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International Journal of Environmental Research
Number of Followers: 0  Hybrid journal (It can contain Open Access articles)ISSN (Print) 1735-6865 - ISSN (Online) 2008-2304 Published by Springer-Verlag  [2469 journals]
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- Box-Behnken Response Surface Design for Modeling and Optimization of
Electrocoagulation for Treating Real Textile wastewater-
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Abstract: Abstract The textile industry uses large amounts of water that becomes wastewater contaminated with salts, starches, acids, peroxides, enzymes, dyes, and other pollutants. Here, we optimized the treatment of textile industry wastewater by electrocoagulation (EC) using aluminum and iron electrodes employing a response surface methodology (RSM) approach. Hence, the effects and interactions of the variables of the process (pH, current density, and reaction time) on turbidity and chemical oxygen demand (COD) removal were evaluated using the Box-Behnken mathematical model in a monopolar batch reactor. Analyses of variance were also performed to estimate model responses and optimum conditions. After determining the mathematically optimized variables of the EC process, its efficiency in the removal of heavy metals and cations from textile wastewater was also evaluated for both the electrodes under study. Experimental data yielded 89.92 and 86.38% in COD removal, and 99.75 and 97.67% in turbidity removal for Al and Fe electrodes. Moreover, the theoretical maximum removals are 93.58 and 87.08% of COD for Al and Fe electrodes and 100% of TB for both electrodes. The removal of U, As, V, Si, P, and Pb was above 90% with both electrode materials. Although both electrodes removed part of the cations, the aluminum electrodes yielded higher removals of Ca+2 and Na+1 (46.19 and 31.94%). Therefore, our study demonstrates that the RSM and Box-Behnken are suitable for optimizing the electrocoagulation process to treat textile wastewater and that the EC is an efficient technology for removing different organic and inorganic pollutants.
PubDate: 2022-06-21
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- Study on the Purification of Pollutants from Rainfall Runoff by
Prefabricated Improved Multi-aggregate Ecological Concrete (IMAEC)
Revetment-
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Abstract: Abstract Ecological revetment can purify rainfall runoff, thus reducing river pollution. Aiming at the problems of complex construction of traditional ecological concrete (TEC) revetment, short seepage path, poor cleaning ability and poor treatment ability of large flow rainfall runoff, multi-aggregate filter ecological concrete and multi-aggregate planting ecological concrete were prepared using adsorption materials as coarse aggregate, and a prefabricated improved multi-aggregate ecological concrete (IMAEC) revetment was designed. The seepage characteristics of the IMAEC revetment and the purification effect of different packing layers on rainfall runoff were explored through laboratory simulation tests. Then, the purification effect and engineering benefit of the IMAEC revetment in practical engineering were analyzed. The results showed that the IMAEC revetment had a rapid seepage rate, no overflow, and outstanding permeability. The seepage path and hydraulic residence time (HRT) of the revetment were prolonged, and the water permeated evenly. The average removal rates of ammonia nitrogen (NH3-N), total phosphorus (TP) and chemical oxygen demand (COD) for the IMAEC revetment at 3.5 × 10–4 m3/s, 6.5 × 10–4 m3/s and 9.6 × 10–4 m3/s flows were 64%, 51% and 42%. The planting ecological concrete layer and filter ecological concrete layer in the IMAEC revetment make outstanding contributions to the purification of runoff. With the increase in runoff flow, the contribution rate of the planting ecological concrete layer to pollutants gradually decreased, while the contribution rate of the filter ecological concrete layer gradually increased. The removal rates of NH3-N, TP and COD reached 76%, 54% and 51% in the engineering application of the IMAEC revetment.
PubDate: 2022-06-21
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- The Impact of Air Pollution and Aeroallergens Levels on Upper Airway Acute
Diseases at Urban Scale-
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Abstract: Abstract Air pollution (AP) represents one of the main environmental threats to public health and exposure to AP has been connected to upper airway (UA) disease. We evaluated the relationships between the ENT urgent referrals recorded at the Hospital of Padua and the daily levels of particulate matter (PM) as well as other environmental factors in a single year. Patients with UA disorders were included in the study group while those referred for facial trauma or foreign body inhalation formed the control group. Daily PM concentrations, meteorological data and the concentrations of the commonest aeroallergens were obtained. 6368 patients formed the study group and 910 the control one. The concentration of compositae allergens showed a positive effect on the total number of admissions (p = 0.001). PM10 did not demonstrate an effect on the total number of admissions or either the study or control groups admissions (p = 0.25). Alternaria positively influenced admissions of patients in the study group (p = 0.005). Significant relationships were found between the following: PM10 measured on the seventh day before A&E admission and rhinosinusitis (p = 0.007), PM10 on the fifth day and laryngitis (p = 0.01), PM10 on the second day and otitis media (p = 0.03), PM10 on the admission day and epistaxis (p = 0.0198). Our study confirms the causal relationship between aeroallergen concentration and ENT admissions. The levels of PM10 at specific days preceding A&E admission correlated with certain UA disorders. This study strongly points towards the harmful effects of pollution and climate change on UA disease.
PubDate: 2022-06-21
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- Temperature-Dependent Speciation Analysis of Chromium Immobilized in
Calcium Hydroxyapatite Matrix-
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Abstract: To develop a green, rapid and energy-efficient route for the toxic waste immobilization, chromium was captured from aqueous system and subsequently solidified using calcium hydroxyapatite (HA) powder. The effect of sintering temperatures on the inter-conversion of Cr(III/VI) species in the HA matrix was investigated by synchrotron X-ray absorption fine structure spectroscopy. The results of X-ray absorption near edge structure showed the gradual transformation of Cr(III) to Cr(VI) oxides from ~ 0 to ~ 100% at sintering temperatures of 100–1150 °C. The extended X-ray absorption fine structure results revealed a typical Cr(III) oxide as the dominant structure at a temperature lower than 500 °C and Cr(VI) oxide structure at higher temperatures. Thus, the oxidation behavior of Cr(III) is strongly dependent on sintering temperatures. Therefore, this study will help to design a waste management route for toxic wastes including Cr(VI) to reduce its leaching from the waste matrix. Rapid oxidation of Cr(III) inside HA matrix may be avoided by adopting low-temperature sintering techniques. Graphical abstract
PubDate: 2022-06-18
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- Application for Reprocessing Cattle, Chicken, and Fish Bones in the
Removal of Zn (II) and Cr (VI) from Wastewater Using Batch Adsorption
System-
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Abstract: Abstract To reduce the daily heaps of bone waste which causes environmental contamination and disposal site constraints, three different types of animal bone waste including (Cattle, Fish, and Chicken) were utilized as adsorbents to remove zinc and chromium metal ions from wastewater. Maximum sorption was found to occur at an initial pH of 5 and 3 h of equilibrium contact time. The maximum uptake of Zn (II) ions onto each adsorbent bone was found favorably 36.25, 25.65, and 30.75 mg g−1 compared to 56.5, 32.7, and 38 mg g−1 for Cr (VI) ions. Results proved that the Freundlich expression model described the isothermal equilibrium process. Thermodynamic analysis revealed that interaction of both Zn (II) and Cr (VI) ions with bone adsorbents progressed physically and spontaneously with an exothermic nature, and exhibited randomness increased during the adsorption process with increasing temperature. In isothermal equilibrium adsorption, chromium ions had an excessive affinity to stay with all adsorbents instead of zinc ions. The removal performance followed the trend Cr (VI)> Zn (II). The kinetic model result data showed that adsorption followed the pseudo-second-order kinetic model with the highest determinant coefficient of 0.9888.
PubDate: 2022-06-17
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- Kinetics and Optimization of Azo Dye Decolorisation Using Green
Synthesized Iron-Oxide Nanoparticles: A Pilot Scale Study-
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Abstract: This study aims at optimizing a scalable process for decolorisation of azo dyes, using IONPs synthesized from EPS produced by the bacterium Alcaligenes sp. The developed process was tested for efficacy on effluents collected from washing units of Sanganer Textile Industrial Area, Rajasthan (India). The nanoparticles were characterized and tested for stability. The decolorisation process was optimized for critical parameters using Taguchi optimization method. The optimized method was then scaled up from 50 ml to a pilot scale of 2 l of effluent in the bioreactor. The mechanism of decolorisation was then evaluated. The characterization of IONPs using XRD and FTIR spectroscopy confirmed that IONPs are Fe3O4 in nature. The IONPs were found to be stable over a period of a year with a consistent zeta potential of − 16 mV. Optimization using Taguchi design revealed that a concentration of 1 gm/l of dye, 2.4 × 1011 particles/ml of IONP, and pH 10.0 were optimum conditions for maximum decolorisation for both the dyes. Thus, at optimum conditions, a maximal decolorisation of 79.88 ± 0.04% and 69.27 ± 0.02% was observed for Azo Violet and Congo Red dye, respectively, with mixed order kinetics. Furthermore, scale-up of the decolorisation revealed 81.40 ± 0.03% of decolorisation at a rate of 1.35 ml/ml IONP/min. The mechanistic study revealed aggregation pattern and size enlargement of the IONPs with change in their functional groups post-treatment which is indicative of adsorption. The above findings point to the feasibility of scalability of the process for treatment of textile industry effluents, thereby contributing to development of technologies toward circular economies. Graphical
PubDate: 2022-06-15
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- Modelling of Streamflow and Water Balance in the Kuttiyadi River Basin
Using SWAT and Remote Sensing/GIS Tools-
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Abstract: Abstract The current study uses remote sensing derived products, high resolution gridded rainfall and temperature, and SWAT inside a Geographic Information System (GIS) to assess the Kuttiyadi River's hydrological response and water balance components. As Kuttiyadi basin lacks a rainfall monitoring station, making hydrological studies difficult. Thus, we used satellite-based rainfall data as a solution to data shortages in the basin. The basin has separated into 104 numbers of hydrological response units (HRUs) based on unique land use, soil, and slope. The available streamflow data was divided for the calibration (2004–2013) and validation (2014–2017) for the modelling of both daily and monthly streamflow. The simulation of the streamflow was observed to be good on the daily time step (R2 = 0.65, NSE = 0.62 and R2 = 0.62, NSE = 0.60 for the calibration and validation respectively) which is further improved for the monthly time step (R2 = 0.90, NSE = 0.80 and R2 = 0.88, NSE = 0.85 for the calibration and validation respectively). During the monsoon, PBIAS value for the daily validations exceeded from the permissible limit due to the higher fluctuations in the daily streamflow. Our modelling results found that NE monsoon has a greater influence than the SW monsoon, generating almost 75% of total surface runoff in the basin. Study of the basin's water balance indicates that surface runoff is more prevalent, and contributes 35% to annual precipitation. The curve number, hydraulic conductivity of a channel and soil water capacity are highly sensitive parameters which showed rapid changes in land-use and hydraulic conductivity of the mainstream channel owing to the bi-directional interaction of the groundwater with the streamflow. The current study found that the PET and ET were fairly high, and that ET accounted for 24% of the total precipitation.
PubDate: 2022-06-10
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- Zero-Waste Approach: Assessment of Aluminum-Based Waste as a Photocatalyst
for Industrial Wastewater Treatment Ecology-
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Abstract: Abstract Alum sludge (AS) is produced in inevitable amounts from drinking water treatment plants. Also, dye-contaminating wastewater is usually discharged from textile industries that must be treated to meet the environmental authorities; thus, Fenton’s reagent is a suitable candidate. However, reducing the quantity of chemicals used in Fenton reactions can be partly achieved by an industrial ecology approach. This paper is introducing alum sludge waste as a photocatalyst, (termed as AS-Fenton), that is prepared under mild experimental conditions. Thermogravimetric and differential thermogravimetric analyses were conducted to attain full illustrations of the thermal treatment steps. Its chemical composition and morphology is revealed using X-Ray Diffraction and Scanning Electron Microscope. Thus, this research is of great significance for the application of a waste by-product for being a Fenton source for photocatalytic removal of Levafix Blue dye effluent. A new modified Fenton reagent was applied with the addition of 1.0 g/L and 800 mg/L of catalyst and H2O2, respectively, at pH 3.0 shows high potential for the dye removal. The starting concentration of the Levafix Blue CA was halved during the first 5 min under the UV illumination. The most effective operating variables are optimized through Response Surface Methodology. The kinetics of the dye removal was investigated and the reaction following the pseudo-first-order regime with the kinetic constant (KF), ranged in 0.04–0.57 min−1. Thermodynamic parameters reveal that the reaction is a non-spontaneous and endothermic in nature. Hence, toxicity of the dye is significantly reduced via Fenton reaction to non-toxic end products.
PubDate: 2022-05-31
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- Modeling and Optimization by RSM for the Removal of the Dye "Palanil
blue R” by Coagulation-Flocculation Process-
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Abstract: Abstract This study aims to optimize the factors influencing the removal of textile dyes by a physicochemical treatment, coagulation-flocculation, using an experimental design. By carrying out the tests and analysing the data, the screening of the factors made it possible to identify the optimum conditions necessary to obtain better elimination. These operating conditions are pH, coagulant dose, the concentration of initial solutions, and stirring speed. Our study demonstrated the importance of applying the design of experiments methodology, particularly the response surface methodology (RSM). A full factorial design allowed the optimization of operational parameters affecting flocculation coagulation.
PubDate: 2022-05-30
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- Algae for Wastewater Treatment and Production of Biofuels and Bioproducts
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Abstract: Abstract The third-generation biofuel production from algae could be the cheapest and most promising alternative compared to other sources of renewable energies. Algae can be effectively grown in a nutrient-rich environment and have the potential to accumulate nutrients and heavy metals from the wastewater, which makes them an extremely attractive means for a more extensive remediation role. Moreover, the algal biomass contains carbohydrates, proteins, vitamins, and other high-value elements and can be used as food and animal feedstock. They have the potential to produce renewable biofuels like biohydrogen and provide a future source of clean energy. The key technical aspects of algal cultivation and harvesting techniques are the major bottleneck for the industrial-scale production of algal biomass and biofuel. This review discussed the current state of large-scale algae cultivation utilizing wastewater as a nutrient source to produce biofuels. Finally, the research progress, the challenges, and the future development trend in this field are summarized.
PubDate: 2022-05-10
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- Multi-objective Optimization Method Based on Deterministic and
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Abstract: This paper presents a multi-objective optimization approach for the security assessment of the water–energy–food nexus considering the involved uncertainty. The proposed optimization approach consists of a hybrid strategy that combines deterministic and metaheuristic optimization approaches for solving this complex problem. The deterministic optimization part of the mathematical model is developed in the platform general algebraic modeling system (GAMS). The metaheuristic part is approached using the improved multi-objective optimization differential evolution algorithm programmed in visual basic for applications. The communication between the different software is implemented using GAMS data exchange files and linking routines. The uncertainty associated with the problem is considered using a code that generates random values of uncertain parameters of the mathematical model. The optimization approach is applied to assess the water–energy–food nexus in an arid region. Three objective functions (one economic and two environmental) were incorporated in the proposed formulation. A case study from a region of Mexico is addressed to show the applicability of the proposed approach. The results of the optimization process offer alternatives that conciliate economic and environmental interests considering uncertainty in weather conditions such as rainfall and solar radiation. The obtained results show a set of solution proposals in which different increases are offered in the satisfaction of the demand for energy and water in different sectors and at the same time, the smallest possible increase in the economic and environmental objective functions. In addition, the proposed methodology is replicable to different case studies where approaching the optimal solution becomes a complicated task. Graphical abstract
PubDate: 2022-04-28
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- Modeling of Industrial Strategy Based on Sustainable Development
Approaches-
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Abstract: Abstract To reach sustainable development depends on paying attention to society's economic, social, and environmental elements, and industrial activities as an activity affecting all aspects of development more than ever need to be studied. This study aims to show a strategic model of sustainable industrial development in the Iran-Yazd province. To achieve the research objectives using two methods of targeted non-probabilistic sampling and snowball sampling, this research has been used the views of experts such as managers and organizational policymakers in industrial estates (industry experts). The framework of this research includes the use of several hybrid models: Analysis of sustainable industrial development strategies; Screening strategies and prioritizing them using fuzzy Delphi technique; development of a strategic industrial model with a sustainable development approach in Yazd province and based on the DEMATEL-ISM model. The research results showed that the sustainable industrial development strategy model in Yazd province has four levels. At the highest level, there is a strategy of "conducting a study plan to identify the world's target markets, for Yazd's goods and services, and to prepare the country's trade guidebooks which act as a layer under the model. Therefore, it is necessary to start sustainable industrial development in Yazd province with the mentioned strategy to provide the ground for implementing the fifteen strategies of this research at a higher level. To analyze the strategies, in the non-fuzzy part of MATLAB software, the Wtavar method has been used, and by analyzing the system's output, the SID + ONTO.ANFIS function based on the input variables, the system behavior was observed in 243 cases. This research can be a model for empowering industrial estates towards sustainable industrial development with a strategic perspective and approach.
PubDate: 2022-04-22
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- Enhanced Electrokinetic Remediation of Cadmium (Cd)-Contaminated Soil with
Interval Power Breaking-
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Abstract: Abstract This study compared electrokinetic (EK) remediation with and without interval power breaking in the removal of total and plant available cadmium (Cd) in the soil. Two laboratory experiments, i.e. EK remediation with interval power breaking (24–12 h power-on-off cycles) and conventional EK remediation (continuous power supply), with the same accumulated time (192 h) of power supply, were conducted to remove soil Cd. After the EK remediation with interval power breaking, the total Cd removal efficiency in the soil rose to 38%, in comparison to 28% after the conventional EK remediation. As for the plant available Cd, the removal efficiency was enhanced from 52 to 63%. Additionally, the electric current during the EK remediation and electric conductivity after the EK remediation were higher in the soil treated by interval power breaking, which indicated an enhanced desorption and/or migration of charged species. It further meant that the higher removal efficiency of soil Cd by interval power breaking could be related to the enhanced desorption and/or migration of Cd species. This study indicated that both conventional EK remediation and EK remediation with interval power breaking were effective methods to remove soil Cd but EK remediation with interval power breaking was more efficient.
PubDate: 2022-04-18
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- Synthesize and Characterize Branched Magnetic Nanoparticles for the
Removal of Pb(II), Cu(II), and Co(II) from Aqueous Solution in Batch
System-
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Abstract: In this research, branched magnetic nanoparticles with dendritic amine groups were prepared and functionalized. These nanoparticles have a clear core–shell structure, uniform size, and high magnetization. The synthesized Fe3O4@SiO2/Branched by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray powder diffraction (XRD), scanning electron microscope (SEM), Transmission Electron Microscopy (TEM), zeta-potential measurement, and vibrating sample magnetometer (VSM) Characterization of nanoparticles. The effects of different factors were studied, including pH, equilibration time, metal concentration, Fe3O4@SiO2/Branched dose, and temperature. The kinetic analysis showed that the adsorption process was successfully adjusted using the pseudo-second kinetic model. The adsorption isotherm data are fitted using a Langmuir model. The adsorption of metal ions on Fe3O4@SiO2/Branched is temperature-dependent and increases with the increase of system temperature, indicating the endothermic and spontaneous nature of adsorption. The maximum adsorption capacities of Pb(II), Cu(II), and Co(II) are 311, 204, and 146 mg/g, respectively. The Fe3O4@SiO2/Branched was regenerated and it was found that the adsorption capacity was not significantly reduced after repeated use for five times in the continuous adsorption and desorption cycle. Graphical abstract
PubDate: 2022-04-16
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- Reliability of the Mass Transfer Factor Models to Describe the Adsorption
of NH4+ by Granular Activated Carbon-
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Abstract: Abstract In spite of the adsorption of a solute onto porous material that can be described using the various models, the reliability of these models supported each other needs to be verified. In this work, the adsorption of NH4+ ions from domestic wastewater treatment plant effluent (DWTPE) onto commercial granular activated carbon (CGAC) was processed both in batch and column experiments. The Freundlich and Langmuir isotherm models and the pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models were used for the analysis of data obtained from batch experiments. The bed depth service time (BDST), Thomas, and modified mass transfer factor (MMTF) models were used to describe the behaviors of NH4+ adsorption by the CGAC adsorbent using the data collected from column experiments. The results showed that batch experimental data better matched by the Freundlich isotherm model and by PSO kinetic model indicate the state of multilayer adsorption supported by electrostatic interaction of NH4+ ions with chemical functional groups on the surface of CGAC. The application and limitations of the BDST and Thomas models in the prediction of NH4+ adsorption behaviors require the MMTF models to predict the adsorption kinetics and mass transfer mechanisms of NH4+ ions transported from the bulk water to acceptor sites on the surface of the CGAC adsorbent. The resistance of mass transfer verified for adsorption of NH4+ onto CGAC is dependent on porous diffusion and this may contribute to the development of such porous material for increasing the removal performance of NH4+ ions from DWTPE.
PubDate: 2022-04-16
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- Simultaneous Ecosystem Benefit and Climate Change Control: A Future Study
on Sustainable Development in Iran-
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Abstract: Abstract Sustainable development is a fundamental and essential need for societies. The obstacles regarding the environment can be understood through sustainable development and the cause of current environmental problems is attributed to a lack of applied practices in this field. To achieve sustainability, ecosystems should be restored in a way that’s both economical and follows an international framework, as they have been degraded in the last two decades. Using ecological sciences and biotechnology for restoration while maintaining sustainable development would prove effective while efficiently restoring ecosystems. Degradation of the environment and climate change issues are global concerns and are not limited to the geographical boundaries of a country. Therefore, the problems concerning Iran’s ecology could affect surrounding countries too. Current ecosystem restoration programs began in the early 1900s. One of the causes of drastic climate changes around the world is that forests and wetlands are being annihilated rapidly. Soil erosion and biodiversity loss, as well as dust and haze management, are the most significant side effects of this annihilation, proving the urgency of effective restorative methods. For decades, environmental committees and organizations have been searching for a solution that is both environmentally and economically beneficial. This paper focuses on seven provinces of Iran (Golestan, Gilan, Tehran, Mazandaran, Ilam, Yazd, Khuzestan) and novelty of sustainable development, ecotourism, agroforestry, and permaculture which were suggested by experts in ecological preservation and sustainability fields. The main focus is to conserve our existing environment and then, to improve them and, finally, to restore the annihilated parts.
PubDate: 2022-04-13
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- Synthesis and Characterization of Nano-CoFe2O4 Ferrite: Application to the
Adsorption of AG25 Dye in Aqueous Solution-
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Abstract: Nano spinel of cobalt ferrite CoFe2O4 (NCF) has been synthesized by Sol–gel auto-combustion method and used as an adsorbent to remove Acid Green AG25 dye from aqueous solution. The NCF was investigated by XRD, Rietveld refinement, SEM coupled with EDX, VSM, FTIR and pH of the zero-point charge pHzpc. The efficiency of the treatment was evaluated according to the characteristic parameters influencing the adsorption process: adsorbent dose, contact time, initial dye concentration, initial solution pH and temperature. The adsorption of AG25 followed pseudo-second order kinetic model. The equilibrium adsorption data fit to the Langmuir isotherm with a maximum capacity of 8.71 mg g−1. Thermodynamic data revealed that the process was exothermic, spontaneous and a physisorption nature. Through the established adsorption process and magnetization measurements, a mechanism was proposed to highlight the idea that the nano spinel of cobalt ferrite material has both magnetic and electronic characteristics. NCF is an efficient adsorbent, low cost, easily synthesized and environmental friendly for removal AG25 from aqueous solution. Graphical
PubDate: 2022-04-07
DOI: 10.1007/s41742-022-00405-w
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- Time Trends and Persistence in US Sea Level Data: An Investigation Using
Fractional Integration Methods-
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Abstract: Abstract This paper analyses US sea level data using long memory and fractional integration methods. Specifically, monthly data for 41 US stations covering the period from January 1950 to December 2018 are examined. Fractional integration methods suggest that all series exhibit orders of integration in the interval (0, 1), which implies long-range dependence with positive values of the differencing parameter; further, significant positive time trends are found in the case of 29 stations located on the East Coast and the Gulf of Mexico, and negative ones in the case of four stations on the North West Coast, but none for the remaining 8 on the West Coast. The highest degree of persistence is found for the West Coast stations and the lowest for the East Coast ones. Thus, in the event of shocks, more decisive action is required in the case of West Coast stations for the series to revert to their original trend.
PubDate: 2022-04-07
DOI: 10.1007/s41742-022-00397-7
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- Synthesis and Characterization of Laccase Enzyme Aggregates From Trametes
villosa for Simultaneous Elimination of Rifampicin and Isoniazid-
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Abstract: Laccase from Trametes villosa was immobilized by CLEAs (cross-linked enzyme aggregates), biochemically characterized and applied for the degradation of the antibiotics rifampicin (RIF) and isoniazid (INH). The extracellular laccase purified by Sephadex G-100 chromatography presented a specific activity of 530.07 U/mg with a purification factor of 6.3-fold. SDS–PAGE followed by zymogram provided a single band, indicating that laccase from T. villosa was a monomeric protein with molecular mass of about 45 kDa. The optimum pH and temperature values for the laccase CLEAs (Lac-CLEAs) were 4.0 and 60 °C, respectively, and they remained more active over a broader range of pH and temperature during 60 min of incubation as compared to the partially purified free form. Lac-CLEAs presented less affinity for ABTS than their corresponding free enzyme, and the values for Km and Vmax were 3.521 mM and 137.0 mM min, respectively. Free laccases and Lac-CLEAs were used for simultaneous biodegradation of 5 mg/L RIF and INH in aqueous solutions. Results obtained by high-performance liquid chromatography (HPLC) revealed that 95% and 94% of RIF were biodegraded by free and immobilized laccase, respectively. Lac-CLEAs degraded more than twofold (71%) the amount of INH degraded by the free enzyme (32%). A microbial susceptibility assay demonstrated a stronger inhibition of Staphylococcus aureus by laccase-treated samples, with lower MIC values in comparison to control samples. Graphical abstract
PubDate: 2022-04-04
DOI: 10.1007/s41742-022-00403-y
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- Adsorption of 4-Nitrophenol onto Iron Oxide Bentonite Nanocomposite:
Process Optimization, Kinetics, Isotherms and Mechanism-
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Abstract: Despite its importance in chemical industry, 4-Nitrophenol (4-NP) is a persistent organic pollutant that has serious effects on the ecosystem. In the present study, Box–Behnken design in response surface methodology was used to optimize the adsorption process parameters for the maximum 4-NP removal at 30 ℃ using Fe3O4/Bt NC. The regression model results suggested that the optimum adsorbent dosage, initial concentration, pH and contact time were 0.3182 g, 85 mg/L, 11 and 137.2 min, respectively. The regression model showed an optimum removal of 100%, while 99.5% removal was obtained from batch experiments at the optimum conditions suggested by the regression model, which confirm the model validity. The adsorption data best fitted to Freundlich isotherm model and Pseudo second-order kinetic model suggesting the existence of physical and chemical interaction between the fabricated composite and 4-NP. FTIR analysis suggested that the adsorption mechanism included an electrostatic attraction and the formation of new chemical bonds. Obtained results suggest that Fe3O4/Bt NC can be an effective adsorbent for complete 4-NP removal at the indicated optimum conditions. Graphical
PubDate: 2022-04-02
DOI: 10.1007/s41742-022-00402-z
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