Papers by Keyword: Zinc

Abstract: The paper present results of the research on the laboratory drawing process of zinc obtained in industrial conditions in the CCR by Properzi method. The force drawing, mechanical properties before and after process was measured and formability limit in drawing process was specified. Because the wire drawing process was on hot (above the recrystallization temperature) the material didn’t work hardening as a function of strain which reduces the ductility and breaking just after the die. The microscopic images of microstructure reveal the presence of large twins recrystallization reflecting the dynamic renewal structure.

Abstract: In order to recovery base and precious metals from processing plants tailings of Southern Ural and the Murmansk region, test work on heap biooxidation using these products was carried out. These tests involved the chemical and mineralogical analyses of the samples, the bacteria adaptation for the products tested, heap biooxidation in percolation columns, base metals (copper, nickel, zinc) precipitation and gold cyanidation. The recoveries of base metals to the solution from the products of magnetic separation of the wastes were 75% Ni and 50% Cu. This work is aimed at studying sustainability of magnetic separation products and pyrite tailings biotechnological processing. Also, gold and base metals recovery to the solution and the options of base metals removal from the solutions were studied.

Abstract: The paper deals with the monitoring of utility properties of new coating type on the basis of Zn/Mg (ZM). For the comparison there was used commonly used coating in the series production of car-body panels on the basis of zinc (Z100). Measured results markedly contribute to improve production systems of car-body adhesion bonding on the basic of performed evaluation of applied coatings types utility properties quality with regard to influence of temperature and corrosion environment. Testing was carry out by T-peel test acc. to ISO 11339 when such type of loading represents crucial bonding fracture type. Thus results reveal information about behavior of adhesive joints strength properties together with the type of fracture as a criterion for suitable application of new coatings types on the basis of Zn/Mg and their implementation into series production of automobiles.

Abstract: Chromate conversion coating is an important surface finishing process for electroplated zinc coatings that are widely employed in automotive applications. In addition to providing enhanced corrosion protection, the conversion coating offers a shade of colors to the coated products, both for aesthetic and functional benefits. Due to the stringent requirements on environmental issues, the industry is replacing the conventional hexavalent chromate with a more environmentally friendly trivalent chromate for the production of coatings. This effectively poses the requirement of the fundamental understanding on how the keys processing parameters of trivalent chromate conversion coating may relate to coloring of the coating products. In this work, for the first time, a systematic study is carried out to correlate the electroplating parameters, including the current density and electrolyte’s additives, on the formation of the trivalent chromate conversion coating, and hence the color appearance of the top-coats. Focusing on the black conversion coating, the color and optical properties are analyzed using a colorimeter and an optical spectrometer. The results notably show that, while the additives highly influence the observable shade of blackness, current density affects the optical properties in the visual spectrums. The microstructural and chemical characterization techniques, namely FE-SEM, OM, and XRD, are used to shed some light on the underlying mechanism that controls the color appearance. The understanding developed in this study will impact the design and fabrication of the electrogalvanizing products of desired color and esteemed functional performance.

Abstract: Sn-Zn alloy is one of the Pb-free systems that are promising because of its relatively low melting temperature and low cost. However, Zn exhibits poor corrosion and oxidation resistance that hinders its soldering applications. The objective of this research is to study the effect of Zn and Cu alloying contents on the Sn-Zn performance. Four compositions of Sn-Zn alloys were studied in this research including: Sn-7Zn, Sn-9Zn, Sn-9Zn-2Cu-Bi, and Sn-9Zn-4Cu-Bi. The microstructures were studied using Optical Microscope (OM) and Scanning Electron Microscope (SEM). The melting temperatures and corrosion resistance of the alloys were evaluated by Differential Scanning Calorimeter (DSC) and Potentiodynamic Polarization technique, respectively. The results showed that an increase in the Cu-to-Zn ratio led to better corrosion resistance. The selective corrosion of the Zn-rich phase could be visibly observed, with OM, on the post-corrosion samples. With the Cu alloying, the Cu and Zn formed an intermetallic compound resulting in a higher value of E_corr. However, the higher Cu content caused a significant increase in the liquidus temperature due to the Cu-Zn intermetallic compound, of which the melting temperature is higher than 400 °C, resulting in an incomplete melting at low temperature.

Abstract: For the past few decades, metallic materials that progressively degrade in physiological environment have been receiving attention with aim of finding appropriate biodegradable implant materials. This review focus mechanical and biocorrosion properties of Zn-based alloys that were recently investigated are summarized and discussed. In addition, the strategy for future fabrication to enhance the prospect of these alloys as metallic biodegradable materials is suggested.

Abstract: The heavy metal contain in the industrial wastewater can cause a pollution towards the environment and human due to its toxicity. Therefore extensive studies were conducted for the heavy metal removal. This study was conducted under several conditions by varying pH, biosorbent dosage, initial wastewater concentration and contact time. The results revealed that optimum pH, for high strength synthetic wastewater was 8.0 meanwhile for low strength synthetic wastewater was 7.0. Both high and low strength synthetic wastewater was optimum at 30 minutes of contact time with 1.5g and 0.02g of bisorbent dosage respectively. Meanwhile, the optimum initial metal concentration for high and low strength synthetic wastewater was 400ppm and 1ppm respectively. The results had proven that watermelon rind is able to treat wastewater with high and low concentration of metal.

Abstract: In this study, activated carbon (AC) was produced from honeydew rind, a low-cost agricultural by-product, by chemical activation using H₂SO₄ as an activator was used as an adsorbent for the removal of zinc ions from aqueous solutions. Preparation method on the effect of surface morphology at different carbonization temperatures 450°C, 470°C, 490°C and 510°C was studied. The AC was characterized using FEM-SEM, FTIR and TG. Batch adsorptions were carried out to optimize different variables such as zinc concentration, contact time, pH and biosorbent amount. The results from AAS analysis showed that the maximum adsorption of zinc onto honeydew rind AC was achieved at the conditions of pH 7.5, 1.5g biosorbent amount, 1000mg/L initial zn concentration and 45min contact time. The maximum metal uptake and maximum removal were 66.55mg/g and 99.79% respectively.

Abstract: Groundwater has long been identified as potential alternative of clean water supply due to its reliable quantity. However, pollution of groundwater due to anthropogenic factor still remains a challenging issue. To date, nanoscale zero valent iron (nZVI) has received great attention for its capability to treat various contaminants including chlorinated organics and metals. This study investigate Zinc (Zn) removal in aqueous solution by nanoscale zerovalent iron (nZVI). The characteristics study of the synthesized nZVI particles were investigated by its particle size and surface morphology using Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). SEM and TEM analyses verified that the particles size of synthesized nZVI were 71nm (< 100 nm). Structure of nZVI congragate to each other and a thin layer of oxide layer formed on the outer part of the nZVI particle. In the batch study, removal kinetic of Zn increased from 0.14 to 0.18 mins^-1 as the concentration of Zn increased from 0.1 to 0.5 ppm. However, the removal kinetic decreased from 0.162 to 0.148 mins^-1 as the amount of nZVI was increased from 0.25 mg/L to 2.50 mg/L. At pH 7, removal kinetic reached 0.157 mins^-1. However as the pH suspension decreases to pH 6.5, the removal kinetics decreased significantly to 0.144 mins^-1. The same behaviour was observed at pH 9 where the removal kinetics was decreased to 0.117 mins^-1. Removal kinetic of Zn significantly decreased at basic condition due to the formation of passivation layer which decreased the density of reactive surface area (e.g., Fe⁰ and Fe²⁺) on the surface of nZVI. Experimental results from this study can provide basic knowledge of effectiveness of Zn removal mechanisms by nZVI at different environment conditions and provide potential remediation technology for the treatment of toxic heavy metals in groundwater.

Abstract: This paper represents the results of using phycoremediation technology in treating the wastewater produced from food stall activity by using microalgae of Scenedesmus sp. in removal of heavy metals. Phycoremediation has advantages over physic-chemical approaches as it is can completely degrade organic pollutants without destroy the surrounding flora and fauna. Aim of this study is to determine the effectiveness of microalgae Scenedesmus sp to assimilate the pollutant load based on the optimum time and concentration. Characteristics of food stall wastewater need to be identified and analyse before phycoremediation process taken place. The wastewater sampling was collected at food stall during peak time i.e. at 8 a.m. and 4 p.m. Microalgae Scenedesmus sp. to be injected to the batch reactor based on five (5) different concentration cells. The results shows that the optimum removal of heavy metals are dominant by concentration no. 1 (C1) compare to other concentration in the treatment i.e. removal of Ferum by 88.22% and 69.63%, Copper by 60% and 53.85% at both sampling time while removal of zinc is dominant by concentration no.4 (C4) by 75.61% and 76.63% respectively.