The Use of Ultrasounds in the Preparation of Chemosensory Microstructures

In many fields, the goal is to obtain structures with small dimensions in the order of micro/nanometers. Small-sized systems can have countless applications in various industries such as cosmetology, medicine, and nutrition technology. Many techniques are used to obtain the most miniature possible spheres, such as interference with the composition, use of surfactants, or mechanical interference: rapid mixing, increased pressure, and ultrasound. The use of ultrasound in the development of colloidal systems can be an effective method of reducing the size of particles of dispersed phase and influencing the functions they represent. An important aspect here is the time during which the ultrasound is used. In this work, the influence of ultrasound on the chemosensory properties and size of produced ion-sensitive microspheres was investigated and compared. The chemosensory response of the developed microspheres was studied using spectrophotometry and spectrofluorimetry, while the size of the microsphere optodes was estimated by confocal microscopy.

Quantitative Global-Local Mixing for Accessible Skew Products

We study global-local mixing for a family of accessible skew products with an exponentially mixing base and non-compact fibers, preserving an infinite measure. For a dense set of almost periodic global observables, we prove rapid mixing, and for a dense set of global observables vanishing at infinity, we prove polynomial mixing. More generally, we relate the speed of mixing to the “low frequency behavior” of the spectral measure associated to our global observables. Our strategy relies on a careful choice of the spaces of observables and on the study of a family of twisted transfer operators.

Usage of Cicer Arietinum as a local and eco-friendly natural coagulant in sewage treatment and its ability to increase the formation of floc process.

Cicer Arietinum (CA) or chickpea seeds were used as a local natural coagulant, cheap and cultivable which available in Egypt that can be used to reduce turbidity from wastewater, especially sewage water instead of chemical coagulant that causes different diseases like intestinal constipation, loss of memory, convulsions, so this paper represents the use of chickpea as a natural coagulant and eco-friendly in the environment because it assumed to be safe for the human health and efficient in sewage treatment 6, So the researchers advices now to use natural coagulant as coagulant aids which has a higher ability to raise the consistency of floc and prevent of the coagulation operation. The optimum removal conditions that applied on the research were temperature =250C, pH= 3, Contact time=120 min, agitation speed for 2 minutes =80 rpm (rapid mixing), (CA) dosage is 90 mg/L, and (95.89%) turbidity reduction was achieved on the studied area.

Investigating the feasibility of removing the rapid mixing unit in conventional surface water treatment and its effect on turbidity removal

Coagulation and Flocculation processes play a major role in surface water treatment. The aim of this study was to eliminate the rapid mixing unit in the water treatment plant. This experimental study was conducted on turbid water. Turbid water was synthesized by kaolin powder. The conventional Jar Test method was used. The flocculation and sedimentation processes were performed on the turbid water without rapid mixing unit for getting the new optimal condition. When the PACl coagulant was used alone and in conjunction with chitosan, the percentages of turbidity removal in low, medium and high turbidities were obtained 86.7%, 95.8%, 97.8% and 86.67%, 95.73%, 98.26%, respectively. When the rapid mixing unit was emitted, the efficiency of turbidity removal in the low turbidity was reduced from 5.26% to 21.73%. But, in higher turbidity in two states (presence and absence of the rapid mixing units) did not have a significant difference. This study showed that the removal of the rapid mix unit on the removal efficiency of turbidity in the low turbidity is effective, but does not effect on higher turbid water. Also, to use PACl in conjunction with chitosan were effective on the removal efficiency and to reduce of residual aluminum.

Optimal Precipitation Of Zn+₂ and Ni+₂ From Aqueous Solution: Influence Of Rapid Mixing Parameters

Wastewater containing Zn+₂and Ni+₂is normally treated by chemical precipitation, coagulation, flocculation followed by clarification.The metal precipitation is influenced by chemical (wastewater pH, coagulant type and dose) and physical (rapid mixing speed and time) parameters. The process usually consists of the rapid dispersal of a coagulant into the wastewater followed by an intense agitation commonly defined as rapid mixing. This study focused on the most important parameters of rapid mixing design: mixing intensity and duration. Simulated aqueous solutions containing 50 ppm Zn+₂and 50 ppm Ni+₂were treated with aluminum sulphate, ferrous sulphate and ferric chloride coagulants at different doses and different rapid mixing times and speeds. Experimental results obtained indicate that ferric chloride at 30 mg/l dose was superior over aluminum sulphate and ferrous sulphate at the same dose in Zn+₂and Ni+₂removals. Rapid mixing time had a strong influence on the metal removal. An optimal combination of rapid mixing parameters was determined as: 60 s at 100 rpm for Zn+₂and 30 s at 80 rpm for Ni+₂removals. Scanning electron microscopy images for Zn+₂and Ni+₂flocs at optimum parameters of rapid mixing show that ferric chloride addition compacts the surface texture of the metals flocs. Flocs formed by Zn+₂are denser and larger than flocs formed by Ni+₂.

Optimal Precipitation Of Zn+₂ and Ni+₂ From Aqueous Solution: Influence Of Rapid Mixing Parameters

Wastewater containing Zn+₂and Ni+₂is normally treated by chemical precipitation, coagulation, flocculation followed by clarification.The metal precipitation is influenced by chemical (wastewater pH, coagulant type and dose) and physical (rapid mixing speed and time) parameters. The process usually consists of the rapid dispersal of a coagulant into the wastewater followed by an intense agitation commonly defined as rapid mixing. This study focused on the most important parameters of rapid mixing design: mixing intensity and duration. Simulated aqueous solutions containing 50 ppm Zn+₂and 50 ppm Ni+₂were treated with aluminum sulphate, ferrous sulphate and ferric chloride coagulants at different doses and different rapid mixing times and speeds. Experimental results obtained indicate that ferric chloride at 30 mg/l dose was superior over aluminum sulphate and ferrous sulphate at the same dose in Zn+₂and Ni+₂removals. Rapid mixing time had a strong influence on the metal removal. An optimal combination of rapid mixing parameters was determined as: 60 s at 100 rpm for Zn+₂and 30 s at 80 rpm for Ni+₂removals. Scanning electron microscopy images for Zn+₂and Ni+₂flocs at optimum parameters of rapid mixing show that ferric chloride addition compacts the surface texture of the metals flocs. Flocs formed by Zn+₂are denser and larger than flocs formed by Ni+₂.

An asymmetric flow-focusing droplet generator promotes rapid mixing of reagents

Nowadays droplet microfluidics is widely used to perform high throughput assays and for the synthesis of micro- and nanoparticles. These applications usually require packaging several reagents into droplets and their mixing to start a biochemical reaction. For rapid mixing microfluidic devices usually require additional functional elements that make their designs more complex. Here we perform a series of 2D numerical simulations, followed by experimental studies, and introduce a novel asymmetric flow-focusing droplet generator, which enhances mixing during droplet formation due to a 2D or 3D asymmetric vortex, located in the droplet formation area of the microfluidic device. Our results suggest that 2D numerical simulations can be used for qualitative analysis of two-phase flows and droplet generation process in quasi-two-dimensional devices, while the relative simplicity of such simulations allows them to be easily applied to fairly complicated microfluidic geometries. Mixing inside droplets formed in the asymmetric generator occurs up to six times faster than in a conventional symmetric one. The best mixing efficiency is achieved in a specific range of droplet volumes, which can be changed by scaling the geometry of the device. Thus, the droplet generator suggested here can significantly simplify designs of microfluidic devices because it enables both the droplet formation and fast mixing of the reagents within droplets. Moreover, it can be used to precisely estimate reaction kinetics.