Application of glucose oxidase for the production of metal gluconates by fermentation

The present study deals with the application of glucose oxidase (GOX) for the production of metal gluconates by fermentation method. It provides a method for the conversion of glucose into gluconic acid and its derivatives using the enzyme glucose oxidase (GOX). Due to the presence of calcium carbonate in fermentation medium the gluconic acid is converted into calcium gluconate. Conditions like concentration of substrate, temperature, pH, fermentation period and different phosphate sources were optimized during fermentation. The maximum GOX activity was observed at 35°C (pH 5.5) after 44 h of incubation at 100 rpm. At the maximum enzyme activity, the percentage yield of gluconates are also maximum; both go side by side. Sulphuric and oxalic acids method were employed for the production of gluconic acid. Derivatives of gluconic acid that is, calcium lactate gluconate, sodium gluconate, potassium gluconate, zinc gluconate and copper gluconate were formed by using double displacement and direct methods. The direct method gave the better yield. The percentage yields were 73, 89.63, 81.93, 92.86 and 81.53%, respectively. Keywords: Glucose oxidase (GOX), metal gluconate, double displacement

Gluconates as Corrosion Inhibitor of Aluminum in Various Corrosive Media

Corrosion processes are responsible for huge losses in industry. Though organic, inorganic and mixed material inhibitors were used for a long time to combat corrosion, the environmental toxicity of organic corrosion inhibitors has prompted the search for inorganic corrosion inhibitors. The effect of gluconates as novel corrosion inhibitors on the corrosion of aluminum alloy in acidic and saline media was investigated by electrochemical and weight loss techniques. The effect of inhibitor concentration was also investigated. High resolution scanning electron microscopy equipped with energy dispersive spectroscopy (HR-SEM/EDS) was used to characterize the surface morphology of the metal before and after corrosion. Experimental results revealed that gluconates in the studied solution decreased the corrosion rate at the different concentrations studied. The experimental results obtained from potentiodynamic polarization method showed that the presence of the gluconates in 3.5% NaCl and 0.5 M H2SO4 solutions decreases the corrosion current densities (icorr) and corrosion rates (CR), and increases the polarization resistance (Rp). It was observed that the inhibitor efficiency depends on the corrosive media, concentration of the inhibitor and the substrate material. The adsorption characteristics of the gluconates were also described. Good correlation exists between the results obtained from both methods

Novel Metallo-organic Corrosion Inhibitors for Mild Steel and Aluminum Alloys in Aqueous Solutions and Sol-gel Coatings

The objective of this research was to develop novel metallo-organic corrosion inhibitors for mild steel and aluminum alloys to be employed in aqueous solutions and sol-gel coatings. For this reason, inhibitors that are commonly used for corrosion inhibition of mild steel and aluminum alloys were combined under one formulation in order to result in synergism. Among chosen inhibitor constituents were ?-hydroxyacids and other hydroxy-acids and their salts along with metal oxyanions. Occasionally, these inhibitor constituents had to be synthesized as well if none available commercially. Gluconates and benzilates were the most commonly used hydroxy-acid salts, while molybdates, vanadates, and borates were the most commonly used metal oxyanions. As for cationic constituents, zinc, trivalent chromium, and calcium cations were used the most. Synthesized compounds were then characterized by means of different techniques and were put into test later for their corrosion inhibition efficiencies. First, corrosion inhibition efficiencies in aqueous solutions were measured by weight-loss tests. If any indication of a conversion coating formation on the substrate surface was present, it was characterized using different surface techniques. Immersion solutions before and after completion of weight-loss tests were also characterized for the common solution properties using a variety of probes. Secondly, inhibitors with optimal water solubilities that successfully inhibited aluminum corrosion in aqueous solution were incorporated into sol-gel coating. Aluminum 2024 substrates coated with sol-gel enriched with inhibitor pigments then were tested in a salt-fog chamber in accordance with ASTM methods.Chemistry Departmen

Mixed polyvalent-monovalent metal coating for carbon-graphite fibers

An improved coating of gasification catalyst for carbon-graphite fibers is provided comprising a mixture of a polyvalent metal such as calcium and a monovalent metal such as lithium. The addition of lithium provides a lighter coating and a more flexible coating when applied to a coating of a carboxyl containing resin such as polyacrylic acid since it reduces the crosslink density. Furthermore, the presence of lithium provides a glass-like substance during combustion which holds the fiber together resulting in slow, even combustion with much reduced evolution of conductive fragments. The coated fibers are utilized as fiber reinforcement for composites

Corrosion inhibition of carbon steel in saline solutions by gluconate, zinc sulphate and green clay eluate

U ovom je radu procijenjen utjecaj glukonata, cink sulfata i eluata zelene gline na inhibiciju korozije ugljičnog čelika (EN S235 JRG) u 0,5 % i 3,5 % otopini natrij klorida pomoću metode Tafelove polarizacije. Primjenom umjerenih koncentracija natrij glukonata postignuta je značajna inhibicija opće korozije. U tom je slučaju inhibicija uglavnom ostvarena anodnim mehanizmom inhibicije opće korozije, uz pojavu lokalne "pitting" korozije ugljičnog čelika. Međutim, u slučaju kada je natrij glukonat pomiješan s cinkovim sulfatom i/ili eluatom zelene gline u odgovarajućim koncentracijama, dolazi do smanjenja i opće i lokalne korozije što ukazuje na dobro sinergijsko djelovanje između uporabljenih inhibitora.The effect of gluconate, zinc sulphate and green clay eluate on the corrosion inhibition of carbon steel (EN S235 JRG) in 0,5 % and 3,5 % sodium chloride solution has been evaluated in this work using Tafel polarization technique. Substantial general corrosion inhibition using sodium gluconate solely can be obtained with moderate concentrations. In this case, corrosion inhibition is predominately obtained by anodic mechanism and is limited to general corrosion, whereas carbon steel becomes liable to localised pitting corrosion. However, when sodium gluconate is combined with zinc sulphate and/or green clay eluate in adequate concentrations both general and localized corrosion are diminished which indicates good synergy between applied inhibitors

Protective effect of CV247 against cisplatin nephrotoxicity in rats

CV247 (CV), an aqueous mixture of copper (Cu) and manganese (Mn) gluconates, vitamin C and sodium salicylate increased the antitumour effects of cisplatin (CDPP; cis-diamminedichloroplatinum) in vitro. We hypothesized that the antioxidant and cyclooxygenase-2 (COX-2; prostaglandin-endoperoxide synthase 2) inhibitory components of CV can protect the kidneys from CDPP nephrotoxicity in rats. CDPP (6.5 mg/kg, intraperitoneally) slightly elevated serum creatinine (Crea) and blood urea nitrogen (BUN) 12 days after treatment. Kidney histology demonstrated extensive tubular epithelial damage and COX-2 immunoreactivity increased 14 days after treatment. A large amount of platinum (Pt) accumulated in the kidney of CDPP-treated rats. Furthermore, CDPP decreased renal iron (Fe), molybdenum (Mo), zinc (Zn), Cu and Mn concentrations and increased plasma Fe and Cu concentrations. CDPP elevated plasma free radical concentration. Treatment with CV alone for 14 days (twice 3 ml/kg/day orally) did not influence these parameters. Chronic CV administration after CDPP reduced renal histological damage and slightly decreased COX-2 immunoreactivity, while failed to prevent the increase in Crea and BUN levels. Blood free radical concentration was reduced, that is, CV improved redox homeostasis. CV restored plasma Fe and renal Fe, Mo and Zn, while decreased Pt and elevated Cu and Mn concentrations in the kidney. Besides the known synergistic antitumour effects with CDPP, CV partially protected the kidneys from CDPP nephrotoxicity probably through its antioxidant effect