Use Of Anion Exchange Resin Research Articles

Effective isolation of succinic acid from aqueous media with the use of anion exchange resins.

The primary objective of this study was to examine the isolation of succinic acid (SA) from aqueous-based solutions through the utilization of adsorption and ion exchange methods. Four kinds of anion exchange resins were employed, two of which were strong basic (Lewatit M-500 and Lewatit M-600), and the other two were weak basic (Lewatit MP-64 and Lewatit MP-62). The impacts of various variables on the efficiency of the process were examined. The aqueous pH strongly influenced the separation yield. Weak basic exchangers achieved the maximum yield at pH 2.1. However, the highest performance with Lewatit M-600 and Lewatit M-500 was obtained at pH 5 and 6, respectively. The SA separation with the tested resins reached equilibrium in about an hour. The recovery data revealed consistency with the Langmuir isotherm and pseudo-second-order kinetics. Efficiency improved with resin dosage and reduced with SA concentration. It was found that weak basic anion exchange resins were more efficient than strong basic exchangers for the recovery process. Among the resins tested, Lewatit MP-62 demonstrated the highest sorption capacity of 321 mg g-1 and 97.5% yield. The performance of the system decreased with temperature for all alternatives tested; however, its impact was not notable. The isolation process had an exergonic, exothermic, and favorable character based on the thermodynamic constants. Acid-loaded resins were successfully regenerated using trimethylamine and HCl for weak and strong anion exchange resins, respectively.

Structure properties and industrial applications of anion exchange resins for the removal of electroactive nitrate ions from contaminated water.

The presence of nitrates in lakes, rivers, and groundwater is common. Anion exchange resins (AER) are polymeric structures that contain functional groups as well as a variety of particle sizes that are used for removing nitrate ions from solutions. This article provides a concise review of the types and properties of AER, synthesis methods, characterization, and environmental applications of AER. It discusses how different factors affect the adsorption process, isotherm and kinetic parameters, the adsorption mechanism, and the maximum adsorption capacities. Additionally, the present review addresses AER's regeneration and practical stability. It emphasizes the progress and proposes future strategies for addressing nitrate pollution using AER to overcome the challenges. This review aims to act as a reference for researchers working in the advancement of ion exchange resins and presents a clear and concise scientific analysis of the use of AER in nitrate adsorption. It is evident from the literature survey that AER is highly effective at removing nitrate ions from wastewater effluents.

Xylitol Production by Debaryomyces hansenii in Extracted Olive Pomace Dilute-Acid Hydrolysate

The extracted olive pomace (EOP) is an industrial lignocellulosic by-product of olive pomace oil extraction, currently mainly used for energy production through combustion. In this work, the hemicellulosic fraction of EOP was selectively hydrolyzed by diluted acid hydrolysis to obtain pentose-rich hydrolysates that can potentially be upgraded by Debaryomyces hansenii, targeting xylitol production. The monosaccharides and degradation by-products released along the pre-treatment were quantified and several detoxification methods for the removal of potentially toxic compounds were evaluated, including pH adjustment to 5.5, the use of anion-exchange resins, adsorption into activated charcoal, concentration by evaporation, and membrane techniques, i.e., nanofiltration. The latter approach was shown to be the best method allowing the full removal of furfural, 41% of 5-hydroxymethylfurfural, 54% of acetic acid, and 67% of the phenolic compounds present in the hydrolysate. The effects of the supplementation of both non-detoxified and detoxified hydrolysates were also assessed. The non-detoxified hydrolysate, under aerobic conditions, supported the yeast growth and xylitol production at low levels. Supplementation with the low-cost corn steep liquor of the nanofiltration detoxified hydrolysate showed a higher xylitol yield (0.57 g/g) compared to the non-detoxified hydrolysate. The highest xylitol productivity was found in hydrolysate detoxified with anionic resins (0.30 g/L·h), which was 80% higher than in the non-detoxified culture medium. Overall, the results showed that EOP dilute acid hydrolysates can efficiently be used for xylitol production by D. hansenii if detoxification, and supplementation, even with low-cost supplements, are performed.

Optimal design of a simulated-moving-bed separation process for economical production of xylitol from bamboo-hydrolysis byproducts

Xylitol, which is one of industrially useful sugar-alcohols, has received constant attention from various industries. For the eco-friendly and economical production of xylitol, the byproducts from bamboo hydrolysis treatments for bioethanol-production purposes can be utilized as the source for xylitol. Since such bamboo-hydrolysis byproducts were reported to consist of several polyols such as xylitol, xylose, and glycerol, one essential requirement for ensuring a large-scale production of xylitol will be to secure a highly-efficient process for separation of xylitol from the above-mentioned polyol mixture. To address this issue, we aimed to establish an optimal simulated-moving-bed (SMB) process that can accomplish the xylitol-separation task of interest in a continuous mode while maintaining the best performances. It was found first that the use of an ion-exchange resin of styrene–divinylbenzene copolymer in lanthanum form at 60 °C was most suitable as the adsorbent conditions of the xylitol-separation SMB. Under such adsorbent conditions, the intrinsic parameters of the polyol mixture components were determined and then applied to the optimization of the xylitol-separation SMB with a standard type of configuration (2–2–2–2), which was carried out based on the standing wave design method. It was confirmed that the optimized process was successful in keeping the front and rear of each solute band within their corresponding zones under the maximized degree of adsorbent utilization, which suggested that the yield of xylitol and the removal rates of non-products could be maintained at sufficiently high levels while maximizing the SMB throughput. Further comprehensive optimizations revealed that compared to the standard configuration-based SMB, the 5–2–7–2 configuration-based SMB can more than double the xylitol product concentration as well as almost halve the desorbent usage, while maintaining the same throughput and separation capability.

Studies of Niobium Sorption from Chloride Solutions with the Use of Anion-Exchange Resins

This paper presents the results of studies for niobium sorption from chloride solutions with the use of anion-exchange organic sorbents: Amberlite IRA-67, Purolite A-100, AB-17-8, and AN-2FN. Niobium sorption was performed from model niobium-containing solutions. Data on comparative sorption characteristics of the studied sorbents were obtained, and the static exchange capacity of the sorbents, values of distribution coefficients, and extraction degree during the niobium sorption from chloride solutions were calculated. The Purolite A-100 anion-exchange resin exhibited the highest affinity for niobium ions under the conditions studied. Its distribution coefficient was 184 mL/g; the niobium extraction degree was 41.5%. To study the equilibrium sorption of niobium from solution on the Purolite A-100 anionite, three well-known models of isotherms were applied: Langmuir, Freundlich, and Dubinin–Radushkevich. The data obtained confirm the good agreement of the Langmuir model with the results of experiments and indicate that the process takes place in a monomolecular layer on the adsorbent having homogeneous adsorption centers. The optimum conditions of niobium sorption by the Purolite A-100 anion-exchange resin were determined as follows: hydrochloric acid concentration—5–10 wt.%, process temperature—35–40 °C, and duration—40–50 min. The calculated activation energy values for niobium sorption from hydrochloric acid solution in the temperature range of 20–50 °C were 25.32 kJ/mol, which corresponds to the intermediate region corresponding to the transition from the diffusion to the kinetic mode.

The first stage of refining of post-fermentation corn oil with a high content of free fatty acids and phytosterols – Comparison of neutralisation by an ion-exchange resin without solvent and base neutralisation

Post-fermentation crude corn oil obtained as a by-product in the production of bioethanol from maize grains is characterized by a very high content of free fatty acids. Refining of post-fermentation corn oil will give a product that will be different from the refined oil obtained by extracting oil from corn germs. From the point of view of refining vegetable oils, the neutralisation of this oil is the most important process. Anionic ion-exchange resin was used in the research in a way to avoid the use of harmful organic solvents and a comparatively standard method of neutralising free fatty acids based on the use of a sodium hydroxide solution. Ion-exchange resin can be used in the processes of neutralising vegetable oil with an average content of free fatty acids, then the oil is neutralised in miscela. In the research, no organic solvent was used, but to reduce the flow resistance, a system based on an adjustable reduced pressure in the range of 300–50 mbar was used, to maintain a constant contact time of the oil with the resin in each cycle. The aim of the research was to obtain neutral oil with a high content of biologically active substances such as phytosterols and carotenoids. Both methods showed a reduction of free fatty acids up to 93–96 % and a similar refining loss of 18–19 %. The use of an ion-exchange resin allowed to obtain an oil in which the phytosterol content increased by 5 % for β-sitosterol, by 6.3 % for ϭ5-avenasterol, and the carotenoid content was reduced by 35 %. An increase in the number of fatty acids, such as 18:1 cis-oleic acid and 18:2 cis-linoleic, was observed.

Superhydrophobic Silica Aerogels and Their Layer-by-Layer Structure for Thermal Management in Harsh Cold and Hot Environments.

Personal thermal management (PTM) materials have recently received considerable attention to improve human body thermal comfort with potentially reduced energy consumption. Strategies include passive radiative cooling and warming. However, challenges remain for passive thermal regulation of one material or structure in both harsh hot and cold environments. In this work, silica aerogels derived from sodium silicate were prepared through a solvent-boiling strategy, where hydrophobization, solvent exchange, sodium purification, and ambient pressure drying (HSSA) proceeded successively and spontaneously in a one-pot process. This strategy leads to the synthesis of superhydrophobic silica aerogels with extremely low energy consumption without out the use of an ion-exchange resin or low surface tension solvents. Silica aerogels possess a high specific surface area (635 m2/g), high contact angle (153°), and low thermal conductivity (0.049 W/m K). A layer-by-layer (LBL) structure including the silica aerogel layer and an extra phase change material layer was designed. The structure demonstrates dual-functional thermal regulation performance in both harsh cold (-30 °C) and hot (70 °C) environments, where the time to reach equilibrium is postponed, and the inner temperature of the LBL structure can be kept above 20 °C in harsh cold environments (-30 °C) and below 31 °C in harsh hot environments (70 °C). A proof-of-concept experimental setup to simulate the illumination of sunlight also proved that the inside temperature of a model car protected by the LBL structure was below 28 °C, while the outside temperature was 70 °C. In addition, these results are well supported by theoretical COMSOL simulation results. The findings of this work not only provide an eco-friendly approach to synthesize silica aerogels but also demonstrate that the LBL structure is a robust dual-functional PTM system for thermal regulation in both harsh hot and cold environments.

Development of 148Gd analysis method using stable Gd

The analytical method of Gd determination was developed with the aim to analyse 148Gd in environmental and bioassay samples. It involves the use of anion exchange resin, extraction chromatography, and cation exchange resin. Alkaline fusion and calcium oxalate co-precipitation are used for solid samples dissolution and liquid samples preconcentration, respectively. Total method recovery was tested with natural Gd (157Gd) using ICP-QQQ-MS. A maximum total recovery of 75 % was obtained.

Preservation of minor components and deacidification of rice bran oil using strong anionic resin

Rice bran oil presents high levels of tocopherols/tocotrienols and gamma-oryzanol, which are recognized for their nutraceutical effects. However, these minor compounds can be sensitive to the traditional refining processes, which necessarily include a deacidification step. Therefore, alternative processes are required to preserve these nutraceuticals in the deacidified oil. This study aimed to investigate an alternative deacidification process based on strongly basic anion exchange resin. Aiming to evaluate the adsorption process efficiencies, breakthrough curves were obtained for systems containing Amberlyst A26 OH and a miscella composed of 50% by mass of degummed rice bran oil, with natural acidity (9.74% by mass), and n-propanol. The resin showed a high capacity for removing free fatty acids (90%–99% removal efficiency), and the adsorption process yielded deacidified rice bran oil with a reduced phosphorus content (2.2 mg/kg), preserving 83% of the gamma-oryzanol and 100% of the tocopherols/tocotrienols. Practical applications A softer deacidification process than traditional methods is proposed in this study. It permits to remove free fatty acids, preserving minor compounds of interest, notably nutraceutical compounds in the deacidified oil. The use of anion exchange resins in this step of refining process minimizes the effluent generation when compared to chemical refining, besides could be accomplished under milder conditions of pressure and temperature than physical refining.

Comparative removal of Suwannee River natural organic matter and perfluoroalkyl acids by anion exchange: Impact of polymer composition and mobile counterion

Anion exchange resin (AER) adsorption is an established technology for water treatment and groundwater remediation. Two contaminants amenable to AER treatment are natural organic matter (NOM) and per- and polyfluoroalkyl substances (PFAS), specifically anionic perfluoroalkyl acids (PFAAs) such as perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS). NOM is ubiquitous in natural waters and is often targeted for removal. PFAS occurrence in water resources is a human health concern. Accordingly, the goal of this research was to provide new insights on the use of AER for water treatment considering separate and combined removal of NOM and PFAAs. Batch experiments were conducted comparing polystyrene and polyacrylic AER in both chloride- and sulfate-forms using natural groundwater spiked with Suwannee River natural organic matter (SRNOM) and/or six PFAAs. The polymer composition of the AER had a significant impact on contaminant removal with polystyrene resin more effective for PFAA removal and polyacrylic resin more effective for SRNOM removal. Both resins had type I quaternary ammonium functional groups; however, the polyacrylic resin had trimethyl ammonium whereas the polystyrene resin had triethyl ammonium. Therefore, the influence of polymer composition could not be isolated conclusively from functional group chemistry. Polystyrene AER showed greater removal of PFAAs with sulfonate than carboxylate head group and 8-carbon than 4-carbon chain length. Removal of SRNOM and PFAAs by both resin polymer compositions were greater when sulfate was the mobile counterion ion than chloride. The results of this research have important implications for using AER for water treatment and remediation. Foremost, polymer composition and mobile counterion form of the resin can be selected to target specific contaminants and maximize contaminant removal. When contaminants have unique interactions with AER such as SRNOM and polyacrylic resin and PFAAs and polystyrene resin, the presence of one contaminant does not impact removal of the other contaminant.

High-Capacity Poly(4-vinylpyridine) Grafted PolyHIPE Foams for Efficient Plutonium Separation and Purification.

The use of anion-exchange resins to separate and purify plutonium from various sources represents a major bottleneck in the throughput that can be achieved when this step is part of a larger separation scheme. Slow sorption kinetics and broad elution profiles necessitate long contact times with the resin, and the recovered Pu is relatively dilute, requiring the handling of large volumes of hazardous material. In this work, high internal-phase emulsion (HIPE) foams were prepared with a comonomer containing a dormant nitroxide. Using surface-initiated nitroxide-mediated polymerization, the foam surface was decorated with a brush of poly(4-vinylpyridine), and the resulting materials were tested under controlled flow conditions as anion-exchange media for plutonium separations. It was found that the grafted foams demonstrated greater ion-exchange capacity per unit volume than a commercial resin commonly used for Pu separations and had narrower elution profiles. The ion-exchange sites (quaternized pyridine) were exposed on the surface of the large pores of the foam, resulting in convective mass transfer, the driving force for the excellent separation properties exhibited by the synthesized polyHIPE foams.

Comparison of chemical procedures for Re-isotopic measurements by N-TIMS

Precise and accurate measurements of the isotopic composition of rhenium (Re) in geologic samples are of paramount importance for the successful application of the Re-Os geochronometer. Two methods for chemical isolation of Re are used in the geochronology community – column chemistry using anion exchange resin and solvent-solvent extraction using a sodium hydroxide-acetone mixture. Despite their ubiquitous application, a systematic comparison of these two methods is missing. Here we compare Re-isotopic data on a variety of samples (sulfides, hydrocarbons, shales, and in-house standard solutions) that were processed by both chemical methods. Measured 185Re/187Re ratios for both methods have similar precision and overlap within the propagated long-term analytical reproducibility of ~1‰ for samples that yield moderate to strong intensities (>50 mV on the weaker Re mass). In contrast, measured 185Re/187Re ratios for most samples that yield less intense Re signals (<50 mV on the weaker Re mass) disagree by ~3–6‰ between the two methods, exceeding the propagated analytical uncertainty of ~3‰ for low-intensity measurements. A systematic investigation of samples with natural Re isotopic composition (shale, molybdenite, and standard solutions) shows that use of anion exchange resin (column chemistry) may cause elevated 185Re/187Re ratios. This effect is more pronounced for low-Re shales (<1 ng total Re processed) and becomes nearly or completely insignificant for high-Re samples measured over a wide range of signal intensities. Standard solutions processed through column chemistry, however, preserve their natural Re isotopic composition. Together, these data suggest that complex sample matrices leading to sample-derived impurities passed through column chemistry may cause isobaric interferences that deviate measured 185Re/187Re ratios in geologic samples. In contrast, the acetone-NaOH method produces more consistent Re isotopic results across the same range of sample types, Re loads and signal intensities. Thus, we recommend use of the acetone-NaOH solvent-solvent extraction procedure for low-Re samples, and provide a practical way to lower the typically higher Re blank supplied by NaOH.

Sodium Titanium Phosphate As Cation Insertion Electrode for Electrochemical Separation Systems

Electrochemical separation technologies such as capacitive deionization (CDI) have evolved to be an energy-efficient desalination possible solution for treating brackish and low salinity waters.1 The achievable ion removal capacity in using capacitive carbon electrodes ranges between 0.1-0.2 mmol/g of carbon electrode.2 Further, the capacity retention of carbon electrodes is poor due to electrode ageing. In this work, we investigate the use of sodium titanium phosphate or NaTi2(PO4)3 , a Na-ion superconductor (NASICON) material as a sodium-ion selective cathode for electrochemically-driven aqueous separations. Additionally, we also discuss the importance of self-discharge or diffusive loss of sorbed ions during open circuit conditions specifically in comparing CDI system performance with that of insertion type electrodes such as NaTi2(PO4)3. NaTi2(PO4)3, has until now only been evaluated in concentrated aqueous electrolytes and specifically for aqueous Na-ion batteries. It is however important in the context of water treatment and desalination, that we consider its performance in dilute electrolytes. NaTi2(PO4)3 shows reversible sodium-ion removal behavior over a range of sodium ion concentrations. Round trip coulombic efficiency values for these systems typically range between 40-70%, depending on the operating pH and dissolved oxygen levels in water. The causes of this efficiency loss are competing charge consumption by the hydrogen evolution reaction (HER) during the ion removal step and the chemical de-sodiation of the cathode by dissolved oxygen during ion retrieval step. 3, 4These efficiencies are improved through the use of an ion exchange resin and controlling the composition of the water near the electrode. In addition, retained-ion loss characteristics of electrodes used for water treatment are important from the standpoint of being able to intermittently operate the electrochemical separation process. Our studies show that in even presence of dissolved oxygen, a common constituent in natural and industrial waters, the self-discharge properties of the titanium phosphate electrode are superior to porous carbon electrodes used in CDI systems. In the light of our findings, present a discussion on the utility of NaTi2(PO4)3as a insertion based electrode for sodium removal from aqueous streams.

Removal and recovery of vanadium from alkaline steel slag leachates with anion exchange resins

Leachable vanadium (V) from steel production residues poses a potential environmental hazard due to its mobility and toxicity under the highly alkaline pH conditions that characterise these leachates. This work aims to test the efficiency of anion exchange resins for vanadium removal and recovery from steel slag leachates at a representative average pH of 11.5. Kinetic studies were performed to understand the vanadium sorption process. The sorption kinetics were consistent with a pseudo-first order kinetic model. The isotherm data cannot differentiate between the Langmuir and Freundlich models. The maximum adsorption capacity (Langmuir value qmax) was 27 mg V g−1 resin. In column anion exchange, breakthrough was only 14% of the influent concentration after passing 90 L of steel slag leachate with 2 mg L−1 V through the column. When eluting the column 57–72% of vanadium was recovered from the resin with 2 M NaOH. Trials on the reuse of the anion exchange resin showed it could be reused 20 times without loss of efficacy, and on average 69% of V was recovered during regeneration. The results document for the first time the use of anion exchange resins to remove vanadium from steel slag leachate. As an environmental contaminant, removal of V from leachates may be an obligation for long-term management requirements of steel slag repositories. Vanadium removal coupled with the recovery can potentially be used to offset long-term legacy treatment costs.

CO2 continuous removal using ion exchange as regeneration process

Present work analyses carbon dioxide capture process by means of chemical absorption using a different solvent regeneration technique based on the use of an ion exchange resin. The first part of the manuscript compares the behavior of MDEA aqueous solutions in the carbon dioxide absorption in a bubble column reactor regard the best available technique. On the other hand these MDEA solutions were employed to confirm the suitable behavior of a new regeneration process working in a continuous regime that allows the substitution of the conventional regeneration procedure (stripping). The influence of different experimental variables such as gas flow-rate, liquid flow-rate, amine concentration in the liquid phase and composition of gas stream, upon carbon dioxide absorption rate in the bubble column reactor was studied during the absorption/regeneration process.

Potencialidade de uso da resina AMBERLITE IR 120 no tratamento de resíduos químicos contendo espécies iônicas com Cr2O72-, Fe3+ E MnO4-

As resinas de troca iônica têm sido amplamente usadas como uma opção de tratamento de efluentes químicos por removerem do meio diversas substâncias, principalmente íons metálicos. Neste contexto, o objetivo do trabalho foi avaliaro potencial do uso de uma resina de troca iônica para o tratamento de um resíduoácido contendo Fe3+, ânions metálicos e ácido salicílico. Ascondições experimentais foram otimizadas a fim deremover essas espéciesde umresíduo regularmente geradoem um dos laboratóriosde ensino da UFJF. Foi utilizadaa resina catiônica AMBERLITE IR 120®eos resultados mostraram boa eficiência na remoçãodas espécies de interesse,inclusive daquelas na forma de ânions. Também foiestudado o processo de dessorção da resina, onde os metais podem ser concentrados em um volume 70% menor, possibilitando a reutilização da mesma.

Properties of Lewatit® TP272, a commercial solvent impregnated cation exchange resin for cobalt recovery

The typical hydrometallurgical processing of nickel and cobalt ores involves the precipitation of a mixed nickel–cobalt intermediate product. Alternatively, cobalt could be separated from nickel while in the aqueous phase using solvent extraction. However, solvent extraction has some problems including the need for considerable area for the separators, management of fire hazard, and operational issues such as contamination with organic cross-over with sequential solvent extraction unit operations. The use of an ion exchange resin can mitigate some of these issues; however, conventional cation exchange resins are not sufficiently selective for cobalt over nickel. Solvent impregnated resin offers the engineering advantages of ion exchange resin and the chemical selectivity of the solvent extraction process. This paper describes key properties of a new commercial solvent impregnated resin, Lewatit® TP272, including cobalt and nickel loading as a function of pH and cobalt loading isotherms at pH 5.5 and 5.0 which are identified as the ideal conditions to recover cobalt. The chemical degradation of this solvent impregnated resin was also determined by exposing the resin to greater than pH 6 solutions, which are conditions outside the recommended operating range for this resin. The capacity of the degraded resin was restored by reimpregnating the resin using a Cyanex® 272-ethanol–water mixture. Optical images of resin containing the blue cobalt complex reveal the porous structure.

Xylo-oligosaccharides and Ethanol Production from Liquid Hot Water Hydrolysate of Sugarcane Bagasse

With the objective of maximizing the use of liquid hot water hydrolysate of sugarcane bagasse, xylo-oligosaccharides and ethanol were respectively produced by the methods of purification and microbial fermentation. The processes of purification with activated charcoal, overliming, solvent extraction, vacuum evaporation, and use of an ion exchange resin were evaluated, and the results indicated that anion exchange chromatography performed well in terms of by-product removal. The recovery and purity of xylo-oligosaccharides reached 92.0% and 90.4%, respectively, using column chromatography with the resin LS30 at a flow rate of 2 mL/min at 25 °C. The hydrolysate was used in ethanol fermentation with Pichia stipitis CBS6054 followed by the production of fermentable saccharides and detoxification. The highest ethanol concentration was 4.12 g/L with a theoretical yield of 47.9% for the hydrolysate after xylanase digestion and resin detoxification, similar to the data of the control experiment, which had an ethanol concentration of 4.64 g/L and a yield of 49.6%. However, the former had a higher ethanol productivity of 0.0860 g/(L∙h), and the highest ethanol concentration appeared 12 to 24 h earlier compared to the control. This study suggests that combined generation of xylo-oligosaccharides and cellulosic ethanol could help maximize profits for a cane sugar factory.

“Advances in Biofuel Production: Algae and Aquatic Plants”

“Advances in Biofuel Production: Algae and Aquatic Plants” is a compilation of papers that have previously been published elsewhere, presented as 12 chapters. These have been edited by Barnabas Gikonyo, whose research interests range from the application of biocompatible polymeric materials for the repair of spinal cord injuries to the development of non-food biofuels. The book is intended to provide an overview and evaluation of the current status and prospects for fuel production via algae, microalgae and aquatic plants. As such, the book should appeal to general researchers with an interest in this area, rather than just specialists working in the fi eld. The book is divided into three main sections. Part One provides an overview of the current status and challenges in producing sustainable fuels from algae. Part Two, which consists of seven chapters and makes up the bulk of the book, examines both the supply potential and some of the current technologies relevant to biofuel production. The fi nal section comprises three chapters dealing with next generation research, with a focus on progress in genetic developments. The chapters vary from those presenting more general aspects of biofuel production from algae to reviews of specifi c technological aspects (for example electromagnetic biostimulation of living cultures; use of anion exchange resins; next generation sequence systems). A single chapter deals with the catalytic transformation of biomass-derived acids into advanced biofuels.

Analysis of the carbonatation process of nanosized Ca(OH)2particles synthesized by exchange ion process

Calcium hydroxide nanoparticles in hydro-alcoholic dispersion are introduced as an effective conservation material for carbonatic substrates, thanks to their promising carbonation efficacy in ambient air. However, the current methods to synthesize such dispersions are characterized by some drawbacks that strongly limit applications. The aim of this work is to investigate structure, morphology and carbonatation efficacy of calcium hydroxide nanoparticles in aqueous suspension, produced by our alternative and original method of synthesis, based on the use of an ion exchange resin. Actually, the method allows to produce pure, nanosized and reactive Ca(OH)2particles, operating at room temperature, without intermediate steps to eliminate undesired compounds, drastically reducing the time, and with a potential ability to be easily scaled up to provide larger amounts of nanoparticles. By X-ray diffraction techniques, we have investigated reactivity of the synthesized nanoparticles, in relation to the carbonatation process in air, by varying the suspension concentration. Preliminary results on the kinetics of the carbonatation process are presented too. Morphological analysis, performed by transmission electron microscopy, shows both hexagonal particles, often quarries, of side dimensions less than 100 nm, and spherical particles (&lt;50 nm).