Facile ultrasonic-assisted one-step preparation of sugarcane bagasse carbon sorbent for bio-based odor removal cat litter formulation

To reduce the cost of adsorbents for the removal of cat urine odor there has been concerted research efforts to produce functionalized porous carbon from waste biomass. In this work, a cost-effective and environmentally friendly method was used to prepare a carbon adsorbent (AC-SNP) from sugarcane bagasse through ultrasonic-assisted impregnation of mixed HNO3/H3PO4 on bagasse prior to carbonization. Ultrasonication enhanced structural deformation of bagasse and enriched the N and O-containing groups prior to cabonization which allowed the final carbon material to have increased specific surface area of 1603.1 m2/g and porosity of 1.3858 cm3·g−1 (including micro- and meso-pores), and increased surface functionality of -COOH, -OH, pyrrolic N, and pyridinic N groups. The adsorption capacity of the carbon material for 3-mercapto-3-methyl-1-butanol (MMB), a volatile cat urine component, was up to 207.12 mg/g at 25 °C, and the heterogenous multi-layer Freundlich model and Pseudo-second-order model were used to explain the adsorption mechanism. Density functional theory (DFT) calculations showed that there are electrostatic interactions and hydrogen bonding between the O- and N-containing groups and MMB molecules. AC-SNP was found to be nontoxic in a cat litter formulation, and removes 99.87% volatile MMB at a low loading ratio of 2 wt%. The fabricated sugarcane bagasse-based cat litter (SB_CL) formulation also has anti-bacterial properties, and so has significant commercialization prospects.