Understanding the zinc discharge from sodium sulphate solution in the presence of surfactants

2021 ◽  
pp. 25-28
Author(s):  
P. A. Kozlov ◽  
A. V. Kolesnikov ◽  
V. Yu. Nesmelov
Keyword(s):  
Experimental Data ◽  
Mixed Mode ◽  
Reaction Order ◽  
Zinc Ion ◽  
Sodium Sulphate ◽  
Sulphate Solution ◽  
Zinc Electrowinning ◽  
Electrode Polarization ◽  
Discharge Process ◽  
Potential Region

This paper aims to understand the effect of surfactants on zinc discharge in sulphate solutions on a solid electrode and to collect new experimental data that would give a deeper insight into the processes involved in industrial electrolysis. Anionic and cationic coagulants (flocculants) and an anionic frother were used as surfactants. Electrolysis was conducted in the potential region of –1050 to –1250 mV (Ag/АgCl) in stationary and dynamic conditions in sodium sulphate solution under intensive stirring. The authors obtained comparative data on the zinc discharge current in electrolyte with and without frother at the scan velocities of 2 to 100 mV/sec. It is noted that at higher scan velocities (>10–20 mV/sec) and in the initial electrolysis phase the zinc discharge process develops in a mixed mode. In this case, as the study showed, the positive effect of the frother on zinc discharge is most distinguished. A reaction order was designed based on zinc ion with four potentials to prove that the zinc electrowinning process develops in a mixed mode. It is shown that the addition of frother raises the reaction order from 1.2 to 1.5, which is attributed to a larger effective cathode surface area. The data obtained in a galvanostatic mode under intensive stirring conditions indicate that, at the current density of 1.7 mA/cm2, the electrode polarization is 1.6 times lower in the presence of cationic coagulant and almost 3 times lower in the presence of anionic coagulant. The data given in this paper are also indicative of a changing electrolysis mode. Under stirring, a transition is observed from a diffusion mode of zinc ion reduction to a mixed one. The experimental data obtained under intensive stirring conditions in sodium sulphate solution with frother, as well as anionic and cationic coagulants are in line with the theory of electrochemical processes.

Thaumasite formation in limestone filler cements exposed to sodium sulphate solution at 20 °C

2005 ◽  
Vol 27 (1) ◽  
pp. 77-84 ◽  
Author(s):  
E.F. Irassar ◽  
V.L. Bonavetti ◽  
M.A. Trezza ◽  
M.A. González
Keyword(s):  
Sodium Sulphate ◽  
Sulphate Solution ◽  
Limestone Filler

scholarly journals The effect of pyridine on the electrochemical parameters of the hydroxonium discharge at the copper cathode

2019 ◽  
Vol 60 (12) ◽  
pp. 62-69
Author(s):  
Alexander V. Kolesnikov ◽  
◽  
Egor I. Ageenko ◽  
Keyword(s):  
Sulfuric Acid ◽  
Reaction Order ◽  
Silver Chloride ◽  
Reference Electrode ◽  
Electrode System ◽  
Constant Current ◽  
Transfer Coefficients ◽  
Potential Region ◽  
Average Data ◽  
Hydroxonium Ion

In this work, we studied the electrochemical reduction of hydrogen (hydroxonium ion) from acidic aqueous solutions in the presence of a surface active substance – pyridine. H2SO4 (r.h.) was used as a reagent to study the discharge of hydroxonium cations. The effect of pyridine on the reduction of hydrogen cations was carried out in solutions of sulfuric acid (0.09; 0.18; 0.36 M) with pyridine additives from 1.4·10-3 to 8.4·10-3 M. Potentiostatic studies were performed on a Potentiostat P-30Jcom Elins using a three-electrode cell. The working electrode (cathode) was made of M1 grade copper with an area of 0.09 cm2; auxiliary (anode) – from a platinum plate with an area of 0.20 cm2, the reference electrode is silver chloride (AgCl/Ag). The results are presented according to the average data obtained during 30 s of electrolysis in the potential region (-950-1100 mV for AgCl/Ag), with potentiometric measurements. The results are presented by the average data obtained in the initial 5 s of the process, in studies in the galvanostatic mode at current densities from 0 to 110 mV/cm2. An increase in the constant current of load almost to a small extent influenced the change in overvoltage with time, as shown by galvanostatic studies. Overvoltage, on average, decreased from 3-6 to 1-2 mV in the first 5 seconds of the beginning of the process, during the study with or without pyridine. Overvoltage ceased to depend after 10-15 s on the time of galvanostation. The effect of the addition of pyridine to the electrolyte was studied and it was shown that the negative effect of pyridine on the discharge of the hydroxonium ion increases with increasing acidity of the electrolyte. An increase in the density of exchange currents with a decrease in the content of sulfuric acid in the electrolyte is noted, which is associated with the approach of the electrode system to the equilibrium state. The decrease in the transfer coefficients of the hydrogen discharge reaction with an increase in the acid of content in the electrolyte and pyridine additives was explained by the distant position of the transition state localization from the electrode surface. The calculations of the reaction order for the hydroxonium ion in the presence and absence of pyridine in the electrolyte are presented. The obtained value of the reaction order, taking into account standard errors close to unity, allows us to conclude that at the initial stage, the hydroxonium of molecule is discharged, the products of which are atomic hydrogen, the HSO4 anion and water. In the kinetics of the process of the discharge of hydrogen cations, the stages can further play an important role: surface diffusion of hydrogen ad-atoms, formation of gas bubbles and their desorption, adsorption of hydrogen by metal.

scholarly journals Assessment of Bowel Preparation Using Low-Volume Sulphate-Based Preparations in Comparison with Macrogols: A Multicenter, Randomized, Comparative Clinical Study of the 3rd Phase

2019 ◽  
Vol 29 (1) ◽  
pp. 68-83
Author(s):  
Evgeny D. Fedorov ◽  
Viktor V. Veselov ◽  
Sergey V. Kashin ◽  
Ekaterina V. Tikhomirova ◽  
Alexey V. Veselov ◽  
...  
Keyword(s):  
Bowel Preparation ◽  
Sodium Sulphate ◽  
Sulphate Solution ◽  
P Value ◽  
Common Symptom ◽  
Polyp Detection ◽  
Diagnostic Colonoscopy ◽  
Intention To Treat ◽  
Comparative Clinical Study ◽  
Low Volume

Oral sulphate solution(OSS: sodium sulphate, potassium sulphate and magnesium sulphate) is a low-volume osmotic agent for cleansing the intestines.Aim:in a multicentre, prospective, randomized, 3rd phase study with two parallel groups, the effectiveness, safety and tolerability of OSS was evaluated in comparison with Macrogol 4000 with electrolytes (a reference preparation for bowel cleansing in Russia) in adult patients who were scheduled for routine diagnostic colonoscopy.Methods.This study was conducted in three Russian research centres during the March–December, 2015 period. Men and women over the age of 18 scheduled to undergo routine diagnostic colonoscopy were randomly assigned either to the OSS group or to the Macrogol group with a fractional use mode before the colonoscopy. The colonoscopy researchers were not aware of which preparation had been taken by the patients. Anonymized video records were centrally analysed by three experts. The primary end point was the proportion of patients with a successful bowel preparation for colonoscopy ≥6 points, as determined by theBoston Bowel Preparation Scale of quality assessment(BBPS scale).Results.296 patients were randomized in the study (147 patients were treated with OSS, 149 patients received Macrogol); 294 participants were included in theIntention to Treat population(ITT-population), and 274 participants were included in thepopulation of patients who completed the study according to the protocol(Per-Protocol; PP-population) (139 patients received OSS, 135 patients received Macrogol). The proportion of patients with a successful bowel preparation (BBPS ≥6 scores) was high in both groups (OSS [PP-population]: 97.2 % (95 % confidence interval [CI] 89.5–99.3), Macrogol [PP-population]: 97.7 % (95 % CI: 90.7–99.4)). The corrected difference between the groups was -0.5 % (95 % CI: -4.2–3.3), thereby demonstrating “no less effective” of OSS as compared to Macrogol. Compliance with the drug use regime was higher in the OSS group than in the Macrogol group (95.7 % versus 82.3 %, respectively, p-value = 0.0011, ITT-population).The most common symptom reported in patients was nausea (27.9 % in the OSS group and 12.9 % in the Macrogol group). The proportion of patients who developed nausea was significantly higher in the OSS group than in the Macrogol group (25.2 % compared with 10.2 % when taking the first dose of the preparation (p = 0.0008) and 19.7 % compared with 6.8 % when taking the second dose of the preparation (p = 0.0016)). Differences in other symptoms (bloating, abdominal pain or abdominal discomfort) between the groups were not significant, with the severity of symptoms being generally mild. The safety profile of the investigated preparations in patients withinflammatory bowel disease(IBD) in remission did not differ from that in the general patient population.The differences in terms of secondary endpoints were not identified, including BBPS assessment for different sections of the colon, the level of polyp detection, the duration and completeness of colonoscopy, and the investigator’s satisfaction with the procedure. The analysis by subgroups also did not reveal any significant differences.Conclusion.In this study, the “not less effectiveness” of the sulphate solution was demonstrated as compared to Macrogol in a fractional use mode. Both preparations were well tolerated. Despite the higher incidence of nausea in the OSS group, the patients showed significantly higher compliance with the OSS mode as compared to that of Macrogol.This study is registered with the ClinicalTrials.gov Registry of Clinical Trials, No. NCT02321462.

scholarly journals Assessment of Bowel Preparation Using Low-Volume Sulphate-Based Preparations in Comparison with Macrogols: A Multicenter, Randomized, Comparative Clinical Study of the 3rd Phase

2019 ◽  
Vol 29 (2) ◽  
pp. 60-75
Author(s):  
E. D. Fedorov ◽  
V. V. Veselov ◽  
S. V. Kashin ◽  
E. V. Tikhomirova ◽  
A. V. Veselov ◽  
...  
Keyword(s):  
Bowel Preparation ◽  
Sodium Sulphate ◽  
Sulphate Solution ◽  
P Value ◽  
Common Symptom ◽  
Polyp Detection ◽  
Diagnostic Colonoscopy ◽  
Intention To Treat ◽  
Low Volume ◽  
Research Centres

Oral sulphate solution(OSS: sodium sulphate, potassium sulphate and magnesium sulphate) is a low-volume osmotic agent for cleansing the intestines.Aim: in a multicentre, prospective, randomized, 3rd phase study with two parallel groups, the effectiveness, safety and tolerability of OSS was evaluated in comparison with Macrogol 4000 with electrolytes (a reference preparation for bowel cleansing in Russia) in adult patients who were scheduled for routine diagnostic colonoscopy.Methods. This study was conducted in three Russian research centres during the March–December, 2015 period. Men and women over the age of 18 scheduled to undergo routine diagnostic colonoscopy were randomly assigned either to the OSS group or to the Macrogol group with a fractional use mode before the colonoscopy. The colonoscopy researchers were not aware of which preparation had been taken by the patients. Anonymized video records were centrally analysed by three experts. The primary end point was the proportion of patients with a successful bowel preparation for colonoscopy ≥ 6 points, as determined by the Boston Bowel Preparation Scale of quality assessment (BBPS scale).Results. 296 patients were randomized in the study (147 patients were treated with OSS, 149 patients received Macrogol); 294 participants were included in the Intention to Treat population (ITT-population), and 274 participants were included in the population of patients who completed the study according to the protocol (Per-Protocol; PP-population) (139 patients received OSS, 135 patients received Macrogol). The proportion of patients with a successful bowel preparation (BBPS ≥6 scores) was high in both groups (OSS [PP-population]: 97.2 % (95 % confidence interval [CI] 89.5–99.3), Macrogol [PP-population]: 97.7 % (95 % CI: 90.7–99.4)). The corrected difference between the groups was -0.5 % (95 % CI: -4.2–3.3), thereby demonstrating “no less effective” of OSS as compared to Macrogol. Compliance with the drug use regime was higher in the OSS group than in the Macrogol group (95.7 % versus 82.3 %, respectively, p-value = 0.0011, ITT-population).The most common symptom reported in patients was nausea (27.9 % in the OSS group and 12.9 % in the Macrogol group). The proportion of patients who developed nausea was significantly higher in the OSS group than in the Macrogol group (25.2 % compared with 10.2 % when taking the first dose of the preparation (p = 0.0008) and 19.7 % compared with 6.8 % when taking the second dose of the preparation (p = 0.0016)). Differences in other symptoms (bloating, abdominal pain or abdominal discomfort) between the groups were not significant, with the severity of symptoms being generally mild. The safety profile of the investigated preparations in patients withinflammatory bowel disease (IBD) in remission did not differ from that in the general patient population. The differences in terms of secondary endpoints were not identified, including BBPS assessment for different sections of the colon, the level of polyp detection, the duration and completeness of colonoscopy, and the investigator’s satisfaction with the procedure. The analysis by subgroups also did not reveal any significant differences.Conclusion. In this study, the “not less effectiveness” of the sulphate solution was demonstrated as compared to Macrogol in a fractional use mode. Both preparations were well tolerated. Despite the higher incidence of nausea in the OSS group, the patients showed significantly higher compliance with the OSS mode as compared to that of Macrogol. This study is registered with the ClinicalTrials.gov Registry of Clinical Trials, No. NCT02321462.Conflict of interest: this study was sponsored by Ipsen Pharma.Acknowledgements: the authors express their sincere gratitude to all the patients who participated in the study, as well as to specialists having provided medical care for the patients, researchers and employees of the participant research centres. The authors also express their appreciation to Olga Kapitonova, an employee of the Almedis company (Moscow, Russia) for her assistance in compiling medical texts, which activity was carried out under the financial support of the Ipsen company (Moscow, Russia) in accordance with the Good Publication Practice (GPP).

NTCC 2017: Long-Term Observation of the Resistance of Novel Hybrid Cement Exposed to Sulphate Solution

2018 ◽  
Vol 761 ◽  
pp. 163-168 ◽  
Author(s):  
Michal Bačuvčík ◽  
Pavel Martauz ◽  
Ivan Janotka
Keyword(s):  
Portland Cement ◽  
Building Materials ◽  
Sodium Sulphate ◽  
Sulphate Solution ◽  
Cement Clinker ◽  
Portland Cement Clinker ◽  
Specific Material ◽  
Long Term Observation ◽  
By Products

This work is aimed to investigate four-years impact of 5 % sodium sulphate solution on the mortar made of novel hybrid cement H-CEMENT, being prepared with maximal content of wastes and by-products and only 20 % wt. of Portland cement clinker, compared to that prepared with the reference CEM I 42.5 N (PC). H-CEMENT for its specific material composition does not meet the criteria for inclusion in the cement kinds reported in EN 197-1 but complies with all of the hygienic regulations and standards imposed on similar building materials.

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