bluuebunny/crossref_metadata_2025_split huggingface dataset:
Penicillin acylase release from Escherichia coli cells by mechanical cell disruption and permeabilization
Authors: Fonseca L P , Cabral J M S 
Published: January 2005

AbstractThe release of Penicillin acylase from Escherichia coli cells through mechanical cell disruption using high‐pressure homogenization and sonication was studied. From these cell disruption processes, the enzyme activity was totally released although with low specific activities, 0.1–0.3 IU(mg prot)−1. Intracellular total soluble protein release was quantified and modelled by a first order kinetic model. The effect of the driving force for each mechanical method, namely acoustic power input and homogenization pressure, on the respective kinetic disruption constants was also analysed. The release of Penicillin acylase by cell permeabilization using osmotic shock was also evaluated. The effects of cell concentration, penicillin acylase activity in E coli cells, type of buffer, pH, hypertonic solution composition, temperature and time used for osmotic shock were evaluated. Using cold osmotic shock, highly selective penicillin acylase release was attained with specific enzyme activities of about 4 IU(mg prot)−1 and enzyme activity release yields higher than 90%. The high purity of the penicillin acylase was a consequence of the optimized differential enzyme release method which was validated by SDS gel electrophoresis.© 2002 Society of Chemical Industry
Effect of input power and feeding concentration on MTBE decomposition using an RF plasma reactor
Authors: Hsieh Lien‐Te , Fang Guor‐Cheng , Yang Hsi‐Hsien , Wang Ya‐Fen , Tsao Meng‐Chun 
Published: January 2005

AbstractThe toxicology of the widely used oxygenated fuel additive methyl tert‐butyl ether (MTBE) has recently attracted considerable interest in the public sector. In this study, a radio‐frequency (RF) plasma reactor was used to decompose MTBE gas. The effects of two important plasma operational parameters – including power consumption per unit volume of the plasma (WD, W cm−3) and MTBE feeding concentration (CMTBE, %) – for MTBE decomposition were investigated in detail. The results show that the MTBE decomposition efficiency (ηMTBE) increases with increasing WD and with decreasing CMTBE. In this study, the results reveal that, in the MTBE/Ar plasma, the ηMTBE was over 99.9%, which occurred at the conditions of for WD = 0.96W cm−3, CMTBE = 3%, 20 Torr of operational pressure and a 100 cm3 · min−1 total gas flow rate. In particular, the effects of WD and CMTBE for the species detected in the effluent gas stream are carefully discussed. In addition, the deposition problem which occurred in the reactor was examined by means of Scanning Electron Microscopy (SEM).© 2002 Society of Chemical Industry
Extraction of iron(III) from acidic sulfate solutions with bis(2‐ethylhexyl)phosphoric acid in PENRECO® 170 ES, a new friendly diluent
Authors: Suárez Claudio , Ahumada Eduardo , Orellana Fabián , Hein Hans , Cote Gerard , Lizama Hernan 
Published: January 2005

AbstractThe extraction of iron(III) from acidic sulfate solutions by bis(2‐ethylhexyl)phosphoric acid (HDEHP) is investigated by using PENRECO® 170 ES as a diluent. PENRECO® 170 ES is new diluent which offers advantages such as improved solvency power, more complete phase disengagement and reduced losses in aqueous streams, with reductions of over 50% in diluent usage after 1 year, compared with conventional paraffinic diluents. The chemical analyses performed in the present work suggest that such properties arise, at least in part, from the presence of a series of hydrophobic branched alcohols in its composition (at least 0.6 mol dm−3). In spite of the solvation effects due to these alcohols, HDEHP is dimeric in this diluent and, in the presence of an excess of HDEHP, the extraction of iron(III) takes place according to the classical equation: $Fe^{3+} + 3\overline{H_2L_2} \Leftrightarrow \overline{FeL_3 \cdot 3HL} + 3H^+$ with Kex = 105.7 ± 0.2 (at I  = 1 mol dm−3). Such a value of Kex is similar to that reported for pure hexane, which shows that the presence of long chain alcohols in PENRECO® 170 ES has no perceptible influence on the thermodynamics of iron(III) extraction by HDEHP. The extraction of iron(III) by HDEHP in PENRECO® 170 ES is slightly more rapid than in kerosene, which indicates that the molecules of alcohols constituting PENRECO® 170 ES have no negative effect on the kinetics of metal extraction although they compete with the extractant molecules for adsorption at the liquid–liquid interface. Stripping of iron(III) from loaded organic solutions by sulfuric acid is easy and rapid (95% equilibrium reached within 2 min) when HDEHP is used at moderate concentrations (typically 0.1 mol dm−3). At higher HDEHP concentrations, stripping is difficult and incomplete, as found previously with other diluents. Thus, PENRECO® 170 ES is interesting in its ability to overcome some of the physical problems encountered in liquid–liquid operations, but its use does not modify significantly the chemistry of iron(III) extraction by HDEHP.© 2002 Society of Chemical Industry
Equilibrium and kinetic studies of the extraction of chelated copper(II) anions with Aliquat 336
Authors: Lin Su‐Hsia , Kao Hsiang‐Chien , Huang Shih‐Hung , Juang Ruey‐Shin 
Published: January 2005

AbstractThe equilibrium and kinetics of solvent extraction of Cu2+ from aqueous solutions containing equimolar EDTA with Aliquat 336 in n‐decanol and kerosene at 298 K were investigated. The concentrations of Cu2+ (8–50 mol m−3), Cl− (5–60 mol m−3), and Aliquat 336 (20–100 mol m−3) were varied. A semi‐empirical model with three parameters was proposed to describe the equilibrium behavior, in which the non‐idealities in both aqueous and organic phases were considered. Over the ranges studied, the model agreed reasonably well with the experimental data (standard deviation, 15%). The forward and backward reaction rate constants were determined as (5.31 ± 0.16)×10−6 m9/4 mol−3/4 s−1 and (2.62 ± 0.09)×10−7 s−1, respectively, at 298 K. An interfacial reaction mechanism was proposed, which revealed that the reaction between the chelated anions and trimeric amine molecules at the interface was rate limiting. The derived rate laws were consistent with the experimental results.© 2002 Society of Chemical Industry
Immobilisation of different Candida rugosa lipases by adsorption onto polypropylene powder: application to chiral synthesis of ibuprofen and trans‐2‐phenyl‐1‐cyclohexanol esters
Authors: López Neus , Pérez Rafael , Vázquez Felícitas , Valero Francisco , Sánchez Antoni 
Published: January 2005

AbstractCandida rugosa lipases (CRLs) were immobilised by adsorption onto a commercial polypropylene powder EP100™. Two commercial CRLs from Sigma and Amano were used together with two CRLs obtained by fed‐batch fermentation using oleic acid as a carbon source (UAB‐CRL). Significant differences were observed in the isotherm adsorption patterns for the commercial and fermented lipases, probably caused by differences in their polysaccharide content. The commercial lipases showed a classical Langmuir adsorption pattern, whereas fed‐batch produced lipases with high polysaccharide content tended to conform to a BET multilayer adsorption equation. Immobilised CRLs also showed different behaviour in the resolution of two interesting pharmaceutical products: ibuprofen and trans‐2‐phenyl‐1‐cyclohexanol (TPCH) in the enantioselective esterification reaction in organic media. In the case of ibuprofen, CRLs showed important differences in terms of esterification rate, probably due to diffusional limitation effects caused by the high polysaccharide content present in UAB‐CRLs. In the case of TPCH, however, polysaccharide content did not appear to influence the esterification rate. A high enantioselective esterification was observed for all CRLs tested in the resolution of both products.© 2002 Society of Chemical Industry
Photocatalytic pretreatment of contaminated groundwater for biological nitrification enhancement
Authors: Zhang Zisheng , Anderson William A , Moo‐Young Murray 
Published: January 2005

AbstractThe sequential photocatalytic/biological treatment of a contaminated groundwater from a local industrial site was studied. The ground water contained approximately 100 mg dm−3 ammonia, as well as mg dm−3 levels of nitrification‐inhibiting organics such as chlorobenzene. An existing treatment system uses carbon adsorption pretreatment to remove the nitrification inhibitors before the water is treated in a biological nitrification system. Photocatalysis, using a corrugated plate photoreactor, was studied as an alternative to the carbon adsorption system for inhibitor removal. Photocatalytic pretreatment was found to significantly enhance the extent of biological nitrification. An optimal pretreatment time appeared to exist, since further pretreatment resulted in accumulation of nitrite. Although further study is required, there appears to be a potential for using photocatalysis to remove inhibitors from biological nitrification systems.© 2002 Society of Chemical Industry
Effectiveness test of alginate‐derived polymeric surfactants
Authors: Kang Hyun‐Ah , Jeon Gyu‐Jong , Lee Moo‐Yeal , Yang Ji‐Won 
Published: January 2005

AbstractA series of alginate‐derived polymeric surfactants (APSs) with a linear alkyl group (C8, C12, C16) was synthesized by oxidation followed by reductive amination of 2,3‐dialdehydic alginate. The products were characterized by measuring IR spectra, NMR spectra, surface tension and critical micelle concentration (cmc). They were also tested for the solubilization of azobenzene and adsorption of heavy metal. In the case of 40% CHO‐C8 APSs, the lowest interfacial tension value (31.5 m Nm−1) was obtained at the cmc value of 1.35 g dm−3. The dissolving capacity of 40% CHO‐C8 APS towards azobenzene was 27 times greater than that of alginate. The overall cobalt (Co2+) removal efficiency by adsorption using APSs was high compared with that of sodium alginate at pH 3, 5 and 7. Equilibrium aspects of cobalt adsorption onto 10% CHO‐APSs were studied, and the results show that APSs had high equilibrium capacities for cobalt uptake, 115.5 mgg−1.© 2002 Society of Chemical Industry
Chemical neutralization of acidic wastes using fly ash in Israel
Authors: Polat Mehmet , Lederman Eli , Pelly Ithamar , Cohen Haim 
Published: January 2005

AbstractIsraeli fly ash is highly basic when exposed to water, due to the very low sulfur content allowed in coal imports because of the strict environmental regulations (with respect to SOx emissions). Thus, the fly ash is a potential chemical neutralization/fixation agent for acidic wastes. In this study, coal fly ash has been examined as a neutralization/fixation agent for acidic sludge produced from the regeneration of used engine oils. The initial results show that the fly ash can be used as a very efficient neutralization/fixation agent of the sludge. Furthermore the trace elements and the organic components are efficiently fixed within the fly ash particles. The product can serve as a good aggregate in concrete production. The neutralization and fixation processes are discussed in detail.© 2002 Society of Chemical Industry
Delignification of Pinus taeda wood chips treated with Ceriporiopsis subvermispora for preparing high‐yield kraft pulps
Authors: Mendonça Régis , Guerra Anderson , Ferraz André 
Published: January 2005

AbstractPinus taeda wood chips were treated with the white‐rot fungus Ceriporiopsis subvermispora in 20‐dm3 bioreactors for periods varying from 15 to 90 days. Decayed samples, non‐inoculated controls and extractive‐free wood samples were submitted to kraft pulping using 25% of sulfidity and different active alkali concentrations in the cooking liquor. Cooking reactions were carried out isothermally at 170 °C. Residual lignin contents of pulps prepared from biotreated wood chips were lower than those observed in pulps from the undecayed control. Delignification kinetic studies showed that the initial delignification phase was accelerated and shortened by the fungal pretreatment. At a cooking time fixed before the end of the bulk delignification phase, the fungal pretreatment provided pulps with significantly lower kappa numbers or pulps with a fixed kappa number were obtained by reducing the amount of active alkali added to the liquor. Pulps of kappa 80 were obtained both from the undecayed control cooked with 20.8% of active alkali and from the 15‐day‐biotreated sample cooked with only 15% of active alkali. The biopulping benefits were neither proportional to the extent of the biodelignification nor to the biological removal of some specific wood component. DFRC‐determination (derivatization followed by reductive cleavage) of the amount of aryl–ether linkages in residual lignins of biotreated samples indicated an extensive depolymerization during the initial stages of biodegradation, which suggested that bio‐depolymerized lignin was easily released during the first stages of cooking, resulting in a faster and shorter initial delignification phase.© 2002 Society of Chemical Industry
Production and recovery of poly‐3‐hydroxybutyrate from Methylobacterium sp V49
Authors: Ghatnekar M S , Pai J S , Ganesh M 
Published: January 2005

AbstractBacterial polyesters have shown potential as biodegradable plastics. Microorganisms capable of producing these polyesters from cheaper carbon sources and methods for their efficient recovery are widely studied worldwide. Methylobacterium sp V49, an environmental isolate, was cultivated on a mineral salts medium containing different carbon sources. Maximum accumulation of poly‐3‐hydroxybutyrate (PHB) within the bacterial cell was observed with glucose as the carbon source. Methanol and sugars such as sucrose and lactose also induced PHB accumulation. The effect of C:N ratio on polymer accumulation was studied. Different strategies for the extraction and recovery of the polymer from the cells were compared. A non‐solvent‐based method using a high‐pressure homogenizer in the presence of SDS was found to be the most satisfactory. Maximum recovery of 98% was achieved by homogenizing the cells at 400 kgcm−2 in 5% SDS solution.© 2002 Society of Chemical Industry
Impact of dissolved wastewater constituents on peroxidase‐catalyzed treatment of phenol
Authors: Wagner Monika , Nicell James A 
Published: January 2005

AbstractThe impact of dissolved wastewater constituents on the treatment of synthetic phenol solutions using horseradish peroxidase (HRP) and hydrogen peroxide was investigated under a variety of reaction conditions. The constituents studied included various inorganic salts, organic compounds and heavy metals. Higher H2O2 doses were required to treat phenol in the presence of sodium sulfite, thiosulfate and sulfide; however, enhanced levels of phenol conversion were achieved once sufficient H2O2 was supplied. Sulfide and cyanide inhibited phenol transformation. The inhibition of sulfide was overcome by supplying sufficient H2O2 to oxidize the sulfide to sulfur. However, increasing the H2O2 dose was ineffective in attempting to overcome the strong inhibiting effect of cyanide. Among the heavy metal ions tested, only Mn(II) substantially inhibited phenol removal when it was present at a concentration of 1 mmol dm−3. The presence of inorganic salts including NaCl, CaCl2, MgCl2, NH4Cl and (NH4)2SO4 reduced phenol conversion as compared with the treatment in distilled‐deionized water. This can be attributed to the increased ionic strength of the solution.© 2002 Society of Chemical Industry
Removal of cadmium and production of cadmium powder using a continuous undivided electrochemical reactor with a rotating cylinder electrode
Authors: Grau Javier M , Bisang José M 
Published: January 2005

AbstractThe behaviour of a continuous undivided electrochemical reactor with a rotating cylinder electrode under potentiostatic control is examined for the abatement of cadmium from synthetic sodium sulfate solutions with Cd(II) concentrations lower than 500 mg dm−3 at a reactor inlet pH ≅ 7. The process was designed to convert the metal ions in solution to metal powder, which settles to the conical of the reactor and may be removed at intervals as a sludge by opening a drop valve. The effect of applied potential, inlet cadmium concentration, rotation speed and hydrogen evolution as side cathodic reaction on the ‘figures of merit’ of the reactor are analysed. The best results were obtained for cathode potentials in the range from −0.9 V to −1.0 V against the saturated calomel electrode. Therefore, when the rotation speed was 1000 rpm the space time yield and the normalized space velocity were 0.64 ×10−2 mol m−3 s−1 and 0.89 h−1 respectively, while the fractional conversion per pass was 35% with a current efficiency higher than 74%. The surface morphology of the deposits as a function of the process variables is also reported.© 2002 Society of Chemical Industry
Leaching and electrochemical recovery of copper, lead and tin from scrap printed circuit boards
Authors: Mecucci Andrea , Scott Keith 
Published: January 2005

AbstractThe recovery of copper, lead and tin from scrap printed circuit boards (PCBs) has been achieved using a combination of leaching, electrochemical ion exchange and electrodeposition. A simple aqueous nitric acid stripping solution, with the concentration range of 1–6 mol dm−3, has demonstrated the potential for selective extraction of copper and lead from the PCBs. Precipitation of tin as H2SnO3 (metastannic acid) occurred at acid concentrations above 4 mol dm−3. Preliminary galvanostatic electrolysis from simulated leaching solutions has investigated the feasibility of electrodeposition of copper and lead at different concentrations of HNO3. Cathodic lead deposition, particularly at high electrolyte conditions, resulted in poor current efficiency. This was mainly due to dentritic metal formation and subsequent re‐dissolution. An alternative method investigated for recovering the metal values was the simultaneous electrodeposition of copper at the cathode and lead dioxide at the anode. Electrohydrolysis for acid and base regeneration from the spent nitric acid electrolyte has also been investigated.© 2002 Society of Chemical Industry
Adsorption of lead(II) from aqueous solution by activated carbon prepared from Eichhornia
Authors: Shekinah P , Kadirvelu K , Kanmani P , Senthilkumar P , Subburam V 
Published: January 2005

AbstractActivated carbon prepared from Eichhornia was used for the adsorptive removal of Pb(II) from aqueous solution. As the raw material for the preparation of the activated carbon is an aquatic weed, the production of this carbon is expected to be economically feasible. Parameters such as agitation time, metal ion concentration, adsorbent dose and pH were studied. Adsorption equilibrium was reached in 100 min for a solution containing 15 mgdm−3 and 125 min for solutions containing 20 and 25 mgdm−3 Pb(II), respectively. Adsorption parameters were determined using both Langmuir and Freundlich isotherm models. The adsorption capacity was 16.61 mgg−1 at pH 3.0 for particle sizes of 125–180 µm. Pb(II) removal increased as the pH increased from 2 to 4 and remained constant up to pH 10.0. Desorption studies were also carried out with dilute hydrochloric acid to recover both carbon and Pb(II). Quantitative desorption of Pb(II) from carbon indicates that adsorption of metal ion is by ion exchange.© 2002 Society of Chemical Industry
Application of a carbon sorbent for the removal of cadmium and other heavy metal ions from aqueous solution
Authors: El‐Shafey E I , Cox M , Pichugin A A , Appleton Q 
Published: January 2005

AbstractTreatment of flax shive with sulfuric acid produces a carbonaceous material that has been used to remove metal ions from aqueous solution. Metal ions including Cd(II), Cu(II), Cr(III), Co(II), Ni(II), Zn(II) and Pb(II) have been investigated for kinetic behaviour and sorption capacities. These metal ions show fast sorption kinetics following a first order rate equation. Cadmium was chosen as representative of these metal ions and a detailed study was carried out. The effect of pH on sorption was studied and it was found that maximum uptake occurred above pH 3–7, sorption was accompanied by release of protons into the solution and a ratio of [H+] released to [Cd2+] sorbed of approximately 2 was found. The sorption capacity showed no significant increase with increase of temperature. The presence of other metal ions such as K+, Na+, Mg2+ and Ca2+ decreases the Cd(II) capacity, indicating competition for the ion exchange sites. Successive sorption of Cd(II) shows that the capacity exceeds the monolayer capacity calculated from the Langmuir equation. Column studies showed good performance over a total of seven cycles of loading/stripping. These studies indicate that the sorption mechanism for these metal ions is related to a reversible ion exchange process on the carbon surface.© 2002 Society of Chemical Industry
The treatment of binary VOC mixtures by adsorption and oxidation using activated carbon and a palladium catalyst
Authors: Kullavanijaya Emwajee , Cant Noel W , Trimm David L 
Published: January 2005

AbstractThe adsorption of binary thiophene‐containing mixtures on activated carbon and their subsequent desorption and oxidation over a Pd/CeO2/Al2O3 catalyst has been studied as a model for the treatment of dilute VOC streams by intermittent accumulation and combustion. When adsorbed together, cyclohexene and thiophene have similar breakthrough times with little tendency for one to displace the other. However the adsorption of thiophene continues beyond that of diethylamine in mixtures while thiophene is itself displaced by methylmethacrylate. Oxidation of the binary mixtures is controlled by that of thiophene which requires temperatures somewhat above 300 °C for complete removal. Combustion of the other VOCs proceeds in parallel with thiophene although they react at much lower temperatures when alone. Both components of the mixtures can be removed by a system in which the VOCs are accumulated on carbon and then undergo temperature programmed desorption in air onto Pd/CeO2/Al2O3 held at 350 °C. However it is not possible to operate with the adsorbent and catalyst together since desorption then occurs before the catalyst reaches working temperature.© 2002 Society of Chemical Industry