engleski

Chemical composition of wheat straw as a potential raw material in papermaking industry

In the paper industry as one of the fastest growing industries, cellulose fibres are the main raw material for paper production. According to its origin, cellulose fibres are divided into synthetic and natural fibres. Natural fibres are abundantly present in various plant species such as trees, grasses, reeds and straw. Wood as a raw material still holds a key position in pulp and paper production. As the demand for paper products is growing, different types of conifers and deciduous trees become insufficient raw material for paper production. This lack of raw material is the result of irrational exploitation of the natural resources for different purposes (lumber, heating material, pulpwood). Therefore, alternative sources of quality primary cellulose fibres are of great importance for papermaking industry. Non-wood fibres gained from the by-products of agricultural production of annual crops are an interesting alternative source of cellulose fibres. They are inexpensive and annually renewable source of fibre available in large quantities in many regions of countries across Europe. In Croatia the agricultural crop with highest production that give straw as the by-products is wheat. In this research wheat straw as a potential raw material in papermaking was evaluated through chemical composition. Straw was subjected to alkaline treatments in order to obtain fibres with as large a share of cellulose. The first treatment type was straw cooking in caustic soda and the second treatment type was consisted of straw soaking in caustic soda and then cooking in tap water. On wheat straw and dried isolated fibres determination of organic (cellulose, α-cellulose, lignin, accessory material, moisture) and inorganic compounds were made according TAPPI methods. ICP-MS analysis of straw and isolated fibres was done using digestion method (wet ashing method for organic matter destruction) and in those way 21 chemical elements was explicit. Content of cellulose, especially α-cellulose and lignin in the selected raw material are the most important indicators of its usage in paper production. On the other hand, low content of problematic elements as copper, iron, cobalt, manganese, zinc and silica are desirable. It is very important to use proper method for fibres isolation in order to avoid loss of cellulose content during separation of non-cellulose components from lignocellulose structure of straw. Based on results of provided analysis, wheat straw is a valuable raw material and its utilization is of great importance considering that they are currently burned or ploughed back into the ground.

alkaline treatment; wheat straw; chemical composition; ICP-MS analysis

Ovaj rad je u sklopu SuZ financijske potpore istraživanju: “Slama žitarica kao izvor vlakanaca u proizvodnji novinskog papira” (voditeljica: izv. prof. dr. sc. Željka Barbarić-Mikočević).