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Mmol Dm (mmol + dm)
Selected AbstractsIntegrated Bienzyme Chip for Ethanol MonitoringELECTROANALYSIS, Issue 12 2006Javier Gonzalo-Ruiz Abstract An ethanol chip biosensors based on bienzymatic system has been developed. Horse radish peroxidase and alcohol oxidase have been co-immobilized into a polypyrrole matrix, as well as the mediator, onto the integrated working electrode. Variables that affect to the chronoamperometric response of ethanol have been optimized through the experimental design methodology. Under these conditions, the slopes of several calibrations curves show a reproducibility, repeatability and limit of detection of 6.09% (n=5), 9.03% (n=5) and 2.98±0.38,mmol dm,3 (,=,=0.05, n=3), respectively. Finally, the biosensors based on platinum chips were applied to the determination of ethanol in white wine samples, obtaining successful results. [source] Aerobic biological treatment of waste- waters containing dichloromethaneJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2007Sandra C Moura Abstract BACKGROUND: Volatilization has been advanced as one of the predominant phenomena contributing to volatile organic carbon emissions from wastewater treatment plants (WWTPs). In this study, strategies for minimizing such air stripping losses when treating a liquid stream containing dichloromethane (DCM), aiming at decreasing the overall emission inventory from WWTPs, were investigated. RESULTS: System R1, consisting of a continuous flow stirred tank reactor (CSTR) treating a liquid stream containing DCM at a concentration of 12 mmol dm,3 presented a biodegradation efficiency (BE) of 68%, based upon chloride release, with 10% of measurable losses, mainly due to volatilization, and 22% of unmeasurable losses. System R2 introduced operational designs aiming at decreasing DCM volatilization. In Experiment R2.1, a biotrickling filter, through which the air stripped from the CSTR was driven, was introduced leading to a reduction from 10% to 7% on the measurable losses. In Experiment R2.2, the air stripped from the CSTR was recirculated at a flow rate of 2.4 dm3 h,1 through the reactor medium before entering the biotrickling filter. The BE was improved from 69% to 82% and the losses associated with air stripping were successfully reduced to 2%. The proposed design, including air recirculation and the biotrickling filter, increased the ratio between the biodegradation rate and the volatilization rate from 7 to 41. CONCLUSIONS: Recirculation of the gaseous effluent through the reactor medium, which allowed for higher residence time within the bioreactor, was shown to be a successful strategy for improving the treatment process, thus minimizing DCM volatilization losses. Copyright © 2007 Society of Chemical Industry [source] Mn-peroxidase production by Panus tigrinus CBS 577.79: response surface optimisation and bioreactor comparisonJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2006Daniele Quaratino Abstract This study reports the statistical optimisation through response surface methodology of the growth medium for Panus tigrinus manganese-dependent peroxidase (MnP) production in shaken culture. Three crucial variables, including carbon source, malonic acid and Mn2+, were optimised in a nitrogen-limited medium. Sucrose was the best carbon source for MnP production. Mn2+ ions and malonic acid significantly stimulated MnP production at an optimal concentration of 53 mg dm,3 and 8.2 mmol dm,3, respectively, resulting in 0.83 U cm,3. Further experiments were performed in lab-scale stirred tank (STR) and bubble-column (BCR) reactors using the previously optimised liquid medium. BCR proved to be more adequate than STR in supporting MnP production, leading to 3700 U dm,3 after 144 h with a productivity of 25.7 U dm,3 h,1. On a comparative basis with other production data in lab-scale reactors, these results appear to be compatible with scale transfer. Copyright © 2006 Society of Chemical Industry [source] Removal of cupric ions from acidic sulfate solution using reticulated vitreous carbon rotating cylinder electrodesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2004Gavin W Reade Abstract The potentiostatic deposition of copper from acid sulfate solutions (0.50 mol dm,3 Na2SO4 at pH 2 and 298 K) was studied at four porosity grades (10, 30, 60 and 100 pores per linear inch, ppi) of reticulated vitreous carbon (RVC) rotating cylinder electrode (RCE). The rate of removal of cupric ions from a 200 cm3 volume of electrolyte was examined as a function of the grade of RVC foam, the electrode potential and the initial cupric ion concentration. For the 100 ppi material, the product of the mass transport coefficient and the electroactive area per unit volume of electrode (kmAe) was equal to 0.28 s,1 at a potential of ,500 mV vs SCE for an initial cupric ion concentration of 0.85 mmol dm,3 and a constant rotation speed of 1500 rev min,1. Under the experimental conditions, an initial dissolved copper concentration of 63.5 ppm could be reduced to <0.1 ppm in approximately 60 min using a 100 ppi RVC RCE. SEM studies showed some non-uniform deposition of metal due to heterogeneous nucleation of copper together with the development of rough deposits. Copyright © 2004 Society of Chemical Industry [source] Anaerobic biodegradation of phenol in sulfide-rich mediaJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 6 2004Patricia Olguín-Lora Abstract In the refinery industry, the washing processes of middle-distillates using caustic solutions generate phenol- and sulfide-containing waste streams. The spent caustic liquors generated contain phenols at concentrations higher than 60 g dm,3(638.3 mmol dm,3). For sulfur compounds, the average sulfide concentration was 48 g dm,3(1500 mmol dm,3) in these streams. The goal of this study was to evaluate the specific impact of phenol and sulfide concentrations towards the phenol-biodegradation activity of a phenol-acclimated anaerobic granular sludge. An inhibition model was used to calculate the phenol and sulfide inhibitory concentrations that completely stopped the phenol-biodegradation activity (IC100). A maximum phenol-biodegradation activity of 83 µmol g,1 VSS h,1 was assessed and the IC100 values were 21.8 mmol dm,3 and 13.4 mmol dm,3 for phenol and sulfide respectively. The limitation of the phenol biodegradation flow by phenol inhibition seemed to be related to the more important sensitivity of phenol-degrading bacteria. The up-flow anaerobic sludge bed reactor operating in a non-phenol-dependent inhibition condition did not present any sensitivity to sulfide concentrations below 9.6 mmol dm,3. At this residual concentration, the pH and bisulfide ions' concentration might be responsible for the general collapsing of the reactor activity. Copyright © 2004 Society of Chemical Industry [source] | ||||||||||