Contact Time Research Articles

Effective removal of textile dye via synergy of adsorption and photocatalysis over ZnS nanoparticles: Synthesis, modeling, and mechanism

In this work, we prepared sulfur-zinc nanoparticles (ZnS-TGA) functionalized with thioglycolic acid by a hydrothermal method and tested their photodegradation ability by solar irradiation. ZnS-TGA were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), high-resolution transmission electron microscope (HR-TEM), UV-Vis spectrophotometer and photoluminescence spectroscopy. In the characterization of these nanoparticles, thioglycolic acid proved to be a strong capping ligand, with a specific surface area of 36.82 m2/g and an average size of 7.15 nm. To test the photocatalytic degradability of the product, methylene blue (MB) was used as a model pollutant. Various operational variables were investigated, including pH, amount of nanoparticles, dye concentration, contact time and temperature. The equilibrium adsorption tests, and the statistical physical calculations allowed the analysis of the energetic and steric variables of the adsorption of MB dye molecules on the surface of these nanoparticles. The equilibrium data were well fitted with Langmuir-Freundlich (L-F) and the adsorption kinetics with pseudo-first order. The maximum adsorption capacity of the MB dye removal process was 30.92 mg g−1 at pH 7 and 298 K, and this process was spontaneous and exothermic. The dye molecules and the surface of the nanoparticles exhibited physical interactions with adsorption energies of 23.31 -25.92 kJ/mol. The photocatalytic activity of these nanoparticles resulted in a dye degradation efficiency of 91.1 % in 180 minutes. The photocatalytic efficiency remained almost unchanged after five consecutive degradation cycles, resulting in a methylene blue degradation of 85 %. According to these results, these environmentally friendly nanoparticles have the potential to purify industrial and urban liquids contaminated with harmful organic compounds such as dye molecules.

Thermodynamics, kinetic study and equilibrium isotherm analysis of cationic dye adsorption by ternary composite

This article investigates the kinetics, equilibrium, and thermodynamics of brilliant green dye adsorption on Fe3O4/CdS/MWCNTs. The effects of adsorbent dosage (0.01–0.06 g), contact time (1–120 min), temperature (278, 288,298 and 308 K), ionic strength (NaCl and CaCO3 salt), and initial solution pH (4,6,7, and 10) were all studied in relation to the adsorption of BG dye. Langmuir (R2 = 0.86883), Temkin (R2 = 0.96323) and Freundlich (R2 = 0.96958) and isotherms were fitted to describe the equilibrium of BG adsorption process. Isothermal models showed that BG adsorption was a favorable process on ternary composite Adsorption kinetics were well fitted by Pseudo-second order kinetic model (R2 = 0.99396). The thermodynamic parameters ΔH° = −0.0277 kJ.mol−1 and ΔS° = −60.9031 J mol−1.k−1 indicate endothermic and spontaneous adsorption process, (ΔG° > 0) non-spontaneous, and exothermic. Five adsorption/desorption cycles were demonstrated by the adsorbents’ high reusability.

Valorizing Moroccan Crab Shells to Purify Water from Orange G Dye: Exploring Equilibrium, Kinetics, and Thermodynamics

A successful approach has been taken to develop a biomaterial derived from fish waste, using Moroccan fish processing by-products from crab shells. Moroccan crab (Portunus pelagicus) shell-derived biomaterial has been developed for wastewater treatment, using marine crustacean waste and addressing the challenges of solid fish waste management. The crab shell powder (CSP) was calcined at 800°C for three hours and characterized using SEM, EDS, FTIR, and XRD, revealing a predominantly crystalline structure. The CSP's effectiveness as a biosorbent for the removal of the anionic dye Orange G (OG) was assessed under various conditions, including pH, biosorbent mass, temperature, and contact time. Optimal conditions achieved a 98.84% dye removal rate within 60minutes at an adsorbent dose of 0.09g. The adsorption process adhered to the pseudo-second-order kinetic model and the Freundlich isotherm, indicating a spontaneous, endothermic surface reaction involving multilayer physisorption. The biosorption mechanism is thought to include electrostatic attractions, n-π stacking interactions, hydrogen bonding, and Yoshida hydrogen bonds. The study suggests that CSP is an efficient, eco-friendly adsorbent for industrial wastewater treatment, offering a promising solution for the valorization of fish waste by-products.

Natural deep eutectic solvent-functionalized multiwall carbon nanotubes for lead removal from wastewater

In this study, two natural deep eutectic solvents (NADESs) were prepared from natural hydrogen bond donors (HBDs) based on sugar, namely fructose and sucrose, alongside H2O, and choline chloride as a hydrogen bond acceptor (HBA). The prepared NADESs were used as functionalizing agents with multiwall carbon nanotubes (MWCNTs), and the functionalized MWCNTs were used as adsorbents of Pb(II) lead ions from aqueous solution. The analyses demonstrated that MWCNTs functionalized with sucrose-based NADES to have more sub-stems and functional groups than the MWCNTs functionalized with fructose-based NADES, providing more possible sites for Pb(II) adsorption. The time dependence of Pb(II) adsorption onto these novel adsorbents was found to be better described by a pseudo-second-order kinetic model. Additionally, the Langmuir model better fits the adsorption data due to its higher coefficient of determination. Finally, the operating conditions (pH, adsorbent concentration, and contact time) were optimized using the Box-Behnken model, which demonstrated pH to exert greater influence on the adsorption process than the other studied factors. To the best of our knowledge, this study is the first to apply NADESs as emerging functionalizing agents for carbon nanomaterials in the removal of heavy metals from synthetic wastewater.

Enhanced adsorption of Congo red dye by CS/PEG/ZnO composite hydrogel: Synthesis, characterization, and performance evaluation

Hydrogels are 3D interconnected network polymer chains that are hydrophilic, swell in water and imbibe a significant amount of water. When hydrogel absorb water, dye molecules transfer to their surface, aiding adsorption. Adsorption is efficient, cheap, and versatile technique to remove dye from aqueous media. In this study, high-performance adsorbents from chitosan/polyethylene glycol (CS/PEG) hydrogel cross-linked with intermolecular H-bonds and chitosan/polyethylene glycol/ZnO (CS/PEG/ZnO) composite hydrogel cross-linked with Zn2+ were developed by an instantaneous gelation method. The prepared composite hydrogels were characterized by Fourier transform infrared (FTIR) spectroscopy, Scanning electron microscopy (SEM), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), transmission electron microscopy (TEM) and Zeta-sizer. The developed composite hydrogels effectively adsorbed Congo red (CR) dye from aqueous media. CR adsorption efficiency using adsorbent dosage, contact time, pH and temperature factors were conducted by batch adsorption experiments. The obtained results for CR adsorption equilibrium were compatible with the Langmuir model with maximum adsorption capacity (qmax) of 212.76 mg/g for CS/PEG and 256.41 mg/g for CS/PEG/ZnO composite hydrogel. The qmax was measured at pH 3 and 25 min and kinetic study confirmed that pseudo 2nd order kinetic model was best followed. Thermodynamic study indicated that the nature of the adsorption phenomena was physical, endothermic and spontaneous. The high adsorption efficiency is mainly ascribed to the protonation of –NH2 groups present in CS/PEG and CS/PEG/ZnO composite hydrogels which enhanced its electropositivity. Hydrogen bond formation and electrostatic attraction among adsorbent and dye govern the adsorption mechanism. It can be concluded that CS/PEG hydrogel and CS/PEG/ZnO composite hydrogels could be considered as efficient, beneficial and potential adsorbents for environmental remediation.

Exploring of new Poly(Thiourea-Amide) as a prospective bismarck Brown Y dye adsorbent: Synthesis via ultrasound irradiation, isotherms, kinetic, thermodynamic, and DFT studies

In this work, a facial ultrasound technique was employed to synthesize poly (N1-((6-aminopyridin-2-yl)carbamothioyl)-N3-carbamothioylisophthalamide) (PTUA) as a new polymer from a condensation reaction of isophthaloyl diisothiocyanate and 2, 6-diaminopyridine. Different techniques were utilized to identify the chemical structure of the synthesized polymer including FTIR spectra, 1HNMR spectra, thermal gravimetric analysis (TGA), Brunauer-Emmett-Teller (BET), and field emission scanning electron microscopy (FESEM). The capability of the synthesized polymer to adsorb Bismarck brown Y (BBY) dye from an aqueous solution was analytically evaluated. Several effective parameters on the adsorption process including contact time, pH, dye concentration, adsorbent dose, and temperature were extensively investigated. The adsorption process was found to be completed with a contact time of 45 min. The results indicated that the optimal adsorption pH was 8 with removal efficiency of 85.331 % and the adsorbed amount of BBY dye increased when the temperature was increased. The adsorption isotherms analysis revealed that the Langmuir model with a correlation coefficient (R2 = 0.9982) was the most relevant to describe the adsorption process compared with the Freundlich model (R2 = 0.9863). By applying the Langmuir isotherm, the maximum adsorption capacity was obtained with a value of 132.39 mg/g. The study of adsorption kinetics showed that the adsorption model of BBY dye onto the polymer surface significantly correlated with a pseudo-second-order model. Based on the thermodynamic studies, the calculated ΔG was negative, ΔH was endothermic, and ΔS was positive, verifying the adsorption process is spontaneous. The desorption percentage of BBY dye was calculated with a value of 81.574 % utilizing methanol as an optimal solvent. The density functional theory (DFT) approach was applied to acquire good understanding for the adsorption process.

Fate and transport of chlorine dioxide: Modeling chlorine dioxide in water distribution systems.

This study aims to conduct a comprehensive analysis of switching disinfectants from sodium hypochlorite bleach to chlorine dioxide (ClO2) in the water distribution system of Geyikbayiri, Antalya. For this purpose, bulk decay rates of ClO2 at various water temperatures were determined in laboratory studies. The study revealed ClO2 bulk decay rates of 0.12639 day-1, 0.17848 day-1, and 0.19621 day-1 at temperatures 15°C, 20°C, and 30°C, respectively. The EPANET, a widely employed computer program for simulating the extended-period behavior of hydraulic and water quality in pressurized pipes, was utilized for the analysis of the fate and transport of ClO2. A hydraulic model was first developed, calibrated, and verified using distinct data sets. The Hazen-Williams friction coefficient of the PSA was determined to be 120 by the trial-and-error method with a mean absolute error (MAE) of 0.408 m. A ClO2 model was then integrated with the calibrated and verified hydraulic model, revealing a wall decay rate of 0.01 m/day and an average MAE of 0.034 mg/l. After calibration and verification of the ClO2 model, several management scenarios were developed, and ClO2 dosing rates were determined. The study showed that ClO2 dosing rates of 0.40 mg/l and 0.45 mg/l should be applied to keep ClO2 concentrations within certain limits. PRACTITIONER POINTS: Disinfectants must maintain a sufficient residual in water distribution systems. Chlorine dioxide requires less contact time and is not affected by pH fluctuations. Modeling serves as a decision-making tool for the management of disinfectants. Bulk and wall decay rates of chlorine dioxide are crucial for management strategies. Chlorine dioxide is a good alternative as a disinfectant in such systems.

Separation of Pd from Pt and Rh by solvent extraction method from waste solution

The paper investigated the possibility of extractive separation of palladium from platinum and rhodium with ionic liquid Cyphos IL 101. A technological solution obtained by dissolving waste materials was used as the test material. Based on the experiments performed, it was found that a 10% (v/v) solution of the Cyphos IL 101 ionic liquid in toluene allows the extraction of both Pd and Pt with an efficiency of 99% from the initial solution when extraction is carried out at the pH 0.5, vorg:vaq phase ratio 1:1 and contact time of 15 min. Moreover, the research proved that it is possible to separate Pd from Pt at the stripping stage using a 0.1 mol/dm3 thiourea solution while maintaining a high selectivity coefficient.

Enhancement of adhesion strength in viscoelastic unsteady contacts

We present a general energy approach to study the unsteady adhesive contact of viscoelastic materials. Under the assumption of infinitely short-range adhesive interactions, we exploit the principle of virtual work to generalize Griffith’s local energy balance at contact edges to the case of a non-conservative (viscoelastic) material, subjected to a generic contact time–history. We apply the proposed energy balance criterion to study the approach–retraction motion of a rigid sphere in contact with a viscoelastic half-space. A strong interplay between adhesion and viscoelastic hysteretic losses is reported which can lead to strongly increased adhesion strength, depending on the loading history. Specifically, two different mechanisms are found to govern the increase of pull-off force during either approach–retraction cycles and approach – full relaxation – retraction tests. In the former case, hysteretic losses occurring close to the circular perimeter of the contact play a major role, significantly enhancing the energy release rate. In the latter case, instead, the pull-off enhancement mostly depends on the glassy response of the whole (bulk) material which, triggered by the fast retraction after relaxation, leads to a sort of ‘frozen’ state and results in a flat-punch-like detachment mechanism (i.e., constant contact area). In this case, the JKR theory of adhesive contact cannot be invoked to relate the observed pull-off force to the effective adhesion energy, i.e. the energy release rate G, and strongly overestimates it. Therefore, a rigorous mathematical procedure is also proposed to correctly calculate the energy release rate in viscoelastic dissipative contacts.

Modification of the Biorelevant Release Testing of Esophageal Applied Mucoadhesive Films and Development of Formulation Strategies to Increase the Mucosal Contact Time.

The increasing prevalence of esophageal disease highlights the clinical relevance of novel, long-lasting mucoadhesive oral dosage forms. The EsoCap device enables targeted local application of films in the esophagus. Biorelevant test systems such as EsoPeriDiss are essential for early formulation development. To this end, the developed and already described release model for simulating the esophagus is being further developed for its potential for biorelevant mapping of the application site through complete tempering and investigation of biorelevant release media. Particularly viscous saliva formulations led to an extension of the retention time. In addition, possible formulation strategies for increasing the retention time of esophageal applied films are being evaluated, such as different film thicknesses, polymer grades and the influence of different active ingredient properties on the retention time. For highly soluble active ingredients, the film thickness represents an option for extending the retention time, while for less soluble substances, the choice of polymer grade may be of particular interest.

Environmentally friendly non-saponification solvent extraction and separation process for RE(III) (RE = Eu, Gd and Tb) in acetic acid solution using HEHEHP/n-heptane

The key to achieving sustainable metal extraction development is to avoid the generation of high-salt wastewater from the source. Here, a new system for the extraction and separation of lanthanide elements Eu(III), Gd(III) and Tb(III) from the acetic acid solution using HEHEHP (2-ethylhexyl hydrogen-2-ethylhexylphosphonate) was studied. The corresponding parameters including contact time, HEHEHP concentration, concentrations of rare earth metal ions and acetic acid in the initial solution, aqueous/organic phase volume ratio (R(A/O)), and temperature were considered to optimize the conditions for the separation of different rare earth elements. The results showed that the separation coefficients of Tb(III)/Gd(III) and Gd(III)/Eu(III) in the acetic acid system were approximately 6.2 and 1.7, with HEHEHP of 0.15 mol/L and R(A/O) of 2:1, and the extraction efficiency of RE(III) reached approximately 73.1%, which was higher than that in the hydrochloric acid and sulfuric acid systems. The mechanism associated with the extraction reaction was evaluated and discussed by the maximum loading capacity method, chromatographic analysis, and FT-IR spectrometric analysis. The mechanism followed a cation exchange reaction and acetic acid did not participate in the extraction process. The feasibility of the separation of Tb(III) from Eu(III) and Gd(III)was also given in terms of the separation coefficients between different elements at different extraction conditions. Since saponification is not necessary in the acetic acid extraction system, it can considerably reduce wastewater discharge to the ecological environment from the source.

Removal of Arsenic and Fluoride Ions from Aqueous Solutions Using Electronic Waste-Derived Absorbents

Printed circuit boards are the fundamental component of almost every electronic device with usage intensifying at an average rate of 8.7%. However, this leads to a generation of 45 million tons of electronic waste (E-waste) annually posing significant and concerning environmental risks. Recycling these waste printed circuit boards (PCBs) is vital, in terms of environmental pollution, prevention and resource recycling. Activating these non-metallic fractions of the printed circuit boards results in the development of unique textural properties and functionalities which resemble aluminosilicates; confirmed by FTIR, XRD, XPS, XRF, and TGA and could potentially be applied for the uptake of fluoride and arsenate. In this study, activated non-metallic powder (A-NMP) was used to investigate various physio-chemical parameters, including contact time, pH, adsorbent dose, and initial concentration to optimize the reaction conditions for the uptake of F− and As(V) from aqueous solutions and, compared its adsorption capacity with other natural and synthetic aluminosilicate. The maximum adsorption capacity come out to be 4.33 mg g−1 and 4.65 μg g−1 for F− and As(V) and best-fit to Langmuir and Freundlich adsorption isotherms, respectively. Kinetic modelling reveal that adsorption of F− follow pseudo-first-order kinetics whereas, As(V) follow pseudo-second-order kinetics. Moreover, intra-particle diffusion revealed a chemisorption-controlled process for both the adsorbates. However, in a binary component system, the F− and As(V) showed the maximum percentage removal of 92% and 76%, respectively at pH 5, and best-fit to Langmuir adsorption isotherm.

Development and validation of an adsorption process for phosphate removal and recovery from municipal wastewater based on hydrotalcite-related materials

In the current international context characterized by the tendency to stricter limits for P concentration in treated wastewater and a strong drive towards phosphate recovery, it is crucial to develop cost-effective technologies to remove and recover phosphate from municipal wastewater (MWW). In this study, an initial screening of the phosphate adsorption performances of 9 sorbents including several hydrotalcites led to the selection of calcined pyroaurite - an innovative material composed of mixed Mg/Fe oxides - as the best-performing one. The assessment of calcined pyroaurite by means of isotherms and continuous-flow adsorption/desorption tests conducted with actual MWW resulted in a high P sorption capacity (12 mgP g−1 at the typical phosphate concentration in MWW), the capacity to treat 730 BVs at the 1 mgP L−1 breakpoint imposed by the current EU legislation, and a 93 % phosphate recovery. Calcined pyroaurite resulted in satisfactory performances also in a test conducted with a saline MWW deriving from a hotspot of seawater intrusion, a rapidly increasing phenomenon as a result of climate change. Five consecutive adsorption/desorption cycles conducted in a 20-cm column at a 5-min empty bed contact time resulted stable in terms of P adsorption/recovery performances, specific surface area and chemical structure of calcined pyroaurite. In the perspective to apply phosphate recovery with calcined pyroaurite at full scale, the process scale-up to a 60-cm packed bed - close to the column heights of industrial applications - resulted in stable performances. Calcium phosphate, widely used to produce phosphate-based fertilizers, can be obtained from the desorbed product by precipitation with Ca(OH)2. These results point to calcined pyroaurite as a very promising material for phosphate removal and recovery from MWW and from other P-rich effluents in a circular economy perspective.

Ethanol conversion to hydrocarbons over Sn-doped H-ZSM-5 zeolite catalysts

Sn-based zeolite have been prepared by incipient wetness impregnation by studying the role of the starting precursor either Sn(II) or Sn(IV) chlorides. Catalysts have been deeply characterized through XRD, FT-IR, UV-vis NIR, SEM-EDXS, FE-SEM-EDXS, and IR of probe molecules i.e. pyridine and CO by also investigating the reaction at the surface in static conditions. As well catalytic activity has been carried out by investigating the role of GHSV that has been varied between 2700-8500 h-1, obtaining linear variation of product distribution as a function of contact time. Small amounts of Sn improve the catalytic activity of H-ZSM-5 zeolite in converting ethanol to higher hydrocarbons. In particular, the addition of Sn4+ ions increases the conversion of ethanol to C6-C8 aromatic hydrocarbons up to a very interesting 34% selectivity at 100% ethanol conversion. In fact, bioethanol conversion over Sn-H-ZSM-5 zeolite represents a potentially interesting way to produce a high-octane biogasoline, as well as aromatic (BTX) cut useful as a renewable intermediate in future biorefinery-derived processes. It is proposed that ethylene, the main product, is the key intermediate in the acid-catalysed route, and Sn-ions are favoring the cyclization and dehydrogenation of ethylene-derived oligomers.

Synthesis, characterization and As(III) scavenging behaviours of Mango peel waste loaded with Zr(IV) ion from contaminated water

Raw mango peel (RMP) was first saponified to yield saponified mango peel (SMP), which was then loaded with Zr(IV) ions to form a biosorbent for As(III) scavenging.The biosorption behaviors and mechanisms of As(III) scavenging using RMP and Zr(IV)-loaded saponified mango peel (Zr(IV)-SMP) were investigated batchwise. The As(III) scavenging efficiency of RMP increased from 20.13% to 87.32% after Zr(IV) loading. Optimum contact time of 6 hours has been investigated for As(III) scavenging by Zr(IV)-SMP, and the data on kinetics is well fitted to the pseudo-second-order (PSO) model. Similarly, isotherm data of Zr(IV)-SMP fitted well to the Langmuir isotherm model with the maximum As(III) scavenging potential of 45.52 mg/g. Chloride (Cl⸻) and nitrate (NO3⸻) have negligible influence on As(III) scavenging, but sulphate (SO42⸻) interferes significantly. The exhausted Zr(IV)-SMP could be easily regenerated by treating with 2MNaOH. A mechanistic study indicates that As(III) scavenging is primarily contributed to electrostatic interaction and ligand exchange, which is confirmed from both instrumental and chemical characterizations techniques. Tubewell underground water polluted with a trace amount of arsenic (98.63 μg/L) could be successfully lowered down to the WHO standard (10 μg/L) by applying a small amount of Zr(IV)-SMP. Therefore, the Zr(IV)-SMP investigated in this work can be a low-cost, environmentally benign, and promising alternative for scavenging trace levels of arsenic from contaminated water.

Synergistic effect of CaCO3 particles and porous carbon towards the removal of Zn2+ ions in aqueous solutions

This work describes the preparation of an adsorbent containing CaCO3 particles dispersed in activated carbon and its use for the removal of Zn2+ ions from aqueous solutions. The combination of the large porosity of the activated carbon support with the easy ion exchange occurring at the surface of the carbonate particles led to the achievement of fast adsorption kinetics and excellent ion removal capacity for the composite adsorbent. The material was synthesized by wet impregnation of the porous carbon support with an aqueous solution of Ca(NO3)2, followed by evaporation of the solvent with subsequent heat treatment in an inert atmosphere. X-ray diffraction results demonstrated the presence of CaCO3 crystals in the material, but with broad and low intensity diffraction peaks, corresponding to an average crystallite size of 20 nm; solid-state 13C NMR spectroscopy confirmed the presence of this phase by means of the identification of the signal relative to the 13C nuclei of the CO32− group at ∼170 ppm. The carbon-based adsorbent containing the CaCO3 particles showed excellent ability to remove Zn2+ ions from aqueous solutions, with essentially all ions removed after 30 min of contact time. In addition, the kinetic analysis data were properly fitted using the pseudo-second order model, pointing to the occurrence of chemisorption as the rate limiting of the process. The equilibrium adsorption isotherms were correctly described by the Langmuir model, indicating that the adsorption takes place with the formation of a monolayer on the adsorbent surface. The results evidenced a synergistic effect of the porous carbon and the CaCO3 particles regarding the Zn2+ ions removal, with a fast adsorption kinetics at the initial stage of adsorption attributed to the high availability of the dispersed CaCO3 particles on the carbon surface.

Potential effects of host competence and schooling behavior on parasite transmission in a host-pathogen system: a test of the dilution effect

High species diversity in a community may reduce the risk of infectious disease, termed the dilution effect. However, the generality of the dilution effect in different disease systems remains controversial as both host competence and behaviors of hosts may play roles in dilution or amplification of disease. Using the goldfish (Carassius auratus)-monogenean ectoparasite (Gyrodactylus kobayashii) system, effects of host competence and schooling behavior on parasite transmission were investigated while holding focal host density constant. Following competency tests of 12 fish species as potential hosts for the parasite, infection by G. kobayashii was determined on fins of goldfish mixed with each of three different species based on their level of host competence, including Prussian carp, Carassius gibelio (low competence), grass carp, Ctenopharyngodon idellus (non-competent), swordtail, Xiphophorus helleri (non-competent), and the four species combined. Compared with mean abundance (85.8 ± 25.1) on goldfish in the control group, the mean abundance on goldfish decreased significantly when paired with 10 Prussian carp (30.0 ± 16.5), but did not differ significantly when paired with 10 swordtail (70.0 ± 22.2), 10 grass carp (116.1 ± 33.2), or the multi-species of three Prussian carp, four grass carp and three swordtail (75.9 ± 30.8) during the 11-day experiment. The parasite was also found on the Prussian carp in the Prussian carp group and the multi-species group at a mean abundance of 7.1 and 10.9, respectively. Video recording showed that the school of goldfish mixed well with the Prussian carp, while they maintained separation from the grass carp and swordtail when mixed together. The distance between goldfish increased, and swimming speed and contact time decreased with the additional of other fish species for all groups. The results suggested that the presence of a low-competence host in sufficient numbers was a necessary condition for a dilution effect due to encounter reduction, and the dilution effect may also be enhanced by changes in schooling behavior of goldfish in the presence of low competence hosts. However, the presence of non-competent hosts did not result in any dilution effect owing to the specialist nature of the parasites and the lack of mixing with schools of goldfish.

Reactive extraction of muconic acid by hydrophobic phosphonium ionic liquids - Experimental, modelling and optimisation with Artificial Neural Networks

Muconic acid is a six-carbon dicarboxylic acid with conjugated double bonds that finds extensive use in the food (additive), chemical (production of adipic acid, monomer for functional resins and bio-plastics), and pharmaceutical sectors. The biosynthesis of muconic acid has been the subject of recent industrial and scientific attention. However, because of its low concentration in aqueous solutions and high purity requirement, downstream separation presents a significant problem. Artificial Neural Networks and Differential Evolution were used to optimize process parameters for the recovery of muconic acid from aqueous streams in a system with n-heptane as an organic diluent and ionic liquids as extractants. The system using 120 g/L tri-hexyl-tetra-decyl-phosphonium decanoate dissolved in n-heptane, pH of the aqueous phase 3, 20 min contact time, and 45 °C temperature assured a muconic acid extraction efficiency of 99,24 %. Low stripping efficiency compared to extraction efficiency was observed for the optimum conditions on the extraction step (120 g/L ionic liquids dissolved in heptane). However, re-extraction efficiencies obtained for the recycled organic phase in three consecutive stages were close to the first extraction stage. The mechanism analysis proved that the analysed phosphonium ionic liquids (PILSs) extracts only undissociated molecules of muconic acid through H-bonding.

Removal of ibuprofen and paracetamol from water using a blend activated carbon from paper waste and avocado seeds

The presence of pharmaceuticals in water is a major problem worldwide. To alleviate this, this study produced carbon blends from avocado seeds and paper waste and activated them with hydrogen peroxide (H2O2), nitric acid (HNO3) and potassium permanganate (KMnO4). The effectiveness of the adsorbents was tested in removing ibuprofen (IBU) and paracetamol (PRC) from water. Characterization of the adsorbents by SEM, BET, FTIR and TGA revealed that the morphology was porous, with a large surface area and several functional groups bound to the surface. The concentration effect experiments showed that the uptake of IBU and PRC increased with an increasing initial concentration and that these data were consistent with the Freundlich model. The contact time effect showed that the uptake of PRC was rapid in the initial phase for all the adsorbents. However, the rate gradually slowed down and equilibrium was reached after 40 min for BCMN, 60 min for BCMH and BCMP and 120 min for BCM. IBU, on the other hand, showed that equilibrium was reached after 30 min for BCMN, BCMH and BCMP and after 120 min for BCM. These data complemented the PSOM. The model is based on chemisorption, where electrons are transferred and shared, and hydrogen bonding and π-π interactions. The △Ho value confirms that the sorption of IBU and PRC was endothermic. The △So was positive, indicating greater freedom at the solution interface during uptake.

Droplet Impact on Superhydrophobic Mesh Surfaces.

Reducing the contact time of droplet impacts on surfaces is crucial for various applications including corrosion prevention and anti-icing. This study aims to explore a novel strategy that greatly reduces contact time using a superhydrophobic mesh surface with multiple sets of mutually perpendicular ridges while minimizing the influence of the impacting location. The effects of the impact Weber numbers and ridge spacing on the characteristics of the impact dynamics and contact time are studied experimentally. The experimental results reveal that, for the droplet impact on mesh surfaces, ridges can segment the liquid film into independently multiple-retracting liquid subunits. The retracted subunits provide the upward driving force, which may promote the splashing or pancake bouncing of droplets. At this point, the contact time has a negligible sensitivity for the impacting position and is significantly reduced by up to 68%. Furthermore, the time, dynamic pressure, and energy criteria for triggering splashing and pancake bouncing are proposed theoretically. This work provides an understanding of the mechanism and the design guidelines for effectively reducing the contact time of the impacting droplet on superhydrophobic surfaces.