Bio-based phenolic compounds available from lignin are promising candidates for industrial application, e.g., within polymer resins or as biogenic fuel substitutes. Among numerous conversion methods for the valorization of lignin, the base-catalyzed depolymerization (BCD) has considerable advantages with respect to other processes. By this method, lignin and lignin-containing biorefinery streams can be catalytically transferred to valuable, defined products with tailored specifications. Continuous process operation allows conversions at short residence times and, thus, enables its industrial implementation more easily due to economic reasons. This review reflects the development in the field of BCD on various types of lignin. A historical overview will be given and the principal application of the method is shown. Challenges for operations are addressed, mainly to the development of efficient and selective methods for product separation and purification of the alkylphenolic moieties and the reduction of char formation during the process. An outlook will be given by showing trends and perspectives, especially in the field of industrial applications. Here, hydrotreatment methods for refining BCD intermediates for fuel and platform chemical production are shown. Furthermore, the application of BCD for the conversion of woody biomass and black liquor is discussed.

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Base-Catalyzed Depolymerization of Lignin: History, Challenges and Perspectives

Phenol is a good model compound to study extraction of alkaloids as its acidity constant is close to that of many alkaloids, for example, morphine. In addition, extraction of phenol is important environmentally as it is a water pollutant. In this study the distribution ratio of neutral phenol and total phenol between water and toluene with varying pH and varying concentration of sodium hydroxide is determined and discussed. The phase equilibrium is modelled by the symmetric electrolyte nonrandom two-liquid model and the calculated values agree well with the experimental results.

Extraction of Phenol by Toluene in the Presence of Sodium Hydroxide

OF DISSERTATION DEVELOPMENT OF NOVEL TEMPERATURE RESPONSIVE POLYMERIC SORBENTS AND THEIR APPLICATIONS IN WATER REMEDIATION Water remediation utilizing sorption has found strong interest due to its inexpensiveness, universal nature and ease of operation. In particular, thermo-responsive sorbents consisting of N-isopropylacrylamide (NIPAAm) offer significant potential as “smart” and advanced materials to remove multiple aqueous pollutants. NIPAAm exhibits excellent thermo-responsiveness, which senses the external temperature variation and changes its swelling and sorption behaviors in a sharp and rapid manner. At the beginning of this work, an extensive review of literature has been compiled to provide a summary of NIPAAm-based thermo-responsive sorbents in water/wastewater remediation applications. Initially, we developed a novel approach to synthesize and characterize NIPAAm copolymeric hydrogels. Four different polyphenolic crosslinkers including curcumin multiacrylate (CMA), quercetin multiacrylate (QMA), 4,4’-dihydroxybiphenyl diacrylate (44BDA) and chrysin multiacrylate (ChryMA) were successfully incorporated into crosslinked hydrogels. Their temperature responsiveness and lower critical solution temperature (LCST) were characterized using swelling studies and differential scanning calorimetry (DSC). Increasing the crosslinker content resulted in a significant decrease in the swelling ratio and LCST, which was due to the increased crosslinking and hydrophobicity introduced by the polyphenolic crosslinkers. We also demonstrated the application of two sets of aforementioned crosslinked hydrogels (NIPAAm-co-CMA and NIPAAm-co-44BDA) as effective gel sorbents to capture phenol as a model contaminant. Temperature-dependent sorption was evaluated through a binding study of phenol at 10°C and 50°C. Significant enhancement in the sorption was observed at 50°C, and this can be attributed to the phase transition induced hydrophobic interactions between the copolymer gel and phenol. Moreover, the obtained hydrogels possessed facile and efficient regeneration ability in water at 10°C, without requiring harsh solvent treatment or high energy input. Building on the sorption behavior observed with crosslinked NIPAAm hydrogels, we extended the investigation to linear copolymer systems, and these were demonstrated as a temperature responsive flocculants. Here, NIPAAm copolymers consisting of 2phenylphenol monoacrylate (2PPMA) were successfully developed as smart flocculants to remove metal oxide nanoparticles (e.g., Fe3O4, CeO2, TiO2). The incorporation of 2PPMA enhanced the flocculation at temperatures above the LCST (e.g., 50°C), which was due to the combined hydrophobicity of 2PPMA and NIPAAm. Overall, NIPAAm-based sorbents have a variety of applications in aqueous pollutant removal and are a promising class of materials for cost-effective water remediation technology.

Development of novel temperature responsive polymeric sorbents and their applications in water remediation

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Katalitička obrada fenolnih otpadnih voda

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Energy reduction in phenol recovery systems

Methyl isobutyl ketone (MIBK) and diisopropyl ether (DIPE) were evaluated as solvents for extraction of phenols from water by measuring the equilibrium distribution coefficients (K/sub d/) as a function of pH for phenol, dihydroxybenzenes, and trihydroxybenzenes at 25/sup 0/C. MIBK gave much higher K/sub d/ values than DIPE, particularly for the polyhydric phenols, so that solvent-to-water mass flow ratios (S/W) exceeding 0.14 and 0.39 would be required at low pH for effective removal of di- and trihydric phenols, respectively, with MIBK, compared with S/W greater than or equal to 1.4 and 8, respectively, for DIPE. The effect of pH was described by a simple ionization model. In the phenol/water/MIBK system, K/sub d/ values increased with decreasing temperature (30 to 75/sup 0/C) at all concentrations, and at 30/sup 0/C, they were high enough for the effective extraction of phenol contained at up to 20% by wt in the organic phase. Vacuum steam stripping was the best choice for the removal of residual dissolved MIBK. Extraction with MIBK may thus be used to recover, rather than degrade, phenols contained in aqueous streams from refining, petrochemical, and coal conversion processes.

S. Lynn

Papers

Solvent extraction of phenols from water