Effective treatment for environmental enhancing the performance of undesirable agro-waste in production of carbon nanostructures as adsorbent

摘要

The work in this article deals with enhancing the performance of rice straw (RS) for production of carbon nanostructures (CNSs), as aqueous phase adsorbents, as well as benefit solution for disposing of this undesirable waste and for avoiding the environmental risk from burning. In this respect, controlling the constituents of RS by enzymatic treatment, followed by hydrothermal treatment and carbonization was carried out. The benefit role of the performed treatments was supported via comparing these CNSs with those obtained from RS pretreated by chemical pulping processes; moreover, literature reported CNSs. Results deduced from SEM and TEM analyses showing that, the two investigated CNSs samples have different surface morphologies and comprised of graphitic carbons as nodules and multi-layer graphene sheets. The investigated RS-based CNSs own numerous of oxygen-containing functional groups with low specific surface area and high mesopore volume; thus, they exhibited high iodine number of 959 and 863 mg/g, respectively. The CNSs from hydrochar of peroxidase treated RS has higher uptake to methylene blue (MB) dye (358 mg/g) than that produced from hydrochar of cellulase treated RS (202 mg/g), this may be related to its unique nanostructure. Both values are higher than that of reported CNSs, which obtained from chemical pulping processes (similar to 54-119 mg/g). The adsorption of MB dye is well-fitted with Langmuir and described by pseudo-second order kinetic model.