Question

6. Lignin can be used in adhesives but the real application has not been very successful. Please describe the reason and methods to solve this problem (10 pts).

Answer 1

Lignin is great for replace phenol in phenolic based glues for many reason. Lignin is a polyphenolic compound that make up almost one quarter of dry mass of every tree so it is abundant. Its cost is very low so can help in stabilizing cost in housing construction industry . it is also biodegradable and eco friendly . it is ideal for replacement of non renewable petroleum stock.

But as of now there are some challenge for using of lignin like commercial potential of these applications does not match existing production of lignin; e.g. the production of lignin is too high and not enough promising applications exist to fully realize lignin’s potential. On the other hand, the quality of the lignin-based products in well-established fields, e.g. adhesives, sorbents and dispersants, is not always superior to the quality of existing products. Clearly there is a need for applications utilizing technical lignins and operating on a large scale. Opportunities for success would be enhanced by the introduction of very-high-quality lignin-based products exceeding the properties of petroleum-based products. Another option would be the development of new, low- tonnage, high-added value products. In addition to economic factors, the use of technical lignin is also hampered by technical problems. The majority of these problems are caused by the structural features of technical lignins and to some extent by the delignification methods.

Identified problems have been divided into the four major classes -

1. Separation of technical lignin are cost-effectiveness and quality of the obtained lignin .

2.Separation methods cannot ensure complete removal of compounds chemically bonded to lignin.(impurities)

3. The structure of technical lignins differs considerably, with variations in polymer composition, size, and degree of crosslinking, and the presence of functional groups. ( Non uniform Structure)

4. Due to their heterogeneous structure, lignins often show unexpected behavior. ( unique reactivity)

lignin will require a substantial research and development effort going forward in understanding how to co-design lignin solubilization strategies for biological conversion and design microbial biocatalysts optimized for both the feed stream and targeted product. Certainly significant research and development opportunities and challenges remain to ascertain the viability of this new approach.