Characterization of Different Biochars Produced and Composited with Nano Silver Prepared by Eco-friendly method

Abstract

An environmentally friendly and economical material, biochar has drawn great attention to soil and wastewater remediation. However, its properties and behaviors for adsorption pollutants are different depending on feedstock and pyrolysis conditions. This study prepared biochar from different feedstocks (wheat straw and walnut shells) at different temperatures (300 and 600 °C), and composite with nano silver oxide. Nano silver oxide was prepared by using the green method. The obtained biochar with/without nano silver coating was then characterized using XRD, FESEM, etc. The results showed that the nano-size of the silver nanoparticles was about56.44 nm. Biochar was found to contain organic elements such as carbon, hydrogen, sulfur, and nitrogen. For composite biochar with nanosilver, the XRD result confirmed the Nano silver-coated biochar. FE-SEM examination for silver oxide showed the surface image in the form of silver spheroids with an average size of 41.8 nm. For biochar with increasing temperatures, the surface went from rough to smooth, and its porosity increased. The FE-SEM confirmed the nanosilver was distributed over the channels within biochar. The results of EDX showed biochar consists of a wide range of organic and inorganic elements. The percentage carbon content increased with temperature increased and within walnut shells was higher than the wheat straw feedstock. The BET surface area results showed that walnut shells biochar had a higher value than the wheat straw biochar and value with increasing pyrolysis temperature from 300 to 600 ℃, which were 10.44, 210.07, 1.1959 and 80.251, respectively. However, all biochar composited with nanosilver led to a reduction in surface area. The carbon content in biochar increased with increasing temperature pyrolysis, and the biochar produced from wheat straw had higher carbon content than the biochar of walnut shells, as well as reduced in biochar composites with nano silver. Therefore, the adsorption capacity of these materials for pollutants could be differentiated based on these proprites. The biochar for wheat straw at 300 and 600 had a nano size of 152 nm, and at a temperature of 600 °C, it had a nano image and size of 34 nm. For Walnut shells, It was 300 and 600 images. It has a nano size of 26 600 shapes and a size of 28,134.