Showing papers in "Journal of Chemical Technology & Biotechnology in 2014"

Integrated furfural production as a renewable fuel and chemical platform from lignocellulosic biomass

Abstract: Furfural is a natural precursor to furan-based chemicals and has the potential to become a major renewable platform chemical for the production of biochemicals and biofuels. However, current industrial furfural production relies on relatively old and inefficient strategies that have hindered its capacity, and low production yields have strongly diminished its competitiveness withpetroleum-basedalternativesintheglobalmarket.Thismini-reviewprovidesacriticalanalysisofpastandcurrentprogress to enhance furfural production from lignocellulosic biomass. First, important chemical and fuel products derived from the catalytic conversion of furfuralare outlined.Wethen discuss theimportanceof developingintegratedproductionstrategies to co-producefurfuralwithothervaluablechemicals.Furfuralformationandlosschemistriesareexploredtounderstandeffective methods to improve furfural yields from pentosans. Finally, selected relevant commercial and academic technologies that promise to improve lignocellulosic furfural production are discussed. c � 2013 Society of Chemical Industry

Graphene oxide and its application as an adsorbent for wastewater treatment

Abstract: Graphene oxide, particularly as magnetic particles, has recently been used as an adsorbent for wastewater treatment in applications such as heavy metals separation (mercury, cadmium, copper, chromium, arsenic) and also organics (antibiotics, dyes, i.e. Reactive black 5, etc.). Selected examples will be given in the present review – mostly from the literature. The following themes are examined among others: the synthesis route (impregnation, co-precipitation), kinetics of adsorption, thermodynamics, isotherm studies and applications in comparison with other adsorbents. c � 2013 Society of Chemical Industry

Distillation technology - still young and full of breakthrough opportunities

Abstract: Throughout history, distillation has been the most widespread separation method. However, despite its simplicity and flexibility, distillation still remains very energy inefficient. Novel distillation concepts based on process intensification, can deliver major benefits, not just in terms of significantly lower energy use, but also in reducing capital investment and improving eco-efficiency. While very likely to remain the separation technology of choice for the next decades, there is no doubt that distillation technology needs to make radical changes in order to meet the demands of the energy-conscious modern society. This article aims to show that in spite of its long age, distillation technology is still young and full of breakthrough opportunities. Moreover, it provides a broad overview of the recent developments in distillation based on process intensification principles, for example heat pump assisted distillation (e.g. vapor compression or compression–resorption), heat-integrated distillation column, membrane distillation, HiGee distillation, cyclic distillation, thermally coupled distillation systems (Petlyuk), dividing-wall column, and reactive distillation. These developments as well as the future perspectives of distillation are discussed in the context of changes towards a more energy efficient and sustainable chemical process industry. Several key examples are also included to illustrate the astonishing potential of these new distillation concepts to significantly reduce the capital and operating cost at industrial scale. © 2013 Society of Chemical Industry

Use of carbon dioxide as feedstock for chemicals and fuels: homogeneous and heterogeneous catalysis

Abstract: CO2 is considered to play a key role in an eventual climate change, due to its accumulation in the atmosphere. The control of its emission represents a challenging task that requires new ideas and new technologies. The use of perennial energy sources and renewable fuels instead of fossil fuels and the conversion of CO2 into useful products are receiving increased attention. The utilization of CO2 as a raw material for the synthesis of chemicals and fuels is an area in which scientists and industrialists are much involved: the implementation of such technology on a large scale would allow a change from a linear use of fossil carbon to its cyclic use, mimicking Nature. In this paper the use of CO2 as building block is discussed. CO2 can replace toxic species such as phosgene in low energy processes, or can be used as source of carbon for the synthesis of energy products. The reactions with dihydrogen, alcohols, epoxides, amines, olefins, dienes, and other unsaturated hydrocarbons are discussed, under various reaction conditions, using metal systems or enzymes as catalysts. The formation of products such as formic acid and its esters, formamides, methanol, dimethyl carbonate, alkylene carbonates, carbamic acid esters, lactones, carboxylic acids, and polycarbonates, is described. The factors that have limited so far the conversion of large volumes of CO2 are analyzed and options for large-scale CO2 catalytic conversion into chemicals and fuels are discussed. Both homogeneous and heterogeneous catalysts are considered and the pros and cons of their use highlighted. © 2013 Society of Chemical Industry

Methods for Detection of Aflatoxins in Agricultural Food Crops

Abstract: Aflatoxins are toxic carcinogenic secondary metabolites produced predominantly by two fungal species: Aspergillus flavus and Aspergillus parasiticus. These fungal species are contaminants of foodstuff as well as feeds and are responsible for aflatoxin contamination of these agro products. The toxicity and potency of aflatoxins make them the primary health hazard as well as responsible for losses associated with contaminations of processed foods and feeds. Determination of aflatoxins concentration in food stuff and feeds is thus very important. However, due to their low concentration in foods and feedstuff, analytical methods for detection and quantification of aflatoxins have to be specific, sensitive, and simple to carry out. Several methods including thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), mass spectroscopy, enzyme-linked immune-sorbent assay (ELISA), and electrochemical immunosensor, among others, have been described for detecting and quantifying aflatoxins in foods. Each of these methods has advantages and limitations in aflatoxins analysis. This review critically examines each of the methods used for detection of aflatoxins in foodstuff, highlighting the advantages and limitations of each method. Finally, a way forward for overcoming such obstacles is suggested.

Deep eutectic solvents can be viable enzyme activators and stabilizers

Abstract: BACKGROUND Deep eutectic solvents (DESs) have recently attracted widespread interests as new green solvents for (bio)chemical transformations. In this study, 24 DESs were prepared to study their effects on enzymatic performance: two cholinium salts (ChCl and ChAc) combined with four H-bond donors (HBDs) (urea, glycerol, acetamide, ethylene glycol) at three molar ratios. RESULTS In DES-containing aqueous solution, Penicillium expansum lipase (PEL) can be activated and stabilized up to 2.4 times and 18.4 times its original values, respectively. When DESs were used alone as the reaction medium to produce biodiesel from Millettia pinnata seed oil, Novozym 435 enabled a better conversion than PEL, with a maximal yield obtained in ChAc/glycerol (1:2). These DES effects arise from the formation of DES rather than from the synergetic action contributed by each of its components. Preliminary toxicity tests on Hydra sinensis suggest that a DES may be less toxic than its components. CONCLUSION DESs are viable solvents/cosolvents for lipase-catalyzed reactions, and both lipase activity and stability are affected by the choice of DES components (salts and HBDs) and their molar ratios. In both reaction systems above, the ChAc-based DESs were superior to the ChCl-based ones, while glycerol showed better compatibility with lipase than the other three HBDs tested. © 2013 Society of Chemical Industry

Advances in photobioreactors for intensive microalgal production: configurations, operating strategies and applications

Abstract: Over the past ten years a great deal of literature has focused on the biotechnological potential of microalgal commercial applications, mainly in the field of biofuel production. However, the biofuel production is not yet competitive, mainly due to the incidence of the photobioreactor technology on the process cost. Besides, major advances in classic photobioreactor design, several novel configurations have been proposed in the last 20 years to improve their performance expressed in terms of light absorption, biomass productivity, light to biomass yield and photosynthetic efficiency. This review aims at analyzing and classifying the most recent advances and the several novel approaches to the design, development, control and modeling of photobioreactors. The diverse approaches are grouped considering irradiance strategies, multiphase hydrodynamics, mass transfer mechanisms, modeling approaches and control strategies. Some innovative applications of the photobioreactor technology are also reported. © 2013 Society of Chemical Industry

Direct conversion of CO2 with diols, aminoalcohols and diamines to cyclic carbonates, cyclic carbamates and cyclic ureas using heterogeneous catalysts

Abstract: CO2 has a large effect on global warming by greenhouse gases, and development of an effective technique for the reduction of CO2 is a crucial and urgent issue. From the chemical viewpoint, CO2 is regarded as a stable, safe and abundant C1 resource, and the transformation of CO2 to valuable chemicals is promising not only for reduction of CO2 but also for production of useful chemicals. This mini-review focuses on the direct conversion of CO2 with diols, aminoalcohols and diamines to cyclic compounds such as cyclic carbonates, cyclic carbamates and cyclic ureas, and in particular discusses the mechanisms for these reactions over heterogeneous catalysts. © 2013 Society of Chemical Industry

Advances in the development and application of ferrate(VI) for water and wastewater treatment

Abstract: Ferrate(VI) ion has the formula FeO42−, and possesses unique properties, vs. strong oxidising potential and simultaneous generation of ferric coagulating species. For this reason, a number of studies have been carried out to investigate the preparation, characterisation and application of ferrate(VI) for water and wastewater treatment. These studies revealed that ferrate(VI) can disinfect microorganisms, partially degrade and/or oxidise organic and inorganic impurities, and remove suspended/colloidal particulate materials in a single dosing and mixing unit process. Most recently, research groups globally have reported using ferrate(VI) to treat emerging micropollutants in water purification processes. Work has not only been limited to fundamental studies but has been driven by the ideas of putting the application of ferrate(VI) into practice; the advantages of the application of ferrate(VI) over existing water and wastewater treatment methods should be shown as should other benefits to the water industry of its use. This paper thus reviews advances in the preparation and use of ferrate(VI), discusses the potential full scale application of ferrate(VI) in water purification and recommends required future research in order to implement ferrate(VI) in practice. © 2013 Society of Chemical Industry

Polymers for medical and tissue engineering applications

Abstract: Recent decades have seen great advancements in medical research into materials, both natural and synthetic, that facilitate the repair and regeneration of compromised tissues through the delivery and support of cells and/or biomolecules. Biocompatible polymeric materials have become the most heavily investigated materials used for such purposes. Naturally-occurring and synthetic polymers, including their various composites and blends, have been successful in a range of medical applications, proving to be particularly suitable for tissue engineering (TE) approaches. The increasing advances in polymeric biomaterial research combined with the developments in manufacturing techniques have expanded capabilities in tissue engineering and other medical applications of these materials. This review will present an overview of the major classes of polymeric biomaterials, highlight their key properties, advantages, limitations and discuss their applications. © 2014 Society of Chemical Industry

Recent trends in (ligno)cellulose dissolution using neoteric solvents: switchable, distillable and bio-based ionic liquids.

Abstract: Recent years have witnessed the use of different ionic liquids for biomass processing, either at the level of lignocellulose pre-treatment, to fractionate biomass in its main components, separating hemicellulose and lignin from cellulose, or directly in cellulose decrystallization by dissolving it in the ionic liquid and subsequent precipitation by adding anti-solvents. Yet, most of the ILs employed in these strategies (e.g. imidazolium-based solvents) are (still) expensive for such applications, and provide discussable ecological footprints. In an attempt to combine the highly useful generated knowledge with novel neoteric solvents with improved properties, economics, availability and ecology, several new trends have appeared in these areas during recent years. They comprise the use of switchable ILs, based on strong organic bases and CO2, the application of distillable ILs, as well as the use of bio-based and low-cost ILs and deep-eutectic-solvents (DES), e.g. choline chloride-based derivatives. Apart from other emerging uses, for all these solvents some preliminary applications in biomass processing involving pretreatments, cellulose dissolution and other applications have been successfully reported. This Minireview contextualizes these recent trends and discusses them with emphasis on future use of them in biorefineries and biomass valorization. © 2013 Society of Chemical Industry

The use of microfluidic devices in solvent extraction

Abstract: Solvent extraction (SX) is an important separation method with countless applications in the chemical industry. The water/oil interface is an essential feature of SX systems. Microfluidic technology is ideally suited for exploitation in SX due to intrinsic advantages of the micro dimensions that result in laminar flow conditions, high surface-to-volume ratio and the reduced chemical quantities needed. This review describes the use of microfluidic devices in SX. © 2014 Society of Chemical Industry.

Esterification of renewable levulinic acid to ethyl levulinate biodiesel catalyzed by highly active and reusable desilicated H-ZSM-5

Abstract: BACKGROUND In the near future, fossil fuel will have limitations in terms of availability and also great concerns over its environmental impact. New routes and related technologies based on renewable feedstocks can overcome most of these problems associated with fossil fuel. Among current biodiesel sources, ethyl levulinate (EL) biodiesel obtained from catalytic esterification of renewable levulinic acid (LA) with ethanol has received a great deal of attention. The use of desilicated H-ZSM-5 (DH-ZSM-5) as heterogeneous acid catalyst for EL biodiesel production in a closed system (under autogeneous pressure) was studied. RESULTS The effect of reaction parameters such as ethanol to LA molar ratio (4:1 to 10:1), catalyst to LA ratio (0.10–0.25), speed of agitation (100–400 rpm), particle size (53–355 µm), reaction temperature (363–403 K) and reaction time (7 h) was investigated to maximize LA conversion. CONCLUSION Levulinic acid conversion reached 95% over DH-ZSM-5 and the catalyst was reusable for up to six cycles. This LA conversion and the catalyst reusability values are higher than others reported in the literature. A pseudo-homogeneous (P-H) kinetic model indicated that reaction rate constants increased with increasing molar ratio, catalyst to LA ratio and reaction temperature. The activation energy decreased from 73.14 to 21.08 kJ mol-1 when increasing the catalyst to LA ratio from 0.10 to 0.25, which implies a kinetically controlled reaction. © 2013 Society of Chemical Industry

Production and use of biochar from buffalo‐weed (Ambrosia trifida L.) for trichloroethylene removal from water

Abstract: BACKGROUND Ambrosia trifida L. (buffalo-weed) is a ubiquitous invasive plant species in Korea, causing severe allergy problems to humans and reduction in crop yields. Converting buffalo-weed biomass to biochar and its use as an adsorbent for the depuration of trichloroethylene (TCE) contaminated water could help resolve two existing environmental issues simultaneously. RESULTS The plant biomass was converted to biochar at 300 °C (BC300) and 700 °C (BC700). The pyrolysis temperature strongly influenced the properties of resulting biochars. The higher temperature resulted in a higher degree of C-enrichment. The loss of H- and O-containing functional groups shifted the BC700 composition towards a less polar, more aromatic carbon structure evidenced by lower O/C (0.06) and H/C (0.15) values compared with those of BC300 (0.07 and 0.65, respectively). These properties of BC700 further highlighted its greater efficiency of TCE removal (88.47%) from water, compared with that of BC300 (69.07%). The TCE adsorption data was well described by the Hill isotherm model indicating the mechanism of adsorption to be cooperative interaction. Linear correlations between model parameters and biochar properties were also observed. CONCLUSIONS Buffalo-weed can be converted to value-added biochar that can be used as an effective adsorbent for the treatment of TCE contaminated groundwater. © 2013 Society of Chemical Industry

N-doped TiO2/s-PS aerogels for photocatalytic degradation of organic dyes in wastewater under visible light irradiation

Abstract: BACKGROUND Heterogeneous photocatalysis for the degradation of non-biodegradable organic contaminants in wastewater is an alternative to traditional treatment techniques. Since the applications developed employ photocatalysts in powder form, a main disadvantage remains related to the recovery of photocatalysts from the treated wastewater, resulting in damage and shorter lifetime for the recirculation pumps. Structured photocatalysts offer a valid solution to simplify the process; however, they have to guarantee light transmission, long-term stability under different operating conditions and under mechanical stress. RESULTS The photocatalytic performances of N-doped TiO2 nanocomposite syndiotactic polystyrene aerogels (Nt-sPS) were analyzed in the presence of visible light. A widely used model pollutant, methylene blue (MB), was chosen to verify the photocatalytic performance. After about 180 min of irradiation, on Nt-sPS, the conversion of MB reached 30%, higher than that obtained (16%) when the photocatalyst is suspended as powder in the liquid reaction medium. CONCLUSION N-doped TiO2, obtained by direct nitration during the hydrolysis of titanium tetraisopropoxide with ammonia solutions, was immobilized in s-PS aerogels, yielding high activity in the removal of methylene blue under visible light irradiation, in comparison with N-doped TiO2 dispersed as powder in solution. © 2014 Society of Chemical Industry

Synthesis and characterization of Magnetic Ionic Liquids (MILs) for CO2 separation

Abstract: BACKGROUND The behaviour of a new generation of Ionic Liquids (ILs) containing transition metals, Magnetic Ionic Liquids (MILs), has recently been reported in the literature. Due to the early stage of development of MILs, it is necessary to evaluate their properties in order to develop new applications. In this work, four MILs based on the trihexyl(tetradecyl)phosphonium cation and different magnetic anions ([P66614]2[CoCl4], [P66614][FeCl4], [P66614]2[MnCl4] and [P66614]3[GdCl6]) were synthesized and characterized by measuring magnetic susceptibility, density, viscosity, thermal properties and carbon dioxide solubility for CO2 separation. RESULTS The magnetic susceptibility showed a paramagnetic behaviour in all the MILs tested, in good agreement with other MILs reported in the literature. The density and viscosity of MILs were obtained experimentally and correlated using Fitteia software. All MILs studied showed very good thermal stability, with decomposition temperatures higher than 619 K. CO2 solubility in the MILs was lower than in other ILs reported in the literature for CO2 capture under the same operational conditions. CONCLUSIONS This work provides further information related to the synthesis and characterization of phosphonium-based MILs and offers potential for the development of new applications. © 2014 Society of Chemical Industry.

Optimization of microalgae oil extraction under ultrasound and microwave irradiation

Abstract: Background. Microalgae are one of the most promising biofuel sources that the world has to offer, although the conversion process is hampered by technical and economic problems mainly related to de-watering and extraction. The efficiency of the process can be dramatically improved by means of non-conventional techniques such as ultrasound (US) and microwaves (MW). However, their energy efficiency must also be taken into account. Results. In the present work different solvents (chloroform/methanol mixtures, hexane, acetone and pure methanol) and procedures (Bligh-Dyer and Folch as conventional, MW and US as non-conventional) were tested to find the best conditions for lipid extraction from Nannochloropsis gaditana microalga. The energy consumption of USand MW-assisted microalgae oil extraction processes have been compared with classical procedures.

Bioremediation of petroleum hydrocarbons-contaminated soil by bacterial consortium isolated from an industrial wastewater treatment plant

Abstract: BACKGROUND Bioaugmentation is a promising technology to clean up sites contaminated by the petrochemical industry The paper reports on the bioremediation of a refinery soil containing hydrocarbons in a semi-arid climate and its impact on the soil microbial community Two trial plots were established in autumn 2008 to compare two sets of conditions The first trial is a control (contaminated soil with indigenous microorganismes) and the second is a trial where an acclimatized bacterial consortium was added RESULTS The proposed bioremediation technology resulted in significantly higher hydrocarbons removal efficiencies than the control The total amount of petroleum hydrocarbon (TPH) was decreased from 634 mg g−1 to 25 mg g−1 at the end of the treatment The treated soil could be considered non-phytotoxic since the germination index of Lepidium sativum ranged between 80 and 115% Further, a GC/MS profile proved that the acclimatized bacterial consortium could effectively remove medium- and long-chain alkanes in the contaminated soil after a 30-day treatment period Microbial community analysis (16S rRNA and Denaturing Gradient Gel Electrophoresis (DGGE) fingerprints) confirmed the dominance of hydrocarbon degrading genera such as actinobacteria and gamma-proteobacteria phyla CONCLUSION These results show that bioaugmentation may be a suitable tool for the remediation of soil contaminated with petroleum hydrocarbons © 2013 Society of Chemical Industry

Microwave-assisted aqueous two-phase extraction of phenolics from grape (Vitis vinifera) seed

Abstract: BACKGROUND The wine making process produces a large quantity of grape marc, which includes grape seeds, skins, and stems. These byproducts comprise approximately 20% of the harvested grapes. Aqueous two-phase extraction (ATPE) composed of short-chain alcohol, inorganic salt, and water is a novel approach used to separate active constituents from fermentation broth or natural plant. A microwave-assisted aqueous two-phase extraction (MAATPE) method was used to obtain phenolic compounds from grape seeds. The partitioning behavior of the phenolic compounds in the MAATPE system was assessed. RESULTS Phenolic compounds were extracted into the top acetone-rich phase at 32% (w/w) acetone/16% (w/w) ammonium citrate. The maximum yield of total phenolics, flavonoid, and proanthocyanidin were 82.7, 52.6, and 30.7 mg g−1, respectively. The corresponding recovery rates were 97.1%, 97.9%, and 99.3%. The antioxidant activity of seed extracts was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) radical-scavenging ability (IC50). No significant correlation was found between free radical scavenging capacity and TP content. CONCLUSION MAATPE required lower solvent concentration and less treatment time to extract high amounts of phenolics from grape seeds compared with the other methods. MAATPE has the potential for the extraction, clarification, and concentration of target products using a single step. © 2013 Society of Chemical Industry

Adsorption of rare earths (III) by calcium alginate-poly glutamic acid hybrid gels

Abstract: BACKGROUND Adsorption is believed to be an effective and green technology for the removal and recovery of rare earths (III) from dilute solution. RESULTS A novel hybrid gel, abbreviated as ALG-PGA, has been prepared through crosslinking calcium alginate (ALG) and γ-poly glutamic acid (PGA), and its adsorption behavior towards whole rare earths (III) has been examined. Taking Nd(III) as a representative element, the adsorption capacity, kinetics, reusability, selectivity and mechanism have been investigated. Cation exchange is proposed as a possible adsorption mechanism. Doping PGA molecules into calcium alginate beads can significantly enhance the adsorption capacity and the selectivity of rare earths from non-rare earths. The maximum adsorption capacity obtained for Nd(III) was 1.65 mmol g−1. Reutilization of ALG-PGA gel was confirmed for up to eight consecutive sorption–desorption cycles with no damage to the gel. CONCLUSION The prepared biosorbent, ALG-PGA, was biocompatible and cost effective with a good adsorption ability for Nd(III), and provides a new approach to the recovery of rare earths (III) from rare earths-containing wastewater. © 2013 Society of Chemical Industry

A review on fermentative hydrogen production from dairy industry wastewater

Abstract: Hydrogen (H2) is one of the most promising alternative fuel sources for satisfying future energy demand, and fermentative hydrogen production is advantageous over other processes. In recent decades, considerable research has been conducted on H 2 production from carbohydrate-rich materials since it is a cost-effective approach and has the ability to generate intensive renewable energy from organic wastes. Dairy wastewater is a high volume industrial wastewater and with its immense carbohydrate content is an attractive candidate for sustainable fermentative H 2 production. The present paper provides comprehensive evaluation of recent reports on fermentative H 2 production from dairy wastewater. Important effective parameters and current bioreactor technologies for H 2 production from dairy wastewater are discussed. © 2014 Society of Chemical Industry

Functionalized magnetic nanoparticles as new adsorption materials for arsenic removal from polluted waters

Abstract: BACKGROUND One of the most harmful pollutants to human health present in natural water is arsenic. In this work magnetic silica/magnetite nanoparticles functionalized with aminopropyl groups incorporating Fe3+ (S1-F3) were investigated for their suitability as materials to adsorb As5+ and As3+ from polluted groundwater. RESULTS Magnetite nanoparticles obtained by a co-precipitation method were coated with a mesoporous silica layer generated by hydrolysis and condensation of tetraethyl orthosilicate. The resultant material was grafted with amino derivatives coordinated with Fe3+. The synthesis was confirmed by FT-IR, TGA and BET analyses. After analysis of the affinity of solids with different degrees of functionalization towards arsenate and arsenite species, the material S1-F3 resulted in maximum arsenic adsorption capacities (14.7 ± 0.3 mg As3+g-1 and 121 ± 4.1 mg As5+g-1). The adsorption equilibrium was satisfactorily described by the Langmuir model and exhibited low sensitivity to temperatures in the range 288–308K. Kinetic data were correlated with a pseudo-second-order kinetic model based on solid capacity that considers the rate of the surface reaction as the rate-limiting step. CONCLUSION The promising results confirm that the material S1-F3 is an effective adsorbent for the removal of arsenate from polluted water. More research is being conducted to analyse the influence of competing anions and sorbent regeneration. © 2014 Society of Chemical Industry.

Effect of moisture on in situ transesterification of microalgae for biodiesel production

Abstract: Background A major hurdle with algal biodiesel production has been the energy required to dry algal biomass prior to lipid extraction and/or conversion. Water interferes with the extraction and/or conversion of algal lipids to biodiesel. The focus of this study was to evaluate the efficiency of the in situ transesterification method for biodiesel recovery when processing algal biomass with varying amounts of moisture and to evaluate changes in efficiency as in situ transesterification reaction parameters were varied. Results Results indicated that moisture content affected biodiesel recovery. Specifically, algal biomass moisture contents above 20% by mass led to statistically significant reductions in biodiesel recovery. However, increasing the amount of catalyst and/or methanol in the reaction resulted in higher recoveries when using wet algal biomass containing 84% moisture. Using 10% (v/v) sulfuric acid in methanol with the wet biomass to solution ratio of 25 mg (dry mass equivalent) mL-1 resulted in the recovery of approximately 81% of the maximum biodiesel yield. Conclusion This study showed that the presence of moisture at greater than 20% by mass in algal biomass significantly decreased biodiesel recovery when using in situ transesterification. Increasing the amount of methanol and/or catalyst in the reaction improved biodiesel recovery from wet algal biomass. © 2013 Society of Chemical Industry

Innovative anaerobic bioreactor with fixed‐structured bed (ABFSB) for simultaneous sulfate reduction and organic matter removal

Abstract: BACKGROUND The anaerobic treatment of wastewaters is usually applied to remove the organic matter, converting it into methane. The presence of sulfate in some wastewaters produces sulphide during anaerobic biological processing, which is known as an inhibitor of biological processes. In this study, a novel anaerobic bioreactor with a fixed structured bed (ABFSB) was subjected to simultaneous sulfate reduction and organic matter removal. RESULTS Synthetic wastewater was used as organic substrate and the bioreactor performance was studied with different COD/[SO42−] ratios: 0.72, 1.7, 3.5 and 6.1. The highest COD and sulfate removal efficiencies were achieved at a COD/[SO42−] ratio of 1.7 (82 and 89%, respectively). Also, in this condition a greater overall kinetic apparent parameter (0.96 h−1) was observed. The kinetic parameters indicate that the sulfate reducing bacteria played an important role in the organic matter removal process over a range of COD/[SO42−] ratios from 6.1 to 1.7. CONCLUSIONS Concerning the organic matter removal, the best synergy between sulfate reduction bacteria and metanogenic archaea communities was achieved in COD/[SO42−] ∼1.7. The ABSFB was suitable for the simultaneous organic matter and sulfate removal, especially when the COD/[SO42−] ratio was 1.7, but demonstrating a stable and efficient process in all conditions studied. © 2013 Society of Chemical Industry

Exergy analysis of energy‐intensive production processes: advancing towards a sustainable chemical industry

Abstract: Exergy analysis is becoming a very powerful strategy to evaluate the real efficiency of a process Its application in the chemical industry is still at an early stage but many interesting remarks can be obtained from the recent research in the most energy intensive processes of the chemical industry: the production of chemicals, the cement industry, the paper industry and, the iron and steel industry The present review analyzes the opportunities and challenges in those sectors by considering exergy analyses as the first required step (although not sufficient) to advance towards a more sustainable chemical industry Social, environmental and economic factors play a role in the critical evaluation of a process and exergy could be considered as the property that joins together those three cores of sustainability

Suppression of methanogenic activity in anaerobic granular biomass for hydrogen production

Abstract: BACKGROUND Several pretreatment methods at lab-scale have been developed to inactivate methane-producing and hydrogen-consuming microorganisms. The need to obtain a hydrogen-producing inoculum by a more practical method is still necessary. The objective of this study was to evaluate the adaptation of anaerobic granules to suppress the methanogenic activity for hydrogen production. RESULTS Preliminary tests in discontinuous operation indicated that methanogenic bacteria were hardly suppressed. The continuous adaptation of the granules, at pH of 4.5 and HRT of 5.5 h, produced hydrogen and successfully suppressed the methanogenic activity. An even distribution of β-polysaccharides and cells was observed when the adapted granules were stained with fluorescent molecular tags. The reactor productivity was 71 ± 6 mL-H2 Lreactor−1 h−1 with a yield of 2.6 ± 0.2 mol H2 mol–1 glucose. CONCLUSION Hydrogen was produced from methanogenic granules. The continuous strategy successfully suppressed the methanogenic activity of the seeded granules and the hydrogen production was stable. The high yield and even distribution of cells suggests that the continuous adaptation generated a more active biomass due to an improved mass transfer present in the process. © 2013 Society of Chemical Industry

Mixotrophic growth of Chlorella vulgaris and Nannochloropsis oculata: interaction between glucose and nitrate

Abstract: Background A major obstacle to the application of microalgae for bio-fuel production is light intensity reduction in high density cultures. Mixotrophic operation can solve this problem by exploiting the ability of microalgae to grow on organic carbon in dark conditions. In this article, mixotrophic growth of Nannochloropsis oculata and Chlorella vulgaris is analyzed. The influence of nitrate and glucose concentration on cell growth in 300 mL Erlenmeyer flasks was investigated using an experimental factorial design. The analysis was extended and validated by analyzing mixotrophic growth in a 6 L bubble column. Results The addition of glucose at concentration 0.1 g L-1 inhibited or enhanced the growth of Chlorella depending on nitrate concentration, while it increased the growth rate of Nannochloropsis at all nitrate concentrations tested. Statistically significant interaction between glucose and nitrate concentration was revealed for Chlorella; negligible interaction was found for Nannochloropsis. A kinetic characterization, shedding light on the influence of glucose on microalgal growth, was conducted through identification of a Monod-like model. Experimental tests in 6 L bubble column confirmed for both Chlorella and Nannochloropsis the possibility to significantly enhance growth in the presence of light deficiency through mixotrophic operation. Conclusions Mixotrophic growth is governed by the interaction between organic carbon and nitrogen. This can have a profound impact on kinetic modeling of microalgal growth and on the operation of cultivation systems. Controlling the C/N ratio is in particular fundamental to optimize reactor operation. © 2013 Society of Chemical Industry

Comparative study of the extraction methods for recovery of carotenoids from algae: extraction kinetics and effect of different extraction parameters

Abstract: Carotenoid extraction from algae is currently under intensive research due to the increased demand for naturally occurring compounds, which are especially rich in biologically active isomers. Furthermore, natural carotenoids exhibit greater stability than synthetic ones. Conventional liquid extraction suffers from several drawbacks, such as use of high amounts of solvent, and several extraction steps. In this work carotenoid extraction from algae using different methods, such as microwave and ultrasound assisted extraction as well as pressurized liquid extraction and extraction with supercritical CO2 and ethane, is summarized together with modelling of extraction kinetics. In addition carotenoid availability, algae pretreatment, stability of extracts, their antioxidative and antimicrobial activities as well as downstream processing and storage of algae extracts have been reviewed. As a conclusion it can be stated that carotenoid extraction is complex, demanding optimization of the carotenoid yield and antioxidative stability, which are often inversely proportional. © 2014 Society of Chemical Industry

Novel mutant strains of Rhodosporidium toruloides by plasma mutagenesis approach and their tolerance for inhibitors in lignocellulosic hydrolyzate

Abstract: BACKGROUND: Rhodosporidium toruloides can transform carbohydrates from lignocellulosic hydrolyzate into long-chain fatty acids that contribute to biodiesel production. However R. toruloides cannot survive in lignocellulosic hydrolyzate due to the inhibitory effects of the byproducts co-produced by hydrolysis. RESULTS: To circumvent the limitation, atmospheric room temperature plasma (ARTP) mutagenesis was utilized to obtain R. toruloides mutant strains M11, M14, and M18 that had strong tolerance for the inhibitory compounds and could grow in lignocellulosic hydrolyzate without detoxification. It was demonstrated that acetic acid and vanillin (phenoliccompounds) were major inhibitors that decreased lipid productivity by 30%. Furthermore, acetic acid and vanillin changed the fatty acid composition of the lipids. Among the mutants, M18 exhibited the highest tolerance for all the inhibitory compounds and had near 50% lipid content. CONCLUSIONS: This work provides novel potential strains for biodiesel production using lignocellulosic biomass and a useful foundation for optimization of the pretreatment of lignocellulose. c � 2013 Society of Chemical Industry Supportinginformationmaybefoundintheonlineversionofthisarticle.

Effects of noble metals doped on mesoporous LaAlNi mixed oxide catalyst and identification of carbon deposit for reforming CH4 with CO2

Abstract: BACKGROUND The effect of the B cation on the surface properties and catalytic activity in the dry reforming reaction over La0.4M0.6Al0.2Ni0.8O3 (M=noble metal) perovskite-type oxides with surface area 3.26–4.14 m2 g–1 and rhombohedral structure was studied. RESULTS Among LaAlxNi1-xO3 series, LaAl0.2Ni0.8O3 had the highest catalytic activity, but suffered a slow deactivation with time-on-stream (TOS). It is observed that all samples presented similar activity at low reaction temperatures (500–600°C), while at higher temperatures (600–850°C) the prepared solid was more active and perovskite phase was transformed into Ni0 or La2O2CO3. It was found that among the noble metal samples, La0.4Rh0.6Al0.2Ni0.8O3 possessed the highest surface area and surface oxygen concentration and the best low-temperature reducibility. For the Rh catalyst the CH4 and CO2 conversions were 89.1 and 86.2%, which were the most resistant against coke deposition and showed very high stability without decrease in reforming and remained constant during the 3000 min TOS. The following order of activity was observed: La0.4Rh0.6Al0.2Ni0.8O3 > La0.4Ru0.6Al0.2Ni0.8O3 > LaAl0.2Ni0.8O3> La0.4Ir0.6Al0.2Ni0.8O3 ≥La0.4Pt0.6Al0.2Ni0.8O3 > La0.4Pd0.6Al0.2Ni0.8O3. CONCLUSIONS It is believed that the high surface area and surface oxygen concentration and good low-temperature reducibility were responsible for the good catalytic performance of the La0.4Rh0.6Al0.2Ni0.8O3 sample. © 2013 Society of Chemical Industry