PABCs prepared at higher temperatures tended to possess a bigger proportion of microporous structure.The adsorption capacity and initial rate of PABCs for sulfadiazine(SDZ)were notably improved to 139.2 mg/g and 9.66 mg/(g min)as calculated from the Langmuir model.The adsorption equilibrium time was only one quarter of that without modification.The H_(3)PO_(4) modification was advantageous to produce phosphate and break functional groups to form disordered carbon structure abundant of micropores.The enhancement in the adsorption of SDZ was due to the confinement effect of hydrophobic cavities from the mircoporous structure and theπ-πelectron-donor-acceptor interaction.Specially,PABCs exhibited stable adsorption capacities at a wide pH range(3.0-9.0)or relatively high concentrations of coexisting ions.

Degradation of sulfadiazine antibiotics by water falling film dielectric barrier discharge

A new water falling film dielectric barrier discharge was applied to the degradation of sulfadiazine in the aqueous solution. The various parameters that affect the degradation of sulfadiazine and the proposed evolutionary process were investigated. The results indicated that the inner concentrations of 10 mg/L sulfadiazine can be all removed within 30 min. The optimum pH value was 9.10 and both strong acidic and alkaline solution conditions were not suitable for the degradation. The degradation of sulfadiazine can be enhanced by the addition of hydrogen radical scavengers, but be inhibited by adding hydroxyl radical scavengers. The water falling film dielectric barrier discharge was rather ineffective in mineralization, because of the intermediates were recalcitrant to be degraded. The existence of Fe2＋ and CCI4 in the liquid phase can promote the degradation and mineralization of sulfadiazine. It was found that the degradation of SDZ was enhanced by CC14 was mainly because of the increase of＇OH due to the reaction of CC14 with ＊H that reduce the chances of their recombination with ＂OH. Based on the 8 intermediate products identified by LC-MS, the proposed evolution of the degradation process was investigated.

Electrocatalytic response of poly(cobalt tetraaminophthalocyanine)/multi-walled carbon nanotubes-Nafion modified electrode toward sulfadiazine in urine

A highly sensitive amperometric sulfadiazine sensor fabricated by electrochemical deposition of poly(cobalt tetraaminophthalocyanine) (poly(Co II TAPc)) on the surface of a multi-walled carbon nanotubes-Nafion (MWCNTs-Nafion) modified electrode is described.This electrode showed a very attractive performance by combining the advantages of Co II TAPc,MWCNTs,and Nafion.Compared with the bare glassy carbon electrode (GCE) and the MWCNTs-Nafion modified electrode,the electrocatalytic activity of poly(Co II TAPc)-coated MWCNTs-Nafion GCE generated greatly improved electrochemical detections toward sulfadiazine including low oxidation potential,high current responses,and good anti-fouling performance.The oxidation peak currents of sulfadiazine obtained on the new modified electrode increased linearly while increasing the concentration of sulfadiazine from 0.5 to 43.5 μmol/L with the detection limit of 0.17 μmol/L.

Ordered mesoporous carbon as an efficient heterogeneous catalyst to activate peroxydisulfate for degradation of sulfadiazine

Catalytic potential of carbon nanomaterials in peroxydisulfate(PDS)advanced oxidation systems for degradation of antibiotics remains poorly understood.This study revealed ordered mesoporous carbon(type CMK)acted as a superior catalyst for heterogeneous degradation of sulfadiazine(SDZ)in PDS sys-tem,with a first-order reaction kinetic constant(k)and total organic carbon(TOC)mineralization efficiency of 0.06 min^(–1) and 59.67%±3.4%within 60min,respectively.CMK catalyzed PDS system exhibited high degradation efficiencies of five other sulfonamides and three other types of antibiotics,verifying the broad-degradation capacity of antibiotics.Under neutral pH conditions,the optimal catalytic parameters were an initial SDZ concentration of 44.0mg/L,CMK dosage of 0.07g/L,and PDS dosage of 5.44mmol/L,respectively.X-ray photoelectron spectroscopy and Raman spectrum analysis confirmed that the defect structure at edge of CMK and oxygen-containing functional groups on surface of CMK were major active sites,contributing to the high catalytic activity.Free radical quenching analysis revealed that both SO_(4)•−and•OH were generated and participated in catalytic reaction.In addition,direct electron transfer by CMK to activate PDS also occurred,further promoting catalytic performance.Configuration of SDZ molecule was optimized using density functional theory,and the possible reaction sites in SDZ molecule were calculated using Fukui function.Combining ultra-high-performance liquid chromatography(UPLC)–mass spectrometry(MS)/MS analysis,three potential degradation pathways were proposed,including the direct removal of SO_(2)molecules,the 14S-17N fracture,and the 19C-20N and 19C-27N cleavage of the SDZ molecule.The study demonstrated that ordered mesoporous carbon could work as a feasible catalytic material for PDS advanced oxidation during removal of antibiotics from wastewater.

Photocatalytic degradation of sulfadiazine in suspensions of TiO_(2)nanosheets with exposed(001)facets

Antibiotics such as sulfonamides are widely used in agriculture as growth promoters and medicine in treatment of infectious diseases.However,the release of these antibiotics has caused serious environmental problems.In this paper,photocatalytic oxidation technology was used to degrade sulfadiazine(SDZ),one of the typical sulfonamides antibiotics,in UV illuminated TiO_(2)suspensions.It was found that TiO_(2)nanosheets(TiO_(2)-NSs)with exposed(001)facets exhibit much higher photoreactivity towards SDZ degradation compared to TiO_(2)nanoparticles(TiO_(2)-NPs)with a rate constant increases from0.017 min^(-1)to 0.035 min^(-1),improving by a factor of 2.1.Under the attacking of reactive oxygen species(ROSs)such as superoxide radicals(*O_(2)^(-))and hydroxyl radicals(*OH),SDZ was steady degraded on the surface of TiO_(2)-NSs.Based on the identification of the produced intermediates by LC–MS/MS,possible degradation pathways of SDZ,which include desulfonation,oxidation and cleavage,were put forwards.After UV irradiation for 4 h,nearly 90%of the total organic carbon(TOC)can be removed in suspensions of TiO_(2)-NSs,indicating the mineralization of SDZ.TiO_(2)-NSs also exhibits excellent stability in photocatalytic degradation of SDZ in wide range of pH.Even after recycling used for 7 times,more than 91.3%of the SDZ can be efficiently removed,indicating that they are promising to be practically used in treatment of wastewater containing antibiotics.

Two episodes of anaphylaxis caused by a chlorhexidine sulfadiazine-coated central venous catheter

Central venous catheters （CVCs） are widely used to monitor the circulation and for administering fluids,parenteral nutrition, and chemotherapy, especially in patients undergoing major surgery. In patients who require prolonged use of a catheter, clinicians sometimes use antiseptic catheters to reduce the risk of catheter-related infection. Anaphylaxis in response to chlorhexidine sulfadiazine-coated central venous catheters is uncommon, but it can lead to severe problems.

Removal of sulfadiazine from aqueous solution on kaolinite

The adsorption of sulfadiazine onto kaolinite clay as an alternative adsorbent was examined in aqueous solution, hnpacts of the contact time, pH, temperature, ionic strength and coexistent surfactants on the adsorption process were evaluated. The pH significantly influenced the adsorption process, with adsorption being promoted at lower pH due to the cation exchange mechanism. Decreasing ionic strength in the solution was favorable for adsorption, and the addition of cationic and anionic surfactants had negative effects on the adsorption capacity of sulfadiazine on kaolinite. Kinetic experiments showed that the adsorption followed the pseudo-second-order model. The equilibrium adsorption was well described by both Freundlich and Dubinin-Radushkevich （DR） models. According to the DR model, the adsorption mechanism was determined by cationic exchange and weak physical forces. The thermodynamic study showed that sulfadiazine adsorption onto kaolinite was a sponta- neous and endothermic reaction.

Micrometer-sized NiOOH hierarchical spheres for enhanced degradation of sulfadiazine via synergistic adsorption and catalytic oxidation in peroxymonosulfate system

As an antibiotic,sulfadiazine has posed a serious threat to humans and ecosystems due to its chronic toxicity.The advanced oxidation processes (AOPs) via heterogeneous catalytic activation of peroxymonosulfate (PMS) have significant potential for the degradation of antibiotics.However,there are multiple restrictions including non-specifically binding to target contaminants,which would deplete oxidation capacity,and lacking energy effectiveness due to inefficient utilization of reactive oxygen species (ROS).To overcome these obstacles,we adopted the“bait-hook&destroy”strategy in this study.Herein,we synthesized a novel micrometer-sized Ni OOH hierarchical spheres assembled from nanosheets,which have relatively large specific surface areas and yield specified cavities to“bait-hook”sulfadiazine and PMS onto the surface cavities.This process was further conductive to effective generation of ROS and subsequently“destruction”of sulfadiazine with elevated mass transformation rate.20.4%of sulfadiazine can adsorb to Ni OOH surface in less than 30 min (0.0051 min^(-1)),and then sulfadiazine was completely degraded in 90min intervals in the Ni OOH/PMS system.The degradation rate constant (k=0.0537 min^(-1)) was about5.3,2.5 and 2.2 times higher than that in Ni_(2)O_(3)/PMS,NiO/PMS and Ni(OH)_(2)/PMS system,respectively.This was ascribed to the synergistic catalytic oxidation and adsorption process occurred on the surface of Ni OOH.Appreciably,there were both non-radicals (^(1)O_(2)) and radicals (O_(2)^(·-)and SO_(4)^(·-)) involved in the Ni OOH/PMS system,and^(1)O_(2)was distinguished as the dominated ROS for degradation of sulfadiazine.This study provides a novel strategy via synergistic adsorption and catalytic oxidation,and indicates that the micrometer-sized Ni OOH hierarchical sphere as heterogeneous catalyst is an attractive candidate for potential application of the SR-AOPs technology in water treatment.

Synthesis and Crystal Structure of (E)-4-(3-oxo-3-((4-(N-(pyrimidin-2-yl)-sulfamoyl)phenyl)amino)prop-1-en-1-yl)-1,2-phenylene diacetate Dimethanol

The title compound, （E）-4-（3-oxo-3-（（4-（N-（pyrimidin-2-yl）sulfamoyl）-phenyl）ami- no）prop- 1-en- 1-yl）- 1,2-phenylene diacetate dimethanol, was synthesized by the reaction of caffeic acid with sulfadiazine and characterized by FT-IR, 1H-NMR spectroscopy, ESI-MS and X-ray single-crystal diffraction. It crystallizes in triclinic, space group P1 with a = 10.302（7）, b = 11.621（8）, c = 12.107（8）A, a = 100.904（9）, β = 102.624（8）, y = 95.501（9）°, V= 1374.5（15）A3, Z= 2, F（000） = 588, D,= 1.354 Mg/m3, Mr = 560.57,μ= 0.176 mm-1, 2 = 0.71073 A, the final R = 0.0666 and wR = 0.1950 for 4774 observed reflections with I 〉 2σ（I）.

Kinetics of Ozonation of Typical Sulfonamides in Water

Objective To investigate the kinetic rate constants ozone and hydroxyl radicals towards two groups of antimicrobials --sulfadiazine （SD） and sulfamethoxazole （SMX）.Methods The solute consumption method was used to detect the rate constants of ozone alone with sulfadiazine and sulfamethoxazole, and tertiary butanol was selected as a scavenging agent and pH was adjusted to 2.5 by adding orthophosphate buffers （OB）; and the competition kinetics studying methodwith nitrobenzene as a reference was applied to measure the rate constants of hydroxyl radicals towards sulfadiazine and sulfamethoxazole, and oH was adjusted to 7.0 bv adding OB.Results The rate constants of SD and SMX with ozone alone were 261 mol^-1· dm^3 · s^-1 and 303 mol^-1· dm3 · s-1 by calculating in low reaction system. The rate constants of hydroxyl radicals with SD and SMX were 2.2×1010 mol^-1 · dm^3 · s^-1 and 2.7×1010 mol^-1· dm^3 · s^-1, respectively. Moreover, the rate constants of hydroxyl radicals with SMX were found to have increased from 3.6×109 mol^-1· dm^3 · s^-1 to 2.8×1010 mol^-1· dm^3 · s^-1 with pH value rising from 5.0 to 7.8. Conclusion SMX and SD are both refractory to ozone oxidation alone, and are liable to be degraded by hydroxyl radicals, and the rate constants of SMX with the hydroxyl radical slightly increases with pH rise.

La^(3+)@BC500-S_(2)O_(8)^(2−)system for removal of sulfonamide antibiotics in water

Sulfonamide antibiotics(SAs)widely used have potentially negative effects on human beings and ecosystems.Adsorption and advanced oxidation methods have been exten-sively applied in SAs wastewater treatment.In this study,compared with Al^(3+)@BC500 and Fe^(3+)@BC500,La^(3+)@BC500 for activating persulfate(S2O82−)had the best effect removal per-formance of sulfadiazine(SDZ)and sulfamethoxazole(SMX).Morphology,acidity,oxygen-containing functional groups,and loading of La^(3+)@BC500 were analyzed by techniques,in-cluding EA,BET,XRD,XPS,FT-IR.XRD results show that with the increase of La^(3+)loading,the surface characteristics of biochar gradually changed from CaCO_(3)to LaCO_(3)OH.Through EPR technology,it is proved that LaCO_(3)OH on the surface of La^(3+)@BC500 can not only acti-vate S2O82−to generate SO_(4)^(−)•,but also to produce•OH.In the optimization experiment,the optimal dosage of La^(3+)is between 0.05 and 0.2(mol/L)/g.SDZ had a good removal effect at pH(5-9),but SMX had a good removal effect only at pH=3.Zeta potential also proves that the material is more stable under acidic conditions.The removal process of SDZ is more in accord with pseudo-first-order kinetics(R^(2)=0.9869),while SMX is more in line with pseudo-second order kinetics(R^(2)=0.9926).

Coupled effects of pH and kaolinite colloids on antibiotic transport in porous media

Antibiotics can interact with natural colloids and the surrounding media upon entry into soil and groundwater systems,which significantly alters their dynamic behavior and complicates our understanding of antibiotic fate and transport in porous media.In this study,co-transport of antibiotics and kaolinite colloids was systematically investigated using combined column experiments and numerical simulation under different pH conditions.Sulfadiazine(SDZ)transport was enhanced by kaolinite colloids under neutral and alkaline conditions,which was attributed to the higher mobility of colloids as SDZ carriers,as well as competitive sorption.However,most injected SDZ was transported in a dissolved form owing to the low sorption capacity of SDZ to kaolinite colloids and quartz sand.The colloid-facilitated transport model provided a good description of total SDZ transport,but underestimated colloidal SDZ transport using parameters from kinetic sorption experiments.Kaolinite colloids significantly promoted ciprofloxacin(CIP)transport at pH 4.0,but inhibited it at pH 7.0 and9.0.Interestingly,enhanced CIP transport was due to the decreased number of effective sorption sites on quartz sand and the increased desorption of CIP from kaolinite colloids.Under neutral and alkaline conditions,deposited colloids provided additional sorption sites for CIP,which contributed to CIP retention.Moreover,CIP significantly inhibited the transport of kaolinite colloids owing to the increases in colloidal aggregate size and zeta potential.Overall,our results highlighted the different effects of mobile and immobile colloids on antibiotic transport,in addition to the implications of antibiotic speciation and clay colloids when predicting the transport behavior of these compounds.

Propolis modulates vitronectin,laminin,and heparan sulfate/heparin expression during experimental burn healing

Objective:This study was aimed at assessing the dynamics of vitronectin (VN), laminin (LN), and heparan sulfate/heparin (HS/HP) content changes during experimental burn healing. Methods:VN, LN, and HS/HP were isolated and purified from normal and injured skin of domestic pigs, on the 3rd, 5th, 10th, 15th, and 21st days following thermal damage. The wounds were treated with apitherapeutic agent (propolis), silver sulfadiazine (SSD), physiological salt solution, and propolis vehicle. VN and LN were quantified using an immunoenzymatic assay and HS/HP was estimated by densitometric analysis. Results:Propolis treatment stimulated significant increases in VN, LN, and HS/HP contents during the initial phase of study, followed by a reduction in the estimated extracellular matrix molecules. Similar patterns, although less extreme, were observed after treatment with SSD. Conclusions:The beneficial effects of propolis on experimental wounds make it a potential apitherapeutic agent in topical burn management.

Degradation of sulfonamides and formation of trihalomethanes by chlorination after pre-oxidation with Fe(Ⅵ)

Sulfonamides are used in human therapy, animal husbandry and agriculture but are not easily biodegradable, and are often detected in surface water. Sulfamethazine （SMZ） and sulfadiazine （SDZ） are two widely used sulfonamide antibiotics that are used heavily in agriculture. In this study, they were degraded in an aqueous system by chlorination after pre-oxidation with ferrate（VI） （FeVIO2-, Fe（VI））, an environmentally friendly oxidation technique that has been shown to be effective in degrading various organics. The kinetics of the degradation were determined as a function of Fe（VI） （0-1.5 mg/L）, free chlorine （0-1.8 mg/L） and temperature （15- 35℃）. According to the experimental results, SMZ chlorination followed second-order kinetics with increasing Fe（VI） dosage, and the effect of the initial free chlorine concentration on the reaction kinetics with pre-oxidation by Fe（VI） fitted a pseudo-first order model. The rate constants of SDZ and SMZ chlorination at different temperatures were related to the Arrhenius equation. Fe（VI） could reduce the levels of THMs formed and the toxicity of the sulfonamide degradation systems with Fe（VI） doses of 0.5-1.5 mg/L, which provides a reference for ensuring water quality in drinking water systems.