BiOI Microspheres Research Articles

A visual biosensor chip based on the enhanced electrochemiluminescence with low triggered potential for ochratoxin A detection

The introduction of a coreaction accelerator can effectively enhance the electrochemiluminescence (ECL) response. However, the development of coreaction accelerators for ruthenium (Ru) complex, one of the most widely used ECL emitters, is still in its early stages. In this study, the application of BiOI as a multifunctional coreaction accelerator for the Ru/N-Butyldiethanolamine (DBAE) system for the first time. The BiOI microspheres not only exhibit a fivefold enhancement in ECL signal but also reduce the trigger potential, potentially mitigating interference factors associated with high applied voltage. The nanoflower structure of BiOI microspheres also facilitates the immobilization of Ru(bpy)32+. Building upon this, a portable visual biosensor chip was developed for the detection of ochratoxin A (OTA). The biosensor chip comprises a sensing cell and a reporting cell. When OTA toxins are detected in the microenvironment, the aptamers attached to the surface of the sensing cell are released, resulting in a decrease in impedance on the electrode surface. Consequently, the ECL emission from Ru(bpy)32+/BiOI microspheres modified onto the reporting cell is enhanced. The concentration of OTA can be determined by analyzing the intensity change of ECL imaging, eliminating the need for specific instruments. This visual ECL biosensor chip offers the advantages of portability, ease of operation, low cost, and demonstrates excellent performance in detecting beer samples.

Bi2O3 microspheres combined electron-deficient B-reduced graphene oxide as functional electrocatalyst for effective synthesis urea from N2 and CO2

Electrochemical synthesis urea, which couples N2 and CO2, is seen as a potential promising and sustainable alternative to traditional harsh industrial process. However, the significance of the rational design electrocatalyst has been enthused due to the hard activation of N≡N, the prevalence of sub-reactions, and the low current density. Herein, an electrocatalyst, Bi2O3/B-reduced graphene oxide (RGO) was prepared for synthesis urea with a Faraday efficiency (FE) of 12.8 %, urea yield of 9.2 mmol g−1h−1 and urea current density 0.47 mA cm−2 at −0.8 V, while maintaining long-term stability. The Bi2O3/B-RGO possess a unique porous structure with continuous micron pores that facilitated the rapid mass transfer, improved kinetic efficiency and enlarged electroactive sites, which together improve the urea synthesis performance. Interestingly, the Bi2O3/B-RGO electrocatalyst is not only have excellent electrochemical properties, but also favours the adsorption and activation of reactants (N2 and CO2) due to the B-RGO (Lewis acid) and the Bi2O3 (Lewis base). This work may provide new insights into the exploration of advanced catalysts for electrochemical urea synthesis and other sustainable applications.

A novel photoelectrochemical aptasensor based on 3D flower-like g-C3N4/BiOI p-n heterojunction for the sensitive detection of kanamycin

BackgroundKanamycin (KAN) residues in animal-derived foods continuously enter the human body, which will pose serious threats to human health such as hearing loss, nephrotoxicity and other complications. Therefore, to sensitively detect KAN residues by a reliable technology is extremely urgent in food quality and safety. Compared with traditional methods being limited by cost and complexity, photoelectrochemical (PEC) biosensors benefit from some merits such as rapid response, excellent sensitivity and good stability. In this study, the construction of a highly efficient PEC platform to realize KAN residues detection is discussed. ResultsHerein, a novel p-n heterojunction consisting of flower-like BiOI microspheres and graphite carbon nitride (g-C3N4) nanoflakes was developed to establish a PEC aptasensor for KAN detection at 0 V. The prepared g-C3N4/BiOI heterostructure showed not only significantly enhanced PEC activity due to the larger specific surface area but also greatly increased charge separation efficiency owing to the strong internal electric field. Meanwhile, using g-C3N4/BiOI as a highly efficient photoactive material for binding amine-functionalized aptamers to capture KAN, the photocurrent signals showed a ‘turn off’ mode to achieve the sensitive detection of KAN. The proposed PEC aptasensor exhibited linear response for KAN from 5 × 10−9 to 3 × 10−7 mol L−1 with a low detection limit of 1.31 × 10−9 mol L−1, and satisfactory recoveries (97.44–107.38 %) were obtained in real food samples analysis. SignificanceThis work presented a novel p-n heterojunction-based PEC aptasensor with strong selectivity and stability, rendering it allowed to detect KAN in animal-derived foods including milk, honey and pork. Additionally, the detection range satisfied the MRLs for KAN specified by the national standards, demonstrating the potential application for food analysis. The study provides a new insight into the development of efficient and practical biosensors for antibiotic residues detection.

Photoelectrochemical sensing of isoniazid and streptomycin based on metal Bi-doped BiOI microspheres grown on book-shape layers of Ti3C2 heterostructures.

Isoniazid and streptomycin are vital drugs for treating tuberculosis, which are utilized as efficient anti-tuberculosis agents. This paper presentsa novel visible-light-driven composite photocatalyst Ti3C2/Bi/BiOI, which was built from Ti3C2 nanosheets and Bi/BiOI microspheres. Photoelectrochemical (PEC) sensors based on Ti3C2/Bi/BiOI were synthesized for isoniazid identification, which showed a linear concentration range of 0.1-125 μM with a detection limit of 0.05 μM (S/N = 3). Moreover, we designed a PEC aptasensors based on aptamer/Ti3C2/Bi/BiOI to detect streptomycin in 0.1 M PBS covering the electron donor isoniazid, because the isoniazid consumes photogenerated holes thus increasing the photocurrent effectively and preventing photogenerated electron-hole pairs from being recombined. Furthermore, PEC aptasensors based on aptamer/Ti3C2/Bi/BiOI were synthesized for streptomycin identification, which exhibited a linear concentration range of 0.01-1000 nM with a detection limit of 2.3 × 10-3 nM (S/N = 3), and are well stable in streptomycin sensing.

Micro-Spherical BiOI Photocatalysts for Efficient Degradation of Residual Xanthate and Gaseous Nitric Oxide.

BiOI microspheres were synthesized using the solvothermal method for the degradation of residual xanthate and gaseous nitric oxide (NO) under visible light irradiation. The as-prepared BiOI nanomaterials were then characterized using various technologies, including XRD, FE-SEM, TEM, UV-Vis DRS, and XPS. The photodegradation results show that the removal efficiency of isobutyl sodium xanthate can reach 98.08% at an initial xanthate concentration of 120 mg/L; that of NO is as high as 96.36% at an inlet NO concentration of 11 ppm. Moreover, the effects of operational parameters such as catalyst dosage, initial xanthate concentration, and pH value of wastewater on the removal of xanthate were investigated. The results of scavenging tests and full-spectrum scanning indicate that ·O2- radicals are the main active species in xanthate degradation, and peroxide xanthate is an intermediate. The reusability of BiOI was explored through cyclic experiments. Furthermore, the reaction path and the mechanism of NO removal using BiOI were analyzed, and the main active species was also ·O2-. It is concluded that BiOI photocatalysts have high potential for wastewater treatment and waste gas clean-up in the mineral industry.

Characterization and photocatalytic properties of porous ZrO2/Al2O3 ceramic bead supported BiOI catalyst

Porous ZrO2/Al2O3 ceramic bead carriers were prepared through the gel-dripping method using sodium alginate as gelling agent with sucrose as pore-forming agent. The BiOI photocatalyst was loaded on the porous ceramic bead carrier with the solvothermal method. The effects of sucrose content and sintering temperature on the pore structure, porosity and compressive strength of the carriers were investigated. The influences of reaction time and reaction temperature on the microstructure and visible light photocatalytic properties of supported BiOI catalyst were also studied. The results show that, the porous ceramic bead with 30 wt% sucrose content sintered at 1300 °C exhibits a porosity of 71.60 % and a compressive strength of 5.06 MPa, which is suitable for the catalyst carrier. BiOI nanosheets assemble into microspheres with bonding force in the supported BiOI catalyst. BiOI microspheres distribute on the surface or in the pores of carriers. The supported BiOI catalyst prepared at 160 °C soaking for 6 h exhibits the highest degradation rate of 98.5 %. The microsphere diameter, loading amount, and photocatalytic activity of supported BiOI can be regulated through optimizing the reaction time and reaction temperature of solvothermal method. Compared with BiOI powder, the supported BiOI catalyst is easily recycled.

Tapping the Tunisian sunlight's potential to remove pharmaceuticals in tap water and secondary effluents: A comparison of Ag2O/TiO2 and BiOI photocatalysts and toxicological insights

In this study, BiOI microspheres and the Ag2O/TiO2 heterostructure were synthesized to photocatalytically degrade atenolol (ATL) and carbamazepine (CBZ) in tap water and secondary effluent under Tunisian summer season sunlight. The materials were characterized through XRD, SEM, TEM and DRS. The Ag2O/TiO2 material excelled by completely removing both pharmaceuticals from tap water within 180 min of irradiation, while less than 20 % of CBZ persisted in effluent after 3 h of irradiation. Stability tests using the Ag2O/TiO2 heterostructure over five reaction cycles indicated consistent degradation rates for ATL (k ranged from 3.1 × 10-2 to 5.9 × 10-2 min−1). Conversely, CBZ degradation rates increased from k = 6.4 × 10-3 min−1 to k = 1.8 × 10-2 min−1 in the fifth cycle. This increase was attributed to changes in the oxidation state of silver nanoparticles deposited on TiO2. Quenching tests identified OH radicals as dominant in photocatalytic degradation, followed by photo-holes for CBZ, and O2− radicals for ATL. Through LC-MS/MS, degradation byproducts were identified, allowing for proposed degradation kinetics. Lastly, the toxicity of the byproducts was estimated using the ECOSAR model, displaying a decrease in the toxicity of hydroxylated intermediates, while aminated species represented higher potential for acute and chronic toxicity.

Preparation of 3D BiOI microspheres for highly efficient visible light-induced photocatalytic degradation of tetracycline

Semiconductor photocatalysts for pharmaceutical antibiotic wastewater treatment are subject to increasing attention. Herein, BiOI photocatalysts were prepared by a one-step solvothermal method using ethylene glycol (EG) as solvent and their tetracycline (TC) degradation activities under visible light irradiation were compared. Catalyst preparation temperature, time, and pH conditions were optimized, and the catalyst physicochemical properties were characterized. Solution pH was found to have a significant effect on the morphology, electronic structure, and surface exposed facet of BiOI. Catalysts synthesized in the absence of NaOH presented more regular 3D flower-like microspheres, possessed larger surface area, were composed of many small nanosheets predominantly exposing the (001) facet, and showed better photogenerated electron-hole pairs separation efficiency. The optimized BiOI presents superior TC degradation efficiency (73.6%) under visible light irradiation, and recycling experiments indicated that the catalysts have good stability and reusability. The active species were investigated by free radical trapping experiments, revealing that •O2− plays a major role in the photodegradation process. Possible TC degradation pathways are proposed according to mass spectrometry analysis.

Facile construction of Z-scheme g-C3N4/BiOI heterojunction for improving degradation of tetracycline antibiotics

Tubular g-C3N4 derived from melamine and trithiocyanuric acid was coupled with flower-like BiOI microspheres to form Z-scheme heterojunction photocatalyst for efficient photocatalytic degradation of tetracycline (TC). The structure, morphology, and optical properties of the prepared g-C3N4/BiOI were characterized. When the mass fractions of g-C3N4 in the composites was 5 wt%, g-C3N4/BiOI exhibited the highest removal efficiency of 84.2 % within 60 min. The enhanced photocatalytic performance of g-C3N4/BiOI could be ascribed to stronger absorption in the visible region and faster charge transfer rate. Trapping experiments revealed that h+ and ·O2− radicals were the main active species. Based on the band structure and trapping experiments, the Z-scheme pathway was proposed to clarify the photocatalytic mechanism.

Achieving high energy density in supercapattery by employing CuFe2O4 microsheets and Bi2O3 microspheres

In this work, we report a high energy density supercapattery device were employing hydrothermally synthesized two-dimensional CuFe2O4 microsheets as cathode and synthesized redox-active Bi2O3 microsphere as the anode. The charge storage characteristics of the electrode materials were detailed studied. Herein, the 2D-CuFe2O4 microsheet-based positive electrode showed an enhanced areal capacitance and cyclic stability of 1279 mF cm−2 and 98% after 5000 GCD cycles, respectively. Moreover, Bi2O3 microspheres electrode material delivered a favourable capacitance of 1368.25 mF cm−2 and noticeable cyclic stability of 81% even after 3000 GCD counts. Both the positive and negative electrodes showed excellent electrochemical performance owing to their vast electrochemical active sites, which induce fast electron/ion transportation. Furthermore, a supercapattery device was assembled employing CuFe2O4/Ni-foam as cathode and Bi2O3/Ni-foam as anode for evaluating its real-time performance. This supercapattery device delivers a high energy density and power density of 67.55 µ Wh cm−2 and 3200 µ W cm−2, respectively, in the optimal 1.6 V cell voltage. Moreover, the device showed a good cycling stability value of 87.4% with noticeable coulombic efficiency of 99.2% with the 10,000 cycles. These electrochemical results suggest that the assembled device was esteemed the highly beneficial energy storage system.

Upgrading CO2 into acetate on Bi2O3@carbon felt integrated electrode via coupling electrocatalysis with microbial synthesis

AbstractUpgrading of atmospheric CO2 into high‐value‐added acetate using renewable electricity via electrocatalysis solely remains a great challenge. Here, inspired by microbial synthesis via biocatalysts, we present a coupled system to produce acetate from CO2 by bridging inorganic electrocatalysis with microbial synthesis through formate intermediates. A 3D Bi2O3@CF integrated electrode with an ice‐sugar gourd shape was fabricated via a straightforward hydrothermal synthesis strategy, wherein Bi2O3 microspheres were decorated on carbon fibers. This ice‐sugar gourd‐shaped architecture endows electrodes with multiple structural advantages, including synergistic contribution, high mass transport capability, high structural stability, and large surface area. Consequently, the resultant Bi2O3@CF exhibited a maximum Faradic efficiency of 92.4% at −1.23 V versus Ag/AgCl for formate generation in 0.5 M KHCO3, exceeding that of Bi2O3/CF prepared using a conventional electrode preparation strategy. Benefiting from the high formate selectivity, unique architecture, and good biocompatibility, the Bi2O3@CF electrode attached with enriched CO2‐fixing electroautotrophs served as a biocathode. As a result, a considerable acetate yield rate of 0.269 ± 0.009 g L−1 day−1 (a total acetate yield of 3.77 ± 0.12 g L−1 during 14‐day operation) was achieved in the electrochemical–microbial system equipped with Bi2O3@CF.

S-scheme tubular g-C3N4/BiOI heterojunctions for boosting photodegradation of tetracycline and Cr(VI): Mechanism insight, degradation pathway and DFT calculation

A unique tubular g-C3N4 (TCN)/BiOI S-scheme heterojunction with BiOI microspheres grown on the surface of 1D TCN was successfully prepared by hydrothermal treatment and calcination. Herein, adjusting BiOI additive amount can effectively tune electronic band structures and photocatalytic properties of TCN/BiOI heterojunctions. Impressively, the TCN/BiOI composite (CB-2) with a TCN: Bi3+ molar ratio of 1:2 shows the best photocatalytic performance, where the photodegradation efficiencies for tetracycline (TC) and Cr(VI) ions can both achieve more than 77 % and 90 % within 10 and 30 min, respectively. Particularly, the photodegradation efficiencies for TC and Cr(VI) reach up to 90.1 % and 96.8 % at 30 and 40 min, respectively. Notably, the rate constants for photodegradation of TC and Cr(VI) reach 0.1687 and 0.0718 min−1, which are 27.2 and 8.5 times higher than those of bulk g-C3N4, respectively. The distinguished photocatalytic performance of CB-2 is attributed to the high-quality electron transport channels provided by its tubular structure and the effective separation of photogenerated carriers based on the S-scheme heterojunction. Further, O2−, 1O2 and h+ are manifested to be the main active species for the photodegradation of TC. DFT calculations and radical-related experiments fully confirm the formation of S-scheme heterojunctions. Several crucial factors (such as pH, inorganic salts) for wastewater purification are verified to be little effect on the photocatalytic performance. The degradation pathways of TC are proposed. This work establishes a new route to design and prepare high-efficiency S-scheme photocatalysts for the photodegradation of antibiotics and the photoreduction of heavy metal ions in wastewater.

Novel Ag-bridged dual Z-scheme g-C3N4/BiOI/AgI plasmonic heterojunction: Exceptional photocatalytic activity towards tetracycline and the mechanism insight

Rational design and synthesis of highly efficient and robust photocatalysts with positive exciton splitting and interfacial charge transfer for environmental applications is critical. Herein, aiming at overcoming the common shortcomings of traditional photocatalysts such as weak photoresponsivity, rapid combination of photo-generated carriers and unstable structure, a novel Ag-bridged dual Z-scheme g-C3N4/BiOI/AgI plasmonic heterojunction was successfully synthesized using a facile method. Results showed that Ag-AgI nanoparticles and three-dimensional (3D) BiOI microspheres were decorated highly uniformly on the 3D porous g-C3N4 nanosheet, resulting in a higher specific surface area and abundant active sites. The optimized 3D porous dual Z-scheme g-C3N4/BiOI/Ag-AgI manifested exceptional photocatalytic degradation efficiency of tetracycline (TC) in water with approximately 91.8% degradation efficiency within 165 min, outperforming majority of the reported g-C3N4-based photocatalysts. Moreover, g-C3N4/BiOI/Ag-AgI exhibited good stability in terms of activity and structure. In-depth radical scavenging and electron paramagnetic resonance (EPR) analyses confirmed the relative contributions of various scavengers. Mechanism analysis indicated that the improved photocatalytic performance and stability were ascribed to the highly ordered 3D porous framework, fast electron transfer of dual Z-scheme heterojunction, desirable photocatalytic performance of BiOI/AgI and synergistic effect of Ag plasmas. Therefore, the 3D porous Z-scheme g-C3N4/BiOI/Ag-AgI heterojunction had a good prospect for applications in water remediation. The current work provides new insight and useful guidance for designing novel structural photocatalysts for environment-related applications.

Preparation of Porous Ellipsoidal Bismuth Oxyhalide Microspheres and Their Photocatalytic Performances.

Well-dispersed and uniform porous ellipsoidal-shaped bismuth oxyhalides (nominal composition: 80%BiOCl/20%BiOI) microspheres were obtained by a facile solvothermal method, in which process the use of polyvinylpyrrolidone (PVP) as template agent was found to be crucial. At 150 °C, elliptical porous particles with a particle size of 0.79 μm were formed. Instead of forming solid solutions, the study of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) shows that the prepared 80%BiOCl/20%BiOI microspheres are composite of BiOCl and BiOI in nature and the obtained crystallite size is about 5.6 nm. The optical bandgap of 80%BiOCl/20%BiOI was measured to be 2.93 eV, which is between the bandgap values of BiOCl and BiOI. The 80%BiOCl/20%BiOI microspheres were able to decompose various organic dyes (rhodamine B-RhB, methyl orange-MO, methylene blue-MB, methyl violet-MV) under an illuminated condition with the degradation rate in the order of RhB > MB > MV > MO, and 98% of RhB can be degraded in 90 min. Radical scavenger tests showed that photogenerated holes are the main active species for the photocatalytic decomposition of all of the tested organic dyes. Our results show that the obtained porous ellipsoidal-shaped 80%BiOCl/20%BiOI microspheres are promising for the degradation of various organic pollutants under the illumination of visible light.

Synthesis of novel graphene aerogel encapsulated bismuth oxyiodide composite towards effective removal of methyl orange azo-dye under visible light.

Development of novel and eco-friendly composite photocatalysts for the efficient removal of contaminants from wastewater is the need of the hour. In this study, visible light responsive novel graphene aerogel/bismuth oxyiodide (GA/BiOI) composite was synthesized via low-temperature solvothermal method. The synthesized GA/BiOI composite was tested for methyl orange (MO) azo-dye degradation under visible light. The graphene aerogel nanosheets were wrapped onto the surface of the each individual BiOI microsphere, which encourages the interconnection charge transfer process. The light absorption properties of GA/BiOI composite were increased with the addition of graphene aerogel. The optimal 5%-GA/BiOI composite displayed higher MO removal efficiency, which is ∼2 fold more than the bare BiOI photocatalyst. This enhanced photocatalytic activity was on account of lower recombination rate of charge carriers, improved light absorption, and the high surface area. In addition, the 5%-GA/BiOI composite showed good stability until 3 cycles without deactivation. The plausible MO degradation mechanism was also proposed over GA/BiOI under visible light. This work provides a new perspective on the design and synthesis of graphene aerogel-based composite for environmental applications.

Enhancing the intrinsic properties of flower-like BiOI by S-doping toward excellent photocatalytic performances

• A new S-doped flower-like BiOI was synthesized via two-step hydrothermal-sulfuration method. • BiOI via engineering the surface oxygen vacancy and exposed {001} crystal planes. • S-BiOI exhibited enhanced photocatalytic Cr(VI) reduction activity. A facile strategy was proposed to fabricate the S-doped flower-like BiOI microspheres (S-BiOI) for boosting the photocatalytic performance of BiOI via engineering the surface oxygen vacancy and exposed {001} crystal planes. The S-doping generated oxygen vacancies in BiOI lattice structure to create point defects and exposed {001} crystal planes, resulting in a decrease in bandgap and an enhancement in charges separation, which could significantly hasten the photocatalytic reaction. The concentration of CH 4 N 2 S was a key factor to promote the Cr(VI) reduction activities. The optimized S-BiOI 1.25 presented a superior Cr(VI) removal efficiency of 100% for 60 min, which Cr(VI) reduction rate was 11.3 times higher than the pristine BiOI and still remained 97.5% Cr(VI) removal after 5 cycles. DFT calculation confirmed that the bandgap of the S-BiOI was narrowed compared to that of BiOI, but the S-BiOI still remained the intrinsic band structure of the pristine BiOI. .

Z-type heterojunction of Cu2O-modified layered BiOI composites with superior photocatalytic performance for CO2 reduction

For solar energy conversion and energy mitigation relief, the development of an efficient and stable photocatalyst is critical. A Z-type Cu2O-modified BiOI microspheres were synthesized by chemical deposition. A series of xCu2O/BiOI (x = 0.6, 0.8, 1.0) has improved CO2 photoreduction performance under simulated sunshine irradiation, and the best yields of CH3OH and C2H5OH were 609.05 and 273.96 μmol/gcat, respectively, which were 2.65 and 2.88 times larger than that of pure BiOI. The material exhibits strong photocatalytic performance, which is mainly owing to a greater interaction between Cu2O and BiOI, which promotes the separation and migration of photogenerated carriers as well as the use of sunlight. The specific surface areas of pure BiOI and 10% Cu2O/BiOI were 12.05 and 22.85 m2/g, respectively, as shown in the N2 adsorption-desorption characterization, indicating that the introduction of Cu2O increased the specific surface area of BiOI and provided more active sites. Various characterizations were carried out to evaluate the morphological structure of the Z-type composite of Cu2O/BiOI composite catalyst and to investigate a possible mechanism of CO2 reduction. The CO2 reduction performance of the composite catalyst did not decrease significantly through five cycles of testing, indicating that the material has good stability and redox performance. This research suggests that photocatalysts could be useful in solar energy conversion and energy crisis mitigation.

Use of mesoporous BiOI microspheres for sonocatalytic degradation of tetracycline hydrochloride

Self-assembled mesoporous BiOI microsphere with nanosheets were prepared by a solvothermal method and used as sonocatalysts. The sonocatalytic performances of the BiOI microspheres were evaluated in terms of the degradation rate of tetracycline hydrochloride (TCH) as a model pollutant. We designed three comparative experiments to explore the degradation of TCH solution under natural light, namely with sonication, with BiOI alone, and with ultrasound (US)/BiOI synergy. The degradation rate of TCH with US/BiOI synergy was 227 times higher than that achieved with sonication and 83 times higher than that achieved with BiOI alone. The maximum TCH degradation rate was 93.0%. The synergistic effect was therefore significant, and the synergy factor was estimated to be 61. Many factors such as the ultrasonic duty cycle, applied power, catalyst concentration, and initial TCH dye concentration may affect the ultrasonic degradation efficiency. Box–Behnken design of the response surface method were used to optimize the parameters and to study the effects of the catalyst concentration, ultrasonic duty cycle, and applied power. Analysis of variance confirmed that the quadratic response surface model for predicting the sonocatalytic efficiency was good for the corresponding parameters (R2 = 0.9936 and adjusted R2 = 0.9854). The optimization results were verified by replicate experiments. The high TCH degradation rate may be related to the generation of reactive oxygen species at the end of cavitation bubble collapse, which can improve the chemical yields.

A magnetic separable 3D hierarchical BiOI/rGO/Fe3O4 catalyst for degradation of Rhodamine B under visible light: Kinetic studies and mechanism of degradation

A magnetically separable BiOI/rGO/Fe3O4 photocatalyst was prepared at room temperature using a one-step chemical co-precipitation method. X-ray diffraction, scanning electron microscopy, FT-Raman spectroscopy, etc. were used to characterize the photocatalyst. The photocatalytic activity of the magnetically separable photocatalyst was tested for its ability to degrade Rhodamine B (RhB). On the rGO sheet, a flower-like 3D hierarchical BiOI microsphere was loaded with distributed Fe3O4 nanoparticles. Within 180 min, 98.1% of 20 mg/L RhB had been degraded. In MATLAB 2014, the degradation kinetics were investigated using a non linear method. According to free radical trapping analysis the photocatalytic activity of RhB was conquered by superoxide and hydroxyl radicals rather than the direct hole. LC/MS/MS analysis was used to identify the intermediates formed during the degradation of RhB. These findings showed that magnetic separable BiOI/rGO/Fe3O4 prepared by a simple co-precipitation method had the potential to be used on a large scale in the treatment of RhB in wastewater.

Study on Sonocatalytic Degradation of Tetracycline Hydrochloride by Mesoporous BiOI Microspherical Under Ultrasonic Irradiation

Degradation of tetracycline hydrochloride (TCH) was carried out using natural light driven BiOI photocatalyst through sonophotocatalytic technique. Sonocatalytic degradation was considered as a new and advanced strategy for the elimination of hazardous organic pollutants from wastewater. Until now, the synergy of employing ultrasonic irradiation with BiOI based on catalysts for the removal of antibiotic residues is rarely reported. BiOI was an excellent semiconductor catalyst of Bi class. In this paper, mesoporous BiOI microspheres self-assembled from nanosheets were prepared by solvothermal method and its ultrasonic catalytic performance was studied. The sonocatalytic performance of BiOI was evaluated in terms of the degradation of tetracycline hydrochloride (TCH) as a simulate pollutant under ultrasonic irradiation. Three comparative experiments were designed to explore the degradation of TCH in natural light as follows: ultrasound alone, BiOI alone and ultrasound/BiOI synergy. The degradation rate of TCH by ultrasound/BiOI synergy was 227 times higher than that catalyzed by ultrasound alone and 83 times higher than that catalyzed by BiOI, and the maximum degradation ratio of TCH could reach to 93.0%. Therefore, the synergistic effect was significant, and the value of synergy factor was estimated as 61. Many factors, such as the ultrasonic power, catalyst concentration (Ccatalytic), ultrasonic duty cycle, concentration of initial TCH dye (CTCH), could affect the ultrasonic degradation efficiency. The BBD methodology with RSM was applied for modeling, optimization and investigation of influence of operational parameters, i.e. ultrasonic power, catalyst concentration, ultrasonic duty cycle. Analysis of variance (ANOVA) confirmed a good quadratic response surface model for predicting the sonocatalytic efficiency at various operational parameters (R2= 0.9936 and Adjusted R2=0.9854. The possible mechanism of the high degradation rate of TCH might be associated with the generation of reactive oxygen species (ROS) which could improve the chemistry yields.