Terms Of Contact Time Research Articles

Removal of Crystal Violet Dye from Aqueous Solutions through Adsorption onto Activated Carbon Fabrics

The removal of contaminants from aqueous solutions by adsorption onto carbonaceous materials has attracted increasing interest in recent years. In this study, pristine and oxidized activated carbon (AC) fabrics with different surface textures and porosity characteristics were used for the removal of crystal violet (CV) dye from aqueous solutions. Batch adsorption experiments were performed to investigate the CV adsorption performance of the AC fabrics in terms of contact time, temperature, adsorbate concentration and adsorbent amount. Evaluation of the thermodynamic parameters and the adsorption performance of the AC fabrics in ground water and sea water solutions were also carried out. Langmuir isotherm model, pseudo first and pseudo second order kinetics models were utilized to analyze and fit the adsorption data. The introduction of oxygen-based functional groups on the surface of AC fabrics was carried out through a nitric acid treatment. This oxidation process resulted in a significant reduction in the surface area and pore volume, along with a small increase in the average pore size and a significant enhancement in the CV adsorption capacity, indicating that the dye molecules are mainly adsorbed on the external surface of the carbon fabrics. The herein evaluated 428 mg/g adsorption capacity at 55 °C for the oxidized non-woven AC fabric is one of the highest adsorption capacity values reported in the literature for CV removal using AC materials. Thermodynamic studies showed that the adsorption occurs spontaneously and is an endothermic and entropy-driven reaction. Furthermore, pristine and oxidized non-woven AC fabrics displayed more than 90% CV uptake from sea water samples, underlining the great potential these fabrics possess for the removal of dyes from natural/multicomponent waters.

Modelling and optimization of Victoria blue uptake using response surface methodology (RSM) with novel magnetic folic acid-mannitol/mosquito coil ash nanocomposite

Recently, natural, and environmentally safe polymer-metal oxide hybrid nanocomposites have been increasingly noticed as cost-effective adsorbents for pollutant removal. In this context, a novel hybrid nanocomposite was prepared from a FAM copolymer synthesized by thermal poly-esterification and FAM-MCA/Fe3O4 obtained by the simple in-situ co-precipitation method. Following its structure elucidation using XRD, the nanomaterials were further characterized by FTIR and their surface analysis by using SEM-EDX, TEM and BET methods. The physicochemical characterization of the nanohybrid was accomplished and its performance and effectiveness in removing VB dye from simulated effluents was evaluated. The reaction surface method was used to optimize the operating conditions in terms of contact time (59.9 min), initial concentration VB (60 mg/L), dose of nanocomposite (0.15 g/L), and initial solution pH (6.0). The equilibrium results modelled with nonlinear isothermal and kinetic models complied well with the Langmuir isotherm and pseudo-second-order kinetics with both intraparticle and film diffusion driving the adsorption process. The enhanced adsorption performance of the NC was demonstrated by the significantly higher Langmuir saturation capacity (FAM-MCA/Fe3O4: 279; Fe3O4: 244 mg VB /g) at 303 K compared to other previously reported adsorbents and the strong recyclability while maintaining the adsorption effectiveness of 61.46 % up to five consecutive cycles. Using the deduced thermodynamic parameters, an exothermic, spontaneous, and practicable VB elimination process was established. The adsorption process was principally controlled by electrostatic contact, Yoshida H-bonds, dipole-dipole, n-π stacking, cation-π and, π-π interactions. A complete cost study was performed to assess the economic viability of the adsorbents. FAM-MCA/Fe3O4 was discovered to be the most affordable (551 INR/kg) approach for VB removal. The investigative findings unveiled that the as synthesized hybrid nanocomposite was a potent adsorbent for effective and efficient liquid-phase amputation of VB.

Repeat-exposure in vitro protocol to assess the risk of antimicrobial resistance (AMR) development from use of personal care products: Case study using an antibacterial liquid handwash

The global crisis we are facing with regard to antibiotic resistance has been largely attributed to the overuse and misuse of antibiotics in healthcare and agriculture. However, there is also growing global concern about cross-resistance between biocides and antibiotics. This has made clear the need for more research in this area along with easy-to-perform, but realistic, methods to characterise the potential risk associated with cross-resistance to antibiotics due to biocide use. The primary aim of this work was to develop a repeat-exposure method for predicting bacterial resistance to microbicides, including their cross-resistance to antibiotics. Realism is incorporated in the presented protocol through the use of relevant concentrations and contact times, validated neutralisers, appropriate test organisms and repeat-exposures. The protocol can be applied to formulated microbicides, as shown in the liquid handwash case study presented here. Five bacterial strains were included in the study: Staphylococcus aureus ATCC 6538, Pseudomonas aeruginosa ATCC 15442, Staphylococcus epidermidis ATCC 14990, Escherichia coli ATCC 10536 and Enterococcus hirae ATCC 10541. The protocol parameters used in the case study reflected a worst-case exposure scenario (in terms of contact time and concentration). The results demonstrated that repeated exposure to the liquid handwash would not be expected to lead to development of bacterial resistance or cross-resistance to antibiotics. It is envisaged that this protocol could be used by manufacturers of microbicidal formulations to assess whether repeated use of the test products would contribute to bacterial resistance development or cross-resistance to antibiotics.

Preparation, characterization of chitin-based activated carbon for Orange II removal

Chitin-based activated carbon (CAC) was prepared by a two-step process of carbonization and potassium carbonate chemical activation. The CAC was characterized using scanning electron microscopy (SEM), N2 adsorption/ desorption, Fourier transform infrared (FT-IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The adsorption performance of CAC for Orange II (O II) was evaluated in terms of contact time, adsorption temperature, initial concentration, adsorption kinetics, adsorption isotherms, and thermodynamics. The CAC had a surface area of 1320 m2 g-1 and a total pore volume of 1.10 cm3 g-1. The maximum monolayer adsorption capacity was 1010 mg g-1 at 318.2 K for O II, respectively. Equilibrium isotherms showed that the Langmuir model had a higher coefficient of determination than the Freundlich model. The thermodynamic results indicated that the adsorption process of O II onto CAC 800 was spontaneous and endothermic. Given the results of this work, CAC can be used as an efficient adsorbent for the removal of dyes from wastewater.

In vitro and in vivo removal efficacy of insoluble Prussian blue in combination with calcium polystyrene sulfonate for thallium.

The similarities between thallium and potassium have suggested the use of calcium polystyrene sulfonate (CPS), an oral ion exchange resin, as a potential agent against thallium intoxication. Therefore, the study was an attempt to evaluate the efficacy of CPS and Prussian blue when given alone or in combination against thallium toxicity. The effect on binding capacity was investigated in terms of contact time, amount of CPS, influence of pH, simulated physiological solutions and interference of potassium ions. Also, rats were given single dose of thallium chloride (20mgkg-1) and the treatment with PB and CPS was given for 28days as CPS 30gkg-1, orally, twice a day, PB 3gkg-1, orally, twice a day and their combination. The effect of antidotal treatment was evaluated by calculating the thallium levels in various organs, blood, urine and feces. The results of the in vitro study indicated exceedingly quick binding in the combination of CPS and PB as compared to PB alone. Also, it was found that the binding capacity at pH 2.0 was considerably increased for PB with CPS (184.656mgg-1) as compared to PB (37.771mgg-1). Furthermore, statistically significant results were obtained in the in vivo study as after 7th day, thallium levels in blood of rats treated with combination were reduced by 64% as compared to control group and 52% as compared to alone PB treated group. Also, Tl retention in liver, kidney, stomach, colon and small intestine of combination treated rats was significantly reduced to 46%, 28%, 41%, 32% and 33% respectively, as compared to alone PB treated group. These findings demonstrate this as a good antidotal option against thallium intoxication.

Tremor, finger and hand dexterity and force steadiness, do not change after mental fatigue in healthy humans.

The effects of mental fatigue have been studied in relation to specific percentages of maximal aerobic or anaerobic efforts, maximal voluntary contractions or the performance of sport specific skills. However, its effects on tremor, dexterity and force steadiness have been only marginally explored. The present work aimed at filling this gap. In twenty-nine young individuals, measurement of postural, kinetic and isometric tremor, pinch force steadiness and finger and hand dexterity were performed before and after either 100 min of mental fatigue or control tasks. During the interventions blood pressure, oxygen saturation and heart rate and perceived effort in continuing the task were recorded every 10 minutes. Tremor was analysed in both time (standard deviation) and frequency domain (position, amplitude and area of the dominant peak) of the acceleration signal. Finger dexterity was assessed by Purdue pegboard test and hand dexterity in terms of contact time in a buzz wire exercise. Force steadiness was quantified as coefficient of variation of the force signal. Postural, kinetic and isometric tremors, force steadiness and dexterity were not affected. Higher oxygen saturation values and higher variability of heart rate and blood pressure were found in the intervention group during the mental fatigue protocol (p < .001). The results provide no evidence that mental fatigue affects the neuromuscular parameters that influence postural, kinetic or isometric tremor, force steadiness and dexterity when measured in single-task conditions. Increased variability in heart rate may suggest that the volunteers in the intervention group altered their alert/stress state. Therefore, it is possible that the alterations that are commonly observed during mental fatigue, and that could have affected tremor, steadiness and dexterity only last for the duration of the cognitive task and are not detectable anymore soon after the mental task is terminated.

Environment Friendly and Low-Cost Method for Removal of NO2 from Aqueous Media using Paper Pulp

An efficient and economic method to remove NO2 from aqueous media using paper pulp has been developed. In this context, work has been carried out on analysis of NO2 in laboratory and developing a control technology for its removal using news paper pulp as an adsorbent. Newspapers were collected from the scrap stalls and were used as an adsorbent. The tests are performed in terms of contact time, concentration, adsorbent dosage and temperature. FTIR spectral studies were carried out before and after adsorption of NO2 aqueous solution on the paper pulp. Results revealed that NO2 molecules are completely adsorbed. The developed method can also be implemented to remove NO2 from air pollution.

Adsorption and Desorption Behavior of Ectoine Using Dowex® HCR-S Ion-Exchange Resin

Dowex® HCR-S ion-exchange resin was used to adsorb ectoine in a batch system under varying operation conditions in terms of contact time, temperature, pH value, initial concentration of ectoine, and type of salt. Six adsorption isotherm models (Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, Sips, and Redlich–Peterson) and three kinetic models (pseudo-first-order, pseudo-second-order, and intraparticle diffusion) were used to investigate the ectoine adsorption mechanism of ion-exchange resin. According to the experimental results, the mechanism of ectoine adsorption using an ion exchanger includes the ion-exchange reaction and physisorption. Both the Langmuir and Freundlich models were found to have a high fitting. For the kinetic analysis, the pseudo-second-order and intraparticle diffusion models were suitable to describe the ectoine adsorption. Dowex® HCR-S resin has an average saturated adsorption capacity of 0.57 g/g and 93.6% of ectoine adsorption at 25~65 °C, with an initial concentration of 125 g/L. By changing the pH of the environment using NaOH solution, the adsorbed ectoine on the ion-exchange resin can be desorbed to 87.7%.

Kinetic Modeling Characterization of Cellulose Modified Surface for Methylene Blue Removal from Aqueous Media

AbstractIn this work, commercial cellulose is modified with allylthiourea (Cel‐AT) to remove methylene blue (MB) from aqueous solution. Characterization study includes FTIR analysis along with UV spectrophotometer. A variety of physico‐chemical properties such as kinetic, total sorption capacity loaded and pH effect by using Cel‐AT sorbent is carried out. The main finding is the adsorption total capacity of Cel‐AT for MB is three times more than commercial cellulose (Cel) when the concentration of MB increases in batch mode. In kinetic study, the MB removal efficiency is at 90% after 5 min of removal using Cel‐AT as a sorbent and Cel‐AT fulfil pseudo second order of reaction. The optimum MB removal is at pH 11 with 95% of removal. There is spectral peak which is observed in the spectrum of FTIR and it is addressed accordingly. As a conclusion, the suggested method improves the quality of MB sorption onto the Cel‐AT in terms of contact time and less laborious.

CRUSTACEAN WASTE SHELLS AS ADSORPTION MATERIALS FOR HEAVY METALS IN AN AQUEOUS SOLUTION

Laguna de Bay is one of the country’s major lakes, providing a third of the fish consumed by Metro Manila’s 16 million residents. It also provides support for agriculture, industry, and hydropower generation, as well as providing a welcome respite for many Filipinos. However, because of the lake’s importance, it is threatened by a variety of issues, including pollution. Heavy metals such as mercury and lead are present in high concentrations in the lake. And these heavy metals may persist in fish, water, air and the human body. As a result, an adsorption technique for heavy metal removal in an aqueous solution was investigated. As an adsorbent, the produced chitosan from crustacean waste shells was employed. The study’s parameters were contact time, adsorbent quantity, and pH. Results showed that 0.5 g of chitosan has a higher absorption rate of 99% in 500 mg/L solutions compared to 1.0 g of chitosan with an adsorption rate of 98%. In terms of contact time, 60 minutes showed almost 100% adsorption rate while 120 minutes was 98%. With increasing pH, the amount of metal adsorption rises. This developed chitosan from crustacean waste shells indicates high capacity as adsorbent materials for heavy metals. As a result, it appears to be a viable material for water treatment.

CRUSTACEAN WASTE SHELLS AS ADSORPTION MATERIALS FOR HEAVY METALS IN AN AQUEOUS SOLUTION

Laguna de Bay is one of the country's major lakes, providing a third of the fish consumed by Metro Manila's 16 million residents. It also provides support for agriculture, industry, and hydropower generation, as well as providing a welcome respite for many Filipinos. However, because of the lake's importance, it is threatened by a variety of issues, including pollution. Heavy metals such as mercury and lead are present in high concentrations in the lake. And these heavy metals may persist in fish, water, air and the human body. As a result, an adsorption technique for heavy metal removal in an aqueous solution was investigated. As an adsorbent, the produced chitosan from crustacean waste shells was employed. The study's parameters were contact time, adsorbent quantity, and pH. Results showed that 0.5 g of chitosan has a higher absorption rate of 99% in 500 mg/L solutions compared to 1.0 g of chitosan with an adsorption rate of 98%. In terms of contact time, 60 minutes showed almost 100% adsorption rate while 120 minutes was 98%. With increasing pH, the amount of metal adsorption rises. This developed chitosan from crustacean waste shells indicates high capacity as adsorbent materials for heavy metals. As a result, it appears to be a viable material for water treatment.

The Synthesis of PbS NPs and Biosorption of Pb(II) by Shinella Zoogloeoides PQ7 in Aqueous Conditions

Increasing heavy metal pollution in water continues to endanger human health. The genus Shinella has potential for heavy metal bioremediation but has rarely been studied. In this study, we report that Shinella zoogloeoides PQ7 turns black in the presence of lead ions. Transmission electron microscopy (TEM), Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDS), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) indicated that PbS nanoparticles (NPs) were synthesized by PQ7. Moreover, PQ7 was used as a biosorbent to remove Pb(II) from aqueous solutions. Biosorption performance was evaluated in terms of contact time, pH, biomass dosage and initial Pb(II) concentration. The equilibrium and kinetic data were consistent with the Freundlich isotherm model (R2 = 0.986) and pseudo-second-order model (R2 = 0.977), respectively. The maximum (qmax) Pb(II) adsorption reached 222.22 mg/g, which was higher than that of other bacteria reported in previous literature. SEM–EDS, XRD and Fourier transform infrared (FTIR) analyses also confirmed the adsorption of Pb(II) by the PQ7 cells. In conclusion, PQ7 is a promising strain in removing and recovering Pb(II) from wastewater.

HOGLA LEAF AS A POTENTIAL BIO-ADSORBENT FOR THE TREATMENT OF REACTIVE DYES IN TEXTILE EFFLUENTS

A new bio-adsorbent to remove reactive dyes from textile effluent was investigated in the present study. The adsorbent was the leaves of locally available hogla plant (Typha angustata). Initially, sunfix yellow, a reactive dye widely used in textile effluents, was used to check the removal efficiency in terms of contact time, pH of dye solution and adsorbent dosage. Complete removal (100%) of dye was achieved at adsorbent/dye ratio of 2300:1 at pH 10 with 180 minutes contact time. The adsorbent was then applied to deep colored, raw textile wastewater samples and it was found that 2.3 g of adsorbent was able to convert 100 mL of deep colored wastewater to transparent water at pH 10. Additionally, treatment by the adsorbent resulted in significant decreases in pH, BOD, COD, TS, TDS and TSS of wastewater, while improving the DO level.

Unintentional plagiarism and academic integrity: The challenges and needs of postgraduate international students in Australia

ABSTRACT The rapid increase in the number of international students from different academic backgrounds studying in Australian higher education has required universities to reconsider how to support these students while ensuring academic integrity in new academic settings. The high number of studies on academic integrity and student support programmes at universities shows that unintentional plagiarism is still on the rise, particularly amongst postgraduate international students. Thus, this article reviews the literature with a focus on factors inducing plagiarism by international students at Australian universities. The results highlight the inadequate and insufficient quality of many support programmes in terms of contact time and teaching students about the necessity of attribution and proper ways of referencing. The findings also show that, because of the different practices of education regarding academic integrity throughout the world, simply having high proficiency in English writing skills is insufficient for international postgraduate students to avoid unintentional plagiarism in a new academic setting. Considering these factors, new pedagogical strategies are recommended to help international students become aware of the academic form and context of the target communities and assist them in adjusting, rather than criticising their academic works and undermining their confidence in the new educational system.

Numerical simulation of a drop impact on a superhydrophobic surface with a wire

Superhydrophobic surfaces patterned with macroscale (≈1 mm) structures have gained increasing interest in the past years because of their potential in reducing the contact time between impacting liquid drops and the solid surface. The reduced wettability of these surfaces is of interest in numerous technical applications, as, for example, in anti-icing on airplane wings. Several experimental studies have been carried out on this topic in the literature; on the other hand, only very limited numerical investigations are available in the literature. In this paper, we present a numerical study based on a volume of fluid code for direct numerical simulation of incompressible multiphase flows. A necessary condition for the realization of this study was the implementation of arbitrary-shaped boundaries using a Cartesian grid system. Our implementation of embedded boundaries is based on a volume fraction representation of the boundaries and on a piecewise linear approximation of their surface. The discretized boundaries are then cut off from the computational domain, leading to an altered formulation of the discretized governing equations. To validate the method, we show simulation results for different impact velocities for the case of a droplet impacting on a wire, which has been investigated experimentally in the literature. The simulations show good agreement in terms of contact time and impact morphology, thus, showing the validity of the implementation. Moreover, an extensive analysis of the velocity field for this setup is presented, helping us to better understand the underlying physical phenomena.

Are We Doing What is Best for the Children? Parenting Arrangements on Children's Outcome

In light of the growing research on family diversity, the field of family science has yet another critical topic to explore: the implications of family structures on children’s outcomes. With family policy and laws in many countries providing the option for shared parenting, this research on how children cope in different parenting arrangements comes at a necessary and opportune time. For this special issue, shared parenting is broadly defined as a collaborative arrangement regarding child custody where parental responsibilities for caregiving are shared by parents after divorce or separation occurs. Our first paper examines the co-parenting relationship following divorce with an emphasis on co-parenting support, overt, as well as covert conflict on child outcomes. Parental alienation is discussed in the following two papers – the first examining parental alienation in terms of contact time while the second extends this to an examination of parental alienation as a form of child abuse. The final paper in this set examines how parents make decisions about custody arrangements following divorce through an exchange theory framework.

ADSORPTIVE BEHAVIOR OF LOW-COST MODIFIED NATURAL CLAY ADSORBENTS FOR ARSENATE REMOVAL FROM WATER

Millions of people in more than 70 countries are at risk of developing arsenicosis and otherhealth issues due to consuming elevated arsenic contaminated water. The present study aimed to use naturalclays heated at high temperature and treated with ferrous and ferric solutions through a simple coatingtechnique enhanced by moderate temperature for arsenate uptake from water. BET, XRF, XRD and SEMmethods were applied for the adsorbent characterization. Adsorption experiments were conducted in a seriesof batch systems in terms of contact time, solution pH, initial concentration and the presence of coexistinganions. The results indicated that the adsorption kinetics was better described by the pseudo-second order ratemodel for all adsorbents. All adsorbents exhibited higher arsenate uptake efficiency in the acidic condition.Langmuir model provided the maximum arsenate adsorption capacity of 250µg/g, 429.74µg/g and747.38µg/g for calcined clay (MC), ferric calcined clay (MC-FeIII) and ferrous calcined clay (MC-FeII),respectively. Among added coexisting anions, phosphate (PO3-) significantly decreased the arsenateadsorption capacity of all adsorbents. Overall, regarded to a wide availability of raw materials, simplicity ofthe modification and improvement of arsenate adsorption capacity, modified natural clay adsorbents,especially MC-FeII, could be considered to be effective and low-cost to remove arsenate from water.

Removal of Zn2+ and SO4 2− from aqueous solutions on acidic and chelating dehydrated carbon

The agricultural waste, date palm leaflets, was carbonized chemically using sulfuric acid treatment. Produced dehydrated carbon (DC) was subjected to surface functionalization using ethylene diamine producing chelating dehydrated carbon (CDC). In the process, ∼80% of the carboxylic content on DC was converted to amide successfully. DC acts as a cation exchanger because of the high content of carboxylic groups on its surface showing acidic nature. However, CDC possesses amine and amide groups showing basic nature. Both amine and amide groups are capable of chelating Zn2+ at high pH; however, at low pH, the amine group becomes protonated acting as anion exchanger. Sorption of Zn2+ and SO42- was investigated in terms of contact time, initial pH, concentration, and carbon reuse. Zn2+ shows maximum sorption at initial pH 5; however, maximum sorption of SO42- takes place at initial pH 2. Kinetic and equilibrium studies were carried out at initial 5 and 2 for Zn2+and SO42-, respectively. Sorption kinetics data follow well the pseudo second-order model. The equilibrium sorption data follow the Langmuir isotherm more than the Freundlich isotherm. CDC shows better sorption performance for Zn2+ and SO42- than DC. DC and CDC show combined equimolar removal of both Zn2+ and SO42- at initial pH 2.3 and 2.6, respectively, with efficient recycle properties. Combined removal of Zn2+ and SO42- from spiked municipal wastewater shows less uptake on both carbons than from deionized water.

Lower Limb Power in Young Volleyball Players

The aim of the study is to assess the level of specific lower limb power and reactive force in young volleyball players. The 15 female subjects were involved in three pre-tests: 15s jumps, 30s jumps and stiffness test performed according to the Bosco Protocol by using the Optojump Next System. After a 10-week plyometric training programme, a post-test was applied. Compared to the pre-test, the flight times, contact time, height jumps and power revealed significantly higher scores post-test for 15s and 30s jumps test. No significant differences were observed on any variables for the stiffness test. We conclude that the 10-week plyometric training programme increases the anaerobic power in terms of contact time, flight times, height jumps and power jumps.

Preparation and application of grafted Holarrhena antidycentrica fiber as cation exchanger for adsorption of dye from aqueous solution

Present investigation deals with the removal of methylene blue from waste water using Holarrhena antidycentrica cellulose based cation-exchanger. Initially hydroxyethylmethacrylate was graft copolymerized onto H. antidycentrica cellulose and was converted into cation exchanger through phosphorylation. On optimization of different reaction parameters maximum graft yield obtained was 632.0%. Characterization of the synthesized samples was done by FTIR, SEM–EDX and XRD techniques. Thermal stability of samples was investigated through TGA/DTA/DTG techniques. Dye removal study was done in terms of contact time, initial concentration of dye and dose of cation exchanger. Ion-exchanger was found to be highly efficient for removal of methylene blue with maximum removal of 85%. The results showed that ion exchanger could be employed as effective and low cost eco-friendly material for removal of dyes and color from aqueous solution.