Stabilization/solidification of zinc containing sludge using Portland cement

[EN] Stabilization/Solidification process using Portland cement was applied for the treatment of sludge from hot-dip galvanization process. It is a process aimed at protecting and improving the quality of steel parts against the corrosion and oxidation caused by the humidity. Ordinary Portland cement was chosen as a binder for its affordability as a one of the cheapest type of binder and well known for its usability for hazardous waste treatment. Effectiveness of the process was evaluated using leaching tests according to both the EN 12457-4 standard and the Toxicity Characteristic Leaching Procedure. The effect of the mixture composition on the process was analysed in terms of the extract toxicity and ability to retain pollutants in the concrete matrix. Furthermore, the obtained data were evaluated using statistical analysis, namely, multi-level factorial design of experiment. This paper deals with the waste from the pretreatment of steel pieces by degreasing and chemical cleaning the surface before the hot-dip galvanization process. This waste does not meet the regulatory levels of the pollutant leaching and thus its treatment is required before land disposal. The aim of this study was to stabilize and solidify this toxic waste and thus fulfil the limit values required for land disposal.This research was carried out with the support of Internal Grant Agency of TBU in Zlin, project no. IGA/FT/2015/012 and IGA/FT/2017/003. The authors wish to express their gratitude to GALVANIZADORA VALENCIANA, S. A. for providing samples for this researchVinter, S.; Montañés, M.; Bednarik, V. (2017). Stabilization/solidification of zinc containing sludge using Portland cement. Waste Forum. (4):254-266. http://hdl.handle.net/10251/153047S254266

Effect of Temperature on Galvanic Corrosion of Non-Welded/Welded AISI 316L Stainless Steel in H3PO4

[EN] Galvanic corrosion of non-welded/welded AISI 316L SS at different temperatures (25 degrees C to 60 degrees C) at a Reynolds number of 1456 in phosphoric acid has been studied using polarization curves (by the mixed potential theory) and zero resistance ammeter (ZRA) measurements. Imposed potential measurements provide more active predicted coupled potentials and higher Galvanic current densities than those obtained using ZRA measurements. Polarization curves show that the anode of the pair is the non-welded AISI 316L. Galvanic current density values obtained from polarization curves increase with temperature. ZRA tests present the highest i(G) values at 60 degrees C; however, the values are very close to zero for all the temperatures studied. This is in agreement with the low value of the compatibility limit and of the parameter which evaluate the Galvanic phenomenon importance. Both techniques present the most positive potentials at the highest temperature.The authors would like to express their gratitude to the Spanish MAEC (PCI Mediterráneo C/018046/08).Sánchez Tovar, R.; Montañés, M.; Garcia-Anton, J.; Guenbour, A. (2010). Effect of Temperature on Galvanic Corrosion of Non-Welded/Welded AISI 316L Stainless Steel in H3PO4. ECS Transactions. 25(37):63-81. https://doi.org/10.1149/1.3407548S6381253

Influence of the Flowing Conditions on the Galvanic Corrosion of the Copper/AISI 304 Pair in Lithium Bromide Using a Zero-Resistance Ammeter

[EN] In this work, the influence of Reynolds number (Re) on the galvanic corrosion of the copper/AISI 304 stainless steel pair in an 850 g/L lithium bromide solution was evaluated in a hydraulic circuit using a zero-resistance ammeter; this technique has the advantages that it can be used without disturbing the system under investigation and in continuous-time. Results show that copper is the anodic member of the pair for all the Re analyzed. The galvanic current density values are always greater under flowing than under stagnant conditions. A general tendency of galvanic current density to decrease with time is observed due to the formation of a film of corrosion products on copper surface. Under flowing conditions, initially, galvanic current density increases with Re; however, with time, this tendency is reversed. As Re increases, greater quantities of corrosion products are initially produced and, as a result, a thicker film is formed.This work was supported by the MICINN (reference number: CTQ2009-07518) and FEDER (Fondo Europeo de Desarrollo Regional). The authors also wish to express their gratitude to Asunción Jaime for her translation assistance.Montañés, M.; Sánchez Tovar, R.; Garcia-Anton, J.; Pérez-Herranz, V. (2010). Influence of the Flowing Conditions on the Galvanic Corrosion of the Copper/AISI 304 Pair in Lithium Bromide Using a Zero-Resistance Ammeter. INTERNATIONAL JOURNAL OF ELECTROCHEMICAL SCIENCE. 5(12):1934-1947. http://hdl.handle.net/10251/98931S1934194751

Effluents from the copper electrorefining as a secondary source of antimony: Role of mass transfer on the recovery by electrodeposition

[EN] The limited availability of antimony has increased the need for exploiting alternative sources to its direct extraction from stibnite deposits. Furthermore, introducing recovery techniques in industries where antimony is released in wastewaters leads to more responsible production routes. In this work, electrodeposition is employed to recover the antimony present in a secondary waste effluent of the copper electrorefining that is highly concentrated in hydrochloric acid. The electrochemical characterization of the system was conducted by voltammetry to identify a range of suitable operating conditions for the potentiostatic and galvanostatic electro-recovery of antimony. In potentiostatic mode, the progress of the secondary electrode reactions of hydrogen and chlorine evolution at potentials more cathodic than ¿0.38 V vs. Ag/AgCl causes the detachment and redissolution of the deposited antimony. Operating under galvanostatic control, similar effects were observed when the limiting current density is exceeded. Current efficiency and specific energy consumption values above 50 % and below 65 kW·h·kg¿1, were achieved below the limiting current density (1.265 mA·cm¿2). The operational range where electrodeposition of antimony is accelerated at increasing current densities can be broadened at intensified hydrodynamic conditions and higher concentrations of antimony. The detrimental effect of the hydrogen evolution reaction on the recovery of antimony decreases at high HCl concentrations.The authors thank the financial support from the Agencia Estatal de Investigacion (AEI/10.13039/501100011033) (Spain) under the project PCI2019-103535 and by FEDER A way of making Europe. Funding for open access charge: CRUE-Universitat Politecnica de Valencia.Hernández-Pérez, L.; Carrillo-Abad, J.; Pérez-Herranz, V.; Montañés, M.; Martí Calatayud, MC. (2023). Effluents from the copper electrorefining as a secondary source of antimony: Role of mass transfer on the recovery by electrodeposition. Desalination. 549. https://doi.org/10.1016/j.desal.2022.11632254

Voltammetric and electrodeposition study for the recovery of antimony from effluents generated in the copper electrorefining process

[EN] Antimony is a metalloid with limited availability as a primary resource, but it is commonly found as an impurity in effluents generated in the copper metallurgy. Thus, the development of clean and selective processes to recover antimony from these wastewaters would improve the sustainability of the copper production. In this work, an emulated effluent of the copper electrorefining industry that contains antimony and hydrochloric acid was characterized by means of voltammetric and electrodeposition tests using two different cell configurations: a static cell, and a dynamic cell with a rotating disk electrode (RDE). Voltammograms were obtained at varying hydrochloric acid and antimony concentrations, inversion potentials, scan rates and RDE rotation rates. Two main conclusions were drawn: (a) the deposition of antimony is a mass transfer-controlled process; and (b) an increase in hydrochloric acid concentration improves the deposition of antimony. The diffusion coefficient of antimony species was obtained applying the Randles-Šev¿ík and the Levich equations; both of them providing very similar values (5.29 ± 0.20 · 10¿6 cm2 s¿1). The effective electrodeposition of antimony from highly concentrated hydrochloric acid solutions was demonstrated. The surface examination of the electrodes revealed that compact and adherent deposits of antimony could be obtained under operating conditions that minimize the hydrogen evolution reaction in both potentiostatic and galvanostatic modes. Intensified convective regimes by using the RDE improve the supply of dissolved antimony towards the electrode surface, thus leading to a notorious increase in current density and, consequently, in the rate of antimony deposition.The authors thank the financial support from the Agencia Estatal de Investigacion (AEI/10.13039/501100011033) (Spain) under the project PCI2019-103535 and by FEDER A way of making Europe. Funding for open access charge: CRUE-Universitat Politecnica de Valencia.Hernández-Pérez, L.; Carrillo-Abad, J.; Ortega Navarro, EM.; Pérez-Herranz, V.; Montañés, M.; Martí Calatayud, MC. (2022). Voltammetric and electrodeposition study for the recovery of antimony from effluents generated in the copper electrorefining process. Journal of Environmental Chemical Engineering. 11(1). https://doi.org/10.1016/j.jece.2022.10913911

Study of the chlorfenvinphos pesticide removal under different anodic materials and different reactor configuration

The present manuscript focuses on the study of the electrochemical oxidation of the insecticide Chlorfenvinphos (CVP). The assays were carried out under galvanostatic conditions using boron-doped diamond (BDD) and low-cost tin dioxide doped with antimony (Sb-doped SnO2) as anodes. The influence of the operating variables, such as applied current density, presence or absence of a cation-exchange membrane and concentration of supporting electrolyte, was discussed. The results revealed that the higher applied current density the higher degradation and mineralization of the insecticide for both anodes. The presence of the membrane and the highest concentration of Na2SO4 studied (0.1 M) as a supporting electrolyte benefited the oxidation process of CVP using the BDD electrode, while with the ceramic anode the elimination of CVP was lower under these experimental conditions. Although the BDD electrode showed the best performance, ceramic anodes appear as an interesting alternative as they were able to degrade CVP completely for the highest applied current density values. Toxicity tests revealed that the initial solution of CVP was more toxic than the samples treated with the ceramic electrode, while using the BDD electrode the toxicity of the sample increased

Metabolic Syndrome as a Cardiovascular Disease Risk Factor: Patients Evaluated in Primary Care

To estimate the prevalence of metabolic syndrome (MS) in a population receiving attention in primary care centers (PCC) we selected a random cohort of ostensibly normal subjects from the registers of 5 basic-health area (BHA) PCC. Diagnosis of MS was with the WHO, NCEP and IDF criteria. Variables recorded were: socio-demographic data, CVD risk factors including lipids, obesity, diabetes, blood pressure and smoking habit and a glucose tolerance test outcome. Of the 720 individuals selected (age 60.3 ± 11.5 years), 431 were female, 352 hypertensive, 142 diabetic, 233 pre-diabetic, 285 obese, 209 dyslipemic and 106 smokers. CVD risk according to the Framingham and REGICOR calculation was 13.8 ± 10% and 8.8 ± 9.8%, respectively. Using the WHO, NCEP and IDF criteria, MS was diagnosed in 166, 210 and 252 subjects, respectively and the relative risk of CVD complications in MS subjects was 2.56. Logistic regression analysis indicated that the MS components (WHO set), the MS components (IDF set) and the female gender had an increased odds ratio for CVD of 3.48 (95CI%: 2.26–5.37), 2.28 (95%CI: 1.84–4.90) and 2.26 (95%CI: 1.48–3.47), respectively. We conclude that MS and concomitant CVD risk is high in ostensibly normal population attending primary care clinics, and this would necessarily impinge on resource allocation in primary care

The effect of temperature on the galvanic corrosion of the copper/AISI 304 pair in LiBr solutions under hydrodynamic conditions

[EN] The corrosion behaviour of copper and AISI 304 stainless steel and the galvanic corrosion generated by the copper/AISI 304 pair, have been studied by electrochemical methods. These materials have been tested in an 850 g/L LiBr solution at different temperatures (25-75 degrees C) and at different Reynolds numbers (1456-5066) in order to study their performance in absorption machines. Results show that copper was always the anodic element of the pair and its corrosion resistance decreases due to the AISI 304 stainless steel galvanic effect. Galvanic corrosion increases with temperature and Reynolds number. However, it was proved that the effect of temperature on galvanic corrosion is more influential than the Reynolds number effect. This fact is also certain for corrosion of uncoupled copper and for corrosion of AISI 304 stainless steel. Experimental values of the corrosion current densities fit well the Arrhenius plot at all the Reynolds numbers analysed and a potential relation between the corrosion current densities and the Reynolds number has been found. (C) 2009 Elsevier Ltd. All rights reserved.This work was supported by the MICINN (reference number: CTQ2009-07518) and FEDER (Fondo Europeo de Desarrollo Regional). The authors also wish to express their gratitude to Asuncion Jaime for her translation assistance.Sánchez Tovar, R.; Montañés, M.; Garcia-Anton, J. (2010). The effect of temperature on the galvanic corrosion of the copper/AISI 304 pair in LiBr solutions under hydrodynamic conditions. Corrosion Science. 52(3):722-733. doi:10.1016/j.corsci.2009.10.032S72273352

Effect of different micro-plasma arc welding (MPAW) processes on the corrosion of AISI 316L SS tubes in LiBr and H3PO4 solutions under flowing conditions

[EN] This work studies the corrosion under flowing conditions of four kinds of AISI 316L materials welded by the micro-plasma arc welding technique in different media: a basic (LiBr) and an acidic (H3PO4) solution by means of polarization measurements. Sensitization tests, galvanic corrosion evaluation, microstructural analyses and microhardness tests have been also carried out. Corrosion parameters revealed that, among the materials welded with backing gas, the alloy which presented better corrosion behaviour was the one welded without filler alloy. However, this kind of material could undergo several corrosion problems if a crack is formed or due to an inadequate joint penetration. (C) 2009 Elsevier Ltd. All rights reserved.The authors would like to express their gratitude to the MICINN (CTQ2009-07518), to FEDER, to the MAE (PCI Mediterraneo C/018046/08) and to Asuncion Jaime for her translation assistance.Sánchez Tovar, R.; Montañés, M.; Garcia-Anton, J. (2010). Effect of different micro-plasma arc welding (MPAW) processes on the corrosion of AISI 316L SS tubes in LiBr and H3PO4 solutions under flowing conditions. Corrosion Science. 52(4):1508-1519. doi:10.1016/j.corsci.2009.12.023S1508151952

Stabilization/solidification of hot dip galvanizing ash using different binders

[EN] This study focuses on solidification of hot dip-galvanizing ash with a high content of zinc and soluble substances. The main purpose of this paper is to immobilize these pollutants into a matrix and allow a safer way for landfill disposal of that waste. Three different binders (Portland cement, fly ash and coal fluidized-bed combustion ash) were used for the waste solidification. Effectiveness of the process was evaluated using leaching test according to EN 12457-4 and by using the variance analysis and the categorical multifactorial test. In the leaching test, four parameters were observed: pH, zinc concentration in leachate, and concentration of chlorides and dissolved substances in leachate. The acquired data was then processed using statistical software to find an optimal solidifying ratio of the addition of binder, water, and waste to the mixture, with the aim to fulfil the requirement for landfill disposal set by the Council Decision 2003/33/EC. The influence on the main observed parameters (relative amount of water and a binder) on the effectiveness of the used method and their influence of measured parameters was also studied. (C) 2016 Elsevier B.V. All rights reserved.This work was supported by the Internal Grant Agency of Tomas Bata University in Zlin (project numbers IGA/FT/2015/012 and IGA/FT/2016/012).Vinter, S.; Montañés, M.; Bednarik, V.; Hrivnova, P. (2016). Stabilization/solidification of hot dip galvanizing ash using different binders. Journal of Hazardous Materials. 320:105-113. https://doi.org/10.1016/j.jhazmat.2016.08.023S10511332