Establishment of electrochemical treatment method to dye wastewater and its application to real samples

It is of great significance to study the treatment of organic dye pollution. In this work, a method of electrochemical treatment for reactive blue 19 dye (RB19) wastewater system was established, and it was applied to the actual dye wastewater treatment. The effects of applied voltage, electrolyte concentration, electrode spacing, and initial concentration on the removal effect of RB19 have been studied in detail. The results show that the removal rate of RB19 can reach 82.6% and the chemical oxygen demand (CODcr) removal rate is 54.3% under optimal conditions. The removal of RB19 in the system is mainly the oxidation of hydroxyl free radicals. The possible degradation pathway is inferred by ion chromatography: hydroxyl free radicals attack the chromophoric group of RB19 to make it fall off, and then decompose it into ring-opening. The product is finally oxidized to CO2 and water. The kinetic fitting is in accordance with the zero-order reaction kinetics. At the same time, using the established electrochemical system to treat the actual dye wastewater has also achieved good results. After 3 hours of treatment, the CODcr removal rate of the raw water is 44.8%, and the CODcr removal of the effluent can reach 89.5%. The degradation process conforms to the zero-order reaction kinetics. The result is consistent with the electrochemical treatment of RB19.

Kinetic modeling of the biodiesel production process using neem seed oil: An alternative to petroleum-diesel

Promoting the green technology campaign that would actualize a biorefinery establishment and would promote cleaner fuel production and air in our environment. This study carried out kinetics studies of biodiesel production over a mixed oxide, Ca-Mg-O catalyst, providing relevant kinetics parameters. This study indicated that biodiesel production is a zero-order reaction, a process independent of the concentration. The results obtained from this study confirm the activation energy, Ea, of the reaction to be 406.53 J/mol, while the pre-exponential factor A was found to be 0.01618 1/min (or 0.9 1/h). Other are kinetics models that were developed for the prediction of the reaction kinetics for the production process is also reported in this study. The findings reported in this study would go a long way to facilitate the modeling, simulation, and design of the biodiesel production process.

Study the Polymerization Kinetics of Polyaniline by UV-Vis and HPLC and Determination of the Thermodynamic Functions using Coats-Redfern Equation from TGA Curves

This study includes the preparation of the polyaniline at the laboratory temperature in an acidic medium. The Scanning Electron Microscopy (SEM) analysis of Polyaniline shows smooth surface and uniform nanoparticles formation with diameters of 56.4 to 90 nm. The polymerization of polyaniline kinetics was studied with two methods: UV-Vis, HPLC. Then the polymerization of polyaniline reaction order was determined and it was the zero-order reaction (n=0) in both of the previous two methods. The study of thermal dissociation indicates the temporal stability of chemicals, and study the decomposition kinetics to determine the thermodynamic functions of material disintegration. There are many methods use mathematical equations applied to TGA to study this phenomenon. The thermodynamic functions of the prepared polymers such as (G*, S*, H*) were determined based on Coats-Redfern equation from TGA curves of the compounds at each step of the disintegration.

DEVELOPMENT OF THE CONDITIONS FOR STORING THALLIUM AMALGAM

It has been established that lNH2SO4 solution and distilled water can be used as a protective medium for a long-term storage (30-40 days) of thallium amalgam of eutectic composition (8.6 mas.%), without sliming of its surface and an insignificant change of its concentration. An inverse dependence between the decomposition reaction rate and the ratio of the solution volume per unit of the contact surface (V:S), which corresponds to the height of the liquid layer (h) above the amalgam, is observed. At h ~ 2.5 cm and higher, the reaction rate becomes stabilized. The value of metal loss during its storage for 10-15 days does not exceed 0.5-1.0 mas.% of the initial thallium content in the amalgam. It has been shown that the rate of dissolution of thallium from amalgam is rather low, and in sulfuric acid solution it is only slightly higher than that in water with all S:V ratios. A similar picture is observed upon thallium amalgam decomposition in the same media in an open vessel; the difference consists only in a higher K value (Table 4). Thus, with S:V = 1:2.5, in an open vessel K in lNH2SO4 makes up 10,5.1011 mol/cm2.sec, and in H2O – 7.3.1011 mol/cm2.sec, whereas in a closed vessel K in lNH2SO4 makes up 1,9.1011 mol/cm2. sec, and in H2O – 1.5.1011 mol/cm2.sec. For 40 days of thallium amalgam (8.54 mas.%) storage in 1NH2SO4 the loss of thallium has been 1.3 mas.%, and in the distilled water - 1 mas.%. The quantity of the dissolved metal increases in proportion to the experiment duration, which is characteristic for a zero-order reaction, and this dependence is observed for all S:V ratios from 1:1 to 1:7. Besides, a possibility to use some saturated hydrocarbons, wherein no sliming of thallium amalgam occurs, as a protective wash liquid has been shown.

Kinetic Study of Iodination of Propanone in Different Acidic Medium by using Colorimeter

Aims: This study aims at the Kinetic Study of Iodination of Propanone in Different Acidic Medium by using Colorimeter. Background: The kinetic experimentation of iodination of propanone has been performed in presence of different acids such as sulphuric acid, hydrochloric acid and acetic acid. The rate law of the iodination of propanone in acidic medium is determined by observing the disappearance of the brownish yellow colour of iodine in aqueous solution. Objective: The objective of this study is the preparation of standard solution, determination of absorbance of iodine solution at λmax= 480 nm, Kinetic study of iodination of propanone with different acidic medium. Method: The kinetic analysis of this reaction has been carried out by colorimetry. The extent of the reaction has been monitored by measuring the absorbance of the reaction mixture after a suitable time interval. Result: The rate law expression is determined to be rate = k [〖"propanone]" 〗_0^0.728 [acid]0. The rates of iodination of propanone in presence of different acidic medium are H2SO4 > HCl > CH3COOH. Conclusion: The rate of the reaction is found to be independent of the concentration of iodine i.e. it is zero order reaction with respect to iodine. However, it depends on the concentration of propanone and acid catalyst. Other: By using this experimental technique, the consumption of chemicals is very less.

An Engineered Contact Lens for Passive and Sustained Release of Lifitegrast, an Anti-Dry Eye Syndrome Drug

Lifitegrast is an FDA-approved drug that inhibits T-cell mediated inflammation associated with dry eye syndrome (DES). Lifitegrast is a potent inhibitor of the interaction between LFA-1 on T-cells and ICAM-1 on endothelial cells at the ocular surface. While effective in treating DES, 5% (81.2 mM) lifitegrast has low drug utilization and elicits off-target effects. Here we engineer contact lenses to release therapeutically relevant doses of lifitegrast to every tear film for up to 10-hours. Lifitegrast is coupled to the polymer of the soft hydrogel lens via a photolabile (caged) crosslinker. Exposures of the lens to the 400-430 nm wavelengths of indoor daylight excite the caged crosslinker molecules and trigger a bond-cleavage reaction that releases authentic lifitegrast passively to the tear film. The photoproduct of the reaction remains chemically linked to the polymer of the single-use lens. Our studies show that passive exposures of the lens to indoor light would generate an average of 990 nM lifitegrast to every tear film in a zero-order reaction for up to 10-hours. This concentration exceeds the Kd for the interaction between ICAM-1 and LFA-1 by ~330-fold and would sustain inhibition of inflammatory responses at the ocular surface. The amount of lifitegrast released from the lens increases during exposures to outdoor sunlight. Over a 10-hour exposure to indoor light, a single lens would release 0.44% of the lifitegrast present in two drops of commercial 5% lifitegrast. Compared to tear-drop approaches, our engineered lenses would sustain the passive delivery of therapeutically relevant doses of lifitegrast over a longer period, and exhibit improved drug utilization at a lower cost. Our technology could easily be integrated into daily-use contact lenses in order to prevent inflammation at the ocular surface, dry-eye and contact lens-mediated discomfort.

Chemical, Microbiological and Sensory Stability of Steam Extracted Jaboticaba (Myrciaria jaboticaba) Juice

Jaboticaba (Myrciaria jaboticaba) is a Brazilian berry rich in phenolic compounds, much appreciated for its sweet and slightly acid taste, and highly perishable. Thus, we aimed at producing jaboticaba juice by steam extraction and at investigating its microbiological, sensorial and chemical qualities during storage for up to 168 days. Juice was microbiologically safe and even though unsweetened juice was well accepted, sucrose addition further improved flavor (21%), overall impression (11%) and purchase intent (21%) scores. Cyanidin-3-O-glucoside (C3G) was the major phenolic (40%), followed by gallic (28%) and ellagic acids (21%). Total phenolics contents decreased from 27% (50 °C) to 50% (25 °C), mainly driven by C3G degradation. At 60 °C, total phenolics contents did not change after 42 days since C3G degradation was counterbalanced by gallic acid formation (129%), which followed zero-order reaction kinetics. Anthocyanins degradation followed first-order reaction kinetics (C3G half-life at 25 °C = 21.7 days) and was associated with color changes during storage. In conclusion, steam extraction followed by hot-filling technique ensured a juice with at least six months of shelf life.

Aggressive Impacts Affecting the Biodegradable Ultrathin Fibers Based on Poly(3-Hydroxybutyrate), Polylactide and Their Blends: Water Sorption, Hydrolysis and Ozonolysis

Ultrathin electrospun fibers of pristine biopolyesters, poly(3-hydroxybutyrate) (PHB) and polylactic acid (PLA), as well as their blends, have been obtained and then explored after exposure to hydrolytic (phosphate buffer) and oxidative (ozone) media. All the fibers were obtained from a co-solvent, chloroform, by solution-mode electrospinning. The structure, morphology, and segmental dynamic behavior of the fibers have been determined by optical microscopy, SEM, ESR, and others. The isotherms of water absorption have been obtained and the deviation from linearity (the Henry low) was analyzed by the simplified model. For PHB-PLA fibers, the loss weight increments as the reaction on hydrolysis are symbate to water absorption capacity. It was shown that the ozonolysis of blend fibrils has a two-stage character which is typical for O3 consumption, namely, the pendant group’s oxidation and the autodegradation of polymer molecules with chain rupturing. The first stage of ozonolysis has a quasi-zero-order reaction. A subsequent second reaction stage comprising the back-bone destruction has a reaction order that differs from the zero order. The fibrous blend PLA/PHB ratio affects the rate of hydrolysis and ozonolysis so that the fibers with prevalent content of PLA display poor resistance to degradation in aqueous and gaseous media.

Interactions of Cd2+, Co2+ and MoO42− Ions with Crushed Concrete Fines

Construction and demolition activities generate approximately two thirds of the world’s waste, with concrete-based demolition material accounting for the largest proportion. Primary aggregates are recovered and reused, although the cement-rich fine fraction is underutilised. In this study, single metal batch sorption experiments confirmed that crushed concrete fines (CCF) are an effective sorbent for the maximum exclusion of 45.2 mg g−1 Cd2+, 38.4 mg g−1 Co2+ and 56.0 mg g−1 MoO42− ions from aqueous media. The principal mechanisms of sorption were determined, by scanning electron microscopy of the metal-laden CCF, to be co-precipitation with Ca2+ ions released from the cement to form solubility limiting phases. The removal of Co2+ and MoO42− ions followed a zero-order reaction and that of Cd2+ was best described by a pseudo-second-order model. The Langmuir model provided the most appropriate description of the steady state immobilisation of Cd2+ and Co2+, whereas the removal of MoO42− conformed to the Freundlich isotherm. Long equilibration times (>120 h), loose floc formation and high pH are likely to limit the use of CCF in many conventional wastewater treatment applications; although, these properties could be usefully exploited in reactive barriers for the management of contaminated soils, sediments and groundwater.

Technical note: Inexpensive modification of Exetainers for the reliable storage of trace-level hydrogen and carbon monoxide gas samples

Atmospheric trace gases such as dihydrogen (H2), carbon monoxide (CO) and methane (CH4) play important roles in microbial metabolism and biogeochemical cycles. Analysis of these gases at trace levels requires reliable storage of discrete samples of low volume. While commercial sampling vials such as Exetainers® have been tested for CH4 and other greenhouse gases, no information on reliable storage is available for H2 and CO. We show that vials sealed with butyl rubber stoppers are not suitable for storing H2 and CO due to release of these gases from rubber material. Treating butyl septa with NaOH reduced trace-gas release, but contamination was still substantial, with H2 and CO mixing ratios in air samples increasing by a factor of 3 and 10 after 30 d of storage in conventional 12 mL Exetainers. All tested materials showed a near-linear increase in H2 and CO mixing ratios, indicating a zero-order reaction and material degradation as the underlying cause. Among the rubber materials tested, silicone showed the lowest potential for H2 and CO release. We thus propose modifying Exetainers by closing them with a silicone plug to minimise contamination and sealing them with a stainless-steel bolt and O-ring as a secondary diffusion barrier for long-term storage. Such modified Exetainers exhibited stable mixing ratios of H2 and CH4 exceeding 60 d of storage at atmospheric and elevated (10 ppm) mixing ratios. The increase of CO was still measurable but was 9 times lower than in conventional Exetainers with treated septa; this can be corrected for due to its linearity by storing a standard gas alongside the samples. The proposed modification is inexpensive, scalable and robust, and thus it enables reliable storage of large numbers of low-volume gas samples from remote field locations.