Search for dissertations about: "carbonyl groups"

Showing result 1 - 5 of 37 swedish dissertations containing the words carbonyl groups.

2. 1. Fenton Pre-treatment of a Birch Kraft Pulp for MFC preparation

   Author : Pia Hellström; Helena Håkansson; Anette Heijnesson Hultén; Magnus Paulsson; Monica Ek; Karlstads universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Microfibrillated cellulose; Fenton chemistry; carbonyl groups; surface charge; total charge; Enzymatic hydrolysis; Tensile strength; z-directional strength; Chemical Engineering; Kemiteknik;

   Abstract : The potential to use acidic hydrogen peroxide in the presence of ferrous ions (Fenton’s reagent) as a pre-treatment when producing microfibrillar cellulose (MFC) from a fully bleached birch (Betula verucosa) kraft pulp was investigated and the properties of the produced MFC was compared to the properties of a MFC produced with enzymatic pre-treatment with a monocomponent endoglucanase (FiberCare® R). The mechanical treatment to MFC was performed in a laboratory colloid mill or in a pilot high-pressure homogeniser and the pre-treated pulps as well as the produced MFCs were chemically and morphologically characterised. READ MORE

4. 2. Transition metal-catalyzed reduction of carbonyl compounds : Fe, Ru and Rh complexes as powerful hydride mediators

   Author : Elina Buitrago; Hans Adolfsson; Robert Morris; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Asymmetric catalysis; amino acid; N-heterocyclic carbene; iron; ruthenium; rhodium; mechanistic investigation; kinetic study; asymmetric transfer hydrogenation; hydrosilylation; organisk kemi; Organic Chemistry;

   Abstract : A detailed mechanistic investigation of the previously reported ruthenium pseudo-dipeptide-catalyzed asymmetric transfer hydrogenation (ATH) of aromatic ketones was performed. It was found that the addition of alkali metals has a large influence on both the reaction rate and the selectivity, and that the rate of the reaction was substantially increased when THF was used as a co-solvent. READ MORE

5. 3. On the oxidation of kraft pulp - Formation of carbonyl groups during acidic hydrogen peroxide oxidation

   Author : Axel Martinsson; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; bleaching; Hydrogen Peroxide; wet-strength; cellulose oxidation;

   Abstract : A shift from fossil based to bio based raw material is necessary if the needs of a growing population are to be fulfilled sustainably. Today, the packaging industry is heavily dependent on products originating from fossil feedstocks. READ MORE

6. 4. Oxidation of Kraft Pulp Fibres - Hydrogen Peroxide Oxidation under Acidic Conditions and its Influence on the Properties of Pulp

   Author : Axel Martinsson; Chalmers tekniska högskola; []
   Keywords : TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY;

   Abstract : An increase in the use of bio-based products, combined with a decrease in the use of fossil-based products, is important for fulfilling the demands of a growing population in a sustainable manner. Moreover, reducing the usage of single-use plastics is vital in combating the plastic pollution that is afflicting our environment. READ MORE

7. 5. Long-term properties of polyethylene films : efficiency of a natural antioxidant

   Author : Clara Strandberg; Ann-Christine Albertsson; Jukka Seppälä; KTH; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Polymer Technology; alfa-tocopherol; Polyethylene PE ; Thermal aging; Infrared Spectroscopy FT-IR ; Chemiluminescence CL ; Solid-phase microextraction SPME ; Chemistry; Kemi;

   Abstract : There is a growing awareness of the risks of pollution in biological systems and one potential problem is the synthetic antioxidants, used for e.g. the stabilisation of polymeric materials. Natural antioxidants are an interesting alternative, if the high efficiency and thermal stability of the synthetic compounds can be reached. READ MORE