No abstract

No abstract

Separation of organic and inorganic compounds from black liquor was investigated. Black liquor from the pulp and paper industry contains hundreds of different compounds and several high-value organic chemicals are formed during alkaline pulping. These organic compounds can be used in the fine chemicals, pharmaceutical and food industries. The main aim of this study was to recover and purify high value-added organic compounds (organic acids) from lignin and inorganic compounds by combining membrane filtration, acid precipitation and cooling crystallization. The effect of membrane filtration on the efficiency of precipitation and crystallization was also studied. A number of separation methods were studied under a variety of operating conditions. The results showed that a combination of membrane separation and crystallization is an efficient method for recovering and purifying valuable organic compounds in black liquor. The amount of major impurities in black liquor could be reduced significantly.

No abstract

Adsorptive fouling, by phenolic compounds, is a serious issue regarding the development and use of membrane based filtration technologies for water purification and wastewater treatment. We have developed a novel, combined, protocol of Raman spectroscopy and surface plasmon resonance (SPR) experiments, along with molecular dynamics (MD) simulation, to study the interaction of vanillin, a model phenolic compound, with the polyethersulfone (PES) surface of a membrane. The adsorption of vanillin to the PES surface was found to be highly pH dependent; the source of this was determined, by MD simulation, to be the stronger interaction with the protonated form of vanillin, predominant at low pH. Vanillin interacts with the PES surface, both through entropy driven, hydrophobic, interactions and, for the case of the protonated form, H-bonding of the hydroxyl group with the sulphur oxygens of the PES molecules. In addition to general insight into the fouling process that can be used to develop new methods to inhibit adsorptive fouling, our results also elucidate the specific interaction of the PES membrane with vanillin that can be used in the development of anti-fouling coatings, based on the structure of vanillin.

No abstract

Fouling as an intricate process is considered as the main obstacle in membrane technologies, and its control is one of the main areas of attention in membrane processes. In this study, a commercial polyethersulfone ultrafiltration membrane (MWCO: 4000 g/mol) was surface modified with different concentrations of vanillin as an antifouling and hydrophilicity promoter to improve its performance. The presence of vanillin and its increasing adsorption potential trends in higher vanillin concentrations were clearly confirmed by observable changes in FTIR (Fourier transform infrared) spectra after modification. Membranes with better hydrophilicity (almost 30% lower contact angle in the best case) and higher polyethylene glycol solution (PEG) permeability were achieved after modification, where a 35–38% increase in permeability of aqueous solution of PEG was perceived when the membrane was modified at the highest exposure concentration of vanillin (2.8 g/L). After filtration of wood extract, surface modified membrane (2.8 g/L vanillin) showed better antifouling characteristics compared to unmodified membrane, as indicated by approximately 22% lower pure water flux reduction, which in turn improved the separation of lignin from the other organic compounds present in wood extract.

We present a rapid method based on 2D thin layer chromatography (TLC) for the simultaneous separation and quantification of organic, lipophilic extractives occurring in lignocellulosic biorefineries. The separation is based on alkaline followed by acidic elution for a 2D separation of the different compound classes (sterols, fatty alcohols, fatty acids, and resin acids). Staining with Nile Blue A and subsequent scanning and image analysis of the plates provides quantitative information on the concentration of each compound class. Correlation coefficients between 0.92 (abietic acid, resin acid) and 0.98 (β-sitosterol, sterol) are determined in these experiments. Besides the analysis of the composition, this procedure indicates the relative polarity as the acidity or basicity of the constituents. TLC results of an industrial lipophilic extractives sample correlate with state-of-the-art GC × GC–MS measurements with differences being in the range between 0.5 (fatty alcohols) and 6% (resin acids), respectively.