A novel natural lignocellulosic biosorbent of sunflower stem-pith for textile cationic dyes adsorption

The naturally occurring agricultural waste based biosorbents have gained increasing attention for green production and environmental protection, due to their biodegradability, economic viability, and ecological benefits. In the present study, an agricultural waste of sunflower stem-pith (SSP) was used directly as a biosorbent to treat the textile cationic dyes, and the correlations of sorption properties, such as physicochemical structure, treating conditions, and adsorption properties were examined. The maximum sorption capacity of SSP for methylene blue (MB) was 346.32 mg/g, and the modeling of the adsorption data followed the pseudo-second-order kinetic model. SSP sorption test showed that 97% of MB could be adsorbed after 30 min contact time at temperatures between 35 and 70 °C and over a broad pH range of 3.5–12, indicating that SSP possessed acid resistances, with rapid and temperature-insensitive adsorption process. Furthermore, the five cycles recovery test revealed the recyclability of SSP. Finally, the prevalence of SSP towards the adsorption of textile cationic dyes was verified by comparing MB with malachite green (MG), which further highlighted its practical applications. Overall, the natural SSP material with high regeneration efficiency could be promising and a suitable alternative adsorbent for treating dye wastewater contamination.