Search results for " Carboxylic acids"

Alkali consumption of aliphatic carboxylic acids during alkaline pulping of wood and nonwood feedstocks

2013

Abstract The carbohydrate degradation products have been examined, which are formed during the conventional kraft pulping of a softwood, hardwoods, bamboo, and wheat straw as well as soda and soda-anthraquinone pulping of wheat straw. The focus was on “volatile” acids such as formic and acetic acids and “nonvolatile” hydroxy monocarboxylic and dicarboxylic acids. The different consumption profiles were obtained for the charged alkali required for the neutralization of these aliphatic acids depending on the feedstock and the cooking method. The relative composition of the acid fraction in the black liquors of softwood and hardwood and nonwood feedstocks showed characteristic variations. Howe…

Electrochemical incineration of organic pollutants: effect of the nature of the pollutants and of the operative conditions

2010

NonclassicalPschorr andSandmeyer Reactions in Pyrazole Series

2005

The diazonium salt derived from 4-amino-N,1,3-trimethyl-N-(3-methyl-1-phenyl-1H-pyrazol-5-yl)-1H-pyrazole-5-carboxamide (14) was reacted with a mixture of CuSO4 and NaCl, with ascorbic acid as an initiator to afford the planar derivative 4,6-dihydro-1,4,6,8-tetramethyl-3-phenyldipyrazolo[3,4-b:4′,3′-d]pyridin-5(3H)-one (16) and its unexpected isomer 4,6-dihydro-3,4,6,8-tetramethyl-1-phenyldipyrazolo[4,3-b:4′,3′-d]pyridin-5(1H)-one (17), as well as the epimers (3S,4S)- (or (3S,4R)-) and (3S,4R)- (or (3S,4S)-) 4-chloro-2,4-dihydro-1′,3′,5,5′-tetramethyl-2-phenylspiro[pyrazole-3,4′(1′H)-pyrrolo[3,4-c]pyrazol]-6′(5′H)-one (18a and b, respectively). Epimers 18a and b were converted under basic c…

A method for measuring low-weight carboxylic acids from biosolid compost

2006

Concentration of low-weight carboxylic acids (LWCA) is one of the important parameters that should be taken into consideration when compost is applied as soil improver for plant cultivation, because high amounts of LWCA can be toxic to plants. The present work describes a method for analysis of LWCA in compost as a useful tool for monitoring compost quality and safety. The method was tested on compost samples of two different ages: 3 (immature) and 6 (mature) months old. Acids from compost samples were extracted at high pH, filtered, and freeze-dried. The dried sodium salts were derivatized with a sulfuric acid–methanol mixture and concentrations of 11 low-weight fatty acids (C1–C10) were a…

Behavior of carbohydrate-based material in black liquor during heating

2004

One industrial softwood Kraft black liquor was heat-treated (at 175 ?C and 190 ?C for 15-60 min) together with laboratory-made soda-AQ (wheat straw and reed canary grass) and Kraft (reed canary grass) black liquors (at 190 ?C for 30 min). The feedstock black liquors were characterized with respect to their polysaccharide (mainly xylem) and aliphatic carboxylic acid contents before and after the heat treatments. It was noted that, due to the higher amount of polysaccharides in the non-wood black liquors (8.2-16.6% of d.s) compared to that in the softwood black liquor (1.4% of d.s), the heat treatment in the former case resulted in a 5-30% increase in the amount of aliphatic acids formed by v…

Novel concepts on the recovery of by-products from alkaline pulping

2016

Innovative biorefinery concepts were developed for the separation and utilization of organic materials, especially aliphatic carboxylic acids, lignin, and extractives, which are formed as by-products during wood-based alkaline delignification processes. The partial recovery of sodium as NaOH and aliphatic carboxylic acids from hardwood soda-AQ black liquor was studied via electrodialysis. The lignin was partly (about 59 % of the initial lignin) precipitated from black liquor by carbonation (pH to about 8.5) followed by electrodialysis or H2SO4 (pH to about 2), with subsequent precipitation of more lignin and the liberation of aliphatic acids. The Na2SO4 formed was successfully separated fro…

p-Nitrophenolate: A Probe for Determining Acid Strength in Ionic Liquids

2009

In order to obtain an acidity scale in room-temperature ionic liquid solutions, the protonation equilibrium of sodium p-nitrophenolate in [bm(2)im][NTf(2)] and in [bmpyrr][NTf(2)], at 298 K, has been studied by means of spectrophotometric titration. Carboxylic acids differing in both structure and in water solution strength have been used. Data collected indicate that in the analyzed ionic liquid solutions carboxylic acids are less dissociated than in water solution. Furthermore, by virtue of a mutual interaction, the studied equilibrium seems to be affected by both the nature of the ionic liquids and the carboxylic acids.

Combustion Properties of Birch (Betula pendula) Black Liquors From Sulfur-Free Pulping

2016

Sulfur-free pulping has an environmental advantage over the traditional kraft process. This article describes the combustion properties of the black liquors produced from silver birch (Betula pendula) sawdust using three different cooking processes: two sulfur-free cooks (soda-anthraquinone and oxygen-alkali), and one reference kraft cook. It also considers the corresponding black liquors from an integrated forest biorefinery, in which a hot-water pretreatment of feedstock was performed prior to pulping. With the same cooking time, the total burning times for the sulfur-free black liquors were higher (15–55%) than those for the conventional kraft black liquors. However, no significant diffe…

Combustion behavior of black liquors : droplet swelling and influence of liquor composition

2017

The combustion of black liquor (BL) in a recovery boiler is a central process in a kraft pulp mill for recovering the cooking chemicals and for producing heat and power. This work explored the most important combustion behavior of BL, the swelling of in-flight droplets, from the viewpoint of liquor composition. It also studied the combustion behavior of BL droplets obtained from two biorefining subprocesses (carbonation and hot-water pretreatment, HWP) and sulfur-free pulping alternatives (soda-anthraquinone (AQ) and oxygen-alkali pulping). The formation of a plastic state essential for the swelling of BL droplet was found to result from the melting of an array of carbohydrate-derived aliph…

Low-weight carboxylic acids as potential risk factor of compost phytotoxicity

2009

Being intermediates of organic matter degradation, low-weight carboxylic acids (LWCA) can occur at phytotoxic concentrations on bioactive soils or in the processed organic material applied to soil. While toxicity potentials and mixture effects of LWCA are still poorly known, the potential phytotoxicity of the biomaterials is difficult to assess. In the study effective concentrations (EC) of formic, acetic and propionic acids at non adjusted pH were obtained in short-term germination assays (48 h for cress, Lepidium sativum, and 120 h for ryegrass Lolium multiflorum) and subchronic growth assays (21d). Based on the EC values, LWCA inhibited more strongly plant growth than seed germination. I…