Showing papers in "Journal of Chemical Technology & Biotechnology in 2006"

Lactic acid: recent advances in products, processes and technologies - a review

Abstract: Lactic acid, the most widely occurring hydroxycarboxylic acid, is an enigmatic chemical. It was discovered a long time ago and its use in food preservation and processing and as a specialty chemical has grown over the years with current production of about 120 000 t yr−1. Its potential as a major chemical feedstock, derived from renewable carbohydrates by sustainable technologies, to make plastics, fibers, solvents and oxygenated chemicals, had also been recognized. Recently, new technologies have emerged that can overcome major barriers in separations and purification and processing. Advances in electrodialysis (ED) and bipolar membranes and one particular process configuration termed the ‘double ED’ process, a specific combination of desalting ED followed by ‘water-splitting’ ED with bipolar membranes, has given very promising results, showing a strong potential for an efficient and economic process for recovery and purification of lactic acid without generating a salt waste. For the production of polymers, several advances in catalysts and process improvements have occurred in the technology to produce dilactide and its polymerization to produce plastics and fibers by Natureworks LLC, which is the leader in lactic polymer technology and markets. Other advances in esterification technology with pervaporation and development of biosolvent blends also have a high potential for ‘green’ solvents in many applications. Recently, a considerable amount of pioneering effort in technology, product development and commercialization has been expended by several companies. To overcome the barriers to replace long-established petroleum-derived products, further real support from consumer, regulatory and government organizations is also needed. Copyright © 2006 Society of Chemical Industry

Technologies for olive mill wastewater (OMW) treatment: a review

Abstract: Olive mill wastewater (OMW) arises from the production of olive oil in olive mills. It is produced seasonally by a large number of small olive mills scattered throughout the olive oil-producing countries. OMW has a very high organic load, recalcitrant in nature and with a high amount of toxicity/phytotoxicity-associated compounds. Several physicochemical, biological and combined processes have been examined for the treatment of OMW, resulting in considerable organic load and toxicity abatement. Biological processes, aerobic and anaerobic, including anaerobic co-digestion with other effluents and composting, are predominant in the treatment of OMW. Advanced oxidation processes have attracted much attention owing to the strong oxidation potential of the agents used, which can result in a high degree of treatment. Recent research studies employing physical, chemical, biological and combined technologies are reviewed in the current work.

Organic acids: old metabolites, new themes

Abstract: Fumaric, L-malic and citric acids are intermediates of the oxidative tricarboxylic acid (TCA) cycle which in eukaryotes is localized in mitochondria. These organic acids are synthesized and accumulated in the medium to very high concentrations by filamentous fungi such as Aspergillus spp. and Rhizopus sp. This article reviews basic research on the unusual acid production capability and the associated metabolic pathways operating under defined stress conditions in these specific fungi. In particular, we describe and discuss the importance of the cytosolic reductive TCA pathway, which includes the cytosolic activities of pyruvate carboxylase, malate dehydrogenase and fumarase, for production of fumaric and L-malic acids. This article also describes the differences between fumaric acid, L-malic acid and citric acid production by different organisms (filamentous fungi, yeast, and higher eukaryotes), and the possible application of novel technologies (genetic engineering and bioinformatics) to fungal systems which may offer new industrial potential of filamentous fungi for the production of valuable metabolites. Copyright © 2006 Society of Chemical Industry

Microbial production, immobilization and applications of β-D-galactosidase

Abstract: β-D-Galactosidase (β-D-galactoside galactohydrolase, E.C. 3.2.1.23), most commonly known as lactase, is one of the most important enzymes used in food processing, which catalyses the hydrolysis of lactose to its constituent monosaccharides, glucose and galactose. The enzyme has been isolated and purified from a wide range of microorganisms but most commonly used β-D-galactosidases are derived from yeasts and fungal sources. The major difference between yeast and fungal enzyme is the optimum pH for lactose hydrolysis. The application of β-D-galactosidase for lactose hydrolysis in milk and whey offers nutritional, technological and environmental applications to human life. In this review, the main emphasis has been given to elaborate the various techniques used in recent times for the production, purification, immobilization and applications of β-D-galactosidase. Copyright © 2006 Society of Chemical Industry

Removal of nickel(II) from aqueous solution by carbon nanotubes

Abstract: Single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs) were oxidized by NaClO solutions and were employed as sorbents to study sorption characteristics of nickel(II) from aqueous solution. The surface properties of CNTs such as functional groups, total acidic sites and negatively charged carbons were greatly improved after oxidation, which made CNTs become more hydrophilic and resulted in sorption of more Ni2+. The amount of Ni2+ sorbed onto oxidized CNTs increased with a rise in agitation speed, initial Ni2+ concentration and solution pH in the range 1–8, but decreased with a rise in CNT mass and solution ionic strength. The sorption mechanisms are complicated and appear attributable to electrostatic forces and chemical interactions between the Ni2+ and the surface functional groups of the CNTs. The oxidized SWCNTs and MWCNTs have shorter equilibrium time and better Ni2+ sorption performance than the oxidized granular activated carbon, suggesting that both NaClO oxidized CNTs are efficient Ni2+ sorbents and that they possess good potential applications in water treatment. Copyright © 2006 Society of Chemical Industry

Chemical characterization and liberation of pentose sugars from brewer's spent grain

Abstract: The chemical composition of brewer's spent grain (BSG), generated from a process using 100% malted barley, was investigated. BSG is mainly composed of (g kg−1) hemicellulose (284), lignin (278), cellulose (168) and protein (152.5), but it also contains extractives and ashes in smaller proportions. Minerals in BSG include calcium, sodium, potassium, magnesium, aluminum, iron, barium, strontium, manganese, copper, zinc, phosphorus, sulfur, chromium and silicon. In order to find alternative uses for BSG, this by-product was subjected to acid hydrolysis process to recover the hemicellulosic sugars, which have a large number of industrial applications. The process was carried out under different conditions of liquid-to-solid ratio and acid concentration to evaluate the influence of these two variables on BSG hemicellulose hydrolysis. Under all the hydrolysis conditions evaluated, arabinose was recovered with higher efficiency than xylose. Under the best evaluated reaction conditions (liquid-to-solid ratio of 10 g g−1 and 120 mg H2SO4 g−1 dry matter) 76.2% of the hemicellulose was hydrolyzed and the xylose and arabinose sugars were recovered with 67 and 97.8% efficiency, respectively. Copyright © 2005 Society of Chemical Industry

Are ionic liquids kosmotropic or chaotropic? An evaluation of available thermodynamic parameters for quantifying the ion kosmotropicity of ionic liquids

Abstract: The original article to which this Erratum refers was published in Journal of Chemical Technology and Biotechnology (81: 877–891).

Photopolymerization of biomaterials: issues and potentialities in drug delivery, tissue engineering, and cell encapsulation applications

Abstract: Photopolymerization is a widely explored technology that has recently been recognized to have also great potentialities in the biomedical field. This paper aims to provide a general overview of this technology by briefly describing materials and methods used to produce linear or crosslinked polymer networks for drug delivery, tissue engineering and cell encapsulation. In addition, potentialities and areas of investigation that are not fully explored but that could provide solutions for better control over the technology when applied to the biomedical field will be indicated as well. Copyright © 2006 Society of Chemical Industry

Peptide nucleic acid (PNA) — a review

Abstract: Peptide nucleic acid (PNA) is a nucleobase oligomer in which the entire backbone has been replaced by a backbone composed of N-(2-aminoethyl)glycine units In other words, PNA can be regarded as DNA with a neutral peptide backbone instead of a negatively charged sugar-phosphate backbone It is chemically stable and resistant to hydrolytic (enzymatic) cleavage and thus not expected to be degraded inside a living cell, although its transportation within the cell is difficult PNA is capable of recognising specific sequences of DNA and RNA obeying the Watson-Crick hydrogen bonding scheme, and the hybrid complexes exhibit extraordinary thermal stability and unique ionic strength effects It may also recognise duplex homopurine sequences of DNA to which it binds by strand invasion, forming a stable PNA/DNA/PNA triplex with a looped-out DNA strand PNA exhibits superior hybridisation characteristics and improved chemical and enzymatic stability relative to nucleic acids, which is why PNA finds major applications in the diagnostic and pharmaceutical fields Studies indicate that PNA is capable of inhibiting transcription as well as translation, so it can be used as a new tool for antigene and antisense therapy Owing to its superior properties, PNA could replace DNA as a probe for many investigation purposes This paper reviews the synthesis of PNA, its important properties making it a new hot tool in the market and its major applications  2006 Society of Chemical Industry

Zymomonas mobilis : an alternative ethanol producer

Abstract: Zymomonas mobilis is a unique bacterium in the microbial world, and offers a number of advantages over the existing ethanol-producing microorganisms. Being a prokaryote, it is more amenable to genetic manipulations. Thus, it has attracted great attention in the ethanol production world and efforts have been made to commercialize its application for the purpose. Despite the various efforts made worldwide, none of the processes using this microbe has been commercialized owing to certain bottlenecks. To circumvent the hindrances currently associated with a Zymomonas process, researchers have made various attempts to improve the technology using different techniques. This paper reviews the different substrates and the genetic improvement techniques with special emphasis on mutagenesis and recombinant DNA technology used for ethanol production by Zymomonas strains. Copyright © 2006 Society of Chemical Industry

Investigation of gaseous ozone as an anti‐fungal fumigant for stored wheat

Abstract: In this study, gaseous ozone was used as a fungicide to preserve stored wheat. The following operating parameters were investigated for their effects on the fungicidal efficacy of ozone: (1) the applied ozone dose; (2) ozonation time; (3) water activity of the wheat; and (4) temperature of the wheat. The effect of ozonation on germination of the wheat was also studied. Experimental results revealed that gaseous ozone was very effective in the inactivation of fungi associated with the wheat. Within 5 min of ozonation, 96.9% of the fungal spores were inactivated by applying 0.33 mg of ozone (g wheat)−1 min−1. It was also found that increases in both water activity and temperature of the wheat enhanced the fungicidal efficacy of ozone. In addition, results of this study indicated that the inactivation processes could be controlled by simply monitoring the ozone exiting from the reactor and, consequently, the time-consuming microbial examination processes could be avoided. This finding would make the application of ozone in the preservation of cereal grains easier, simpler, and more cost-effective. It was also found that although the applied ozone doses above certain thresholds may reduce the germination of wheat, the inactivation of fungi could be achieved using applied ozone doses far below those thresholds. Copyright © 2006 Society of Chemical Industry

Enhanced anaerobic bioremediation of chlorinated solvents: environmental factors influencing microbial activity and their relevance under field conditions

Abstract: Enhanced in situ anaerobic bioremediation of chlorinated solvents is a cost-effective, expanding technology for the clean-up of chlorinated solvent-contaminated sites. However, this technology is knowledge-intensive and its application requires a thorough understanding of the microbiology, ecology, hydrology and geochemistry of chlorinated solvent-contaminated aquifers. This review summarises current knowledge and future perspectives in the area of microbial anaerobic dechlorination of chlorinated solvents, particularly chloroethenes. Main attention is paid to the discussion of environmental factors and conditions that influence microbial activity under field conditions. Approaches to stimulate and manipulate the activity of native dechlorinating populations in order to meet target remediation goals for both plume management and source treatment are reviewed in detail. Possible research efforts needed to increase the likelihood of success of this technology are finally presented.

Primary beer fermentation by immobilised yeast—a review on flavour formation and control strategies

Abstract: Immobilised cells are increasingly being used in bio-industries and may also have benefits for the brewing industry. The major challenge to applying this technology successfully in breweries is focused on the main fermentation in combination with the secondary fermentation. In particular, the control and fine-tuning of the flavour profile during the main fermentation require further investigation. In this review, the influence of immobilised cell technology on the production of the flavour-active compounds (i.e. higher alcohols, esters and vicinal diketones) is discussed. Control strategies that are based on the manipulation of parameters during fermentation such as temperature, feed volume, wort gravity, wort composition and aeration are explained. Finally, bioreactor configurations that may facilitate immobilised cells in performing the primary fermentation are evaluated.  2006 Society of Chemical Industry

Enzyme‐catalyzed regioselective synthesis of sugar esters and related compounds

Abstract: In this review, a comprehensive and illustrative survey is made of the regioselective synthesis of esters of sugars and related compounds using lipases. The main emphasis has been given to the screening and use of commercially available lipases for the enzymatic esterification of neutral monosaccharides, disaccharides, sugar alcohols and their selected ether and ester derivatives. The effect of solvents and solubilizing agents in improving the yields of the resultant sugar fatty acid esters has been incorporated. Further, solvent-free esterification with molten fatty acids, use of ionic liquids and microwave radiations for improvement in the methodology have also been discussed. Copyright © 2006 Society of Chemical Industry

Downstream processing of 1,3‐propanediol fermentation broth

Abstract: The downstream processing of 1,3-propanediol fermentation broth using flocculation, reactive extraction, and reactive distillation was studied. Cellular debris and soluble protein in the broth were flocculated by combined use of chitosan and polyacrylamide at optimal concentrations of 150 ppm and 70 ppm, respectively; the soluble protein in the broth decreased to 0.06 g L−1, and the recovery ratio of the supernatant liquor to broth was greater than 99%. 1,3-Propanediol and other alcohols were extracted from the supernatant liquor by reacting with butyraldehyde. In a four-stage countercurrent extraction with the volume ratio of the extraction solvent to the aqueous phase being 20:100, more than 99% 1,3-propanediol acetal (2-propyl-1,3-dioxane) and 2,3-butanediol acetal (2-propyl-4,5-dimethyl-1,3-dioxolane) were recovered from the aqueous phase; 35% of the glycerol acetals were recovered. The acetals produced were hydrolyzed in a reactive distillation column using the strongly acidic cation-exchange resin as catalyst, the bottom product obtained was a mixture of 1,3-propanediol (407 g L−1), 2,3-butanediol (252 g L−1), glycerol (277 g L−1), and glycerol acetals (146 g L−1). Copyright © 2005 Society of Chemical Industry

The analysis of solvation in ionic liquids and organic solvents using the Abraham linear free energy relationship

Abstract: The original article to which this Erratum refers was published in Journal of Chemical Technology and Biotechnology (81: 1441–1446)

Treatment of Fenton-refractory olive oil mill wastes by electrochemical oxidation with boron-doped diamond anodes

Abstract: In this work, the electrochemical oxidation of an actual industrial waste with conductive diamond anodes has been studied. The wastewater is the effluent of a wastewater treatment plant consisting of a Fenton reactor followed by a settler and a sand filter, in which the wastes generated in an olive oil mill are treated. These wastes contain a residual chemical oxygen demand of nearly 700mgdm −3 which cannot be further oxidized with the Fenton process. The electrolyses were carried out under galvanostatic conditions, using a bench-scale plant equipped with a single-compartment electrochemical flow cell. Boron-doped diamond (BDD) and stainless steel (AISI 304) were use as anode and cathode of the cell, respectively. The complete mineralization of the waste was obtained with high current efficiencies limited only by mass transport processes. This confirms that besides the hydroxyl radical-mediated oxidation that occurs in the Fenton process, the electrochemical oxidation with conductive diamond electrodes combines other important oxidation processes such as direct electro-oxidation on the BDD surface and oxidation mediated by other electrochemically formed compounds generated in this electrode.  2006 Society of Chemical Industry

Characterization of dissolved compounds in submerged anaerobic membrane bioreactors (SAMBRs)

Abstract: Two submerged anaerobic membrane bioreactors (SAMBRs) with essentially 100% cell recycle (150 days retention time, SRT), one with powdered activated carbon addition (PAC 1.7 g L−1) and one without, were continuously fed a low-strength feed (450 mg COD L−1) in order to investigate membrane fouling and to characterize the foulants. The SAMBR which did not receive PAC experienced more fouling, and the molecular weight (MW) distribution showed that there was a greater amount of high-MW compounds in this reactor when compared with the reactor with PAC. Size exclusion chromatography showed that although extracellular polymeric substances (EPS) seemed to contribute to the soluble chemical oxygen demand (COD) inside the reactor, it was mainly rejected by the membrane. High-MW protein and carbohydrate material originating mainly from cell lysis and EPS seemed to be the main organics that contributed to the internal fouling of the membrane. Copyright © 2006 Society of Chemical Industry

Biosorption of phenolic compounds by the brown alga Sargassum muticum

Abstract: Phenol, 2-chlorophenol (2-CP), and 4-chlorophenol (4-CP) biosorption on Sargassum muticum, an invasive macroalga in Europe, has been investigated. The efficiency of this biosorbent was studied measuring the equilibrium uptake using the batch technique. A chemical pre-treatment with CaCl2 has been employed in this study in order to improve the stability as well as the sorption capacity of the algal biomass. The influence of pH on the equilibrium binding and the effect of the algal dose were evaluated. The experimental data at pH = 1 have been analysed using Langmuir and Freundlich isotherms. It was found that the maximum sorption capacity of chlorophenols, qmax = 251 mg g−1 for 4-CP and qmax = 79 mg g−1 for 2-CP, as well as that of a binary mixture of both chlorophenols, qmax = 108 mg g−1, is much higher than that of phenol, qmax = 4.6 mg g−1. Moreover, sorption kinetics have been performed and it was observed that the equilibrium was reached in less than 10 h. Kinetic data have been fitted to the first order Lagergren model, from which the rate constant and the sorption capacity were determined. Finally, biosorption of the phenolic compounds examined in the present study on Sargassum muticum biomass was observed to be correlated with the octanol-water partitioning coefficients of the phenols. This result allows us to postulate that hydrophobic interactions are the main responsible for the sorption equilibrium binding. Copyright © 2006 Society of Chemical Industry

Integrating laccase–mediator treatment into an industrial-type sequence for totally chlorine-free bleaching of eucalypt kraft pulp

Abstract: Enzymatic delignification using the high-redox potential thermostable laccase from the fungus Pycnoporus cinnabarinus and a chemical mediator (1-hydroxybenzotriazole) was investigated to improve totally chlorine-free (TCF) bleaching of Eucalyptus globulus kraft pulps. Different points of incorporation of the enzyme treatment into an industrial-type bleaching sequence (consisting of double oxygen, chelation and peroxide stages) were investigated in pressurized laboratory reactors. The best final pulp properties were obtained using an O-O-L-Q-PoP sequence, where a laccase-mediator stage (L) was incorporated between double oxygen and chelation. The worse results, when the enzymatic and chelation treatments were combined in a unique stage, seemed related to partial inhibition of laccase-mediator activity by the chelator. The new TCF sequence including the laccase stage permitted to improve eucalypt pulp delignification to values around kappa 5 (hexenuronic acid contribution over 50%) compared to kappa 7 using only TCF chemical reagents. In a similar way, the final brightness obtained, over 91% ISO, was 3-4 points higher than that obtained in the chemical sequences. Although technical and economic issues are to be solved, the results obtained show the feasibility of integrating a laccase-mediator treatment into a TCF sequence for bleaching eucalypt kraft pulp.  2006 Society of Chemical Industry

Utilisation of C2–C4 gaseous hydrocarbons and isoprene by microorganisms

Abstract: Microorganisms able to grow on low molecular weight aliphatic hydrocarbon gases, i.e. the n-alkanes, ethane, propane and butane, and the terminal alkenes, ethylene, propylene and butylene, are not uncommon but mainly belong to certain taxonomic groups. These microbes are described in this review together with the pathways by which the hydrocarbons are assimilated. Microbial oxidation of the volatile alkadiene, isoprene, is also discussed. Avenues for possible commercial exploitation of these metabolic activities are also reviewed. Short-chain n-alkane-utilising organisms have been investigated as tools in petroleum exploration and for production of single cell protein. More recently microbes grown on gaseous hydrocarbons other than methane have been evaluated for use in biotechnological production of epoxides, synthesis of chiral epoxyalkanes and as catalysts in bioremediation systems. Copyright © 2005 Society of Chemical Industry

Synthesis and application of dicationic ionic liquids

Abstract: Ionic liquids were synthesised that consisted of two methylimidazolium rings joined by a spacer 1–12 carbon atoms in length. The bis(triflic)imides with spacer ≤C4 were solids; the others were liquid at room temperature. The polarity of the dication liquids and their performance in the extraction of phenol from water were compared with those of similar monocationic liquids. Copyright © 2005 Society of Chemical Industry

Extraction of essential oil from geranium (Pelargonium graveolens) with supercritical carbon dioxide

Abstract: This study investigated the supercritical fluid extraction (SFE) of geranium essential oil from geranium (Pelargonium graveolens) using supercritical carbon dioxide solvent. The extraction yield was measured as a function of pressure, temperature and carbon dioxide flow rate. At low pressure (10MPa) and high temperature (343K), waxes were co-extracted with the essential oil, resulting in artificially elevated essential oil extraction yields as no method was available with the SFE apparatus used to separate co-extracted waxes and oil. At high pressure (30MPa) and low temperature (313K), the amount of wax co-extracted decreased. Under these 'optimum' conditions, the extraction yield increased with decrease in flow rate giving a maximum extraction yield of 2.53%. All samples were analyzed by gas chromatography-mass spectrometry and the effect of pressure and extraction time on oil composition was studied. The percentage compositions of terpene hydrocarbons, terpenols, geraniol and geranyl esters were significantly affected by pressure and extraction time. The oil samples obtained by SFE were also compared with commercially obtained steam distilled samples. All major components of the commercially obtained oils were present in the SFE-obtained oils; however, the percentage composition of the major components differed greatly between steam distilled and SFE oils.  2005 Society of Chemical Industry

Effects of bioaugmentation by an anaerobic lipolytic bacterium on anaerobic digestion of lipid-rich waste

Abstract: The effect of bioaugmentation with an anaerobic lipolytic bacterial strain on the anaerobic digestion of restaurant lipid-rich waste was studied in batch experiments with a model waste containing 10% lipids (triolein) under two sets of experimental conditions: (A) methanogenic conditions, and (B) initially acidogenic conditions in the presence of only the lipolytic strain biomass (4days), followed by methanogenic conditions. The bioaugmenting lipolytic strain, Clostridium lundense (DSM 17049 T ), was isolated from bovine rumen. The highest lipolytic activity was detected at the beginning of the experiments. A higher methane production rate, 27.7cm 3 CH4(STP) g −1 VSadded day −1 (VS, volatile solids) was observed in experiment A with the presence of the bioaugmenting lipolytic strain under methanogenic conditions. The highest initial oleate concentration, 99% of the total oleate contained in the substrate, was observed in the experiments with the bioaugmenting lipolytic strain under treatment A conditions; the levels of palmitate and stearate were also higher until day 15, indicating that the bioaugmentation strategy improved the hydrolysis of the lipid fraction. In general, the results indicated that degradation of the long chain fatty acids (LCFAs) controlled the digestion process.  2006 Society of Chemical Industry

A continuous process for the recovery of lactic acid by reactive distillation

Abstract: Separation and purification of lactic acid from the fermentation broth are difficult because of its non-volatile nature and the presence of other organic acids. Esterification of lactic acid with methanol followed by hydrolysis of the separated methyl lactate is an effective technique for this purpose. A continuous process for recovery is proposed and various aspects are evaluated through simulation and experiments. In the proposed route, a vapor stream containing methyl lactate is removed from a two-phase CSTR, used for esterification, operated under boiling conditions. The ester thus separated from the aqueous solution is further hydrolyzed in a reactive distillation column. Continuous removal of the volatile component (i.e. methanol) from the reaction zone increases conversion, thus pure lactic acid is obtained from the bottom of reactive distillation column. The results obtained in the experiments are compared with the simulation results. Further simulation studies were performed to obtain the suitable operating conditions for higher conversion and concentration of lactic acid. Copyright © 2006 Society of Chemical Industry

Effect of enzymatic pretreatment on acid fermentation of food waste

Abstract: Although food waste is a valuable carbon source for biological nutrient removal systems with low organic wastewater because of high C/N and C/P ratios, it must be pretreated to promote the hydrolysis of particulates, which is considered as a rate-limiting step. This study investigated the effects of enzymatic pretreatment on hydrolytic solubilization of food waste with commercial enzyme. Both acidification efficiency and volatile fatty acid (VFA) production potential of enzymatically pretreated food waste were examined under controlled laboratory conditions. Experimental results indicated that protease exhibited the highest VSS reduction rate among three types of enzymes: carbohydrase, protease and lipase. A mixed enzyme treatment showed better reduction efficiency than a single enzyme treatment, and the highest volatile suspended solids (VSS) reduction was observed at an enzyme mixture ratio of 1:2:1 with carbohydrase:protease:lipase, respectively. It has been noted that pretreatment resulted in both maximum VFA production and the highest VFA content of soluble chemical oxygen demand at an enzyme mixture dosage of 0.1% (v/v). VFA production at this dosage revealed a 3.3 times higher rate than that of no-enzyme added fermenter. The dominant VFAs were n-butyrate followed by acetate. Copyright © 2006 Society of Chemical Industry

Olive oil mill wastewater valorisation by fungi

Abstract: This paper presents a brief survey of studies conducted at the Laboratory of Applied and Environmental Microbiology of the University of Tuscia on the possible biotechnological valorisation of olive mill wastewater (OMW) using fungi. Besides being a serious environmental problem, OMW might be a possible resource owing to the presence of added value products (e.g. antioxidants) and of simple and complex sugars as a basis for fermentation processes. To this end the technical feasibility of various fungal fermentative processes either to obtain products of high added value or to improve its agronomic use has been assessed. With regard to the former aspect the following cases of study are described: production of enzymes, such as lipase by Candida cylindracea NRRL Y-17506, laccase and Mn-dependent peroxidase by Panus tigrinus CBS 577.79 and pectinases by Cryptococcus albidus var. albidus IMAT 4735, and exopolysaccharide production by Botryosphaeria rhodina DABAC-P82. As far as agronomic use of the waste is concerned, a process based on the acidogenic fungus Aspergillus niger NB2 and aimed at increasing the phosphorus content of OMW is also reported.  2006 Society of Chemical Industry

A modified cellulose adsorbent for the removal of nickel(II) from aqueous solutions

Abstract: A series of adsorption studies was carried out on a glycidyl methacrylate- modified cellulose material functionalised with imidazole (Cellulose-g-GMA-Imidazole) to assess its capacity in the removal of Ni(II) ions from aqueous solution. The study sought to establish the effect of a number of parameters on the removal of Ni(II) from solution by the Cellulose-g-GMA-Imidazole. In particular, the influence of initial metal concentration, contact time, solution temperature and pH were assessed. The studies indicated a Ni(II) uptake on the Cellulose-g-GMA-Imidazole sorbent of approximately 48 mg g−1 of nickel from aqueous solution. The adsorption process fitted the Langmuir model of adsorption and the binding process was mildly endothermic. The kinetics of the adsorption process indicated that nickel uptake occurred within 400 min and that pseudo-second order kinetics best describe the overall adsorption process. Nickel(II) adsorption, recovery and re-adsorption studies indicated that at highly acidic pH values the adsorbent material becomes unstable, but in the range pH 3–6, the adsorbent is stable and shows limited but significant Ni(II) recovery and re-adsorption capability. Copyright © 2006 Society of Chemical Industry

Batch production of biosurfactant with foam fractionation

Abstract: Methods of producing the biosurfactant surfactin from cultures of Bacillus subtilis (BBK006) have been investigated. A reactor with integrated foam fractionation was designed and used in batch mode, and the performance compared with that of the same culture in shaken flasks. In the batch reactor, significant foaming occurred between 12.5 h and 14.5 h of culture time. During this period, the foam was routed through the foam fractionation column to a mechanical foam breaker, and a biosurfactant-enriched foamate was collected. Concentration of surfactin in the foamate product was around 50 times greater than that in the culture medium. Using the integrated reactor, 136 mg L−1 of surfactin was produced, significantly more than was achieved in shaken flasks (92 mg L−1). The foam fractionation method allowed a real-time measurement of the rate of surfactin production during growth. This showed that the maximum rate of production occurred at the interphase between log and stationary modes of growth, in contrast to previous work showing that surfactin is exclusively a secondary metabolite. The high value of surfactin yield in relation to biomass (YP/x = 0.262) indicated that surfactin was produced very efficiently by Bacillus subtilis (BBK006) in this integrated bioreactor. Copyright © 2006 Society of Chemical Industry

The extraction of rare earths using mixtures of acidic phosphorus‐based reagents or their thio‐analogues

Abstract: The solvent extraction of rare earths from chloride solution has been investigated using mixtures of 2-ethylhexylphosphonic acid mono-(2-ethylhexyl) ester (HEHEHP, P507) and organophosphorus acids [di-(2-ethylhexyl)phosphoric acid (HDEHP, P204), isopropylphosphonic acid 1-hexyl-4-ethyloctyl ester (HHEOIPP), bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272), bis(2,4,4-trimethylpentyl)monothiophosphinic acid (Cyanex 302), and bis(2,4,4-trimethypentyl)dithiophosphinic acid (Cyanex 301)]. Results show that the extractability of the selected extractants for rare earths decreases in the order: HEHEHP/HDEHP > HEHEHP/Cyanex 301 > HEHEHP/HHEOIPP > HEHEHP/Cyanex 302 > HEHEHP/Cyanex 272. A possible explanation of the different extractabilities is given based on the structure of the extractants. Furthermore, the possibilities of the separation of adjacent rare earths with these mixtures were investigated according to the extractabilities; the results show the possibility of separating the rare earths. Copyright © 2006 Society of Chemical Industry