Maximum Removal Rate Research Articles

Potential of biological sulphur recovery from thiosulphate by haloalkaliphilic Thioalkalivibrio denitrificans

ABSTRACT The aim of this study was to investigate the potential for elemental sulphur recovery from sulphurous solutions under aerobic and anoxic conditions by haloalkalophilic Thioalkalivibrio denitrificans at 0.8–19.6 g S2O3 2−-S L−1 and 0.2–0.58 g NO2 L−1, respectively. The experiments were conducted as batch assays with haloalkaline (pH 10 and ≥ 14 g Na+ L−1) thiosulphate solution. Aerobically, the highest biotransformation rate of thiosulphate obtained was 0.03 h−1 at 8.5 g L S2O3 2−-S. Based on Monod model, the maximum substrate utilisation rate (qm) was 0.024 h−1 with half saturation constant (Ks) 0.42 g S2O3 2−-S L−1 at initial [S2O3 2--S] of 14 g L−1. S0 accumulated at [S2O3 2−-S] ≥ 1.5 g L−1 (10% yield at initial 9.5 g S2O3 2−-S L−1) and the highest S0 yield estimated with the model was 61% with initial [S2O3 2--S] of 16.5 g L−1. Anoxically, the maximum nitrite removal rate based on Monod modelling was 0.011 h−1 with Ks = 0.84 g NO2 − L−1. Aerobically and anoxically the maximum specific growth rates (µm) were 0.046 and 0.022 h−1, respectively. In summary, high-rate aerobic biotransformation kinetics of thiosulphate were demonstrated, whereas the rates were slower and no S0 accumulated under anoxic conditions. Thus, future developments of biotechnical applications for the recovery of S0 from haloalkaline streams from the process industry should focus on aerobic treatment. Highlights Haloalkaline S2O3 2− biotransformations kinetics by Thioalkalivibrio denitrificans Aerobic thiosulphate-S bioconversion up to 0.024 h−1 with Ks = 0.42 g S2O3 2−-S L−1 10% S0 yield with initial 9.5 g S2O3 2--S L−1 in aerobic condition Anoxic NO2 removal up to 0.01 h−1 with Ks = 0.84 g NO2 − L−1

Optimizing nutrient removal and biomass production of the Algal Turf Scrubber (ATS) under variable cultivation conditions by using Response Surface Methodology.

This study investigated and optimized the nutrient remediation efficiency of a simple low-cost algal biofilm reactor, the algal turf scrubber (ATS), for wastewater treatment. Combined effects of three cultivation variables—total inorganic carbon, nitrogen-to-phosphorous (N:P) ratio, and light intensity—were examined. The ATS nutrient removal efficiency and biomass productivity were analyzed considering the response surface methodology (RSM). The maximum removal rates of total P and N were 8.3 and 19.1 mg L−1 d−1, respectively. As much as 99% of total P and 100% of total N were removed within 7 days. Over the same period, the dissolved oxygen concentration and pH value of the medium increased. The optimal growth conditions for simultaneous maximum P and N removal and biomass productivity were identified. Our RSM-based optimization results provide new insights into the combined effect of nutrient and light availability on the ATS remediation efficiency and biomass productivity.

Efficient Adsorptive Performance of Graphene Oxide by Nano Clay

Research regarding the use of Nano clay to remove toxic GO (Graphene oxide) from wastewater was limited. Through a variety of characterization techniques and methods, the adsorption performance and mechanism of Nano clay for GO were systematically studied. The related effects of solution pH, temperature, adsorbent dose, and GO concentration were studied in detail. The results show that the aggregation and deposition of GO on Nano clay depends on the pH value of the solution and the type and concentration of the electrolyte, and the isotherm data fits well with the Langmuir equation. Under the best conditions (pH=3.0), the maximum removal rate is 97.8% (C0=60 mg·L-1), and the adsorption capacity is 245.8 mg.g-1 (C0=80 mg.L-1, T=303K, equilibrium time=24 h, m=10 mg). Specifically, the dissolution of Nano clay at a relatively low pH or a high pH value helps the aggregation of GO. The results of this study provide key information for predicting the fate of GO in the land-water transition zone where Nano clay exists.

The distribution and movement characteristics of fine particles in an electrostatic precipitator with multi-field synergy

An experimental platform was established to study the distribution and motion characteristics of fine particles in an electrostatic precipitator (ESP) with electric, temperature, and particle concentration, multi-field synergistic effect. The fine particle concentrations were tested by measuring reformed ELPI in real-time. For discussion, motion characteristics of fine particles such as trajectory, deposition, re-entrainment and water flushing were analyzed by mechanical modeling, listing up every force acting on the fine particles. The results show that the type and the force order of magnitude of the particle will change correspondingly in different states. The synergistic state is beneficial to the removal of particles in the whole range, especially the particle size of 0.1⁓1 μm, and the maximum removal rate is increased by 15% compared with the wet state. The increasing of Fy (liquid bridge), Fc (particle concentration gradient) and Fth (thermophoresis). increase the removal efficiency of fine particles in synergistic state. • The removal efficiency of 0.1-1 μm particles is the most obvious by synergy effect. • The synergistic fields increase the force of near-wall particles towards the wall. • The root reason of high removal efficiency in synergistic: F y , F C and F th increases. • The multi-field synergy provides a new development direction for ESP.

Multi response optimization and regression analysis of milling parameters of jute fibre reinforced epoxy composite

Multi response optimization is a tool for decision making when a number of characters are to be simultaneously considered. Multicriteria analysis helps in choosing the most feasible outcome from a from a finite set of available data. It is concerned with ranking of various alternatives for a particular case across all criteria. The use of organic materials to derive composites is very popular these days due to the environmental impact caused by artificial and synthetic composites. Organic or green composites are preferred by manufacturers due to their cost effectiveness, strength to weight ratio, durability etc. Jute is one of the cheapest and easily available organic fibres available. In this particular study we are concerned with the analysis of machining process of a jute fibre reinforced epoxy composite. Machining of a composite sheet results in matrix cracking, fibre pull-out, delamination etc. So, it is important to optimize various cutting parameters to obtain the most feasible results. The main objective of this study is to optimize 3 cutting parameters (output parameters) surface roughness (Ra & Rz), material removal rate and tool wear rate. To obtain these output values input parameters feed rate, spindle speed and depth of cut are varied. The Taguchi L27 orthogonal array is chosen and grey relational analysis is used to get the optimum performance parameters, that is, minimum surface roughness and Tool Wear Rate (TWR) and maximum Material Removal Rate (MRR). Regression analysis is also done to obtain empirical formulas for each parameter.

High-efficiency and rapid cyanide removal in SPL derived from aluminum electrolysis production under microwave and sensitizer synergistic action

Spent potliner (SPL) has been listed as a hazardous waste derived from aluminum electrolysis production with high cyanide content. In this study, a novel microwave-sensitizer synergistic technique was proposed to rapidly remove cyanides in SPL. The occurrence states and removal behavior of cyanide in SPL were studied systematically. The results show that cyanide in SPL mainly exists in the form of sodium cyanide and ferricyanide . The maximum cyanide removal rate of 96.67% was successfully achieved under the experimental conditions. Meanwhile, the synergistic removal mechanisms were comprehensively investigated by XRD , XRF , TG-DTA, TG-MS, and FactSage thermal simulation software. The sensitizer Fe 2 O 3 can accelerate the decyanation reaction by decreasing activation energy and acting as an oxidant. This study not only develops a high-efficiency and rapid cyanide removal technique, but also provides theoretical guidance for non-hazardous treatment of other cyanogens-containing wastes.

Evaluation of iron-loaded granular activated carbon used as heterogeneous fenton catalyst for degradation of tetracycline

To optimize the efficiency of general adsorption-Fenton oxidation treatment, iron-loaded granular activated carbon (Fe-GAC) was prepared, characterized, and used as a catalyst in the heterogeneous Fenton oxidation of tetracycline (TC). Characterization revealed that the Fe(II) was successfully introduced onto the original granular activated carbon (GAC) and diversified the materials’ surface morphology and elemental compounds. Under an initial pH of 3.0, the Fe-GAC/Fenton system obtained a maximum removal rate of 92.6%, with hydrogen peroxide (H2O2) dosages of 9 mmol g−1. And the GAC/Fenton without iron supplementation was 89.5%, with H2O2 dosages of 8 mmol g−1. Additionally, the Fe-GAC/Fenton system consumed a lower Fe(II) dosage than GAC/Fenton, with Fe(II)/H2O2 molar ratios of 0.007:1 and 0.04:1, respectively. Analysis of total organic carbon demonstrated higher mineralization efficiency in the Fe-GAC/Fenton system (67.2%), which was approximately 1.3 times of GAC/Fenton. Desorption experiments showed that the adsorption and degradation accounted for 19.22% and 80.78% of the total TC removal by GAC/Fenton, and 10.58% and 89.42% in the Fe-GAC/Fenton system, respectively. Electron paramagnetic resonance (EPR) technique and quenching experiments demonstrated that the dominant reactive oxygen species (ROS) in synergistic treatments were hydroxyl (•OH) and hydroxy peroxyl (HO2•) radicals. In addition, three potential degradation pathways for TC were proposed according to the detected fourteen intermediates. Catalyst regeneration treatments were evaluated over six cycles, and the regeneration was 6.5% higher with the iron-supplemented carbon granules. Overall, the Fe-GAC can be used as an efficient catalyst in practical water treatment, and this study demonstrated a promising method to develop adsorption-Fenton technology.

Multi-Criteria Decision-Making when Surface Grinding 9XC Steel with a Segmented Grinding Wheel

9XC steel is a steel alloy of the commonly used tool to make a variety of products. When manufacturing such products, surface grinding method is commonly used as the final machining method for critical surfaces. Therefore, it is very necessary to research for improving surface quality and machining productivity when grinding this steel. In this study, Multi-Criteria Decision-Making (MCDM) is presented when surface grinding 9XC steel with a segmented grinding wheel. Taguchi method has been chosen to design the experimental matrix. MCDM has been performed using Proximity Indexed Value (PIV). This study has determined the value of workpiece velocity, feed rate and depth of cut to simultaneously ensure the minimum surface roughness and the maximum Material Removal Rate (MRR). The effect of cutting parameters on surface roughness has been also discussed.

Adsorption properties of methylene blue and gentian violet of sodium vanadate nanowire arrays synthesized by hydrothermal method

In the present study, the facile hydrothermal method is used to prepare sodium vanadate (Na5V12O32) nanowire arrays to act as adsorbents for removing cationic dyes. The samples are characterized and compared using scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrum, and X-ray diffraction. The adsorption quantity of methylene blue and gentian violet increases with the increase of adsorbent dose, adsorption time and initial dye concentration. Further, the adsorption kinetic and isotherm are well modeled by the Pseudo-second-order kinetic model and Langmuir isotherm model, respectively. The rate control step is administered by means of intra-particle diffusion during the adsorption process. The maximum adsorption capacities of methylene blue and gentian violet are 1249.0 and 1079.7 mg g−1, respectively. Additionally, the maximum dye removal rates for MB and GV are 85.32 % and 84.46 % after five cycles, respectively. As such, Na5V12O32 nanowire arrays can be used as an efficient, low-cost and recyclable adsorbent for cationic dyes removed from wastewater.

Polyacrylate stabilized ZVI/Cu bimetallic nanoparticles for removal of hexavalent chromium from wastewater.

In this work, a magnetic core-shell composite zero-valent iron/copper-polyacrylate (ZVI/Cu-PAA) was synthesized by a simple liquid-phase reduction process and used for hexavalent chromium Cr(VI) removal from wastewater. The optimization experiments show that the optimal dosages of polyacrylate and Cu are 7.00 wt% and 8.25 wt%, respectively. The maximum adsorption capacity and removal rate of Cr(VI) by ZVI/Cu-PAA reached 106.12mgg-1 and 99.05% at pH 5.5, respectively. Furthermore, the presence of coexisting ions such as Ca2+, Mg2+, Na+, and NO3- had no significant effect on its Cr(VI) removal performance. The excellent performance of ZVI/Cu-PAA is attributed to that the modification of polyacrylate can not only give more active sites but also inhibit agglomeration of nano-metallic particles, while Cu doping promotes the electron generation and transformation of Fe(III)/Fe(II) and Cu(II)/Cu(I) redox cycles. This makes ZVI/Cu-PAA has rich active sites and excellent stability, and has broad application prospects in the remediation of Cr (VI) polluted wastewater. The magnetic core-shell composite ZVI/Cu-PAA has excellent Cr (VI) removal performance because of its rich active sites and high electron transformation efficiency.

Performance of Paracoccus pantotrophus MA3 in heterotrophic nitrification-anaerobic denitrification using formic acid as a carbon source.

Excess amount of nitrogen in wastewater has caused serious concerns, such as water eutrophication. Paracoccus pantotrophus MA3, a novel isolated strain of heterotrophic nitrification-anaerobic denitrification bacteria, was evaluated for nitrogen removal using formic acid as the sole carbon source. The results showed that the maximum ammonium removal efficiency was observed under the optimum conditions of 26.25 carbon to nitrogen ratio, 3.39% (v/v) inoculation amount, 34.64°C temperature, and at 180rpm shaking speed, respectively. In addition, quantitative real-time PCR technique analysis assured that the gene expression level of formate dehydrogenase, formate tetrahydrofolate ligase, 5,10-methylenetetrahydrofolate dehydrogenase, serine hydroxymethyltransferase, respiratory nitrate reductase beta subunit, L-glutamine synthetase, glutamate dehydrogenase, and glutamate synthase were up-regulated compared to the control group, and combined with nitrogen mass balance analysis to conclude that most of the ammonium was removed by assimilation. A small amount of nitrate and nearly no nitrite were accumulated during heterotrophic nitrification. MA3 exhibited significant denitrification potential under anaerobic conditions with a maximum nitrate removal rate of 4.39mg/L/h, and the only gas produced was N2. Additionally, 11.50 ± 0.06mg/L/h of NH4+-N removal rate from biogas slurry was achieved.

Rotten banana powder: A waste-recycling alternative for external carbon source

Although rotten banana (RB) has been proved as a superior carbon source for denitrification, how to maintain its effectiveness while reduce the depressing transportation expenses deserves for more considerations. In this study, a modified carbon source-RB powder (RBP) was prepared and utilized for treating nitrate in wastewater. Results indicated that RBP, equipped with rapid organic release and low residual properties, could achieve a maximum nitrate removal rate of 96.79% and inapparent nitrite accumulation with a denitrification rate higher than RB slurry. Supplementing RBP improved the long-term stability of sludge in the denitrification system while the dosage served as a promoting factor towards sludge dewatering performance but a limiting factor towards system stability. The breeding of unique bacteria was easily altered by increasing nitrate load, contributing to the combined denitrification via various microorganisms. Meanwhile, the phyla and genera related to denitrification and organic fermentation were effectively enriched by improving RBP dosage. Compared with RB slurry and sodium acetate, less denitrification cost would be obtained by RBP when the usage amount respectively exceeded 7.31 tons and 228.18–555.56 tons. All the results demonstrated that RBP would be selected as a more cost-efficient choice for denitrification in view of practical applications.

Treatment of Comprehensive Wastewater from Chemical and Pharmaceutical Parks by Fly Ash-Coated Iron Electrode Electrocoagulation

With the rapid development of the economic system and the continuous development of industry, environmental pollution is becoming more and more important, so wastewater treatment urgently needs to be strengthened. This article uses fly ash-coated iron electrode electrocoagulation method to carry out experimental tests on the treatment of comprehensive wastewater from chemical and pharmaceutical parks. Fly ash is used as a raw material to prepare a shaped adsorbent; in order to analyze whether the adsorbent has many potential applications in actual wastewater treatment and use. The experiment research of iron electrode electrocoagulation was carried out on actual groundwater, aiming to provide data and theoretical support for the utilization of fly ash and the optimization of comprehensive wastewater treatment technology. The article mainly conducts related research on title distribution, firstly the physical and chemical properties of fly ash, and secondly, discusses the related structure of electrocoagulation method, and solves the problem of comprehensive wastewater based on the combination of the two solving issues. Aware of the importance of sewage treatment and the characteristics of related treatment methods such as adsorption, membrane separation technology, and ion exchange, the advantages of these methods are also used for reference in subsequent experiments to achieve the purpose of reliable experimental results. The experimental results show that the effect of sewage treatment with fly ash with different average diameter particles is obvious. Among them, the maximum value of vibration grinding ash before and after application increased from 5.62 to 8.31, and the maximum removal rate is also 8.31; the removal effect is significant. It can be seen that the fly ash-coated iron electrode electrocoagulation method can have a great effect on the treatment of comprehensive wastewater in the chemical and pharmaceutical park.

An electricity-generating bacterium separated from oil sludge microbial fuel cells and its environmental adaptability.

Electricity-generating bacteria as biocatalysts for microbial fuel cells (MFCs), their species, and power generation performance determine the pollution control and power generation performance of MFCs. And there are few studies on the types and performance of electricity-generating bacteria isolated from oily sludge microbial fuel cells. For improving the power generation performance of oily sludge MFCs, an electricity-generating bacterium was isolated from the oily sludge. More importantly, the adaptability of nitrogen to phosphorus ratio, temperature, and pH of the electricity-generating bacteria were adjusted by a controlled variable method. The results of this study showed that the electricity-generating bacterium was identified as Bacillus cereus, with a rod-shaped cell, about 0.5-1.0μm in length. The optimal nitrogen-phosphorus ratio, temperature, and pH of MFCs were 4.67:1, 25 ℃, and pH = 7, respectively. Its maximum power density, COD, and oil removal rate was up to 65 mW·m-3, 90.51%, and 87.76%, respectively. The study of this functional bacterium will provide beneficial assistance for the improvement of oil removal and power generation performance of oily sludge MFCs.

Simultaneous removal of multiple PFAS from contaminated groundwater around a fluorochemical facility by the periodically reversing electrocoagulation technique

Increasing attentions have been paid on widespread contaminations of perfluoroalkyl substances (PFAS). Particularly, simultaneous occurrence of multiple PFAS in the aquatic environments globally has been recognized as a crucial emerging issue. The present study aimed to perform simultaneous removal of multiple PFAS contaminations from groundwater around a fluorochemical facility based upon the technique of periodically reversing electrocoagulation (PREC). Accordingly, the experiments were implemented on the best conditions, actual application, and removal mechanism in the process of PREC with Al–Zn electrodes. Consequently, 1 mg/L synthetic solution of ten PFAS could be eliminated ideally during the initial 10 min, under the optimal conditions involving voltage at 12 V, pH at 7.0, and electrolyte with NaCl. The maximum removal rates of perfluorobutanoic acid (PFBA), perfluorobutane sulfonate (PFBS), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonate (PFOS) were 90.9%, 91.0%, 99.7%, and 100%, respectively. The PREC performed a significant improvement for the wide scope of PFAS removal with the levels ranging from 10 μg/L to 100 mg/L. In addition, the optimized PREC technique was further applied to remove various PFAS contaminations from the natural groundwater samples underneath the fluorochemical facility, subsequently generating the removal efficiencies in the range between 31.3% and 99.9%, showing the observable advantages compared with other removal techniques for the actual application. Finally, the mechanism of PFAS removal was mainly related to enmeshment and synergistic bridging adsorption, together with oxidation degradation that determined by potential formation of short-chain PFAS in the PREC process. As a result, the PREC technique would be a promising technique for the efficient removal of multiple PFAS contaminations simultaneously from natural water bodies.

Preparation of low-nitrogen chlorella based on proteolysis technology and pyrolysis characteristics of the products

The high protein content in the microalgal biomass leads to the high relative content of nitrogen compounds in the pyrolysis oil, which hinders the efficient application of the microalgal pyrolysis oil. In this paper, a method for preparing low-nitrogen chlorella by using alkaline protease based on proteolysis technology was proposed to reduce the nitrogen content of chlorella, and its process conditions were optimized. The results showed that the maximum nitrogen removal rate and yield could reach 20.32% and 52.36 wt%, respectively. The thermal decomposition characteristics of Chlorella and low-nitrogen chlorella were analyzed by TG-DTG technology, and their main thermal decomposition were calculated by Coats-Redfern method. It was found that compared with Chlorella, the low-nitrogen Chlorella had a larger weight loss rate in main thermal decomposition stage and its average activation energy value reduced by 2.23 kJ/mol. The Py-GC-MS technology was further used to study the distribution of pyrolytic products of Chlorella and low-nitrogen Chlorella at 550 °C. It was found that the relative content of nitrogen compounds in pyrolytic products from low-nitrogen Chlorella was 43.02% lower than that of Chlorella. This is because that the proteolysis pretreatment has a significant effect on reducing the relative contents of some nitrogen compounds in bio-oil, such as pyridines, pyrroles and benzyl nitrile. Based on the above experimental results, a brief mechanism of proteolysis pretreatment on removing nitrogen compounds was proposed, mainly through the proteolytic process to reduce the relative content of various amino acids in Chlorella as precursors for the synthesis of nitrile and N-heterocyclic compounds in pyrolysis. In conclusion, proteolysis technology can effectively reduce the relative content of nitrogen compounds in pyrolysis components and improve the potential of microalgal pyrolysis oil as a high-quality alternative fuel.

Effects of ecological restoration on water quality and benthic macroinvertebrates in rural rivers of cold regions: A case study of the Huaide River, Northeast China

Various human activities can damage the structure of rural rivers ecosystems and reduce their self-purification capacity. In Northeast China, the cold climate also poses serious challenges to river restoration. What types of restoration technology should be adopted and what impacts the restoration project will bring, in terms of river ecological function improvements, should be further discussed. To investigate the effects of ecological restoration projects and different restoration measures on water quality and benthic macroinvertebrates of rural rivers in cold regions in Northeast China, benthic macroinvertebrates and 10 indicators of water quality including ammonium (NH4+-N), nitrate (NO3–-N), total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (COD), dissolved oxygen (DO), water temperature (Tem), pH (pH), electrical conductivity (EC) and chlorophyll-a (Chla) were monitored. We analyzed the temporal and spatial changes of benthic macroinvertebrates and 6 typical water quality indicators including NH4+-N, NO3–-N, TN, TP, COD and DO, which were collected in 4 seasons at 7 typical river sections. The Water Quality Index (WQI) was used to evaluate the seasonal and spatial variation of water quality during monitoring period, and a new WQImin model consisting of six crucial parameters, i.e., pH, DO, NH4+-N, TN, TP and COD, was established by principal component analysis. The results showed that the ecological restoration project enhanced the self-purification capacity of the river, and increased diversity of benthic macroinvertebrates. The maximum removal rates of the main pollution indicators NH4+-N, NO3–-N, TN, TP and COD were 96.49 %, 43.92 %, 49.69 %, 8.3 % and 25.95 %, respectively. The maximum increase rates of DO and benthic macroinvertebrates diversity were 77.96 % and 310.9 %, respectively. The operation effect of the restoration project had an obvious seasonal effect, with the best effect during the spring and summer. The project still has good repair effect in winter. In terms of water purification, the effect of the overflow weir combined with aquatic organisms was better than that of the single overflow weir in the river channel. There was the best effect of the engineering measures in summer. The ecological restoration project can improve the river water quality and the benthic macroinvertebrates conditions. Compared to before the restoration, WQImin values increased 168.81 % and 44.21 % in winter and summer, respectively, and Shannon index increased 6.57 % and 41.67 % in summer and autumn, respectively.

Capturing CO2 with NaOH solution from reject brine via an integrated technology based on bipolar membrane electrodialysis and hollow fiber membrane contactor

Discharges of wastewater and waste gas are two major environmental problems which have drawn great attention. To well use the reject brine and realize continuous absorption of CO2, in this work, a green process for the capture of CO2 by NaOH solution produced from reject brine based on bipolar membrane electrodialysis (BMED) has been proposed. By using the BMED, the maximum concentrations of generated acid and base attained 1.88 mol/L and 2.01 mol/L, respectively, with the current efficiency of 64.71 % and energy consumption of 3.97 kWh/kg NaOH. The acid could be recycled for pH adjustment and the alkali could be directly used for CO2 absorption with the help of hollow fiber membrane contactor (HFMC). The optimization of the gas flow rate, liquid flow rate, liquid temperature, and NaOH concentration has been investigated in CO2 absorption process with a maximum CO2 removal rate of 90.85 %. As for absorption of CO2, the absorbent containing NaOH and Na2CO3 could be directly used in the pretreatment process for reject brine softening. It is noted that the process could be performed without adding extra chemicals and the self-cycle could be achieved. In addition, economic and environmental evaluations verify the feasibility of this process, indicating the prospect of industrial application.

Development of a hybrid bifunctional rotating drum electrode system for the enhanced oxidation of ciprofloxacin: An integrated photoelectrocatalysis and photo-electro-Fenton processes

Mismanaged antibiotics ending up in aquatic environment due to inadequate conventional treatment urges the need to develop powerful advanced oxidation techniques. In this study, hybrid bifunctional rotating drum reactor (BRDR) has been developed and its potency in enhancing the degradation of ciprofloxacin has been demonstrated. BRDR is a hybrid reactor that integrates – photoelectrocatalysis (PEC) and photo-electro-Fenton (PEF) processes with UVA irradiation. It consists of MoS2-TiO2-coated carbon cloth as anode and Ferrocene-functionalized graphene-coated graphite felt as cathode. BRDR system significantly improved the removal efficiency (99.9 %) as compared to individual efficiencies of PEC (71 %) and PEF (78.8 %) processes. An increase in electrode rotation speed significantly enhanced the removal without external aeration (0.059 min−1 for 60 rpm). Maximum removal rate was achieved at pH 3 (0.061 min−1) followed by 7 (0.040 min−1) and 9 (0.020 min−1). The increase in applied potential from open circuit voltage to 1.5 V improved the removal rate from 0.005 min−1 to 0.040 min−1. The mechanism of reactive oxygen species production in BRDR system is elaborated. BRDR is demonstrated to be cleaner treatment system which excludes the external chemical addition, aeration, and sludge formation.

High-Performance Photoelectrochemical Desalination Based on the Dye-Sensitized Bi2O3 Anode.

In this work, a solar-driven redox flow desalination system is reported, which combines a solar cell based on a Bi2O3 photoanode and a redox flow desalination cell through an integrated electrode. The Bi2O3 film was prepared through a simple one-step water bath deposition method and served as a photoanode after the coating of the N719 dye. The activated carbon (AC)-coated graphite paper served as both the integrated electrode and counter electrode. The I3-/I- redox electrolyte circulates in the solar cell channel between the photoanode and intergrated electrode, while the [Fe(CN)6]4-/[Fe(CN)6]3- electrolyte circulates in the redox flow desalination part between the integrated electrode and counter electrode. This dye-sensitized solar-driven desalination cell is capable of achieving a maximum salt removal rate of 62.89 μg/(cm2·min) without consuming any electrical power. The combination of the solar cell and redox flow desalination is highly efficient with double functions of desalination and energy release using light as a driving force. This current research work is significant for the development of efficient and stable photoanode materials in photoelectrochemical desalination.