Sulfadiazine Mineralization Research Articles

Light-dependent enhancement of sulfadiazine detoxification and mineralization by non-photosynthetic methanotrophs

Co-metabolism and photodegradation are two approaches for remediating trace organic compounds (TOrCs), however, interactions between the two with regards to TOrCs degradation have not been elucidated. In this study, sulfadiazine (SDZ) was chosen as a representative TOrC and Methylocystis bryophila as a typical strain. Under light conditions, about 80.6% of SDZ was removed by M. bryophila, but only 7.6% or 28.9% of SDZ was eliminated by either individual photodegradation or by co-metabolism. The SDZ stimulated more extracellular organic matter (EOM) production by M. bryophila. The enhanced SDZ degradation was attributed to indirect photolysis caused by the excited triplet state of EOM (3EOM*) and co-metabolism. The UPLC-QTOF-MS analysis showed that due to co-metabolism, the pyrimidine ring was broken and could further be oxidized into smaller molecules under light conditions, such as formic and acetic acids. The SDZ mineralization ratio increased from 9.9% under the co-metabolic condition alone to 36.5% under co-metabolism coupled with photodegradation. The Ames tests confirmed that the SDZ degradation products by co-metabolism were mutagenic, however, their toxicity was ameliorated by light during co-metabolism. In conclusion, light plays a crucial role in co-metabolic processes of TOrCs.

Removal of antibiotics sulfadiazine by a biochar based material activated persulfate oxidation system: Performance, products and mechanism

Nowadays, the harm of antibiotics residues in environments to human health and ecological safety has been causing more and more attention. In this paper, a biochar based iron material (MBC) was used to activate persulfate (PS) for the removal of sulfadiazine (SDZ) from aqueous solution. Experiment results indicate that the degradation and mineralization of SDZ by MBC/PS system reached 91.79% and 60% within 60 min under the optimal reaction conditions, respectively. MBC/PS system exhibited a better performance on SDZ removal compared with MBC/H2O2 system. The addition of Cu2+ ion could enhance the degradation of SDZ by MBC/PS system. PO43-, Cl- and SO42- had a certain degree of inhibitory effect on the SDZ degradation. Both radicals and non-radical species such as SO4•-, •OH and 1O2 participated in the degradation reaction of SDZ by MBC/PS system, but •OH was the main radical species responsible for SDZ degradation. The liquid chromatograph-mass spectrometer (LC-MS) technique was used to identify the intermediate products of SDZ, and it was proposed that the degradation of SDZ might be achieved through hydrolyzation, hydroxylation, deamination and amino-oxidization processes. A possible reaction mechanism involving a synergistic effect between PS homogeneous and heterogeneous activation processes as well as both radicals and non-radicals reactions was finally proposed.

Photocatalytic degradation of sulfadiazine in suspensions of TiO2 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 TiO2 suspensions. It was found that TiO2 nanosheets (TiO2-NSs) with exposed (001) facets exhibit much higher photoreactivity towards SDZ degradation compared to TiO2 nanoparticles (TiO2-NPs) with a rate constant increases from 0.017 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 (O2–) and hydroxyl radicals (OH), SDZ was steady degraded on the surface of TiO2-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 TiO2-NSs, indicating the mineralization of SDZ. TiO2-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.

Sulfadiazine dissipation as a function of soil bacterial diversity.

Antibiotic residues in the environment are concerning since results in dispersion of resistance genes. Their degradation is often closely related to microbial metabolism. However, the impacts of soil bacterial community on sulfadiazine (SDZ) dissipation remains unclear, mainly in tropical soils. Our main goals were to evaluate effects of long-term swine manure application on soil bacterial structure as well as effects of soil microbial diversity depletion on SDZ dissipation, using "extinction dilution approach" and 14C-SDZ. Manure application affected several soil attributes, such as pH, organic carbon (OC), and macronutrient contents as well as bacterial community structure and diversity. Even minor bacterial diversity depletion impacted SDZ mineralization and non-extractible residue (NER) formation rates, but NER recovered along 42d likely due to soil diversity recovery. However, this period may be enough to spread resistance genes into the environment. Surprisingly, the non-manured natural soil (NS-S1) showed faster SDZ dissipation rate (DT90=2.0 versus 21d) and had a great number of bacterial families involved in major SDZ dissipation pathways (mineralization and mainly NER), such as Isosphaeraceae, Ktedonobacteraceae, Acidobacteriaceae_(Subgroup_1), Micromonosporaceae, and Sphingobacteriaceae. This result is unique and contrasts our hypothesis that long-term manured soils would present adaptive advantages and, consequently, have higher SDZ dissipation rates. The literature suggests instantaneous chemical degradation of SDZ in acidic soils responsible to the fast formation of NER. Our results show that if chemical degradation happens, it is soon followed by microbial metabolism (biodegradation) performed by a pool of bacteria and the newly formed metabolites should favors NER formation since SDZ presented low sorption. It also showed that SDZ mineralization is a low redundancy function.

Sonophotocatalytic degradation of sulfadiazine by integration of microfibrillated carboxymethyl cellulose with Zn-Cu-Mg mixed metal hydroxide/g-C3N4 composite

This research aimed to prepare a recoverable sonophotocatalyst, in which microfibrillated carboxymethyl cellulose (MFC) acted as the Zn-Cu-Mg-mixed metal hydroxide/graphitic carbon nitride (MMH/g-C3N4) carrier. The characteristics of bare and composite sonophotocatalysts were analyzed by the XRD, FT-IR, BET, DRS, PL and FE-SEM equipped with the EDX mapping. The performance of prepared composites (MMH/g-C3N4@MFC) with various weight ratios of the MMH/g-C3N4 was studied for the sonophotocatalytic degradation of sulfadiazine (SDZ) as the model emerging contaminant. 93% of SDZ was degraded using the most effective catalyst (MMH/g-C3N4@MFC3) with 15% weight ratio of the MMH/g-C3N4 under the desired operating conditions including solution pH of 6.5, SDZ concentration of 0.15 mM and ultrasonic power of 300 W. The MMH addition to the g-C3N4 structure increased the separation of charge carriers generated via the visible light or ultrasound irradiations. Moreover, the MMH/g-C3N4 was dispersed uniformly on the MFC and consequently, more active sites were available to form reactive oxygen species (ROS), compared to powder form. Hydroxyl radicals (•OH) were determined as the main ROS in the SDZ degradation by performing a series of scavenging experiments. Less than 10% decrease in the degradation efficiency of SDZ was observed during five subsequent experiments, which indicated the proper retention of the MMH/g-C3N4 particles in the MFC. The adequate mineralization of SDZ (83% decrease in chemical oxygen demand (COD)) was obtained after 200 min of treatment. Eventually, ten degradation intermediates were identified by the GC-MS analysis and a plausible degradation mechanism for the contaminant was proposed.

Sulfadiazine dissipation in acidic tropical soils.

Sulfadiazine (SDZ) residues have been detected in manured soils as well as their adjacent water resources, but its behavior is still poorly understood in acidic tropical soils. This research aimed to evaluate sorption, leaching, and biodegradation of 14C-SDZ in four acidic soils from Brazil, using OECD guidelines. Except for the sand soil (Kd = 2.6Lkg-1), SDZ sorption tended to be higher (Kd > 8.4Lkg-1) and more hysteretic (ΔH >> 1) in acidic soils. When freshly applied, SDZ leaching was low (< 0.11% of applied radioactivity (AR)) and could not always be predicted by Kd values; but leaching was restricted when SDZ was aged for 62days. SDZ mineralization was low (< 3%) but its dissipation was fast (DT50 < 2.3days and DT90 < 6.3days) due to fast initial degradation (an unknown metabolite was immediately formed, likely 4-hydroxysulfadiazine) and mainly to fast formation of non-extractable residues (NER) (> 78% of AR up to 7days). For certain acidic soils, the abrupt breakdown of the SDZ suggests that degradation should be initially chemical and then followed by enzymatically driven reactions. The fast formation of NERs was attributed mostly to chemical bounding to soil humic substances (Type II-NER), but SDZ sequestration cannot be ruled out (Type I-NER). NERs represent a long-term environmental reservoir of SDZ that may cause deleterious effects on non-target organisms as well as promote antibiotic resistance to soil microbes.

Ultrasound-assisted photocatalytic degradation of sulfadiazine using MgO@CNT heterojunction composite: Effective factors, pathway and biodegradability studies

Heterogeneous hybrid systems have emerged as effective approaches for decontamination of aqueous solutions containing non-biodegradable compounds. This is the first study employed hexagonal magnesium oxide (MgO) anchored on carbon nanotubes (CNTs), as heterogeneous catalyst, in coupling with UV and ultrasound (US) waves (marked as MCs/UV/US) for degradation of sulfadiazine (SDZ). MgO/CNT nanocomposites (MCs) were synthesized through an ultrasound-assisted hydrothermal method, and their properties were characterized via BET, FESEM, TEM, XRD, FTIR, EIS, TGA, UV–vis DRS, EDAX, and EDS techniques. The FESEM and TEM results indicated that CNTs were well-incorporated into the hexagonal MgO. The ability of MCs/UV/US system for SDZ decontamination was evaluated as a function of solution pH, catalyst loading, US power, UV intensity, initial SDZ concentration, scavenging agents and co-existing chemicals. As-prepared catalyst showed a significant synergistic effect in the presence of both UV and US irradiation for SDZ mineralization. During sono-photocatalytic process, the complete degradation of SDZ (45 mg/L) was achieved at pH: 11.0; MCs: 0.9 g/L; US power: 200 W; and UV intensity: 150 W within 80 min reaction. MCs exhibited high chemical stability and reusability after six consecutive cycles. However, the addition of co-existing anions, especially Cl−, gradually reduced the efficiency of SDZ degradation over MCs/UV/US system. Trapping studies indicated that hydroxyl radicals and holes were responsible for oxidation of organic chemicals during the reaction period. The plausible pathway and mechanism of sono-photocatalytic decomposition of SDZ were determined in details. Kinetic data confirmed that degradation process was fitted to a pseudo first-order kinetic model with a regression coefficient of 0.98. MCs/UV/US process effectively quenched 89% and 96% of TOC and COD in the pharmaceutical wastewater, respectively. The biodegradability and toxicity of the produced organic chemicals were considerably enhanced after the treatment.

How UV photolysis accelerates the biodegradation and mineralization of sulfadiazine (SD).

Sulfadiazine (SD), one of broad-spectrum antibiotics, exhibits limited biodegradation in wastewater treatment due to its chemical structure, which requires initial mono-oxygenation reactions to initiate its biodegradation. Intimately coupling UV photolysis with biodegradation, realized with the internal loop photobiodegradation reactor, accelerated SD biodegradation and mineralization by 35 and 71 %, respectively. The main organic products from photolysis were 2-aminopyrimidine (2-AP), p-aminobenzenesulfonic acid (ABS), and aniline (An), and an SD-photolysis pathway could be identified using C, N, and S balances. Adding An or ABS (but not 2-AP) into the SD solution during biodegradation experiments (no UV photolysis) gave SD removal and mineralization rates similar to intimately coupled photolysis and biodegradation. An SD biodegradation pathway, based on a diverse set of the experimental results, explains how the mineralization of ABS and An (but not 2-AP) provided internal electron carriers that accelerated the initial mono-oxygenation reactions of SD biodegradation. Thus, multiple lines of evidence support that the mechanism by which intimately coupled photolysis and biodegradation accelerated SD removal and mineralization was through producing co-substrates whose oxidation produced electron equivalents that stimulated the initial mono-oxygenation reactions for SD biodegradation.

Performance and Kinetic-Mechanistic Aspects in the Electrochemical Degradation of Sulfadiazine on Boron-Doped Diamond Electrode

The electrochemical performance of boron-doped diamond (BDD) electrode in the electrochemical degradation of wastewaters containing sulfadiazine (SDZ) using a filter-press reactor is presented and discussed. The electrooxidation of the SDZ (volume of 0.5 L, with a SDZ initial concentration of 250 mg L-1) obtained at optimized conditions (current density of 36 mA cm-2, pH 7.0 and volume flow rate of 5.0 L min-1) showed that at the end of only 2 h of electrolysis (corresponding to a charge passed through the cell per unit volume of the wastewater of 5.2 Ah L-1) SDZ was totally eliminated. The reduction of the wastewater organic load, monitored by its chemical oxygen demand (COD) showed that the antibiotic was virtually all mineralized. Under optimized conditions the intermediate compounds were properly identified by gas chromatography-mass spectrometry (GC-MS) and a SDZ oxidation pathway was elucidated. Clearly the BDD electrode proved to be quite efficient for both degradation and mineralization of SDZ.

Degradation of sulfadiazine antibiotics by water falling film dielectric barrier discharge

Abstract 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 CCl4 in the liquid phase can promote the degradation and mineralization of sulfadiazine. It was found that the degradation of SDZ was enhanced by CCl4 was mainly because of the increase of OH due to the reaction of CCl4 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.

Degradation of sulfadiazine by Microbacterium lacus strain SDZm4, isolated from lysimeters previously manured with slurry from sulfadiazine-medicated pigs.

Sulfadiazine (SDZ)-degrading bacterial cultures were enriched from the topsoil layer of lysimeters that were formerly treated with manure from pigs medicated with (14)C-labeled SDZ. The loss of about 35% of the applied radioactivity after an incubation period of 3 years was attributed to CO2 release due to mineralization processes in the lysimeters. Microcosm experiments with moist soil and soil slurries originating from these lysimeters confirmed the presumed mineralization potential, and an SDZ-degrading bacterium was isolated. It was identified as Microbacterium lacus, denoted strain SDZm4. During degradation studies with M. lacus strain SDZm4 using pyrimidine-ring labeled SDZ, SDZ disappeared completely but no (14)CO2 was released during 10 days of incubation. The entire applied radioactivity (AR) remained in solution and could be assigned to 2-aminopyrimidine. In contrast, for parallel incubations but with phenyl ring-labeled SDZ, 56% of the AR was released as (14)CO2, 16% was linked to biomass, and 21% remained as dissolved, not yet identified (14)C. Thus, it was shown that M. lacus extensively mineralized and partly assimilated the phenyl moiety of the SDZ molecule while forming equimolar amounts of 2-aminopyrimidine. This partial degradation might be an important step in the complete mineralization of SDZ by soil microorganisms.

The oxidative degradation of sulfadiazine at the interface of α‐MnO2 and water

AbstractBACKGROUND: Sulfadiazine (SD), a widely used antibiotic chemical, has been detected in contaminated water and soils. Manganese dioxides are common minerals with a high redox potential and can act as active oxidants for SD degradation in wastewater treatment.RESULTS: α‐MnO2 was used to promote SD oxidative degradation. At pH 4.6 and 25 °C, 92.7% of SD (0.02 mmol L−1) was degraded by 1.0 g L−1α‐MnO2. SO42− was detected as the inorganic end product from the mineralization of SD. The ecological toxicity index of average well color development (AWCD) in SD solution was 2.01 after the solution was degraded by α‐MnO2 for 2 h, while the AWCD was 0.48 for the solution without α‐MnO2 treatment. The degradation rate of SD can be improved by increasing the dosages of α‐MnO2 and the reaction temperature, but the rate was limited by increased initial SD concentration and reaction pH.CONCLUSION: SD can be effectively degraded and mineralized with α‐MnO2. These results are helpful for removing antibiotics by manganese dioxides in the environment, and also for exploring new technology for wastewater treatment. Copyright © 2009 Society of Chemical Industry