Browsing by Author "Tyhoda, Luvuyo"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Oxidative ammonolysis of technical lignins and lignites
    (Stellenbosch : Stellenbosch University, 2003) Tyhoda, Luvuyo; Gerischer, G. R. F.; Stellenbosch University. Faculty of AgriSciences. Dept. of Forest and Wood Science.
    ENGLISH ABSTRACT: Today there is renewed interest in using soil improvers with fertilising capability as the use of inorganic fertilisers results in ground water pollution through leaching and formation of nitrates in plant materials. Lignin is an important precursor of humic material in soils and with modification, can be used as a raw material for producing slow release nitrogenous fertilisers. This project focussed on the use of industrial residues such as technical lignins which are produced by the South African pulping industry as well as low grade coals such as lignite occurring in South Africa, for the production of high-grade humic substances like Novihum TM, using the special technology developed by the Institute of Plant and Wood Chemistry of the Technical University of Dresden in Germany. Technicallignins derived from kraft lignin, sugar cane baggase, autohydrolysis lignin with a trade name Sucrolin, a calcium lignosulphonate and South African lignites mined in the Kraaifontein and BraekenfeIl areas as well as German brown coal were subjected to oxidative ammonolysis with the aim to produce slow release nitrogenous fertilizers. Curie Point Pyrolysis GCIMS was used to determine the structural composition of the raw materials and products. Oxidative ammonolysis reactions were carried out on a laboratory and a pilot plant scale. Highest nitrogen contents were obtained with Sucrolin lignin followed by the lignite from Germany. The amount of nitrogen that could be fixed with oxidative ammonolysis varied between 1.44 - 10% for the various raw materials. The CIN ratios obtained were in the range between 5 - 34. Marginal differences were observed between the materials modified on lab and pilot plant scales. There were improvements in the total incorporated nitrogen when the raw materials were pre-activated with oxidising agents such as hydrogen perxide and a fungal species, Phanaerochateae chrysosporium prior to oxidative ammonolysis. Variable amounts of differently bonded nitrogen forms were obtained for the materials tested due to their structural differences.
  • Thumbnail Image
    Item
    Synthesis, characterisation and evaluation of slow nitrogen release organic soil conditioners from South African technical lignins
    (Stellenbosch : Stellenbosch University, 2008-03) Tyhoda, Luvuyo; Liebner, Falk; Rypstra, Tim; Rozanov, Andrei Borisovich; Stellenbosch University. Faculty of AgriSciences. Dept. of Forest and Wood Science.
    ENGLISH ABSTRACT: Today there is renewed interest in using technical lignins and similar ligneous materials as soil fertilising materials as they are available in large quantities from the pulping and agricultural industries. In addition, excessive application of inorganic fertilisers results in ground water pollution, especially in sandy soils through leaching of nitrogen. Lignin is an important precursor of humic material in soils and with modification, can be used as a raw material to produce slow nitrogen release fertilisers (N-lignins). This can be done using a reaction process called oxidative ammonolysis. This process has been developed over the years by the Institute of Plant and Wood Chemistry of the Technical University of Dresden in Germany, and a patent has been obtained for an ambient pressure based, oxidative ammonolysis. The patented product obtained from this process which is prepared from low-grade brown coal (due to its similarity to lignin) is trade named NOVIHUM™. It is a slow nitrogen release and long lasting organo-mineral fertiliser which has similar properties as natural humic substances. This project focussed on the characterisation and use of industrial residues such as technical lignins and similar ligneous materials which are produced by the South African pulping and agricultural industries, and on the production of N-lignins according to the patented NOVIHUM™ technology. Three technical lignins, one derived from the sulphite pulping process (a calcium lignosulphonate), the second from sugar cane bagasse (Sucrolin), and a third a, partially stripped sugar cane bagasse (a lignocellulosic residue with a low lignin content) were subjected to oxidative ammonolysis. A Kraft lignin, lndulin AT, from Westvaco, USA was used for comparison. The N-lignin products obtained were characterised and evaluated in plant growth trials.