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Juice clarification is integral to the sugar-manufacturing process and determines the quality of clarified juice which is subsequently processed to produce sugar. Clarification performance is defined largely by turbidity of the clarified juice, but the presence of soluble impurities, colour and colour precursors, polysaccharides and proteins influence heat-transfer performance of evaporators and evaporating crystallizers, the crystallisation performance in evaporating crystallizers and the achievable yield and quality of sugar. The conventional defecation process is inadequate to remove these nonsucrose impurities, and the gradual worldwide transition to green-cane harvesting is introducing greater levels of impurities into the cane supply. As a result, the clarification station is now having to deal with not only the endogenous impurities (e.g. stalk impurities) but also the trash (leaves and tops) impurities. This paper reviews work that has been conducted over the years to remove these impurities and presents future research directions that should improve clarification performance. Examples of future research directions include development of multi-functional nanoparticles to significantly improve impurity removal; processing strategies to enhance precipitation of proteins and polysaccharides; and ballasting and adsorbent agents.

Low-temperature depolymerization of biomass sugars is a less capital-intensive way to produce secondary fuel precursors. Solvolysis of bagasse using polyol cosolvents reduces sugar dehydration and limits unwanted side reactions. Ethylene glycol (EG) as cosolvent (50 v/v%) was found to increase formic acid, levulinates, and furfural yields from 71 to 100 mol %, 59 to 70 mol %, and 44 to 59 mol %, respectively, based on the theoretical yield of the cellulose component of bagasse. The exceptionally high formic acid yield is attributed to it being produced not only from cellulose but also via hemicellulose and EG conversion pathways. Increasing concentrations of EG proportionally reduced furfural yield. Delignification of bagasse prior to solvolysis with 50 v/v% EG decreased the yields of both formic acid (84 mol %) and furfural (52%) but increased the levulinates yield to 80 mol %.

The effect of pretreatment of sugarcane juice and juice composition on the performance of a ceramic membrane with pore size of 20 nm has been studied. Pretreatment options assessed included heating juice (60, 75 and 90 °C) with and without sedimentation at specified pHs (7.2, 7.5 and 7.8) and using evaporator supply juice (ESJ). The average permeate flux at 75 °C and pH 7.8 for limed juice, and partially clarified juice, and ESJ were 278 L/m2h, 248 L/m2h and 160 L/m2h in that order. It was shown that with ESJ, where the juice is boiled, there are higher proportions of crystalline and microcrystalline phases, and other impurities which reduces the efficiency of the membrane filtration process as the cake resistance (1.17 × 1012/m) is 1.7 times higher than of the partially clarified juice. With respect to the juice quality, the results of the permeate derived from the partially clarified juice at 75 °C, show that the lowest pH value of 7.2 gave the largest impurity reduction, though liming at pH 7.5 would be the preferred treatment for industrial application because of pH drop during processing. The fouling mechanism for the partially clarified juice was shown to be the combined cake filtration-complete blocking model.

The decolorization of remelt syrup is the most critical step in the sugar refining process as it directly affects the quality of refined sugar. Adsorption is a useful method that can be applied to decolorize the syrup. A quaternary ammonium-functionalized chitosan/graphene oxide composite aerogel (GO-QACSA) was developed as an effective adsorbent for the removal of high-molecular-weight reducing sugar alkaline degradation products (HRSADPs), the main class of colorants in remelt syrup. The advantages of GO-QACSA to remove HRSADPs can be attributed to its well-connected 3-D network-like porous structure, nontoxicity, high hydrophilicity, and the richness of quaternary ammonium groups. The equilibrium adsorption capacity of GO-QACSA for HRSADPs reached 364.09 mg/g and the removal rate was > 90%. GO-QACSA exhibited an ultra-fast adsorption rate. Recycling experiments indicated that GO-QACSA exhibited good renewability and reusability. The interaction mechanism for the adsorption of HRSADP on GO-QACSA was studied, and the results revealed that two layers of HRSADPs adhered to the surface of GO-QACSA via electrovalent bonds formed between the quaternary ammonium and carboxylate groups. On average, 2–3 carboxylate ions in one HRSADP molecule bonded with the quaternary ammonium cations of GO-QACSA. Four phenomenological mathematical models, namely, External mass transfer resistance (EMTR), Internal mass transfer resistance (IMTR), combined EMTR–IMTR, and Adsorption on active sites (AAS), were presented based on the best-fit equilibrium isotherms. These models could be used to provide new insights into the adsorption mass transfer behaviors of the system.

Achieving the goal of living in a sustainable and greener society, will need the chemical industry to move away from petroleum-based refineries to bio-refineries. This aim can be achieved by using biomass as the feedstock to produce platform chemicals. A platform chemical, 2,5-furandicarboxylic acid (FDCA) has gained much attention in recent years because of its chemical attributes as it can be used to produce green polymers such polyethylene 2,5-furandicarboxylate (PEF) that is an alternative to polyethylene terephthalate (PET) produced from fossil fuel. Typically, 5-(hydroxymethyl)furfural (HMF), an intermediate product of the acid dehydration of sugars, can be used as a precursor for the production of FDCA, and this transformation reaction has been extensively studied using both homogeneous and heterogeneous catalysts in different reaction media such as basic, neutral, and acidic media. In addition to the use of catalysts, conversion of HMF to FDCA occurs in the presence of oxidants such as air, O2, H2O2, and t-BuOOH. Among them, O2 has been the preferred oxidant due to its low cost and availability. However, due to the low stability of HMF and high processing cost to convert HMF to FDCA, researchers are studying the direct conversion of carbohydrates and biomass using both a single- and multi-phase approach for FDCA production. As there are issues arising from FDCA purification, much attention is now being paid to produce FDCA derivatives such as 2, 5-furandicarboxylic acid dimethyl ester (FDCDM) to circumvent these problems. Despite these technical barriers, what is pivotal to achieve in a cost-effective manner high yields of FDCA and derivatives, is the design of highly efficient, stable, and selective multi-functional catalysts. In this review, we summarize in detail the advances in the reaction chemistry, catalysts, and operating conditions for FDCA production from sugars and carbohydrates.

Quaternary ammonium-functionalized magnetic chitosan microspheres (QAMCM) were fabricated for the removal of high-molecular-weight invert sugar alkaline degradation products (HISADPs), the main class of colorants in beet juice. The equilibrium adsorption capacity of QAMCM for HISADP was 98.03 mg/g at 0.6 mg/mL QAMCM dosage, 333 K temperature, pH 7, and 60 mg/L initial HISADP concentration, and the corresponding removal rate reached 98.03%. The adsorption kinetics were studied by using a pseudo-first-order and pseudo-second-order (PFO–PSO) combined model. Results revealed that HISADP adsorption by QAMCM is a complex process because of the involvement of both chemisorption and physisorption instead of only one mechanism. However, chemisorption (electrostatic attraction and electron sharing) is the dominant kinetic mechanism. Analysis of the mass transfer mechanisms showed that the dynamic characters of the adsorption capacities of the liquid film around QAMCM and the pores of QAMCM could be well described using a film–pore mass transfer model, which could be used to provide insights into the adsorption mass transfer behaviors of the system. Additionally, HISADPs with smaller sizes were preferentially adsorbed by QAMCM compared with larger ones. Research on the isotherms and thermodynamics showed that HISADP adsorption by QAMCM occurred via an endothermic multi-layer process and was spontaneous. Overall, QAMCM was found to be an efficient, green, and recyclable decolorization adsorbent for beet juice.

Retentate is a by-product of the membrane clarification of sugarcane juice process and contains high sucrose concentration which is not recovered during sugar manufacturing. The lack of cost-effective treatment of retentate produced by membrane clarification is one of the main issues that hinder adoption of membrane technology in the sugar industry. The present work evaluates retentate composition and uses the information to explore effective approaches for retentate utilization. Compositional analysis revealed that the insoluble components was 6.25% of the retentate in which 48% was organics, and 52% was inorganics. Sucrose (14.9%) was the dominant component followed by reducing sugars (0.62%). Significant amounts polysaccharides (2%) and proteins (0.5%) were present in the retentate, far higher than those present in mixed juice. Lipophilic compounds (e.g., fatty acids, octacosanol, stigmasterol and β-sitosterol) were accumulated in the retentate (3.56% based on the dry substance), while the phenolic compounds content (equivalent to 1.1 mg gallic acid·g−1) was similar to that in mixed juice. Based on the retentate composition, it is proposed that a multifaceted approach can be used to harness various products from sugarcane retentate concentrate. As the carbohydrate component is the highest component in the retentate, two approaches were evaluated to add value, namely sugar recovery via the carbonation process and production of oleaginous yeast biomass from the retentate by a R. glutinis strain. Carbonation clarification was effective to clarify retentate, and it was estimated that 71.2% of sucrose can be recovered using typical sugar manufacturing processes. Biolipid derived has the potential for biodiesel production and the biomass residue had the potential to be used as a valuable feed supplement. A preliminary comparative economic analysis was conducted with the two approaches considering the value of the final products (i.e., sugar and biolipid/biodiesel) and their operating costs.

Chloromethylfurfural (CMF), a valuable intermediate for the production of chemicals and fuels, can be derived in high yields from the cellulose component of biomass. This study examined the effect of sugarcane bagasse components and biomass architecture on CMF/bio-oil yield using a HCl/dichloroethane biphasic system. The type of pretreatment affected bio-oil yield, as the CMF yield increased with increasing glucan content. CMF yield reached 81.9% with bagasse pretreated by acidified aqueous ionic liquid, which had a glucan content of 81.6%. The lignin content of the biomass was found to significantly reduce CMF yield, which was only 62.3% with an acid-catalysed steam exploded sample having a lignin content of 29.6%. The change of CMF yield may be associated with fibre surface changes as a result of pretreatment. The hemicellulose content also impacted negatively on CMF yield. Storage of the bio-oil in chlorinated solvents prevented CMF degradation.

The combination of dwindling petroleum reserves and population growth make the development of renewable energy and chemical resources more pressing than ever before. Plant biomass is the most abundant renewable source of energy and chemicals. Enzymes can selectively convert the polysaccharides in plant biomass into simple sugars which can then be upgraded to liquid fuels and platform chemicals using biological and/or chemical processes. Pretreatment is essential for efficient enzymatic saccharification of plant biomass and this article provides an overview of how organic solvent (organosolv) pretreatments affect the structure and chemistry of plant biomass, and how these changes enhance enzymatic saccharification. A comparison between organosolv pretreatments utilizing broadly different classes of solvents (i.e., low boiling point, high boiling point, and biphasic) is presented, with a focus on solvent recovery and formation of by-products. The reaction mechanisms that give rise to these by-products are investigated and strategies to minimize by-product formation are suggested. Finally, process simulations of organosolv pretreatments are compared and contrasted, and discussed in the context of an industrial-scale plant biomass to fermentable sugar process.

Simple lignin model compounds containing β-O-4 aryl ether linkages have been utilized as a means to understand lignin depolymerisation. The effects of reaction temperature, time, catalyst concentration, and initial phenethoxybenzene (PEB) concentration on the degradation of PEB in NaOH were investigated. Operating at 300 °C for 1 h resulted in the highest combined yield of the primary products, phenol and styrene, and also resulted in a reduced amount of degradation products formed. The proportion of oligomeric and polymeric materials formed depended on the NaOH concentration, but not on the initial PEB concentration for equal reaction time. The results were used to suggest probable reaction pathways for PEB degradation.

A major challenge that must be overcome for the commercial production of levulinic acid from lignocellulosics is to reduce equipment blockage and corrosion. Methanesulfonic acid (MSA), a relatively low corrosive acid, was used to produce organic acids and furfural from pretreated sugarcane bagasse. In general, the type of pretreatment did not affect levulinic acid yield, though it affected furfural yield. However, soda pretreated bagasse produced the highest yields of levulinic acid (∼75 mol%) and furfural (∼85 mol%), albeit under optimized conditions. Hydrolysis residue consists primarily of lignin that has been modified and/or condensed to humic substances, fatty acids, and oligomeric sugars. A conceptual biorefinery utilizing 1 ton of dry bagasse, alkaline-pretreatment, and MSA as a catalyst produced 165 kg soda lignin, 190 kg and 89 kg of levulinic acid and formic acid respectively, and 40 kg furfural.

5-hydroxymethylfurfural (HMF) is a suitable platform chemical for the production of useful chemicals and fuels. This study examined the hydrolysis of mixtures of sucrose, glucose and fructose (synthetic sugar cane molasses) and industrial molasses using sulfonated carbon-based heterogeneous catalysts derived from sugar cane bagasse (B-SO3H) and sugar cane molasses (M-SO3H). Microwave heating at 150 °C for 4 h produced 39 mol % HMF yield with B-SO3H on the synthetic sugar solution. The addition of a molasses pretreatment step, as well as, increasing the microwave power was necessary to achieve similar HMF yields with the industrial molasses sample. The hydrolysis of molasses pretreated with formic acid or HCl resulted in a slightly higher HMF yield than the hydrolysis of molasses pretreated with H2SO4. The buffering capacity of the formic acid pretreated molasses was lowered through dilution with water; and subsequently HMF yield was increased to 64.3 mol % (170 °C, 3 h).

10 páginas.-- 4 figuras.-- 3 tablas.-- 54 referencias.-- The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acssuschemeng.7b00274., Commercial furfural, an important platform chemical, is produced from acid hydrolysis of lignocellulosic biomass. The manufacturing processes are inherently inefficient, and so it is necessary to value add to substantial amounts of residue obtained. The structural features of bagasse furfural residue and the lignins extracted from it by three NaOH treatments have been studied in order to understand the transformations that occurred by these treatments. 2D-NMR and Py-GC/MS of the furfural residue revealed that it contains mostly lignin and depolymerized cellulose moieties and the complete absence of xylans as a result of their hydrolysis during the furfural production process. In addition, the analyses revealed that the furfural residue contains 44% of H-type lignin units, in comparison to 11% for bagasse, and most of the lignin interunit linkages present in bagasse have disappeared. The pyrograms show that the furfural residue produced unusually high phenol content, which was attributed to the high levels of “H-type” units present in this lignin. The proportion of functional groups, particularly total OH aliphatic groups, where significantly lower in the extracted lignins compared to soda lignin obtained by the normal pulping process. The highest severity of the NaOH extraction process reduced the amount of reactive functional groups present in the lignin, though the S/G ratios of ∼1.1 were independent of the extraction method. The three lignins have high proportions of “H-units” (around 36–37%), which gives them special properties for different applications, particularly in the production of phenolic resins., This study was partly funded by Sugar Research Australia, formerly Sugar Research Development Corporation (QUT004). JoséC. del Rio, Jorge Rencoret, and Ana Gutierrez were partially funded by the Spanish projects AGL2014-53730-R and CTQ2014-60764-JIN (cofinanced by FEDER funds)

Methanesulfonic acid (MSA) was compared with sulfuric acid for the conversion of glucose and xylose mixtures to produce levulinic acid and furfural. The interactions of glucose and xylose, the predominant sugars found in biomass, were found to influence product yields with furfural degradation reactions enhanced under higher reactant loadings. Fast heating rates allowed maximal yields (>60 mol%) of levulinic acid and furfural to be achieved under short reaction times. Under the range of conditions examined, sulfuric acid produced a slight increase in levulinic acid yield by 6% ( P = 0.02), although there was no significant difference ( P = 0.11) between MSA and sulfuric acid in levulinic acid formed from glucose alone. The amount and type of the solid residue is similar between MSA and sulfuric acid. As such, MSA is a suitable alternative because its use minimizes corrosion and disposal issues associated with mineral acid catalysts. The heating value of the residue was 22 MJ/kg implying that it is a suitable source of fuel. On the basis of these results, a two-stage processing strategy is proposed to target high levulinic acid and furfural yields, and other chemical products (e.g. lactic acid, xylitol, acetic acid and formic acid). This will result in full utilization of bagasse components.

A low temperature lignocellulose pretreatment process was developed using acid-catalysed mixtures of alkylene carbonate and alkylene glycol. Pretreatment of sugarcane bagasse with mixtures of ethylene carbonate (EC) and ethylene glycol (EG) was more effective than that with mixtures of propylene carbonate (PC) and propylene glycol (PG). These mixtures were more effective than the individual components in making bagasse cellulose more amenable to cellulase digestion. Glucan digestibilities of ≥87% could be achieved with a wide range of EC to EG ratios from 9 : 1 to 1 : 1 (w/w). Pretreatment of bagasse by the EC–EG mixture with a ratio of 4 : 1 in the presence of 1.2% H2SO4 at 90 °C for 30 min led to the highest glucan enzymatic digestibility of 93%. The high glucan digestibilities obtained under these acidic conditions were due to (a) the ability of alkylene carbonate to cause significant biomass size reduction, (b) the ability of alkylene glycol to cause biomass defibrillation, (c) the ability of alkylene carbonate and alkylene glycol to remove xylan and lignin, and (d) the magnified above attributes in the mixtures of alkylene carbonate and alkylene glycol.

Chemical hydrolysis processes are the focus of this chapter with regard to conversion of the carbohydrate content of lignocellulosic biomass such as bagasse to chemicals. Furans and organic acids such as levulinic acid and formic acid can be produced through acid-catalyzed dehydration and hydrolysis of hexose and pentose sugars. New technologies and processing environments that allow the use of biphasic systems and/or continuous extraction of products would increase reaction rates, yields, and product quality to provide the necessary step change for optimization of key reactions. The choice of solvent in an industrial process is influenced by polarity, boiling point, and partitioning ability as these provide a key measure on the recovery of product, catalyst, and solvent. As an alternative to direct production of levulinic acid or furanic products, solvolysis reactions can produce other chemical products in either one-pot or sequential reactions. The chapter discusses a number of potential products.

Biomass represents an abundant and relatively low cost carbon resource that can be utilized to produce platform chemicals such as levulinic acid. Current processing technology limits the cost-effective production of levulinic acid in commercial quantities from biomass. The key to improving the yield and efficiency of levulinic acid production from biomass lies in the ability to optimize and isolate the intermediate products at each step of the reaction pathway and reduce re-polymerization and side reactions. New technologies (including the use of microwave irradiation and ionic liquids) and the development of highly selective catalysts would provide the necessary step change for the optimization of key reactions. A processing environment that allows the use of biphasic systems and/or continuous extraction of products would increase reaction rates, yields and product quality. This review outlines the chemistry of levulinic acid synthesis and discusses current and potential technologies for producing levulinic acid from lignocellulosics. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd

This paper examines the fouling characteristics of four tubular ceramic membranes with pore sizes 300 kDa, 0.1 μm and 0.45 μm installed in apilot plant at a sugar factory for processing clarified cane sugar juices. All the membranes, except the one with a pore size of 0.45 μm, generally gave reproducible results through the trials, were easy to clean and could handle operation at high volumetric concentration factors. Analysis of fouled and cleaned ceramic membranes revealed that polysaccharides, lipids and to a lesser extent, polyphenols, as well as other colloidal particles cause fouling of the membranes. Electrostatic and hydrophobic forces cause strong aggregation of the polymeric components with one another and with colloidal particles. To combat irreversible fouling of the membranes, treatment options that result in the removal of particles having a size range of 0.2-0.5 μm and in addition remove polymeric impurities, need to be identified. Chemical and microscopic evaluations of the juices and the ...

The combination of dwindling petroleum reserves and population growth make the development of renewable energy and chemical resources more pressing than ever before. Plant biomass is the most abundant renewable source of energy and chemicals. Enzymes can selectively convert the polysaccharides in plant biomass into simple sugars which can then be upgraded to liquid fuels and platform chemicals using biological and/or chemical processes. Pretreatment is essential for efficient enzymatic saccharification of plant biomass and this article provides an overview of how organic solvent (organosolv) pretreatments affect the structure and chemistry of plant biomass, and how these changes enhance enzymatic saccharification. A comparison between organosolv pretreatments utilizing broadly different classes of solvents (i.e., low boiling point, high boiling point, and biphasic) is presented, with a focus on solvent recovery and formation of by-products. The reaction mechanisms that give rise to these by-products are investigated and strategies to minimize by-product formation are suggested. Finally, process simulations of organosolv pretreatments are compared and contrasted, and discussed in the context of an industrial-scale plant biomass to fermentable sugar process.

12 páginas.-- 6 figuras.-- 6 tablas.-- 52 referencias.-- The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acssuschemeng.6b01093., Dilute acid pretreatment is one of the most studied biomass deconstructing technologies due to its relatively low process cost. Typical cellulosic ethanol production process involves three main stages: (1) dilute acid pretreatment, (2) enzymatic hydrolysis, and (3) fermentation/distillation. In this study, three lignins, L1, L2, and L3, were extracted using 1% (w/w) NaOH solution at 80 °C following each stage, respectively. Lignin characterization shows the reduction of aliphatic, guaiacyl, and carboxylic OH groups of the L2 and L3 compared to those of the L1 but increases in both the weight and number molecular weights as well as slight increases in the polydispersity index, probably because, among other reasons, of the removal of a higher molecular weight lignin fraction from the pretreated biomass during enzymatic hydrolysis. While 2D HSQC NMR and Py-GC/MS did not reveal differences in the proportions of syringyl and p-hydroxyphenyl units among the lignins, there is a predominance of the phenylcoumaran substructures and guaiacyl lignin units in L1 and the absence of some substructures/linkages associated with L2 and L3. Lignin extraction following dilute acid pretreatment not only produced the lignin with the highest purity but also resulted in improved glucose yield from 71% to 77%., This study was partly funded by the Australian Indian Strategic Research Fund (AISRF) Grand Challenge Project (GCF020010). Jose Rio, Jorge Rencoret, and Ana Gutierrez who conducted the analytical pyrolysis work were partially funded by the Spanish projects AGL2014-53730-R and CTQ2014-60764-JIN (cofinanced by FEDER funds).

Background Pretreatment of lignocellulosic biomass is a prerequisite for effective saccharification to produce fermentable sugars. In this study, “green” solvent systems based on acidified mixtures of glycerol carbonate (GC) and glycerol were used to treat sugarcane bagasse and the roles of each solvent in deconstructing biomass were determined. Results Pretreatment of sugarcane bagasse at 90°C for only 30 min with acidified GC produced a solid residue having a glucan digestibility of 90% and a glucose yield of 80%, which were significantly higher than a glucan digestibility of 16% and a glucose yield of 15% obtained for bagasse pretreated with acidified ethylene carbonate (EC). Biomass compositional analyses showed that GC pretreatment removed more lignin than EC pretreatment (84% vs 54%). Scanning electron microscopy (SEM) showed that fluffy and size-reduced fibres were produced from GC pretreatment whereas EC pretreatment produced compact particles of reduced size. The maximal glucan digestibility and glucose yield of GC/glycerol systems were about 7% lower than those of EC/ethylene glycol (EG) systems. Replacing up to 50 wt% of GC with glycerol did not negatively affect glucan digestibility and glucose yield. The results from pretreatment of microcrystalline cellulose (MCC) showed that (1) pretreatment with acidified alkylene glycol (AG) alone increased enzymatic digestibility compared to pretreatments with acidified alkylene carbonate (AC) alone and acidified mixtures of AC and AG, (2) pretreatment with acidified GC alone slightly increased, but with acidified EC alone significantly decreased, enzymatic digestibility compared to untreated MCC, and (3) there was a good positive linear correlation of enzymatic digestibility of treated and untreated MCC samples with congo red (CR) adsorption capacity. Conclusions Acidified GC alone was a more effective solvent for pretreatment of sugarcane bagasse than acidified EC alone. The higher glucose yield obtained with GC-pretreated bagasse is possibly due to the presence of one hydroxyl group in the GC molecular structure, resulting in more significant biomass delignification and defibrillation, though both solvent pretreatments reduced bagasse particles to a similar extent. The maximum glucan digestibility of GC/glycerol systems was less than that of EC/EG systems, which is likely attributed to glycerol being less effective than EG in biomass delignification and defibrillation. Acidified AC/AG solvent systems were more effective for pretreatment of lignin-containing biomass than MCC.