Electrochemical Degradation of Reactive Dyes in Textile Industrial Wastewater by Modified Electrodes

This research was formulated to introduce an electrochemical degradation for the degradation of reactive dyes of the textile industrial wastewater applying a full factorial experimental design. Electrochemical degradation is a green process which immensely reduces the chemical consumption of the wastewater leaving no impurities. Three factors with three-levels were used i.e. the NaCl electrolyte concentrations of 2, 4.5, 5.8 g/L, pH 4.2, 5.8, and 6.9, and reaction time 12.4, 15.5, and 20 min. The experiment was expected to generate 27 runs but due to the Design Expert 12, the number of experimental runs became 20. DC power supply of 14.6 V was used for the electrochemical degradation system whereas chemicals such as nitric acid (400 g/L), sulphuric acid (1.5 mg/L), and oxalic acid solution (100 g/L) were used for surface modification of the electrodes. The textile industrial wastewater was characterized based on the standard method of APHA. Dye, COD, BOD5, and pH of the textile industrial effluent were found to be 0.35 ± 1.00 Abs., 1,711.55 ± 2.00 mg/L, 450.00 ± 3.00 mg/L, and pH of 6.63 ± 0.30, respectively. The maximum color removal was 94.89% at the optimum experimental condition after the results validated by design expert 12. These optimum conditions were the electrolyte concentration 5.1 g/L, pH 6.5, and reaction time 17 min, whereas the minimum color removal of 63.0% was recorded. The regression analysis of the color removal (R2 = 0.95) depicts that electrolyte concentration was the dominant factor for the electrochemical degradation.

Depolymerization and Hydrogenation of Organosolv Eucalyptus Lignin by Using Nickel Raney Catalyst

The use of lignocellulosic biomass to obtain biofuels and chemicals produces a large amount of lignin as a byproduct. Lignin valorization into chemicals needs efficient conversion processes to be developed. In this work, hydrocracking of organosolv lignin was performed by using nickel Raney catalyst. Organosolv lignin was obtained from the pretreatment of eucalyptus wood at 170 °C for 1 h by using 1/100/100 (w/v/v) ratio of biomass/oxalic acid solution (0.4% w/w)/1-butanol. The resulting organic phase of lignin in 1-butanol was used in hydrogenation tests. The conversion of lignin was carried out with a batch reactor equipped with a 0.3 L vessel with adjustable internal stirrer and heat control. The reactor was pressurized at 5 bar with hydrogen at room temperature, and then the temperature was raised to 250 °C and kept for 30 min. Operative conditions were optimized to achieve high conversion in monomers and to minimize the loss of solvent. At the best performance conditions, about 10 wt % of the lignin was solubilized into monomeric phenols. The need to find a trade-off between lignin conversion and solvent side reaction was highlighted.

Varroacide Effectiveness of Polyvar Yellow® (Flumethrin 275 mg) Preparation

The aim of the experiment was to check the effectiveness of the varroacide veterinary product called PolyVar Yellow® (flumethrin 275 mg) in field conditions in the area of north-eastern Poland. The experiment was carried out on twenty bee colonies, of which in ten (group PY) were tested with the veterinary product and the remaining ten constituted a control group without anti-varroosis treatment (group C). Treatment began in mid-August and lasted until the end of October when bee flights ceased. A control treatment was then conducted with a 3.2% oxalic acid solution. The effectiveness of Varroacide of PolyVar Yellow® was estimated on the basis of the parasite falls on the Varroa sticky inserts and based on the infestation rate of bees with the parasite before and after the treatment. High varroacide effectiveness of the preparation was obtained at 97%. The tested veterinary product was shown to protect effectively bee colonies against reinvasion of Varroa destructor mites.

Studies on nucleation and crystal growth kinetics of uranium(IV) oxalate

An improved apparatus is used for nucleation measurements according to Nielsen’s method. A new method is proposed to calculate the dilution ratio N of the reaction solution during nucleation rate determination. With the rule, when the initial apparent supersaturation ratio S′ = f(N) in the dilution tank is controlled from 1.2 to 2.7, crystal nucleus dissolving and secondary nucleation can be avoided satisfactorily. Experiments are realized by varying the supersaturation ratio from 26.0 to 297.5 and temperature from 30 °C to 50 °C. Uranium(IV) oxalate is precipitated by mixing equal volumes of tetravalent uranium nitrate and oxalic acid solution. The experimental results show that the nucleation rate of uranium(IV) oxalate in the supersaturation range as show above is characterized by the primary homogeneous mechanism and can be expressed by the equation ${R_N} = {A_N}{\rm{exp}}( - {E_a}/RT){\rm{exp}}[ - B/{({\rm{ln }}S)^2}],$ where AN = 1.9 × 1027 m−3s−1, Ea = 71.2 kJ mol−1, and B = 34.3. The crystal growth rate can be expressed by the equation $G(t) = {k_g}{\rm{exp(}} - {E^{\prime}_a}/RT{\rm{)(}}c - {c_{{\rm{eq}}}}{{\rm{)}}^g},$ where kg = 7.1 × 105 (mol/L)−0.98 (m/s), ${E^{\prime}_a} = 33.1 \ {\rm{ kJ \ mo}}{{\rm{l}}^{ - 1}},$ and g = 0.98. The results indicate that the crystal growth of tetravalent uranium(IV) oxalate is controlled by the BCF model.

Anti-Corrosion Performance of Conductive Copolymers of Polyaniline/Polythiophene on a Stainless Steel Surface in Acidic Media

The composite conductive copolymers of polyaniline/polythiophene (Pani/PTH) were successfully prepared by an electrochemical method on a stainless steel surface containing both aniline and thiophene in a 0.3[Formula: see text]mol/L oxalic acid solution. The anti-corrosion performance of the Pani/PTH on stainless steel surfaces was investigated in acidic media by polarization curve analysis and electrochemical impedance spectroscopy (EIS). Additionally, the surface morphology of Pani/PTH composite conductive copolymers was observed by scanning electron microscopy (SEM). The results showed that the Pani/PTH copolymers strongly adhered to the surface of the stainless steel. Compared with that of bare stainless steel, composite conductive copolymers of Pani/PTH on the stainless steel surface provided good anti-corrosion behavior; additionally, the corrosion potential could be improved by approximately 400[Formula: see text]mV, while the current density decreased by two orders of magnitude in the corrosion media. The above results were in accordance with the SEM characterization results. The SEM spectrum showed that the Pani/PTH film had a uniform, dense and shiny structure, so it had better anti-corrosion behavior.

Low-pickle Processing of Leather: Assessment of Leather Tanning Quality by Methods of Thermal Analysis

Pelt obtained by deliming with peracetic acid can be chromed after additional treatment with sodium chloride or oxalic acid solution, or directly tanned using synthetic tannins. The results of differential scanning calorimetry and thermogravimetric analyses have suggested that any tanning increases thermal stability of leather collagen. The produced chrome-free leather, despite its high tensile strength, is not characterized by high shrinkage temperature what indicates insufficient thermal stability of such leather. This fact contradicts the results of differential scanning calorimetry and thermogravimetric analyses results which show the high thermal stability of the chrome-free leather. It has been concluded that scanning calorimetry and thermogravimetric analyses are not sufficient for the appropriate assessment of leather obtained by the methods of various tanning, and the conclusions about changes in leather structure and quality of leather can not be drawn only upon results of the mentioned analyses.