Contact Time Research Articles

Impact of different phase structure nano Al2O3 arc discharge prepared on MB dye removal

Nanocrystalline ceramic materials have great importance in the field of nanotechnology. Nano-sized materials have properties superior to bulk materials, including improved surface area-to-volume ratio and high strength and toughness. Nano alumina products were prepared in two different phases with different sizes, and shapes via a solid–liquid plasma reactor. Both yields were prepared in identical circumstances, but with different conditions that lead to produce different shapes, and phase structures (γ-Al2O3-NPs with a spherical shape, and δ-Al2O3-Nano-structure rhomboid shape). In this regard, 1.6 million tons of dyes are consumed each year. Trace of dyes in water may cause diseases if it exceeds the WHO limits. This paper describes the adsorption of methylene blue (MB) from aqueous solutions by two different nano structure alumina nano-adsorbents. The optimum contact time, adsorbent mass, and pH were determined, and adsorption isotherms were obtained using concentrations of MB ions ranging from 5 to 50 mg/L. The adsorption process shows significant differences of the coefficient of determination factor R2 for both yields for pseudo-first-order reaction kinetics, as well as Freundlish and intraparticle, film diffusion adsorption isotherms. Our results demonstrate that the adsorption process was spontaneous and exothermic under natural conditions. The maximum capacity of adsorbent for γ-Al2O3-NPs and δ-Al2O3-Nano-structure were 31.56 and 29.49 mg/g, respectively. This study revealed that nano structure γ-alumina was an effective adsorbent for removal of these ions from aqueous solutions.

Effective adsorptive removal of Pb2+ ions from aqueous solution using functionalized agri-waste biosorbent: New green mediation via Seidlitzia rosmarinus extract

Currently, the use of natural adsorbent for the elimination of pollutants, such as heavy metals, from water has been extensively investigated. However, the low adsorption capacity of these natural adsorbent has led researchers towards the use of synthetic surfactants, which can themselves be environmental pollutants. In this research, an investigation was conducted to examine the impact of a surfactant obtained from the Seidlitzia rosmarinus plant on the adsorption properties of Pumpkin seed shell (PSS), a natural adsorbent. As a result, a modified version of PSS, known as Functionalized Pumpkin seed shell (FPSS), was developed, and the effect of these two adsorbents on the elimination of Pb2+ has been investigated. FESEM, EDS, FTIR, and BET analyses were conducted to get detailed information of the adsorbent. Additionally, the effects of contact time, dosage of the adsorbent, pH of the solution, and temperature on the adsorbent were studied. The experimental data was fitted using Langmuir, Freundlich, Temkin, and Jovanovic isotherms. The PSS adsorbent was fitted with the Temkin isotherm, showing an adsorption capacity of 160.80 mg g-1, while the FPSS adsorbent was fitted with the Jovanovic isotherm, exhibiting an adsorption capacity of 553.57 mg g-1. Furthermore, kinetic modeling results indicated that the data for these adsorbents follow pseudo-second-order kinetics. Finally, the impact of coexisting ions and reusability was examined, with the FPSS adsorbent outperforming PSS. Therefore, the investigation of all these aspects demonstrated that the use of this natural surfactant significantly improves the performance of the adsorbent.

Biodegradation kinetics of organic micropollutants in biofilters for advanced wastewater treatment – impact of operational conditions and biomass origin on removal

Biofiltration processes are often part of advanced wastewater treatment (aWWT) technologies for the removal of organic micropollutants (OMP) from conventional wastewater treatment plant (WWTP) effluents. Although biological effects are not always the main focus of these technologies (e.g. filtration through granular activated carbon), they have been shown to contribute significantly to total OMP removal. While OMP biodegradation kinetics in conventional biological wastewater treatment are well researched, no systematic comparison to biomass from aWWT is available. This biomass faces different growth conditions and higher OMP concentrations relative to the background organic matter. Adaptation to these conditions could be possible and could lead to faster OMP biodegradation kinetics, which would show in a larger pseudo first-order biodegradation kinetic constant kbiol. In this work, kbiol values for biomass obtained from aWWT biofilters were determined by evaluating OMP removals measured in lab-scale biofilters using a mechanistic model of the experimental setup. A comparison to kbiol values from literature for conventional wastewater treatment (with nutrient removal) revealed similar OMP biodegradation kinetics without any advantages of biomass from aWWT. A conceptual evaluation of influencing factors on OMP removal in biofilters showed that operational parameters (such as the biomass concentration or the empty bed contact time) and the affinity of OMPs to adsorb on biomass have a significant additional effect on biological OMP removal. Therefore, kbiol values alone are not sufficient to estimate biological OMP removal in biofilters and further information about the system is required.

Adsorptive removal of tetracycline antibiotic by biochars originated in pine leaves (<i>P.kesiya</i>) and rice husk

In this day and age, the excessive use of antibiotics for medical purposes has resulted in antibiotic pollution, which has negative impacts on human health and the environment. Biochars originated in pine leaves (P.kesiya) and rice husk were pyrolyzed to remove tetracycline from aquatic environments. Utilizing physical analysis methods (BET, FT-IR, SEM, and EDX) to determine materialcharacterizations and factors (pH, contact time, initial tetracycline concentration) affecting adsorption efficiency. The adsorption processes of tetracycline onto biochars were fitted by the Langmuir isotherm model. Additionally, the kinetic data of adsorption processes were well-described by the pseudo-second-order model. The maximum adsorption capacities of tetracycline onto biochars originated in pine leaves (P.kesiya) and rice husk were 21,44 and 21,37 mg/g, respectively. Biochars originated in pine leaves (P. kesiya) and rice husk will be potential materials to adsorb antibiotics from aquatic environments.

Evaluation of characterization and adsorption kinetics of natural organic matter onto nitric acid modified activated carbon

Natural organic substances (NOM) found in drinking water are a major contributor to disinfectant by-product formation and are potentially toxic to humans. Traditional water treatment techniques may not always effectively treat NOMs. Therefore, an advanced treatment method such as adsorption can be inexpensive, simple and efficient. The selected adsorbent's and the NOMs properties both affect the removal effectiveness of the adsorption method. Activated carbon (AC), which is widely used in real-scale water treatment plants, has been modified and used in recent years In order to oxidize the porous carbon surface, raise its acidic qualities, eliminate mineral components, and enhance the surface's hydrophilic qualities. In this research, AC was modified with nitric acid (M-PAC) and NOM removal was investigated. In addition, it is discussed how the modification with nitric acid changes the adsorbent structure and chemistry. A morphology with smooth and irregular voids was observed as a result of nitric acid modification of the original AC by SEM analysis. The particle size increased from 387.65 nm to 502.07 nm for the M-PAC adsorbent. The FTIR spectrum indicates that structures connected to aromatic rings get formed in the M-PAC adsorbent as a result of the modification. The highest NOM removal for the original powdered activated carbon (PAC), 47%, was observed at 36 hours of contact time. On the other hand, M-PAC adsorbent achieved 40% NOM removal at contact times of 72 hours and above. It was concluded that the pseudo-second order kinetic model better represented NOM adsorption for both adsorbents.

Erratum to “Variable PFAS removal by adsorbent media with sufficient prediction of breakthrough despite reduced contact time at pilot scale”

Erratum to “Variable PFAS removal by adsorbent media with sufficient prediction of breakthrough despite reduced contact time at pilot scale”

In-silico design of Metal oxide-Biochar composites for enhanced dibenzothiophene adsorption: DFT and statistical physics approach

This study proposes an efficient in-silico adsorbent material selection strategy for clean fuel combustion by leveraging Density Functional Theory (DFT) calculated reactivity parameters to optimize material configurations for enhanced dibenzothiophene (DBT) adsorption from model fuel oil (n-octane). A DFT screening identified TiO2 as the optimal material for DBT adsorption from biochar and four metal oxide (MOx) based on calculated adsorption energies (Eads). Further DFT optimization identified a 10 % TiO2 composition with biochar (TBC10) as the optimal material. This composite exhibited the strongest DBT interaction (−370.3 kcal mol−1) and a remarkably short sulfur-titanium bond (2.64 Å), indicative of an ideal adsorption geometry. Notably, TBC10 features a unique composite structure: TiO2 connected to BC via van der Waals forces, while DBT directly interacts with AC through π-π stacking and covalent sulfur-titanium bonds. To validate theoretical predictions, the designed composites were synthesized and experimentally evaluated. The excellent alignment between experimental adsorption performance and DFT-calculated adsorption energies corroborated TBC10′s superior DBT adsorption capacity. Employing a systematic optimization process, the most effective parameters for TBC10′s DBT removal from a 150 mL solution containing an initial DBT concentration of 45 mg L-1 were established as: a 30 min contact time, an adsorbent dosage of 13 mg, and a temperature of 25 °C. Under these conditions, TBC10 achieved a remarkable removal efficiency (RRDBT) of 99.82 % and a maximum DBT uptake capacity (qDBT) of 31.1 mg g−1. Kinetic and statistical physics modeling revealed a multi-molecular adsorption process with distinct binding sites, characterized by spontaneous endothermic interactions and involving both physical and chemical mechanisms. The in-silico methodology for adsorbent design reduces experimentation time, cost and identifies optimal candidates for DBT removal, enhancing fuel desulfurization and promoting sustainable combustion. This novel in-silico design paradigm holds immense potential for the development of next-generation adsorbents for various environmental remediation and industrial separation processes.

Synthesis and Characterization of Graphene Oxide for Efficient Adsorptive Removal of Hymexazol Pesticide from Aqueous Solutions: Thermodynamic, Kinetic, and Isotherm Studies

Background: Nanomaterials play a significant role in the field of water treatment due to their environment-friendly and appealing physical and chemical characteristics. Objective: The purpose of this research is to evaluate whether graphene oxide adsorbents can effectively remove hymexazol pesticide from an aqueous solution. Methods: Graphene oxide (GO) was prepared by the modified Hummer method, and it was characterized by a number characterization techniques, including XRD, Raman spectroscopy, FE-SEM, TEM, and EDX. Furthermore, the performances of the GO adsorbents for the removal of hymexazol from aqueous solution were investigated. The effect of contact time, GO dosage, initial hymexazol concentration, and temperature was carefully studied. Results: The kinetic experimental data were best described by the pseudo-second-order kinetic model. The equilibrium data were well fitted by the Freundlich and Langmuir isotherm models. The kinetic experimental data were best described by the pseudo-second-order kinetic model. And through the thermodynamic studies, it was found that the adsorption process of hymexazol pesticide is endothermic and spontaneous, in addition to the occurrence of adsorption and absorption together. Conclusions: The findings of the adsorption process demonstrated that graphene oxide is an extremely efficient adsorbent material for pesticide adsorption, owing to its large surface area and the presence of oxygen-rich groups on its surface.

Effect of potassic fertilization on yield of fodder sorghum-sudan grass hybrid and selection of extractants for determination of plant potassium availability

The current study was carried out to assess the effect of potassium (K) fertilization on K-uptake and yield of fodder sorghum-sudan grass hybrid and to choose extractant(s), delineating the K-availability for routine soil testing method. Hybrid sorghum-Sudan grasses were grown in three different soils (red, alluvial, and black) with 100, 50, and 0% recommended K-doses for five seasons. Seven extractants, namely, cold H2SO4, Mehlich-1, 0.1 N CH3COONa, 1 N CH3COONH4 (pH 7), 0.1 N BaCl2, and sodium tetraphenylborate (NaTPB) with 5 and 15 minutes of contact times, were evaluated for elucidating forage K-availability. Results have revealed that biomass yields from all soils were higher (p < 0.05) in K-100% than in K-0%; whereas NaTPB (5 minutes) and ammonium acetate were found as better extractants for the determination of forage K-availability.

Heterogeneous Fenton process using GO@Fe3O4/Cu catalyst for the degradation of reactive dyes from aqueous solutions: modeling and optimisation

ABSTRACT Various industries such as textile, paper, rubber, plastic, and cosmetics use dyes to produce their products. Some dyes used in textile industries are teratogenic, carcinogenic, mutagenic, and dangerous for humans and other organisms. This study aimed to determine the amount of removal of reactive dyes from aqueous solutions during the heterogeneous Fenton process. In this study, iron oxide nanoparticles and copper nanoparticles were loaded on graphene oxide (GO). GO@Fe3O4/Cu catalyst was synthesised and applied to remove reactive dyes from aqueous solutions in a heterogeneous Fenton process. Contact time, pH, catalyst dose, dye concentration, and H2O2 dose were considered effective parameters. Experiments were designed according to the Box-Behnken design in the Design Expert software. Catalyst properties were determined using SEM, VSM, XRD, and FTIR analysis. The ANOVA showed that the selected statistical model with R2 0.965, p < 0.0001, and F-value 27.79 was significant. In the optimal conditions of pH 3, H2O2 dose 0.48 mL, catalyst dose 0.34 g/L, dye concentration 22 mg/L, and contact time 9 min, the degradation efficiency of Reactive Blue 21 (RB21), Reactive Red 195 (RR195) and Reactive Red 19 (RR19) were 92, 97, and 80%, respectively. The results showed that after 5 cycles of recycling, the catalyst had a high efficiency in pollutant removal and could be utilised many times for dye decomposition. GO@Fe3O4/Cu catalyst was successfully synthesised using a simple method. The heterogeneous Fenton process with a magnetic catalyst in the presence of H2O2 has a high potential to remove reactive dyes from the aqueous solution.

Application of artificial intelligence in modeling of nitrate removal process using zero-valent iron nanoparticles-loaded carboxymethyl cellulose.

This study explores nitrate reduction in aqueous solutions using carboxymethyl cellulose loaded with zero-valent iron nanoparticles (Fe0-CMC). The structures of this nano-composite were characterized using various techniques. Based on the characterization results, the specific surface area of Fe0-CMC measured by the Brunauer-Emmett-Teller analysis were 39.6m2/g. In addition, Scanning Electron Microscopy images displayed that spherical nano zero-valent iron particles (nZVI) with an average particle diameter of 80nm are surrounded by carboxymethyl cellulose and no noticeable aggregates were detected. Batch experiments assessed Fe0-CMC's effectiveness in nitrate removal under diverse conditions including different adsorbent dosages (Cs, 2-10mg/L), contact time (t, 10-1440min), initial pH (pHi, 2-10), temperature (T, 10-55°C), and initial concentration of nitrate (C0, 10-500mg/L). Results indicated decreased removal with higher initial pHi and C0, while increased Cs and T enhanced removal. The study of nitrate removal mechanism by Fe0-CMC revealed that the redox reaction between immobilized nZVI on the CMC surface and nitrate ions was responsible for nitrate removal, and the main product of this reaction was ammonium, which was subsequently completely removed by the synthesized nanocomposite. In addition, a stable deviation quantum particle swarm optimization algorithm (SD-QPSO) and a least square error method were employed to train the ANFIS parameters. To demonstrate model performance, a quadratic polynomial function was proposed to display the performance of the SD-QPSO algorithm in which the constant parameters were optimized through the SD-QPSO algorithm. Sensitivity analysis was conducted on the proposed quadratic polynomial function by adding a constant deviation and removing each input using two different strategies. According to the sensitivity analysis, the predicted removal efficiency was most sensitive to changes in pHi, followed by Cs, T, C0, and t. The obtained results underscore the potential of the ANFIS model (R2 = 0.99803, RMSE = 0.9888), and polynomial function (R2 = 0.998256, RMSE = 1.7532) as accurate and efficient alternatives to time-consuming laboratory measurements for assessing nitrate removal efficiency. These models can offer rapid insights and predictions regarding the impact of various factors on the process, saving both time and resources.

The Influence of Simulated Organic Matter on the Inactivation of Viruses: A Review

Viruses impose a significant public health burden globally, and one of the key elements in controlling their transmission is the ability to inactivate them using disinfectants. However, numerous challenges to inactivating foodborne viruses exist due to inherent viral characteristics (such as recalcitrance to commonly used inactivation agents) and external factors (such as improper cleaning before application of inactivation agent, improper contact time, etc.). Given the potential for improper application of disinfectants (such as shorter than recommended contact time, improper disinfectant concentration, etc.), understanding the performance of a disinfectant in the presence of an organic load is important. To accomplish this, the introduction of simulated organic loads is often used when studying the efficacy of a disinfectant against different viruses. However, the different types of simulated organic loads used in foodborne virus inactivation studies or their relative effects on inactivation have not been reviewed. The purpose of this review is to survey different simulated organic load formulations used in studying foodborne virus inactivation, as well as present and compare the influence of these different formulations on viral inactivation. The findings included in this review suggest that many simulated organic load formulations can reduce disinfectants’ efficacy against viruses. Based on the findings in this review, blood, particularly serum or feces, are among the most commonly used and efficacious forms of simulated organic load in many tests.

The modified pomegranate peel as an economical and highly effective adsorbent for malachite green dye removal from wastewater

This research investigated the ability of acid-modified pomegranate peel to remove malachite green (MG) dye from aqueous solutions. Pomegranate peel, an abundant agricultural byproduct, was modified using hydrochloric acid to enhance its adsorption capacity. The effects of parameters like particle size, pH, initial MG concentration, contact time, temperature and adsorbent dosage on the dye removal efficiency were studied. Under optimized conditions of pH 8, 40 min contact time, 25°C temperature and 0.01 g/ml adsorbent dose with 5 mg/L MG solution, about 72478396.8 % dye removal was achieved. Kinetic data fitted well to the pseudo-second order model, indicating chemisorption with electrostatic interactions governing the adsorption. Equilibrium data were best described by the Temkin isotherm model, suggesting a heterogeneous binding energy distribution. Thermodynamic calculations revealed the exothermic and spontaneous nature of MG adsorption. FTIR analysis confirmed introduction of functional groups like carboxyl, amine and alkyl groups on the adsorbent surface after acid modification, enabling interactions with dye cations. SEM images displayed increased surface roughness and porosity for the modified biosorbent relative to the raw form. The acid-modified pomegranate peel proved to be an economical, eco-friendly and effective adsorbent for removing the hazardous cationic dye MG from wastewater. The findings support agricultural waste valorization for environmental remediation applications.

Spatiotemporal parameters and kinematics differ between race stages in trail running-a field study.

Trail running is an emerging discipline with relatively few studies performed in ecological conditions. The aim of this work was to investigate if and how spatiotemporal parameters (STP) and kinematics differ between initial and final stage of a field trial. Twenty trail runners (10 F, 10 M) were recruited and ran a solo 9.1 km trial. During the test, participants wore a GPS watch and an IMU-based motion capture system. Running speed, elapsed time, STP and kinematics were compared between initial and final stage, separately for uphill (UH) and downhill (DH) sections. Running speed decreased in the final stage ( ). Total test time was more correlated to the time elapsed in UH sections. In the final stage and in both UH and DH sections, contact time and duty factor increased, whilst stride length and flight time decreased ( ). In the final stage, ankle joint was more dorsiflexed in stance and swing phases in UH sections and stance phase only in DH sections ( ). In the final stage, knee joint was less extended in swing phase in UH and DH sections, as well as less extended in stance in UH sections ( ). In the final stage, hip joint was less flexed in the swing phase in UH and DH sections ( ). In the final stage, forward trunk lean was higher across the entire gait cycle in in UH sections ( ). Trunk contralateral axial rotation was lower, in DH sections ( ). During the final stage, results indicate a less efficient propulsion phase, in both UH and DH sections. In UH sections, results suggest lower energy generation at the ankle joint. In DH sections, results suggest that the kinematics of swing leg may play a role in sub-optimizing propulsion phase. This study demonstrates how, in UH and DH sections, similar changes in spatiotemporal parameters can be elicited by dissimilar changes in running kinematics. To optimize performance in trail running, coaches and practitioners are advised to work on different (incline-specific) aspects of running technique.

Efficient chromium removal from leather industrial wastewater in batch experimental study: Green synthesis and characterization of zinc oxide nanoparticles using Ficus benghalensis extracts

The urgent need to address the severe environmental risk posed by chromium-contaminated industrial wastewater necessitates the development of eco-friendly cleanup methodologies. Utilizing the Ficus benghalensis plant extracts, the present study aims to develop green zinc oxide nanoparticles for the removal of Cr metal ions from wastewater. The leaves of Ficus benghalensis, often known as the banyan tree, were used to extract a solution for synthesizing ZnO NPs. These nanoparticles were developed with the goal of efficiently eliminating chromium (Cr) from industrial effluents. Batch studies were carried out to assess the efficiency of these synthesized ZnO NPs in treating leather industrial effluent, with aiming for optimal chromium removal. This involved measuring the nanoparticles' capacity to adsorb Cr ions from wastewater samples by comparing chromium levels before and after treatment. Removal efficiency for Cr was estimated through the batches such as optimization of pH, contact time, initial Cr concentration and sorbent dose of ZnO NPs were of the batches. These synthesized ZnO NPs were found to be successful in lowering chromium levels in wastewater to meet permissible limit. The nanoparticles exhibited their highest absorption capacity, reaching 94 % (46 mg/g) at pH 4, with a contact time of 7 hours with the optimum sorbent dose of 0.6 g/L. Hence, the excellent adsorption capabilities of these nanoparticles, together with their environmentally benign manufacturing technique, provide a long-term and efficient solution for chromium-contaminated wastewater treatment. Its novel nature has the potential to significantly improve the safety and cleanliness of water ecosystems, protecting the both i.e. human health and the environment.

Evaluating centrifuged water treatment plant sludge as an adsorbent for nutrients, microorganisms, and heavy metals removal from wastewater

Achieving universal access to clean water, as mandated by SDG 6 – Clean Water and Sanitation, is crucial for supporting human health and environmental sustainability. Water treatment plants generate a by-product known as Water Treatment Plant Sludge (WTPS), comprising organic and inorganic substances. Traditionally, the disposal of WTPS poses environmental risks, including nutrient runoff and heavy metal contamination. This study investigates using centrifuged WTPS, without prior treatment, as an adsorbent to remove contaminants from treated wastewater, offering a sustainable waste management solution. Through comprehensive characterization using Scanning Electron Microscopy, Thermogravimetric Analysis, Fourier Transform Infrared Spectroscopy, and geo-environmental parameter assessment, the research evaluates the adsorption efficacy of WTPS. A factorial design methodology facilitated the systematic examination of adsorption tests. Findings indicate that WTPS exhibits adsorption capacities for phosphorus (q = 0.2 mg g-1), Chemical Oxygen Demand (q = 1.1 mg g-1), and metals under specific conditions. Maximum removal efficiencies for total coliforms and Escherichia coli were achieved with extended contact times, showcasing WTPS's potential as a robust adsorbent. The research demonstrates that centrifuged WTPS can significantly reduce concentrations of metals such as Pb, Co, and Ni (100%), Al (96%), Cu (95%), and Fe (93%) in treated wastewater, presenting a promising approach for enhancing wastewater quality. However, the interaction between WTPS and wastewater resulted in an increased concentration of Mn in the effluent, highlighting the complex dynamics of adsorption processes. In conclusion, centrifuged WTPS emerges as a viable, cost-effective adsorbent, aligning with sustainable waste management practices and circular economy principles.

MOF-derived Co-Al layered double hydroxide modified rice husk biochar nanohybrid for efficient removal of Cu (II) from wastewater

In this study, biochar-derived rice husk (RHB) was modified with Co-Al layered double hydroxide (LDH) derived from Co-based metal-organic framework (ZIF-67) through hydrothermal method to prepare RHB/ZIF-67-derived Co-Al LDH nanohybrid as adsorbent for efficient removal of copper (II) ions from aqueous medium. The nanohybrid was characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, and N2 adorption-desorption. Atomic absorption spectroscopy (AAS) was employed to analyze the concentration of Cu (II) in aqueous solution. In order to investigate the effect of contact time, pH of solution, and adsorbent dose on the removal performance of RHB/ZIF-67-derived Co-Al LDH nanohybrid, batch experimental studies were conducted. The surface adsorption isotherm is well fitted to Langmuir model, and the adsorption mechanism follows the pseudo-second-order kinetic model. In addition, based on the central composite design in the response surface method, the optimal conditions for adsorbent dose, time, pH and initial concentration of Cu (II) are obtained as 2 mg, 3 min, 7 and 50 ppm respectively. In optimal conditions, the nanohybrid shows many advantages including the high removal percent (99.71 %) for Cu (II) ions, excellent adsorption capacity of 1377.94 mg g−1, the ability to reuse for five times, low cost, and compatibility with the environment. The combined properties of RHB and ZIF-67-derived Co-Al LDH provide a large surface area of 849.44 m2 g−1, which increases the contact surface of adsorbent with Cu (II) ions and endows great adsorption performance even in complex environments.

Effect of Electrode Distance, Stirring Speed and Contact Time on Removal of Polyethylene Microplastics (Microbeads) Using Electrocoagulation Method

Abstract: Daily use of personal care products containing microbeads causes severe problems for the aquatic environment. Greywater is a pathway for microbeads to enter domestic waste and wastewater treatment plants (WWTPs) from personal care products. Their tiny size and hydrophobic nature allow microbeads to escape from WWTPs and end up in surface water. Therefore, processing efforts are needed to remove microbeads, one of which is using the electrocoagulation method with aluminum (Al) electrodes. This study aims to evaluate the performance of the electrocoagulation process using Al electrodes arranged in a monopolar configuration in a batch reactor to see the effect of variations in distance between electrodes of 1, 2.5, and 3.5 cm, stirring speed of 150, 200, and 250 rpm; with the contact time 60, 120, and 180 minutes in removing microbeads from artificial wastewater. This research shows that the best efficiency value of 99.30% occurs in operating conditions with a distance between electrodes of 2.5 cm, a stirring speed of 150 rpm, and a contact time of 180 minutes. ANOVA results showed that distance between electrodes, stirring speed, and contact time significantly affected microbead removal efficiency (p&lt;0.05). The results of this research can be a reference for alternative tertiary processing at WWTPs.Abstrak: Penggunaan produk perawatan pribadi sehari-hari yang mengandung microbeads menyebabkan masalah serius bagi lingkungan perairan. Greywater merupakan jalur masuknya microbeads ke dalam limbah domestik dan instalasi pengolahan air limbah (IPAL) dari produk perawatan pribadi. Ukurannya yang sangat kecil dan sifat hidrofobiknya memungkinkan microbeads keluar dari IPAL dan berakhir ke air permukaan. Oleh karena itu diperlukan upaya pengolahan untuk menyisihkan microbeads, salah satunya dengan menggunakan metode elektrokoagulasi dengan elektroda aluminium (Al). Penelitian ini bertujuan untuk mengevaluasi kinerja proses elektrokoagulasi menggunakan elektroda Al yang disusun dalam konfigurasi monopolar dalam reaktor batch untuk melihat pengaruh variasi jarak antar elektroda 1, 2,5, dan 3,5 cm, kecepatan pengadukan 150, 200, dan 250 rpm, dan waktu kontak 60, 120, dan 180 menit dalam menyisihkan microbeads dari air limbah artifisial. Penelitian ini menunjukkan bahwa nilai efisiensi terbaik sebesar 99,30% terjadi pada kondisi operasi dengan jarak antar elektroda 2,5 cm, kecepatan pengadukan 150 rpm, dan waktu kontak 180 menit. Hasil ANOVA menunjukkan bahwa jarak antar elektroda, kecepatan pengadukan, dan waktu kontak berpengaruh signifikan terhadap efisiensi penyisihan microbead (p&lt;0,05). Hasil penelitian ini dapat menjadi referensi alternatif pengolahan tersier di IPAL.

Analysis of Kinematic Variables According to Menstrual Cycle Phase and Running Intensity: Implications for Training Female Athletes

Depending on the phase of the menstrual cycle, different values of running kinematic variables can be obtained. The aim of this study is to analyze whether there are changes in the kinematic variables in running throughout the menstrual cycle and to relate them to running performance and injury prevention. Eight regular female runners and triathletes performed a maximal treadmill test, as well as a submaximal test (6′ stages at 50%, 60% and 80% of maximal aerobic speed) in each of the phases of the menstrual cycle: menstruation phase (day 2.4 ± 0.7), follicular phase (day 10.4 ± 2.2) and luteal phase (day 21.8 ± 2.1). Running dynamics were measured using RunScribe. For parametric data, a general linear model of repeated measures was applied, with two intrasubject independent variables, menstrual cycle phases (with three levels: Menstruation, Follicular, and Luteal) and running intensity (with four levels relative to the maximum speed reached in the test: 100%, 80%, 60%, and 50%). For variables with non-normal distributions, Friedman tests were performed with Wilcoxon post-tests adjusted for significance according to Bonferroni. The maximum stance velocity from foot strike to the point of maximum pronation (°/s) was higher in the menstruation phase than in the follicular and luteal phases (p = 0.008), the step rate (s/min) was higher in the follicular phase than in the menstruation and luteal phases (p = 0.049), the vertical velocity (m/s) was lower in the follicular phase than in the menstruation (p = 0.004) and luteal phases (p = 0.003), and the contact time (ms) was lower in the luteal phase than in the menstruation and follicular phases. These results suggest that training at high intensities could be a factor in greater risk of injury in female athletes, especially in the menstruation phase, finding in the luteal phase and at an intensity of 80% a greater efficiency in the running.

Valorized oxalic acid treated onion peel (Allium cepa) and jute stick (Chorchorus olitorius) wastes for dye removal from tannery effluents

This study employed bio-adsorbents prepared from agricultural waste onion peel (Allium cepa) and jute stick (Corchorus olitorius) to remove anionic dye (Acid Red 73) from tannery wastewater. Increases in pH and temperature exhibited negative impact on dye adsorption, although the adsorbent dose, initial concentration of dye, and contact time had positive effects on the adsorption process. Equilibrium data were fitted with both the Langmuir and Freundlich isotherm models, and the maximum adsorption capacities of the oxalic acid-modified onion peel (OAOP) and jute stick (OAJS) were 151.51 and 133.33 mg/g, respectively at 298 K. Dye adsorption was shown to follow a pseudo-second-order kinetic model (R2 = 0.961 – 0.997 for OAOP and (R2 = 0.945 – 0.999 for OAJS). The adsorption was spontaneous and favorable at various temperatures. The values of ΔH° for OAOP and OAJS were negative (−54.78 and −53.12 kJ/mol), which signify an exothermic process. Moreover, both the adsorbents, showed multilayered physisorption based on isotherm and thermodynamic studies. The used adsorbents were regenerated, and reused with decreasing capacity (78.32 ± 2.78 – 21.37 ± 1.96 mg/g for OAOP and 84.72 ± 3.08 – 24.76 ± 2.66 mg/g for OAJS). The application of adsorbents in real tannery dyeing effluents along were also evaluated and discussed.