Sustainable development of pulping by-product for limiting its pollution risk and production new aerogel-based carbon nanostructures for dyes adsorption

Abstract

A clean approach for disposing the pulping by-product (black liquors- BLs) as an effective component in preparing high surface area aerogel-based carbon nanostructure adsorbents was the objective of this current work. These novel adsorbents were assessed as a benefit for removing the cationic and anionic dyes. In this respect, black liquors from pulping of rice straw by different pulping reagents were used as components together with resorcinol in production of aerogel precursors for carbon nanostructures (CNSs). The effective role of BL-based aerogels was evidenced from comparing their CNSs adsorption capacities with CNSs of aerogels free from BLs, towards dyes together with iodine. Different isotherms (Langmuir, Freundlich, Temkin and Dubinin-radushkevich (D-R) were studied to calculate the adsorption capacities. Results showed that CNSs from BL-based aerogels had higher adsorption capacities to dyes (methylene blue (MB) and brilliant blue (BB) than that produced in absence of BLs; where it increased from 256 to 307 mg/g and from 7 to 61 mg/g, respectively. The BLs from pulping of RS with alkaline reagents (NaOH and KOH–NH4OH) provided highest MB adsorbents, while highest adsorption of BB was noticed in case of BL from sulfite reagent, moreover this BL only provided improvement in Iodine value (increased from 752 to 968 mg/g). It is interesting to note that with this investigation we are able to overcome the problems of obtaining carbon nanomaterials from BLs or extracted lignin with low surface area. The surface area of the CNSs that produced through our investigation (1607 m2/g) surpassed the results from previous published work.