Ozone Flow Research Articles

Mechanism and effect of magnetic biochar on the removal of norfloxacin from water by ozone peroxidation adsorption-coagulation process

Norfloxacin (NOR) is a widely used antibiotic, and its persistent residues in water have become a significant environmental concern. Due to its high concentration and persistence, NOR poses a threat to both the ecological environment and human health. Therefore, the development of effective water treatment technologies for removing NOR from water has become a critical issue. This study developed a novel adsorbent and integrated it with an ozone pre-oxidation-adsorption coagulation process to enhance the removal efficiency of NOR from turbid water. Adsorption experiments were conducted to investigate the effects of various conditions on the removal efficiency of NOR and to explore the underlying removal mechanisms. Additionally, the process parameters in the ozone pre-oxidation-mechanical stirring-clarifier sedimentation system were optimized. The results indicate that when the adsorbent dosage is 1 g/L and the pH is 7, the removal efficiency of NOR reaches 92.1 %. The primary adsorption mechanisms involved include hydrogen bonding, cation exchange, electrostatic attraction, intercalation, π-π interactions, and oxidation. Additionally, under conditions of 1 g/L adsorbent dosage, a 60-min reaction time, 20 mg/L PAC dosage, and a 0.1 m3/h ozone flow rate, the removal efficiencies of NOR and turbidity were 88.69 % and 81.55 %, respectively. In conclusion, the combination of ozone pre-oxidation and adsorption-coagulation technology proves to be an effective method for treating high-concentration antibiotic wastewater.

Simulation of Ozone Distribution in an Innovative Drying and Sanitising Cabinet Chamber

Common designs of workwear drying units require not only energy efficiency but also effective disinfection. One possibility of sanitising clothes during drying is to use the ozone generated inside the drying chamber. This process requires precise management of airflow and a uniform distribution of ozone in the chamber. Therefore, optimising the shape of the drying chamber must include not only the correct flow of drying air but also the correct distribution of ozone. This paper addresses the difficult problem of modelling the flow of sanitising ozone in an innovative drying chamber. The innovative shape of the chamber is shown in this article. Due to the low percentage of ozone in the air (up to 10 ppm), CFD simulation models of the usual mixture type are too inaccurate; therefore, special models have to be used. Therefore, this paper presents an experimentally verified methodology to simulate ozone flow in an innovative drying and sanitising cabinet using two methods: Discrete Phase Model (DPM) and Species Transport (ST). The DPM method uses a Euler–Lagrange approach to qualitatively assess the spread of ozone particles, treated with a description of the movement of the particles and not as a continuous gaseous substance. On the other hand, this already allows the verification of ozone concentrations, with an appropriate conversion of the measured quantities. The ANSYS/FLUENT 2023R1 program was used for the simulations after careful selection of the mesh, closing models, boundary conditions, etc. Simulations made it possible to analyse the distribution of ozone in the workspace and assess the effectiveness of the sanitisation process. The results of the simulations were verified on the basis of empirical tests, which showed the correctness of the model and the correct distribution of the sanitising ozone in the entire volume of the drying chamber in the innovative drying–sanitising chamber. The complete simulation of the air and ozone distribution using the presented models allowed for the optimisation of the opening and shapes, which contributed to improving the energy efficiency of the unit and increasing the efficiency of the sanitisation processes, making the described methodology very effective for optimising the chambers of various types of dryers.

The Degradation of Furfural from Petroleum Refinery Wastewater Employing a Packed Bubble Column Reactor Using O3 and a CuO Nanocatalyst

Furfural is one of the main pollutant materials in petroleum refinery wastewater. This work used an ozonized bubble column reactor to remove furfural from wastewater. The reactor applied two shapes of packing materials and two dosages of CuO nanocatalyst (0.05 and 0.1 ppm) to enhance the degradation process. The results indicated that adding 0.1 ppm of nanocatalyst provided an efficient rate of furfural degradation compared to that of 0.05 ppm. Also, the packing materials enhanced the furfural degradation significantly. As a result, the contact area between the gas and liquid phases increased, and a high furfural removal efficiency was achieved. It was found that the CuO nanocatalyst generated more (OH•) radicals. At a treatment time of 120 min and an ozone flow of 40 L/h, the furfural degradation recorded values of 80.66 and 78.6% at 10 and 20 ppm of initial concentration, respectively. At 60 ppm, the degradation efficiency did not exceed 74.16%. Furthermore, the kinetic study indicated that the first-order mechanism is more favorable than the second-order mechanism, representing the furfural degradation with a correlation factor of 0.9837. Finally, the furfural reaction can be achieved successfully in a shorter time and at low cost.

Preparation and performance of catalyst for organic peroxide wastewater treatment

To improve the oxidation pretreatment efficiency of wastewater from organic peroxides, a catalyst (CeO2-C catalyst) was developed using the calcination method with ceramic particles as the support. The crystalline structure and elemental composition of the CeO2-C catalyst were characterized by Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS), and X-ray diffraction (XRD). This study explored the effects of CeO2 mass ratio, calcination temperature, and calcination time on the performance of the catalyst. The optimal preparation conditions were established through orthogonal experiments. Additionally, the synergistic effect of the catalyst on the ozone oxidation treatment of peroxide wastewater was investigated. The results indicated that the optimal preparation parameters were a CeO2 mass ratio of 4 %, a calcination temperature of 500 °C, and a duration of 5 h, respectively. After five cycles of reuse, the catalytic activity slightly decreased but remained relatively stable. With an ozone flow rate of 6 L/min, the CeO2-C/ozone catalytic oxidation process achieved a Chemical Oxygen Demand (COD) removal rate of 28.11 % in wastewater, and the B/C (the ratio of BOD concentration to COD concentration) of wastewater improved from 0.093 to 0.152. The calcination method proved effective for preparing the CeO2-C catalyst, which demonstrated significant catalytic performance and held promising application prospects in the oxidation pretreatment of organic peroxide wastewater.

Synthesis and characterization of Bi2S3@NH2-MIL125(Ti) and survey the sono-catalytic ozonation process’s efficiency in the degradation of tocilizumab from aqueous

A Bi2S3@NH2-MIL125(Ti) core–shell nanocomposite was synthesized using a solvothermal method for the degradation of tocilizumab through a sono-catalytic ozonation process. The physicochemical properties of the catalyst were characterized using FESEM, EDS, TEM, XRD, FT-IR, DRS, BET, and XPS techniques. The optimum conditions were found to be as 0.75 g/L nanocatalyst, 10 mg/L tocilizumab, 5 L/hr ozone flow, 240 W ultrasonic power, and pH 9.0 over 15 min. Under these conditions, the process achieved approximately 100 % removal of tocilizumab, 86 % reduction in COD, and 76 % reduction in TOC, with only slight decreases in efficiency after five consecutive cycles. The degradation of tocilizumab was attributed to 38 % ozonation, 20 % sorption, and 15 % sonolysis. Methanol had the most significant impact on the process, while sodium azide had the least. The primary reactive species were identified as α-Hydrogen/OH radicals, with e−-h+ pairs playing a minor role. PO43− had the greatest impact on process efficiency, while SO42− had the least. The reaction followed a first-order kinetic model with an R2 value of 0.94. The synergistic effect coefficient of 1.88 indicated a significant synergistic impact from the combined ozonation and sonolysis processes. The energy efficiency (EE/O) of the sono-catalytic ozonation process was calculated to be 66.67 kW/h-m3-order.

Degradation and mineralization of atrazine by ozonation: A toxicological prediction by QSAR toolbox

This work aims to investigate the atrazine (ATZ) mitigation by an advanced oxidative process. Atrazine is one an effective herbicide which has been detected in water sources, causing contamination problems. To address the persistent issue of contamination, ATZ degradation and mineralization were studied by ozonation. In addition, the eco-toxicity of the possible degradation byproducts was also evaluated by the Quantitative Structure-Activity Relationship (QSAR) OECD toolbox. To evaluate the influence and predict the optimum conditions of the ozonation process and the reaction time on the degradation of ATZ, as well as, the percentage of mineralization, an experimental design was performed based on factorial design 23 methodology with center-point analysis. Total organic carbon (TOC) analyses and High-Performance Liquid Chromatography (HPLC) were employed to evaluate the efficiency of ATZ mitigation. The optimal conditions were achieved at an ozone flow rate of 0.4 mL/min, oxidation time = 30 min, and pH=8 where 100 % of ATZ was degraded and the highest percentage of mineralization was obtained (25.61 %). The potential toxicity of the residual concentration of ATZ was obtained by comparing with the values predicted by the QSAR tool, by comparing the outcomes. It was possible to come to the conclusion that the approach had positive implications for environmental safety. The values obtained are below the values considered toxic in aquatic environments, in almost all experiments. Low-concentration byproduct formation suggests that the degradation routes lead to low-hazardous concentrations of compounds for the environment. This implies the ozone treatment strategy might offer a long-term remedy for the ATZ.

Can ozone mass transfer in water treatment be enhanced through independent pressurized ozonation?

The dissolved ozone equilibrium concentration is hard to improve by increasing the gas phase partial pressure due to the low initial pressure and difficulty in pressurization. In this study, a novel hydraulic pressurization technology was developed to reliably elevate the ozonation pressure and improve the solubility of ozone. It was located downstream of the ozone generator to avoid generator overpressure. Specifically, at the optimal pressure of 0.30 MPa with an initial ozone flow rate of 1–6 L min−1, the specific surface area of bubbles and turbulent dissipation rate in the ozonation reactor were up to 2.5- and 1.5-fold that of the atmospheric aeration. Meanwhile, the dissolved ozone equilibrium concentration, redox potential, and volumetric mass transfer coefficient were up to 2.4-, 1.6-, and 2.7-fold that of atmospheric aeration, respectively. The increase in bubble-specific surface area and turbulent dissipation rate, synergistically enhanced the mass transfer, contributing 83.2–94.4 % and 5.6–16.8 %, respectively. As the reactor pressure was increased from 0 to 0.30 MPa, the decolorization time of Acid Red 18 was shortened from 20 to 8 min, and the COD removal rate increased from 48.0 % to 85.0 %. This work provides an alternative approach coupled with a novel device that enhances the ozone mass transfer during water treatment.

Characterization of the ozone effect on a scraped off fouling sample

Fouling deposition on combustion system elements is a problem of interest to the industry. This experimental work analyzes the degradation of fouling using ozone as oxidizing agent. Two independent test benches were used for the experiments, a fouling test bench and an ozone test bench. The fouling generation tests are performed under controlled conditions to obtain characterized fouling. The ozone tests performed are divided into three groups: pre-tests, A-tests and B-tests. The pre-tests were used to determine the effect of different variables affecting the oxidation process. The A, B-tests were performed to characterize the oxidation process under different scenarios. During the ozone treatment tests, flow rate, ozone concentration, temperature and duration of the test were controlled to obtain the fouling mass loss measurement. Finally, an analytical expression was obtained that characterizes the sample mass variation as a function of the input variables, maximizing the reaction between the fouling and ozone.

Advanced oxidation of Arsenic(III) to Arsenic(V) using ozone nanobubbles under high salinity

Arsenic, a highly toxic element, is present in various water resources as As(III) and/or As(V). The removal of As(V) using adsorption is considered to be easier than the removal of As(III). In this work, we report the oxidation of As(III) to As(V) using ozone nanobubbles. Ozone has been widely used in the advanced oxidation process (AOP) to remove organics and inorganics in wastewater. The major advantage of ozone nanobubbles is their enhanced half-life, which leads to higher ozone solubility in water. In addition, the rate of mass transfer by using nanobubbles can be enhanced drastically. The effect of ozone flow rates, initial As(III) concentrations, pH levels, and the presence of salt is systematically studied in this work. The present results revealed that ozone nanobubbles positively impacted the oxidation of As(III) to As(V). AOP process based on O3 NBs (nanobubbles) was most efficient with 99 % oxidation rates of 1 ppm of As(III) within 20 minutes at 6.5 ppm ozone concentrations. An acidic pH of 3–7 promoted quick oxidation due to the high mass transfer coefficient of ozone nanobubbles. About ∼70 % degradation of As(III) to As(V) was achieved with 0.10854 min-1 rate constant at acidic (pH = 3) compared to ∼39 % degradation with 0.046 min-1 rate constant at pH =11. The presence of salt (∼50 mM) in the solution not only hindered the ozone mass transfer coefficient but also reduced the stability of nanobubbles. The detection of reactive oxygen species, particularly hydroxyl radical was unravelled by utilizing 2-propanol as a scavenger.

Methylene blue (MB) removal from aqueous solution by alum; catalytic ozonation process

Textile wastewater is among the most polluted types of industrial waste. Wastewater treatment in the textile industry is notoriously difficult because of the use of complex chemicals and dyes in the textile production steps, and conventional methods are not enough to treat these. Textile wastewater, known for its high pollution levels, poses challenges for treatment due to complex chemicals and dyes. A comparative study was conducted on simple ozonation and catalytic ozonation (CO) using alum to degrade methylene blue (MB). The authors analyzed various factors like time, pH, catalyst loading and ozone dosages during the study. Results showed that catalytic activity in ozonation depends on pH and ozone flow. The maximum MB elimination was achieved at pH 6.6 and 200 V ozone flow. Scanning electron microscopy (SEM) was used to characterize the surface morphology of the catalyst, Fourier transform infrared spectroscopy (FTIR) was used to identify the important functional groups, and energy dispersive X-ray spectroscopy (EDS) was used to characterize the catalyst's elemental composition. Compared to simple ozonation, CO showed higher removal in the initial phase. Real textile wastewater analysis confirmed the effectiveness of alum catalysts in achieving significant removal of MB (87%) through this novel cost-efficient process.Graphical

Low temperature (002)-oriented zinc oxide films prepared using ozone-based spatial atomic layer deposition

In this study, ZnO films are prepared at a low temperature of 150 °C by using spatial atomic layer deposition (sALD) with diethylzinc and ozone as precursor and oxidant. The ozone flow rate is varied to systematically investigate its effect on optical, structural and electrical properties. The experimental results show that the self-limiting surface reactions can occur at the low ozone flow rate of 200 sccm, confirming ALD growth mode. All the ozone flow rates lead to ZnO (002) crystalline orientation, which is difficult to be obtained for conventional water-based ALD ZnO films at the low temperature. The increased ozone flow rate results in an increased amount of oxygen vacancies, enhanced carrier concentration and a reduced stress. The resistivity and carrier concentration can be tuned in the range of 4.75–0.08 Ω-cm and (1.1–5.5) × 1018 cm−3. Finally, the sALD ZnO film on polyethylene terephthalate reveals a high stability in the film property against bending. This study is beneficial for the utilization of ZnO films in optoelectronic devices that demand the (002) preferred orientation, especially under low-temperature conditions.

Comparative analysis of installations for heat treatment of non-food pulp raw materials by the influence of electrophysical factors

Relevance. The objectives of the work are to develop radio-hermetic installations and substantiate the effective design of the working chamber, which provides a comprehensive effect of electrophysical factors on non-food pulp raw materials to preserve feed value at reduced operating costs. Scientific tasks: 1) to develop installations with different designs of resonators; 2) to conduct a comparative analysis of the working chambers according to the main parameters; 3) to evaluate the technical and economic indicators of an effective installation in relation to the basic version.Methods. The effect of electrophysical factors on raw materials is realized in resonators with magnetrons and frequency generators of pulse-modeled high-frequency oscillations of 110 kHz, where a bactericidal flux lamp serves as a high-potential electrode.Results. Several continuous-flow radiohermetic installations with ultrahigh-frequency (microwave) power supply to non-standard resonators have been developed, inside which a complex effect of a high-intensity electric field, a bactericidal flow of UV rays and ozone is realized to reduce bacterial contamination of the product and neutralize odor during heat treatment of raw materials, the dimensions of which are consistent with the depth of penetration of the wave. Features of conical and biconic resonators − provide radio leakage in continuous operation by cutting off the tip at the level of the critical section, depending on the angle of inclination of the cone generator, and allow you to keep the standing wave inside the resonator. The combination of magnetron and cylindrical resonators increases the efficiency of the interaction of the electron flux with the microwave field, and an increase in the inductive volume, which is a “reservoir” of energy, increases the intrinsic quality of the resonator. A quasi-toroidal resonator, presented as a conical resonator in a toroidal resonator, having small overall dimensions and metal consumption, provides a traveling wave in the annular space, and a standing wave in the conical space. The high electric field strength in the capacitor part of the resonator and the corona discharge in the torus contribute to the disinfection of raw materials.

Microwave device for heat treatment of meat by-products and waste

BACKGROUND: In the conditions of farms, there is a problem of neutralizing unpleasant odors during heat treatment of secondary meat raw materials to preserve the consumer properties of protein feed at low operating costs. AIM: Development of the device for heat treatment with disinfection and neutralization of the unpleasant odor of crushed secondary meat raw materials with the integral effect of an ultra−high frequency electromagnetic field, a bactericidal flow of UV rays and ozone in a continuous mode with electromagnetic safety ensured. METHODS: The raw materials are the stomach chambers of ruminants. The basic idea, principle of operation and design of the device are based on the propagation of microwave oscillations in a resonator with a spiral decelerating system. The microwave device contains a non-ferromagnetic cylinder with a perforated lower base, a coaxially arranged non-ferromagnetic spiral cylinder and an electrically driven fluoroplastic auger with a solid screw surface. The average perimeter of the annular volume, between the cylinder and the spiral cylinder forming the coaxial resonator, and its height are multiples of half-wavelength. Corona brushes are mounted to the annular base of the cylinder, under which electric gas discharge lamps powered by 1 kHz frequency generators are radially located, and a ceramic annular spherical surface is located under the lamps. Magnetrons are mounted along the perimeter of the outer cylinder with a shift of 120 degrees. The crackling is removed using a pneumatic conveyor. RESULTS: The feature of the coaxial resonator is that the inner core is formed as a spiral decelerating system. Therefore, the intrinsic Q-factor of the resonator is high, about 115000, therefore, the expected thermal efficiency is 0.7–0.75. The factor of dielectric losses of raw materials with a decrease in humidity from 76% to 30% is reduced by five times. Thus, while keeping the electric stress at the level of 1.2–2 kV/cm, the electromagnetic field power dissipated in a unit of the volume of the crackling decreases by five times, from 34 500 to 6800 W/cm3. CONCLUSIONS: A new design solution with a spiral coaxial resonator, the use of a ceramic reflector, and a number of physical factors made it possible to develop the design of the operation chamber for the heat treatment of ruminant slaughter waste with the neutralization of unpleasant odors with a capacity of 30–35 kg/h and specific energy costs of 0.16–0.19 kWh/kg.

A New Sight of Ozone Usage in Textile: Improving Flame Retardant Properties.

Ozone, widely recognized as an environmentally friendly gas, is extensively used in various textile industry applications. These include pre-treatment processes like bleaching and desizing, as well as creating pattern and vintage effects, wastewater clarification, and surface modification. This study focuses on ozone as a novel solution to a specific challenge: addressing the reduction in flame retardancy properties experienced by flame-retardant (FR) polyester fabrics during post-treatment processes in the production line. Experimentation involved subjecting the fabrics to ozonation and exploring different combinations of ozone flow rates and treatment durations. Mechanical and functional properties of the fabrics were examined, with flammability tested according to International Maritime Organization (IMO) standards. Notably, treatment with a 5 L/min ozone flow rate, a 7.01 g/h ozone concentration ratio, and a duration of 10 min showed significant improvements in IMO values, ensuring compliance with required standards. Furthermore, treated samples underwent comprehensive tests for fastness and strength, yielding results within acceptable ranges. Fourier-transform infrared (FT-IR) and thermogravimetric analysis (TGA) measurements were conducted to evaluate the impact of ozonation. FT-IR results indicated that the presence of C-H groups associated with dyestuff contributed to decreased flame retardancy in the original fabric post-dyeing. However, these groups were effectively eliminated through ozonation, thereby enhancing the fabric's flame retardancy.

Modeling of tubular membrane contactors for ozonation of water reveals reduced bromate formation with static mixers

Bromate formation and insufficient micropollutant degradation are two major problems in wastewater ozonation. The conventional process using bubble columns has the drawback of an inhomogeneous ozone distribution, causing increased bromate formation. Membrane contactors are a promising alternative as they can dissolve ozone bubble-free. This work presents a simulation of a tubular membrane contactor in COMSOL Multiphysics that includes flow, mass transfer, ozone decay, and reactions of organic molecules and bromide with ozone and hydroxyl radicals. Gaseous ozone and water flow on the lumen and shell side of the membrane, respectively. Static mixers are placed in the water channel, coaxial between the membrane and housing. The simulations show a 75% increase in ozone flux through the membrane, a homogenized ozone distribution, and 13 times higher degradation of a medium-oxidizable micropollutant in the presence of additional static mixers. Furthermore, static mixers enable the use of a lower gaseous ozone concentration, resulting in 31% lower bromate formation at the same ozone exposure without affecting micropollutant degradation. Overall, we demonstrate that membrane contactors with static mixers can be used as a strategy to reduce bromate formation.

Efficient treatment of veterinary pharmaceutical industrial wastewater by catalytic ozonation process: degradation of enrofloxacin via molecular ozone reactions.

The study focused on the efficacious performance of bimetallic Fe-Zn loaded 3A zeolite in catalytic ozonation for the degradation of highly toxic veterinary antibiotic enrofloxacin in wastewater of the pharmaceutical industry. Batch experiments were conducted in a glass reactor containing a submerged pump holding catalyst pellets at suction. The submerged pump provided the agitation and recirculation across the solution for effective contact with the catalyst. The effect of ozone flow (0.8-1.55mg/min) and catalyst dose (5-15g/L) on the enrofloxacin degradation and removal of other conventional pollutants COD, BOD5, turbidity was studied. In batch experiments, 10g of Fe-Zn 3A zeolite efficiently removed 92% of enrofloxacin, 77% of COD, 69% BOD5, and 61% turbidity in 1L sample of pharmaceutical wastewater in 30min at 1.1mg/min of O3 flow. The catalytic performance of Fe-Zn 3A zeolite notably exceeded the removal efficiencies of 52%, 51%, 52%, and 59% for enrofloxacin, COD, BOD5, and turbidity, respectively, achieved with single ozonation process. Furthermore, an increase in the biodegradability of treated pharmaceutical industrial wastewater was observed and made biodegradable easily for subsequent treatment.

Enhancing the quality attributes of mint medicinal plant (Mentha spicata L.) through simultaneous combined ozone and infrared drying

AbstractMedicinal plants are widely used in various traditional and modern medical methods due to their therapeutic properties. Drying is a common method used to preserve the biochemical compounds of medicinal plants. Still, conventional drying methods can lead to the loss of active compounds due to exposure to high temperatures. This research aimed to design and construct an ozone generator for use in a combined dryer and evaluate the ozone, temperature, and hot air flow rate on the quality properties of mint (Mentha spicata L.). Drying experiments were conducted at varying temperatures, air flow speeds, and ozone levels. Results indicated that increasing temperature reduced total phenol and flavonoid content while increasing antioxidant capacity. Higher airflow speed positively influenced total phenol, total flavonoid content and antioxidant potency but reduced drying time. Ozone exposure increased total phenol, flavonoid content, antioxidant activity, and had minimal effect on drying time. Optimization revealed that a temperature of 52.47°C, air flow rate of 1.5 m/s, and 90.37% ozone concentration yielded favorable outcomes, including enhanced phenolic and flavonoid content, antioxidant power, and decreased energy consumption. Compared to other drying methods, the proposed ozone‐enhanced method proved superior in preserving bioactive compounds and maintaining a reasonable drying time. Overall, the research highlights the potential of ozone‐assisted drying for optimizing the quality of medicinal plants during preservation.Practical ApplicationThe paper introduces a novel and efficient method for preserving the quality of medicinal mint. By concurrently applying ozone and infrared drying techniques, this approach aims to capitalize on their synergistic effects in maintaining the plant's beneficial compounds. Ozone acts as a natural antimicrobial agent, preserving the plant's integrity, while infrared drying expedites the process without compromising the phytochemical profile. This innovative method not only ensures microbial safety and extended shelf life but also enhances the mint's aroma, flavor, and nutrient retention. The practical application of this combined technique holds promise for pharmaceutical and herbal industries, providing a valuable approach for optimizing the drying process and preserving the medicinal attributes of Mentha spicata L.

Combined electrolytic iron dissolution and ozonation process for arsenic removal from water

In some regions, underground water contains dissolved arsenic and this is a health risk for the population. In this work, arsenic was reduced to acceptable levels. Water from Zacatecas, Mexico, containing 1.58, 1.72 and 2.03 mg/L of As, Fe and Mn respectively, and pH 2.0, was treated with Fe from electrolytic dissolution, then with a mixture of ozone and air. The parameters considered during the treatment were agitation rate, ozone flux, pH, temperature, and dissolution time of iron. The concentration of As was reduced by co-precipitation with Fe from the electrolytic dissolution and by co-precipitation with Mn contained in the water when ozone was injected. The results indicated that the co-precipitation reactions depended on the mass transport. The ozone oxidizes the Mn in two steps (pH 2): firstly, the Mn (II) is oxidized to Mn (IV) and precipitated and secondly, the precipitated Mn (IV) is oxidized and dissolved as Mn (VII). Arsenic co-precipitated in the first Mn oxidation step, and then it turned into a solution together with the Mn at high flow of ozone. The residual concentrations of Fe, Mn and As in the water at pH 7 are 0.014, 0.07 and 0.00512 mg/L, respectively.

Treatment of oil-based drilling cuttings by floatation-advanced oxidation two-step process.

In this paper, a floatation-advanced oxidation two-step process was proposed for deep oil removal of oil-based drilling cuttings (OBDC). In the first stage, a novel and simple degreasing solution was prepared and most of the base oil contained by OBDC was removed by flotation; in the second stage, the oil content of OBDC was further reduced by combined ultrasound + ozone (US + O3) advanced oxidation. The recommended degreasing solution was a mixture of methanol, ammonium chloride, and water with a mass ratio of 1.48.1 : 0.25. The best flotation process was as follows: a mass ratio of OBDC to degreasing solution of 1 : 10, stirring speed of 400 rpm and N2 flotation with a flow rate of 400 mL min-1 for 60 min. The oil content of OBDC can be reduced from 14.57% to 1.42% after flotation treatment and the degreasing solution can be reused more than five times. The optimal process of US + O3 advanced oxidation was as follows: a mass ratio of OBDC to water of 1 : 10, ultrasonic power of 1000 W, and an ozone flow rate of 4.0 L min-1 for 100 min. The oil content of OBDC can be reduced from 1.42% to 0.14% after US + O3 treatment at room temperature. The results of this paper provide a new method and idea for OBDC treatment.

Kinetics of catalytic ozonation of methylene blue in wastewater with Fe/Ce co-doped in attapulgite

In this study, the attapulgite (ATP) was modified by Fe and Ce with the method of impregnation-roasting, and the degradation of Methylene Blue (MB) in the presence of ozone was investigated. The results showed that the degradation rate of 80 mg/L MB wastewater could reach about 94%, when the ozone flow rate is 250 mL/min, the reaction temperature is 35 ℃, the catalyst is 0.4 g, and the initial pH of the solution is 7. The characterization results of the modified ATP showed that the Fe3+ and Ce4+ had been successfully loaded on the gravimetric clay. Finally, the degradation mechanism of MB was speculated, and the reaction kinetic equation was obtained. The model fit and reliability are good.