Photocatalytic Degradation Of Ammonia Research Articles

Efficient photocatalytic degradation of ammonia nitrogen by Z-scheme NH2-MIL-101(Fe)/BiVO4 heterostructures

A promising Z-scheme NH2-MIL-101(Fe)/BiVO4 heterostructure was fabricated by in-situ growth of monoclinic BiVO4 onto the surface of NH2-MIL-101(Fe) nanoparticles and employed for ammonia nitrogen removal in water for the first time. Experiments demonstrated that NH2-MIL-101(Fe)/BiVO4 composites displayed boosted performance for ammonia nitrogen removal. And 10%-MBVO exhibited optimal removal rate of ammonia nitrogen as 95.7% and N2 selectivity as 92.3% in 90 min at pH of 9.0 with initial concentration as 30 mgN/L. Moreover, effects of initial solution pH, stirring speed and impurity ions (k+, Ca2+, SO42− and CO32−) were investigated. The end products and net contributions of stripping, adsorption, photolysis, photocatalysis in ammonia nitrogen removal were revealed. The functions of ·OH, ·O2− and h+ in photocatalytic degradation of ammonia were explored by scavenging experiments. The proposed mechanism indicated that the enhancement may be primarily owing to the improved light harvesting capacity and stronger redox ability of photogenerated carriers provided by Z-scheme heterostructures.

Floatable photocatalyst LaFeO3/modified expanded perlite composite for photocatalytic ammonia degradation

In this research, visible-light active perovskite photocatalyst, lanthanum orthoferrite (LFO), and floating photocatalyst composites, namely LFO/expanded perlite (EP) and LFO/modified EP (MEP) were successfully synthesized for ammonia degradation. Sodium hydroxide was used to modify EP as it could transform the structure of EP into a mesoporous structure, thereby increasing the surface attachment of LFO and improving contact with ammonia. The characterization of EP, MEP, LFO/EP, and LFO/MEP composites was performed using UV–Vis, XRD, BET surface area, FTIR, SEM, FESEM, and zeta potential. Photocatalytic degradation of ammonia was studied and LFO/MEP showed the best performance. The optimal operational parameters for degrading ammonia using LFO/MEP were the catalytic dosage of 8 g L−1, the initial ammonia concentration of 10 ppm, and the pH of the reaction medium of 8, with the maximum ammonia degradation efficiency of 45.7%. A reusability study of LFO/MEP composite on the photocatalytic degradation of ammonia was performed for 3 cycles, where the composite demonstrated high stability. The reaction rate constant, k, was 0.0079 min−1, the kinetic data was 10.08 μmol/g-catalyst/h, and the quantum yield was 6.686 × 10−6 molecules/photon. The floatable photocatalyst LFO/MEP composite can be an effective method for the photodegradation of ammonia. The photocatalyst could be easily recovered and is reusable for several cycles of treatment. The reaction occurs at ambient conditions under visible light and there is limited by-product production, with the nitrate and nitrite ions of 0.48 and 0.0024 ppm, respectively. These properties demonstrated that the proposed method is an environmentally friendly method for removing ammonia from water.

Photocatalytic Generated Oxygen Species Properties by Fullerene Modified Two-Dimensional MoS2 and Degradation of Ammonia Under Visible Light

In this study, photocatalytic degradation of ammonia in petrochemical wastewater is investigated by solar light photocatalysis. Two-dimensional ultra-thin atomic layer structured MoS2 are synthesized via a simple hydrothermal method. We examine all prepared samples by means of physical techniques, such as SEM-EDX, HRTEM, FT-IR, BET, XRD, XPS, DRS and PL. And, we use fullerene modified MoS2 nanosheets to enhance the activity of photochemically generated oxygen (PGO) species. Surface area and pore volumes of the MoS2-fullerene samples significantly increase due to the existence of MoS2. And, PGO oxidation of MB, TBA and TMST, causing its concentration in aqueous solution to decrease, is confirmed by the results of PL. The generation of reactive oxygen species is detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). It is found that the photocurrent density and the PGO effect increase in the case with modified fullerene. The experimental results show that this heterogeneous catalyst has a degradation of 88.43% achieved through visible light irradiation. The product for the degradation of NH3 is identified as N2, but not NO2−or NO3−.

Heterostructure Cu2O/(001)TiO2 Effected on Photocatalytic Degradation of Ammonia of Livestock Houses

In this paper, a heterogeneous composite catalyst Cu2O/(001)TiO2 was prepared by the impregnation-reduction method. The crystal form, highly active facet content, morphology, optical properties, and the photogenerated electron-hole recombination rate of the as-prepared catalysts were investigated. The performance of Cu2O/(001)TiO2 was appraised by photocatalytic degradation of ammonia under sunlight and was compared with lone P25, Cu2O, and (001)TiO2 at the same reaction conditions. The results showed that 80% of the ammonia concentration (120 ± 3 ppm) was removed by Cu2O/(001)TiO2, which was a higher degradation rate than that of pure P25 (12%), Cu2O (12%), and (001)TiO2 (15%) during 120 min of reaction time. The reason may be due to the compound’s (Cu2O/(001)TiO2) highly active (001) facets content that increased by 8.2% and the band gap width decreasing by 1.02 eV. It was also found that the air flow impacts the photocatalytic degradation of ammonia. Therefore, learning how to maintain the degradation effect of Cu2O/(001)TiO2 with ammonia will be important in future practical applications.

Properties of photocatalytically generated oxygen species produced by Ag2Se-graphene oxide heterojunction and its application for the visible-light degradation of ammonia

Reactive oxygen species (ROS) can be produced by the interactions between sunlight and light-absorbing substances in aqueous environments, and these ROS are capable of destroying various organic pollutants in wastewater. In this study, the photocatalytic degradation of ammonia in petrochemical wastewater was investigated by solar light photocatalysis. We used graphene oxide modified Ag2Se nanoparticles to enhance the activity of photochemically generated oxygen (PGO) species. There was a catastrophic decrease in the surface area and pore volume of the Ag2Se-graphene oxide (Ag2Se-G) samples because of the deposition of Ag2Se. The generation of ROS was detected by the oxidation of 1,5- diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). It was revealed that the photocurrent density and PGO effect increased with the graphene oxide modified. The experimental results indicate that this heterogeneous catalyst achieved a degradation of 88.43% under visiblelight irradiation. The NH3 degradation product was N2 and neither NO2− nor NO3− were detected.

Experimental study of Siri-Island refinery wastewater treatment using a photocatalytic process

ABSTRACTIn this study, photocatalytic degradation of ammonia in petrochemical wastewater was investigated by solar light/TiO2 photocatalysis. The TiO2 nanoparticles were used as photocatalysts, which were immobilized on light expanded clay aggregate (LECA) granules as a new porous and light-weight support. A real Siri (Iran) petroleum refinery wastewater, containing a range of aromatic organic compounds, was treated using TiO2 photocatalyst. Samples were collected from the inlet point of the biological treatment unit. Optimal suspended catalyst concentration, fluid pH, and temperature were obtained at amounts of near 100 mg·L−1, 3, and 45°C, respectively. The identification analysis of the organic pollutants, provided by means of a gas chromatography–mass spectrometry, equipped with headspace injection technique, showed that different petroleum compounds were degraded with high efficiencies.

Preparation of ZnO/Ag heterostructure material by one-pot method for enhanced photocatalytic performance

A porous ZnO/Ag heterostructure photocatalyst was prepared by a simple one-pot method. The photoca-talytic degradation of ammonia and dye indicated that compared with pure ZnO, the photocatalytic activity of ZnO/Ag was significantly improved after Ag modification. The main reason for the improvement of photocatalytic activity is that the recombination process of photoinduced electrons and holes of ZnO was inhibited by interconver-sion of Ag+ and Ag0 at the surface of ZnO. In addition, the effective separation of the photogenerated carriers can generate more active groups, which can promote the degradation of ammonia and organic dyes.

Application of solar light for degradation of ammonia in petrochemical wastewater by a floating TiO2/LECA photocatalyst

In this study, photocatalytic degradation of ammonia in petrochemical wastewater was investigated by solar light/TiO2 photocatalysis. The TiO2 nanoparticles were used as photocatalysts which were immobilized on light expanded clay aggregate (LECA) granules as a new porous and light weight support. Maximum concentration of ammonia (975mg/L) in petrochemical wastewater was selected, and to optimize the photocatalytic reaction, the effect of pH and catalyst dosage was investigated in two aerated and agitated reactor systems. Also, the morphology and chemical structure properties of the prepared catalysts were characterized by SEM and XRF analyses. The experimental results were shown that the performance of two types of aeration reactor systems was almost the same. Also, the ammonia removal efficiency was increased by increasing the pH value, and after solar light irradiation in three days, the solar reactor system lead degradation of ammonia in pH=11–96.5%. The floating of photocatalyst can be reused at least three consecutive times with 14% decreases on the ammonia removal efficiency. The results suggest that the photocatalytic purification followed by solar photocatalytic reactor would be a promising method for the purification of chemical wastewater.

Photocatalytic degradation of ammonia by light expanded clay aggregate (LECA)-coating of TiO2 nanoparticles

Photocatalytic degradation of ammonia on supported TiO2 nanoparticles was investigated. The TiO2 nanoparticles used as photocatalyst were coated on light expanded clay aggregate granules (LECA), which is a porous and light weight support. Photocatalytic reaction activity of prepared catalyst was determined by ammonia degradation from water synthetically polluted with ammonia. Experiment results showed significantly high photocatalytic activity for the immobilized catalysts. The ammonia was removed more than 85% within 300 min of the process with optimum calcinations temperature 550 °C and pH 11. Kinetics of the photocatalytic reaction followed a pseudo-first order model. XRF, XRD and SEM analyses revealed a rather uniform coating of TiO2 on the support. By using floated TiO2/LECA as a photocatalyst in aqueous solution of NH 3 − , the ammonia was photodegraded into N2 and H2 gases, while NO 2 − and NO 3 − were formed at very low concentrations.

Photocatalytic degradation of ammonia and butyric acid in plug-flow reactor: Degradation kinetic modeling with contribution of mass transfer

Photocatalytic treatment of polluted air by odorous contaminants – ammonia and butyric acid – is investigated in a plug-flow reactor covered by non-woven fiber textile coated with TiO 2. For the first time, the single-component degradation pathway of ammonia by photocatalysis at ambient condition is highlighted. It appears fundamentally different compared to the butyric acid degradation pathway. The ammonia degradation pathway highlights a possible auto-accelerated behavior of the reaction. The chemical degradation kinetics follows the Langmuir–Hinshelwood model, though observed oxidation rates depend upon flow conditions in the reactor. Thus, interpretation of degradation results through a model considering the Langmuir–Hinshelwood approach and mass transfer phenomenon is presented. This model succeeds with a pair of determined kinetic constants and mass transfer coefficients to describe experimental results for different flow rates and for both pollutants, though they present wide dissimilarities in their degradation pathways.

Heterogeneous Photocatalytic Degradation Kinetic of Gaseous Ammonia Over Nano-TiO 2 Supported on Latex Paint Film

To investigate the photocatalytic degradation of gaseous ammonia in static state by using nano-TiO2 as photocatalyst supported on latex paint film under UV-irradiation. Experiments were conducted to study the relationship between the initial concentration of ammonia and the degradation products competing to be adsorbed on catalyst surface. Degradation of ammonia and its products were detected by spectrophotometry and catalytic kinetic spectrophotometry, respectively. On the one hand, TiO2 catalyst was excellent for degradation of ammonia, and the crystal phase of TiO2, anatase or rutile, had little effect on degradation of ammonia, but the conversion of ammonia grew with the increase of catalyst content. On the other hand, apparent rate constant and conversion of ammonia decreased with the increase of initial concentration of ammonia, and the photocatalytic degradation reaction followed a pseudo-first-order expression due to the evidence of linear correlation between -lnC/C0 vs. irradiation time t, but the relationship between initial concentration and the degradation products was not linear in low initial concentration. Whether the photocatalytic degradation of ammonia in static state follows a first-order reaction depends on the initial ammonia concentration due to competition in adsorption between reactant and the degradation products.

Photocatalytic degradation of ammonia with t102 as photocatalyst in the laboratory and under the use of solar radiation

A laboratory set-up for the photocatalytic degradation of NH 3/NH 4 + was designed. It includes a tube reactor (volume 12.3 ml) and a Xe-lamp (α > 300 nm) as irradiation source. Suspended TiO 2 powder was used as photocatalyst. For the on-line determination of NH 3 a gas-sensing probe was shown to be useful down to the lower mg/l level (detection limit: 2.2 10 −6 mol/l). After optimization a breakdown of NH 3/NH 4 + at the 5 10 −4 mol/l level for up to 70 % after 6 h if irradiation could be realized. The influence of the pH, the TiO 2 concentration, the temperature and the flow rate on the degradation of NH 3/NH 4 + was examined. The anionic degradation products, which were found to occur beside the N 2 itself, were determined by single column ion chromatography (SCIC). As a function of the pH and the concentration of TiO 2 variable concentrations of NO 2 − and N0 3 − were found (optimum: 9.9 % and 19.0 % of the decomposed NH 3/NH 4 + or 4.0 and 7.3 % of the NH 3/NH 4 + originally present). Experiments with solar radiation were carried out in a parabolic trough reactor at pilot plant-scale and were found to give degradation rates and reaction products similar to those obtained with the laboratory set-up.