Physico-chemical properties and use of waste biomass-derived activated carbons

Abstract Activated carbons are widely used in different industrial processes for example as adsorbents or as support materials. Advantageously these carbons can be prepared from residual or waste biomass materials. Different raw material type and activation procedure plays an important role in the physico-chemical characteristics of activated carbon e.g. surface area, porosity and pore distribution. In this study, activated carbon has been prepared from lignocellulosic waste materials (e.g. saw dust, lignin residue) and characterized by a number of methods. Further, adsorption properties of carbons were evaluated. Adsorption capacity of dyes and metals was high (methylene blue dye 86 % and zinc metal 97 % removal) onto prepared activated carbons

Acid-catalyzed mechanocatalytic pretreatment to improve sugar release from birch sawdust:structural and chemical aspects

Abstract This study examined acid-catalyzed mechanocatalytic pretreatment of birch sawdust without a separate impregnation step. Catalyst amount and pretreatment time were the key variables. Pretreated material was mixed with water for hydrolysis (100 °C, 60 min). The efficient release of total reducing sugars from birch sawdust is significant to the path towards biofuels and biochemicals. Based on the results, the structure and surface of birch sawdust changed as a function of mechanocatalytic pretreatment. Milling time caused significant transformations in birch structure and also increased the yields of reducing sugars. The highest yield of total reducing sugar from pretreated sawdust was 23.0% after 30 min of hydrolysis with 1.0 mmol/g acid catalyst, whereas the highest glucose yield was 23.8 g/kg (1.5 mmol/g catalyst, 60 min) and the highest xylose yield was 37.5 g/kg (1.0 mmol/catalyst, 30 min). Overall, acid-catalyzed mechanocatalytic treatment seems to improve sugar yields from birch

The effect of mechanocatalytic pretreatment on the structure and depolymerization of willow

Abstract In this study, the effect of a mechanocatalytic pretreatment on the structure of willow and sugar release from pretreated willow was explored. In the mechanocatalytic approach, the pretreatment consists of solvent-free impregnation with sulfuric acid and a mechanical treatment with ball milling. Willow sawdust and pretreated samples were analyzed with field emission scanning electron microscope and X-ray diffraction. The products in the sugar solution were determined as the total reducing sugars with the 3,5-dinitrosalicylic acid method and monosaccharides with capillary electrophoresis. According to the results, milling increased the sugar production, depending on the sulfuric acid load. The milling parameters, such as the rotation speed of the mill, the catalyst-to-willow ratio, and the milling time influenced the amount of sugars in the hydrolysate and the composition of the sugar solution produced. Changes were observed in the surface of the willow particles as well as changes in the crystalline structure. Glucose and xylose yields increased after 15 min of milling and reached their maximum level after 45 min of milling with the 0.5 mmol/g sulfuric acid load

Selective hemicellulose hydrolysis of Scots pine sawdust

Abstract The depletion of fossil resources is driving forward the search for new and alternative renewable feedstocks in the production of renewable chemicals, which could replace the petroleum-based ones. One such feedstock is pine (Pinus sylvestris) sawdust, which is generated enormous amounts in Finnish sawmills yearly. However, prior to the utilization in high-value applications, it needs to be fractionated into its constituents. In this work, the objective was to produce monomeric hemicellulose sugars from pine sawdust without degrading cellulose or lignin simultaneously. The influence of the reaction temperature and time, as well as acid type and concentration, was studied. Based on the results, the temperature was the main distinguishing feature between cellulose and hemicellulose hydrolysis. Promising results were achieved with acid mixtures consisting of 0.5% sulfuric acid and 5.5 or 10% formic acid. At 120 °C with the reaction time of 2 h, the mixtures produced hemicellulose sugars with the yields of 62%. These yields were comparable to the yields achieved in similar conditions with 1.5% sulfuric acid or 40% formic acid. Therefore, by using an acid mixture, the concentration of a single acid could be reduced significantly. The solid fractions remaining after the hydrolysis consisted mainly of cellulose and lignin, which verified the selectivity of the hemicellulose hydrolysis. Also, the fractionation of the remaining solids confirmed that the utilization of all the sawdust components is feasible

Rapid one-step solvent-free acid-catalyzed mechanical depolymerization of pine sawdust to high-yield water-soluble sugars

Abstract One-step absolute solvent-free acid-catalyzed mechanical depolymerization of pine sawdust (PSD) and commercially available α-cellulose to water-soluble sugars was carried out using ball milling. For comparison purposes, the commonly reported “solvent-free” mechanocatalytic depolymerization of lignocellulose method, which normally involves three steps (acid impregnation in solvent, vacuum drying, and mechanical depolymerization of lignocellulose), was performed. The 3,5-dinitrosalicylic acid (DNS) method was used to measure the total reducing sugar (TRS) of the obtained sugar solution, and major monosaccharides in the solution were analyzed by capillary electrophoresis (CE). More than 90% of the PSD became water-soluble through milling. Furthermore, most of the PSD was converted into TRS in approximately 30 min, and the highest TRS yield obtained was 31%, based on the dry mass. Interestingly, the TRS solutions obtained from the processed PSD were much darker than those obtained from α-cellulose due to the chromophores that formed during the depolymerization of lignin

Activation of type IV procollagenases by human tumor-associated trypsin-2

Sorsa T, Salo T, Koivunen E, et al. Activation of type IV procollagenases by human tumor-associated trypsin-2. JOURNAL OF BIOLOGICAL CHEMISTRY. 1997;272(34):21067-21074.Increased production of proteinases, such as matrix metalloproteinases (MMPs), is a characteristic feature of malignant tumors. Some human cancers :Ind cell lines derived from them also express trypsinogen, but the function of the extrapancreatic trypsin has remained unclear, In this study we cloned and sequenced trypsinogen-a cDNA from human COLO 205 colon carcinoma cells and characterized the ability of the enzyme to activate latent human type TV procollagenases (proMMP-2 and proMMP-9). As shown by cloning and N-terminal amino acid sequencing, the amino acid sequence of tumor associated trypsin-a is identical to that of pancreatic trypsin-a. We found that both pancreatic trypsin-a and tumor cell-derived trypsin-a are efficient activators of proMMP-9 and are capable of activating proMMP-9 at a molar ratio of 1:1000, the lowest reported so far. Human trypsin-a was a more efficient activator than widely used bovine trypsin and converted the 92-kDa proMMP-9 to a single 77-kDa product that was not fragmented further. The single peptide bond cleaved by trypsin-a in proMMP-9 was Arg(87)-Phe(88), The generation of the 77-kDa species coincided with the increase in specific activity of MMP-9. In contrast, trypsin-2 only partially activated proMMP-2. Trypsin-a cleaved the Arg(99)-Lys(100) peptide bond of proMMP-2 generating 62-65-kDa MMP-2 species. Trypsin-a-induced proMMP-2 and -9 conversions were inhibited by tumor-associated trypsin inhibitor added either prior to or during activation indicating that proMMPs were not activated autocatalytically. Trypsin-2 also activated proMMPs associated with tissue inhibitor of matrix metalloproteinases, the complexes of which are thought to be the major MMP forms in vivo. The ability of human tumor cell-derived trypsin-a to activate latent MMPs suggests a role fbr trypsin-a in initiating the proteinase cascade that mediates tumor invasion and metastasis formation

Regulation of matrix metalloproteinases by human tumor-associated trypsin(ogen)-2

A critical step in cancer progression is the dissolution of the extracellular matrix surrounding the malignant tumor leading to invasion and dissemination of tumor cells. This process involves increased production of matrix-degrading proteinases, e.g. matrix metalloproteinases, plasminogens and plasminogen activators. Recently tumor-associated trypsins (TATs) have been implicated in this process. We now show that the major isoenzyme of tumor-associated trypsin (TAT)-2 directly activates latent human promatrix metalloproteinases (proMMP)-9 and -2. TAT-2 converted the proMMP-9 to the 77 kD MMP-9 species in a time-and dose-dependent manner causing a significant superactivation of MMP-9. The activation was inhibited by the tumor-associated trypsin inhibitor (TATI), a specific endogenous inhibitor of TATs. ProMMP-2 was also activated by TAT-2 but less efficiently. ProMMP-2 can also be activated by membrane-type MMP that is induced in human MDA-MB-231 breast carcinoma cells by Concavalin A (Con A). Addition of TATI to the Con A-induced MDA-MB-231 cells did not, however, inhibit the conversion of exogenous 72 kD proMMP-2 to 59 kD active MMP-2 species. The ability of TAT-2 to directly activate type IV procollagenases-especially proMMP-9 - suggests a previously unrecognized function for TAT-2 in the degradation of extracellular matrix and basement membrane associated with tumor progression and metastasis. Inhibition of human trypsin (TAT)-2 by TATI and/or potent synthetic inhibitors may prevent TAT-2-induced proMMP-9 activation cascade associated with human malignancies