Preparation Of Functional Value-Added Products Based On Biochar And Ethyl Cellulose From Straw And Their Applications

Straw is a renewable biomass resource,and biomass utilization technology can solve global food security and energy crisis.The straw was prepared into burning incense,essential oil sustained-release formulation and degradable mulch film,which realized the comprehensive utilization of straw and provided a new way for the resource utilization of agricultural waste.Straw biochar is a biomass material with rich surface functional groups and well-developed pore structure,which has excellent adsorption capacity and extremely strong stability.Ethyl cellulose is a biodegradable polymer material with good compatibility,corrosion resistance,and biodegradability.In this paper,straw was converted into biochar and ethyl cellulose.By using the combustion characteristics of straw,the adsorption property of biochar and the film-forming ability of ethyl cellulose,these materials were applied to the preparation of burning incense,essential oil sustained-release formulation and degradable mulch film,and the related properties and application effects of the prepared products were analyzed.The main conclusions are as follows:（1）In the experiment,straw and biochar were used as the combustion components,lavender was used as the aroma source,and cochineal vermilion was used as the staining agent to prepare the combustion aroma.The results showed that the addition of straw promoted the combustion of lavender in the low-temperature zone,accelerate the combustion of lavender,significantly improving its combustion performance,burnout performance,and combustion stability.When the addition amount of straw was between25%and 50%,the burning effect of incense could be improved and the fragrance of lavender could be more intense and prominent.Biochar with a pyrolysis temperature of300℃has the characteristics of low ash content and high calorific value,making it suitable for use as an auxiliary fuel for burning incense.As the proportion of biochar added in the combustion process increases from 0%to 25%,the total suspended particulate matter generated during the combustion process decreases from 13.25 mg/g to 9 mg/g.The content of harmful substances in incense meets national standards,and the levels of PM_2.5 and PM₁₀released during combustion are relatively low.（2）An antibacterial essential oil sustained-release formulation was prepared using biochar as the carrier and ethyl cellulose as the coating agent in the experiment.The structure of biochar composite essential oil sustained-release formulation（PO-BC）was characterized by scanning electron microscopy,Fourier transform infrared spectroscopy,and laser scanning confocal microscopy.The results showed that biochar with a pyrolysis temperature of 600℃had a high specific surface area and rich pore structure,which was conducive to the filling and dispersion of essential oils.There is an adsorption force between essential oil and biochar,which makes it difficult for essential oil to detach from the pores of biochar,and there is no chemical reaction during the adsorption process,which is beneficial to protecting the integrity of the natural structure of the essential oil.The antibacterial experiment showed that PO-BC not only expanded the antibacterial range of the essential oil,but also extended the duration of its antibacterial activity.Ethyl cellulose coating can enhance the slow-release performance of PO-BC.The cumulative release of untreated essential oil reached 74.75%on Day 7,while the cumulative release of essential oil from PO-BC and ethyl cellulose coated treatments during the same period were 41.31%and 21.37%,respectively.（3）The preparation of biochar and ethyl cellulose degradable mulch film and their promoting effect on crop growth were experimentally studied.When the dosage of ethyl cellulose is 0.06 g/m L,the mulch film has a stable high transmittance（65%～85%）in the visible light band,and the ultraviolet transmittance of the ethyl cellulose composite biochar mulch film is less than 1.5%,demonstrating excellent ultraviolet barrier performance.The addition of biochar improved the degradability of the plastic film.Ethyl cellulose mulch film（EC）and ethyl cellulose composite biochar mulch film（EC-BC）were buried in natural soil environment for 60 days,and their degradation rates were 5.44%and 10.27%,respectively.In the pot experiment,compared to the group without film covering,EC and EC-BC increased soil moisture content by about 5.5%and nitrate nitrogen content by 25.82%to 45.00%.Meanwhile,compared with commercial degradable mulch film,EC-BC can increase the dry weight of wheat by 11.32%to 17.51%,and the nitrogen content by 10.88%to 12.68%.Prove that ethyl cellulose and biochar are ideal materials for preparing degradable mulch films.Based on the above three applications,this study provides a new approach for the utilization of straw resources,which is of great significance to reduce straw open burning and natural resource depletion.