Clean Applications Research Articles

An advanced design to generate power and hydrogen with CO2 capturing and storage for cleaner applications

The present study aims to conduct a thermodynamic analysis of a novel concept that synergistically integrates clean hydrogen and power production with a liquefied natural gas (LNG) regasification system. The designed integrated energy system aims to achieve hydrogen production, power production, LNG regasification, carbon capture, storage, and in situ recirculation. Hydrogen sulfide (H2S) from industrial waste streams is used as a major feedstock, and a specific combustion of H2S is employed as a hydrogen production method. CO2 obtained from the combustion process is liquefied and pumped at a high pressure to be recirculated back into the power generation combustion process. The entire plant is simulated in the Aspen Plus simulation environment, and a comprehensive thermodynamic assessment including the energy and exergy analysis is conducted. Additionally, several parametric studies are conducted to identify suitable operating parameters. From the sensitivity analyses, it is found that at 20 % CO2 recirculation, the hydrogen production rate decreases by 48.27 % when the operating pressure is increased from 0.05 bar to 3 bar. The adiabatic temperature is reduced by 56.86 %, 52.26 %, and 49.45 %, when 50 %, 60 %, and 70 % CO2 is recirculated in the oxidant stream atan oxygen to natural gas (ONG) ratio of 0.5. The energy and exergy efficiencies of the system are found to be 71.48 % and 60.69 %, respectively. The present system avoids 2571.94 tons/yr of CO2 emissions for clean hydrogen production and 1426.27 tons/yr of CO2 for clean power production which would otherwise be emitted from steam methane reforming and coal gasification.

CFD modeling of reactive species air cleaner applications in a classroom

Due to increasing concerns related to airborne virus spread indoors, more reactive species air cleaners are being utilized in classrooms. Reactive species generated by air cleaners decompose airborne pathogens chemically, decreasing the risk of infection. Due to the high reactivity of these oxidants, reactive species may be distributed nonuniformly in indoor environments, as are viral aerosols emitted by infectors. Heterogeneous distributions of reactive species may cause spatially non-uniform removal rates of viral aerosols. However, there is little information regarding spatial distributions of either reactive species or viral aerosols in ventilated classrooms. Thus, the objective of this study was to investigate spatial distributions of reactive species and infectious aerosols and to examine how operating conditions of air cleaners affect viral aerosol removal rates. A CFD model simulated the operation of a reactive species air cleaner generating hydrogen peroxide (H2O2) in a mechanically ventilated 237 m3 classroom with nine occupants. The reactive species air cleaner showed a 3–20 times higher equivalent air change rate to a HEPA filter air cleaner with the same inlet and outlet flows. During the operation of reactive species air cleaners, elevated viral aerosol concentration was confined to regions near infectors. This was due to the high reactivity of reactive species, decreasing the infection probability of receptors from 3.2 % to 0.1 % with a 1-hour exposure time. As the room average concentration of reactive species increased from 15.6 to 50.4 ppb, both below the US Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) of 1000 ppb, the room average infection probability decreased from 0.3 % to 0.1 %. Due to the residence times of reactive species, the location of reactive species air cleaners affected the inactivation rate of viral aerosol, resulting in a 24 % variation of concentration difference of infectious aerosol with air cleaner locations.

Smart Public Toilet Management and Monitoring System using IOT

This paper addresses the pervasive issue of inadequate public sanitation in various regions of India and slums, marked by rampant urination and poorly maintained public toilets. Despite significant governmental expenditure and efforts to maintain cleanliness, the absence of a centralized monitoring mechanism renders these endeavors ineffective. To overcome this challenge, the paper proposes an Internet of Things (IOT)-based toilet monitoring system utilizing a web server and a mobile cleaner application. The system aims to simplify monitoring processes for toilet cleaners and administrators by tracking multiple cleaning metrics and providing real-time alerts based on user input. The motivation behind this project stems from the alarming state of hygiene in government schools, where students or teachers often bear the responsibility of cleaning due to labor shortages and insufficient funds. The relevance of the proposed system lies in its potential to revolutionize the maintenance of school and public toilets, addressing the unhygienic conditions prevalent in India. The novelty of the system includes features like automatic water flush, UV sanitization, timely floor cleaning, automatic sanitary pad vending, water monitoring, smell detection, and automatic ventilation, all facilitated through IOT technology. By presenting a cost-effective and efficient solution, this research contributes to the improvement of public sanitation in various settings, including homes, schools, colleges, hospitals, businesses, and industries, thereby promoting urban sanitation in the contemporary environment

A novel wind model downscaling with statistical regression and forecast for the cleaner energy

This study proposes an innovative statistical downscaling approach for meteorological wind models, enhancing cleaner energy applications. This method efficiently and swiftly incorporates topographic and meteorological data into wind park modelling by integrating regression-diagnosis-feature selection with statistical regression and forecasting techniques. The novel method in a de facto reduce predictive errors by approximately an average of 23.21%, lower errors downscaling and forecasting by 5.94% compared to existing methods, and optimise the balance between computational efficiency and forecasting accuracy. In an Arctic wind park case study, we systematically analysed meteorologically simulated wind speeds at various geographic points surrounding the park. The method enabled effective meteorological statistical mapping and accurate wind speed forecasting. Additionally, using the Granger causality test, the model identified a significant influence of surrounding terrain features on wind patterns. This research contributes by 1. introducing a novel downscaling technique surpassing current methods, 2. providing a resource-efficient approach for managing wind energy in complex terrains, and 3. offering a versatile model applicable to broader scenarios. The work marks an advancement in the field, promoting more reliable and efficient wind power and highlighting the importance of statistical downscaling in meteorological contexts for cleaner applications.

Effects of an MDP-based surface cleaner on dentin structure, morphology and nanomechanical properties

ObjectiveTo analyze the effect of Katana™ Cleaner (KC) in nanomechanical and triboscopic properties of etched dentin. MethodsDentin disks from human third molars were prepared. Two main groups of study were established in function of the etching conditioning, phosphoric acid (PA) and Clearfil SE Bond primer (CSEB). Four subgroups were tested within each group: i) untreated dentin (UD), ii) etched dentin (ED) [(PAED/CSEB)], iii) etched dentin contaminated with saliva (PAED+S)/(CSEB+S), and iv) etched and contaminated dentin treated with KC (PAED+S+KC)/(CSEB+S+KC). Nano-DMA testing and imaging, atomic force microscopy (AFM) analysis and nanoroughness (SRa) measurements were obtained. Field emission scanning electron microscopy (FESEM) images were also acquired. ResultsPhosphoric acid etched dentin samples and those specimens contaminated with saliva (PAED+S) attained the highest SRa values, that decreased after Katana™ Cleaner application (PAED+S+KC). In the group of dentin treated with CSEB primer, all subgroups performed similar, except in CSEB+S that attained the highest SRa values. The treatment with KC restored the original values of complex modulus of the untreated dentin. KC application produced the lowest and the highest tan delta values on PAED and CSEB groups, respectively. ConclusionKatana™ Cleaner provided equally mature dentin surfaces after any of the etching methods. Tan delta increased when Katana™ Cleaner was applied on the dentin surface previously etched and contaminated with saliva, regardless the kind of etchant, thus facilitating the dissipation of energy for elastic recoil during loading. Clinical significanceKatana™ Cleaner application after saliva contamination originated similar low roughness levels, regardless the type of etching method. Both complex and storage moduli were similar, after Katana™ Cleaner application, in any case.

Development and assessment of an integrated underground gasification system for cleaner outputs

In this study, an underground coal gasification-based integrated multigenerational system is developed to generate multiple useful outputs, including electricity, heating, cooling, hydrogen, ethanol and sulfuric acid, for achieving cleaner applications and meeting the community needs. An application of this conceptually developed system is considered for a community as identified in Kutahya, Turkey. The proposed system is developed, modelled, and analyzed using thermodynamic-based, sensitive modeling tools and software packages. The effects of operating conditions such as oxygen, steam, as well as lignite feed rate, reference temperature, and gasifier temperature are investigated to evaluate the performance of the integrated underground coal gasification system. This research further aims to analyze the influence of varying system parameters and operational conditions on ethanol and hydrogen generation and increase energetic and exergetic efficiencies while reducing harmful product gas emissions. In this regard, many parametric studies of the underground coal-powered multigeneration system are conducted. According to the results, the integrated underground lignite gasification combined system's overall system energetic and exergetic efficiencies are found to be 68.8% and 66.56%, respectively.

The techno-economic-environmental analysis of a pilot-scale positive pressure biomass gasification coupled with coal-fired power generation system

Biomass gasification coupled with coal-fired power generation (BGCPG) is of great significance for alleviating energy shortages and environmental pollution. Here we propose, analyze and validate a BGCPG system under positive pressure for cleaner applications based on a pilot-scale fluidized bed gasification plant and discussed the possibility of higher economic output and operating stability with reduced pollution emissions. Then the effects of temperature, air equivalence ratio and operating pressure were experimentally investigated for parameter optimization. The processes under positive and negative pressure were simulated and compared based on the pilot-scale experimental data, and the effects of the mixing ratio and operating pressure were investigated. Furthermore, the economic and sensitivity analyses were conducted for both a traditional coal-fired power plant and simulated BGCPG systems. The results demonstrated that the gas calorific value, gas yield, and gasification efficiency increased with the gasification temperature increasing, whereas the opposite trend was observed for the gas calorific value with the air equivalence ratio increasing. The positive pressure operation had little influence on the gasification process. The flue gas flow rate increased, and the furnace temperature decreased with an increase in the mixing ratio of biomass and coal. The reduction in fuel NOx and SOx was caused by the decreasing coal content, whereas the decrease in thermal NOx and boiler thermal efficiency was due to the increasing exhaust temperature. Compared with functioning under negative pressure, operation under positive pressure at a 20% mixing ratio could effectively reduce the pollutant emissions of SOx, NOx and dust by 5.64%, 8.8% and 20%, respectively. The generation costs of the BGCPG system under negative and positive pressure conditions were 0.05593 $/kW·h and 0.05582 $/kW·h respectively, indicating that a positive operating pressure would increase the economic benefit of a 660 MW generator by 5.808 × 105 $/year. These findings suggest the effectiveness of clean power generation with a higher economy and lower pollution emissions.

Development of a waste tires-based integrated energy system for multiple useful outputs in sustainable communities

In this study, a geothermal energy-supported integrated gasification system fed with waste tires for multigenerational purposes is developed to generate multiple useful commodities, including ethanol, sulfuric acid, hydrogen, electricity, cooling, and heat to achieve cleaner applications and meet the essential needs of the community in a sustainable manner. A potential application of this conceptually designed system is for a community identified in the Tuscany region of Italy's Larderello field. The proposed system is then analyzed and assessed by utilizing sensitive the thermodynamic simulations and software. The effects of operational and state-related parameters, such as steam, oxygen, waste tire input rate, reference temperature, and gasifier temperature are examined to analyse and evaluate the integrated waste tire gasification system's performance. The present study further aims to determine the effects of varying system parameters and operating circumstances on the ethanol and hydrogen production rates, with the goal of increasing energy and exergy efficiencies while minimizing hazardous wastes and gas emissions. Furthermore, numerous parametric studies on the waste tire-powered multigeneration system are undertaken accordingly. Both Engineering Equation Solver (EES) and Aspen Plus software packages are utilized as potential tools to perform analysis andsimulation studiesfor this system. The proposed system is fed with 10 kg/s of waste tires, and the energy production is supported by using 14.7 kg/s of geothermal spring water. While the net electricity generation, cooling and heating capacities of this system are obtained to be 18752 kW, 49236 kW and 5363 kW, respectively, while the total hydrogen and ethanol production rates within the integrated system are found to be 3.02 kg/s and 0.13 kg/s. The results also show that the waste tire-based integrated gasification system's overall energetic and exergetic efficiencies become 71.45 % and 69.87 %, respectively.

H2-Driven Reduction of Flavin by Hydrogenase Enables Cleaner Operation of Nitroreductases for Nitro-Group to Amine Reductions

Hydrogenase-mediated reduction of flavin mononucleotide by H2 is exploited to enable cleaner application of nitroreductase enzymes for reduction of aromatic nitro functional groups. This turns the overall reaction into a biocatalytic hydrogenation. Use of flavin-containing nitroreductases in industrial biotechnology typically relies upon NADH or NADPH as reductant, together with glucose dehydrogenase and glucose as a regeneration system for the reduced nicotinamide cofactor, with 3 equivalents of the carbon-intensive glucose required for a single 6-electron nitro to amine conversion. We show here that reduced flavin mononucleotide is an alternative reductant for nitroreductases, and by combining this with H2-driven recycling of reduced flavin, we avoid glucose, thereby enabling atom-efficient biocatalytic nitro reductions. We compare this biocatalytic system, via green chemistry metrics, to existing strategies for biocatalytic nitro-group reductions, particularly with respect to replacing glucose with H2 gas. We take steps towards demonstrating industrial viability: we report an overexpression system for E. coli hydrogenase 1, giving a 12-fold improvement in enzyme yield; we show a reaction in which the hydrogenase exhibits > 26,000 enzyme turnovers; and we demonstrate reasonable solvent tolerance of the hydrogenase and flavin reduction system which would enable reaction intensification.

Alumina beads decorated copper-based coordination polymer particle filter for commercial indoor air cleaner

This paper provided an insight into the dual functionalities of air filter for the removal of multiple volatile organic compounds (VOCs) and Escherichia coli (E. coli) pathogen pollutants. In this regard, a cost-effective and eco-friendly method was developed to grow copper coordination polymer particles (Cu-CPP) onto porous alumina (Al2O3) support, resulting in the formation of Cu-CPP /Al2O3 composite beads. The use of coordination polymer particles can allow more control of the physical and chemical properties of the adsorptive materials at a molecular level through rational selection of metal nodes and organic ligands. Notably, excellent toluene adsorption capacities (256.97 mg g−1) and breakthrough behaviors were observed in Cu-CPP/Al2O3 beads. For the first time, the Cu-CPP/Al2O3 beads air filter was successfully scaled up and installed on a commercial air cleaner with 1 m3 test chamber for various VOCs adsorption. The Cu-CPP/Al2O3 beads air filter exhibited removal efficiency for formaldehyde (99.5%), toluene (99.5%), acetic acid (100%) and ammonia (100%), which are superior to conventional activated carbon. The E. coli was chosen as a model for testing the inactivation performance. The Cu-CPP/Al2O3 beads showed an efficiency of 97.02%, which was substantially higher than that of activated carbon (43.78%) after 120 min of exposure. This research paves the way for the development of multifunctional air filters based on copper coordination polymer particles, which would be excellent for commercial indoor air cleaner applications.

Chemistry and human exposure implications of secondary organic aerosol production from indoor terpene ozonolysis.

Surface cleaning using commercial disinfectants, which has recently increased during the coronavirus disease 2019 pandemic, can generate secondary indoor pollutants both in gas and aerosol phases. It can also affect indoor air quality and health, especially for workers repeatedly exposed to disinfectants. Here, we cleaned the floor of a mechanically ventilated office room using a commercial cleaner while concurrently measuring gas-phase precursors, oxidants, radicals, secondary oxidation products, and aerosols in real-time; these were detected within minutes after cleaner application. During cleaning, indoor monoterpene concentrations exceeded outdoor concentrations by two orders of magnitude, increasing the rate of ozonolysis under low (<10 ppb) ozone levels. High number concentrations of freshly nucleated sub–10-nm particles (≥105 cm−3) resulted in respiratory tract deposited dose rates comparable to or exceeding that of inhalation of vehicle-associated aerosols.

Sustainable applications of textile waste fiber in the construction and geotechnical industries: A retrospect

Textiles and apparel are amongst our primary necessities. The increasing environmental problems associated with the voluminous textile waste discarded in landfills have urged the textile and fashion industries to adopt and implement environmentally sustainable waste management and disposal strategies. The critical need for textile waste diversion from landfills instigated many researchers to seek novel and sustainable solutions for the circular textile economy by its value-addition and beneficial applications. In this review paper, a total of 49 studies were considered to formulate the application-based characterization of textile waste fibers comprehensively, to determine its appropriateness as a composite material in sustainable construction and geotechnical practices. This paper presents a plethora of innovative strategies for the cascaded use of textile fibrous waste by transforming it into non-hazardous secondary raw materials for potential environment-friendly and cleaner applications in the fields of building materials and geotechnical engineering. The findings of this study will help formulate experimentation techniques and methods to develop novel composite materials based on blended textile waste fibers and various other industrial by-products for specific applications.

A cleaner application on hydrogen sulfide

With the increasing industrial production, there was a significant number of toxic and harmful hydrogen sulfide (H2S) gas generated. Due to the industrial activities, converting H2S gas from the waste of industrial process is environmentally attractive. This paper focuses on the conversion of H2S to elemental sulfur (S°) and other sulfur species (i.e., sulfite ion (SO32-); sulfate ion (SO42-) using Fenton reagent. The effects of some reaction parameters such as Fe2+ ion concentration, amount of hydrogen peroxide (H2O2), reaction time, initial H2S concentration and, liquid-gas ratio on H2S conversion percentage were explored thoroughly. The results revealed that the increase of the Fe2+ ion concentration and H2O2 quantity could promote the conversion of H2S. Besides, the comparable results were recorded for each reaction parameter. An apparent positive effect was observed with increasing the amount of H2O2 on H2S conversion. However, the conversion percentage was decreased while increased in the initial concentration of the H2S in the Fenton reactor. It was well accepted that the main conversion pathway of H2S was hydroxyl radical (•OH). Additionally, the oxidative reaction of H2O2 on H2S is thought another removal pathway. The expected products are sulphuric acid and S°.

A novel multigeneration ammonia-based carbon capturing system powered by a geothermal power plant for cleaner applications

This work presents a novel integrated system for the multigeneration of power, space heating, freshwater, and ammonium bicarbonate as a useful chemical commodity with a geothermal-based carbon capturing system. A thermodynamic model based on energy and exergy analyses is developed for this integrated system. The results from the model show that the new carbon capturing unit that is based on an electrochemical ammonia synthesizer requires 13.3% less energy to capture the carbon dioxide released from the solid-oxide fuel cell subsystem than using a combination of proton-exchange membrane electrolyzer and a Haber-Bosch process. Also, the present integrated system produces ammonium bicarbonate sufficiently at a rate of 0.634 kg s−1, when the fuel cell produces 2010 kW of electric power. In addition, the energy and exergy efficiencies of the solid-oxide fuel cell subsystem are found to be 44.5%, and 50.5%, respectively. Then, parametric studies are conducted to see how this integrated system behaves under varying conditions. It is found that the geothermal fluid and the faradaic efficiency of the electrochemical ammonia synthesizer have major effects on the performance of the geothermal-based carbon capturing system and they can lower the energy requirements of the carbon capturing to as low as 8.28 MJ kg−1 of carbon dioxide.

Using zooplankton metabarcoding to assess the efficacy of different techniques to clean-up an oil-spill in a boreal lake.

Regulators require adequate information to select best practices with less ecosystem impacts for remediation of freshwater ecosystems after oil spills. Zooplankton are valuable indicators of aquatic ecosystem health as they play pivotal roles in biochemical cycles while stabilizing food webs. Compared with morphological identification, metabarcoding holds promise for cost-effective, high-throughput, and benchmarkable biomonitoring of zooplankton communities. The objective of this study was to apply DNA and RNA metabarcoding of zooplankton for ecotoxicological assessment and compare it with traditional morphological identification in experimental shoreline enclosures in a boreal lake. These identification methods were also applied in context of assessing response of the zooplankton community exposed to simulated spills of diluted bitumen (dilbit), with experimental remediation practices (enhanced monitored natural recovery and shoreline cleaner application). Metabarcoding detected boreal zooplankton taxa up to the genus level, with a total of 24 shared genera, and while metabarcoding-based relative abundance served as an acceptable proxy for biomass inferred by morphological identification (ρ ≥ 0.52). Morphological identification determined zooplankton community composition changes due to treatments at 11 days post-spill (PERMANOVA, p=0.0143) while metabarcoding methods indicated changes in zooplankton richness and communities at 38 days post-spill (T-test, p < 0.05; PERMANOVA, p≤0.0429). Shoreline cleaner application overall seemed to have the largest impact on zooplankton communities relative to enhanced monitored natural recovery, regardless of zooplankton identification method. Both metabarcoding and morphological identification were able to discern the differences between the two experimental remediation practices. Metabarcoding of zooplankton could provide informative results for ecotoxicological assessment of the remediation practices of dilbit, advancing our knowledge of best practices for remediating oil-impacted aquatic ecosystems while serving to accelerate the assessment of at-risk freshwater ecosystems.

A frequency generator of 40-60 kHz based on arduino for ultrasonic cleaner applications

In this study, the design and implementation of a frequency generator of 40 to 60 kHz based on Arduino were carried out by using the pulse width modulation (PWM) technique for ultrasonic cleaner applications. The components used in the study are Arduino Uno, Stainless Tank, four digits seven segment, 4×4 keypad module, TM 1637 module, dimmer module, frequency generator module, and switching mode power supply (SMPS). Calibration of the voltage, frequency, and vibration strength using are multimeters, Equivalent Series Resistance (ESR) meters, and vibration meters. This study aims to design and analyze ultrasonic generator drivers used an Arduino for controlling frequency and time. The regulated input frequency of 50-200 Hz produces an output voltage of 0.3-4.0 volt and an output frequency of 40-60 kHz from an ultrasonic generator. The output voltage is more stable and precision than the frequency output. The ultrasonic cleaner produced has a very high level of precision and accuracy. The relationship of vibration to frequency is directly proportional, the greater the frequency, the greater the vibration produced. The voltage and frequency are inversely proportional; the greater the frequency, the voltage will be smaller.

Development and performance investigation of a biomass gasification based integrated system with thermoelectric generators

A biomass gasification based multi-generation system integrated with thermoelectric generators is developed and proposed for cleaner applications. The paper presents, analyzes and validates a novel integration of the thermoelectric generators in the proposed biomass gasification based system and discusses the possibility of better efficiency and energy use with reduced carbon emissions. The influences of varying biomass gasification parameters are also studied against the syngas composition. The major subsystems of the integrated system, such as gasification, cryogenic air separation unit, Brayton cycle, heat recovery and domestic hot water production is simulated using Aspen plus while the Engineering Equation Solver (EES) is employed to model thermoelectric generators, proton exchange membrane electrolyzer and organic Rankine cycle. The system operating conditions and their effects on system performance are investigated. The waste heat from the thermoelectric generators is employed to the organic Rankine cycle to produce power and work generated by thermoelectric generators is employed to the proton exchange membrane electrolyzer to produce hydrogen. The amount of hydrogen produced is about 0.13 kg/day, and the amount of heating achieved by the system is 1.4 MW. Likewise, the proposed system is capable of producing 22 kg/s of hot water for the domestic purposes. The overall energy and exergy efficiencies are found to be 58.03% and 32.78%. As compared to conventional systems with thermoelectric generation, the system proposed in this study carries unique and superior characteristics.

Tuning of renewable biomass lignin into high value-added product: Development of light resistant azo-lignin colorant for coating application

The valorization of lignin by virtue of functionalization of its aromatic backbone with different moieties through diazo coupling reaction and its utilization as a leather chemical has been attempted. The 4-aminoazobenzene functionalized lignin based azo polymer (4-AAB-IL) was characterized using Nuclear Magnetic Resonance Spectroscopy (NMR), Heteronuclear Single Quantum Correlation (HSQC), Fourier - Transform Infrared Spectroscopy (FT-IR), UV–visible absorption, and dynamic light scattering techniques. The CHNS analysis reveals the increase in the percentage of nitrogen after diazotization which could have originated from the diazo functional groups. UV–visible absorption spectra of azo-modified lignin exhibit the characteristic features of azobenzene. The photoisomerization of lignin bearing azobenzene from trans→cis isomer was understood from the characteristic UV–visible spectral changes monitored during the course of the reaction. Notably the photostationary state (PSS), an indicator for the extent of trans isomer converted into cis isomer, PSStrans/cis is found to be 92:8 for 4-AAB-IL whereas that of the parent compound 4-aminoazobenzene (4-AAB) is 32:68. This indicates the higher photostability of 4-AAB-IL which would have originated from the restrictions in the structural motions around the diazo moiety imposed by the lignin skeleton, which is essential for the isomerization reaction. Since the azo compounds are evolved as dyes in leather industries, the applicability of synthesized 4-AAB-IL on leather was tested and the results showed excellent light fastening properties even after prolonged irradiation. In addition, the 4-AAB-IL provides darker shade to the crust leather when compared to the 4-AAB, thus these results suggest that functionalization of lignin could pave the way to alter the color of the lignin in a desired way by employing suitable substituents. This functional lignin based colorant would find a new green and sustainable pathway for cleaner application of lignin in coating.

Production, purification and characterization of a proteolytic enzyme from Streptomyces sp. 2M21

The recent application studies on keratinase lead to new application areas for the enzyme to be used in novel industries such as pharmaceuticals and biodegradable composites. Thus, designing an economical and environmentally friendly keratinase production and purification with new features turned into an intriguing objective for its commercialization. In this study, keratinase enzyme was produced using a bioreactor of 5 L by a native Streptomyces sp. 2M21 and purified by ion exchange chromatography using step-wise gradient with 24.1-fold purification. Purified keratinase showed optimum activity at pH 9 and 30 °C. The enzyme was shown to be able to decompose different complex substrates such as chicken feather, wool and nail. Moreover, the addition of DTT enhanced the hydrolysis of wool and chicken feather to 3.4- and 3.2-fold, respectively. The potential of Streptomyces sp. to produce significant levels of keratinase using feathers as a substrate might establish cleaner applications for the production of high value-added products and degrading of keratin-containing wastes.

Active {001} Facet Exposed TiO2 Nanotubes Photocatalyst Filter for Volatile Organic Compounds Removal: From Material Development to Commercial Indoor Air Cleaner Application.

TiO2 nanotubes (TNT) have a highly ordered open structure that promotes the diffusion of dioxygen and substrates onto active sites and exhibit high durability against deactivation during the photocatalytic air purification. Herein, we synthesized {001} facet-exposed TiO2 nanotubes (001-TNT) using a new and simple method that can be easily scaled up, and tested them for the photocatalytic removal of volatile organic compounds (VOCs) in both a laboratory reactor and a commercial air cleaner. While the surface of TNT is mainly composed of {101} facet anatase, 001-TNT's outer surface was preferentially aligned with {001} facet anatase. The photocatalytic degradation activity of toluene on 001-TNT was at least twice as high as that of TNT. While the TNT experienced a gradual deactivation during successive cycles of photocatalytic degradation of toluene, the 001-TNT did not exhibit any sign of catalyst deactivation under the same test conditions. Under visible light irradiation, the 001-TNT showed degradation activity for acetaldehyde and formaldehyde, while the TNT did not exhibit any degradation activity for them. The 001-TNT filter was successfully scaled up and installed on a commercial air cleaner. The air cleaner equipped with the 001-TNT filters achieved an average VOCs removal efficiency of 72% (in 30 min of operation) in a 8-m3 test chamber, which satisfied the air cleaner standards protocol (Korea) to be the first photocatalytic air cleaner that passed this protocol.