Thorium (Th(IV)) has low radioactivity, occurs naturally and widely distributed over the earth's crust, making it roughly three times as plentiful as uranium (Liu et al. 2014) (Mastren et al. 2018) (Mastren et al. 2017). Th(IV) has widespread application in an extensive palette of disciplines, including radios, optics, aerospace, chemistry, metallurgy, nuclear industry, nuclear medicine and materials research, giving it both scientific and economic significance. The accumulation of massive amounts of trash around the world has exacerbated the pollution crisis, as this garbage has the aptitude to ascend the food chain and be consumed by human beings, where it can cause long-term harm to vital organs and even death (Baybaş & Ulusoy 2011) (Keshtkar & Hassani 2014). Harmful Th(IV) pollution is significant because it bioaccumulates in human tissues via the food chain. After being exposed to Th(IV), human liver cells proliferated at a rate that was 40–60% higher than usual (Rezk 2018). Consequently, the separation and recovery of Th(IV) from radioactive wastewater has substantial scientific and practical importance.
Precipitation (Hamed et al. 2016), solvent extraction, membrane separation (Li et al. 2018), ion exchange (Ang et al. 2018), and adsorption (Ding et al. 2019b) (Varala et al. 2019) are just a few of the methods developed recently for Th(IV) extraction, preconcentration, and separation from wastewater. Chemisorption systems are the most ubiquitous method for Th(IV) elimination from fluids because they are simple and straightforward technologies with a convenient process, increased practicability, pricing, and prospective removal routine (Xiong et al. 2017). The luckiness of this layout improves the efficiency with which the extraction is accomplished. This means that a line–up consisting of silica nanoparticles (Gomez et al. 2018), natural polymers, and magnetically sorptive materials (Atta & Akl 2015) (Wu et al. 2013) are ready to capture Th(IV) with the required level of efficiency. However, many of these materials suffer from flaws that limit their effective enforcement in environmental therapies, such as poor selectivity Th(IV) adsorption and limited chemical stability in powerful alkaline and acidic conditions. Consequently, designing a high-efficiency sorbent for thorium removal that has the right sorption capacity, exceptional selectivity, and pH is an exciting task.
To that end, the scientists' focus has been dragged toward waste management in an effort to preserve the planet. Waste management strategies include source reduction, proper disposal, and pollution elimination or mitigation (Ding et al. 2019a). Adsorption methods are first developed for Th(IV) recovery to extract radioactive components from liquid waste (Kaynar et al. 2021). A wide variety of sorbents have been used to purge radioactive elements from wastewater, including activated carbon (Omar & Moloukhia 2008), algae (Kim et al. 2019), modified nanoparticles (Xia et al. 2020), zeolites (Jiménez-Reyes et al. 2021), imprinted mesoporous silica (Yang et al. 2017), and so on. As a result of their wide availability, low cost, and low impact on the environment, adsorbents made from biomass waste have also attracted a lot of interest (Khosravi et al. 2022). The bagasse from sugarcane production is a type of agricultural waste that could be processed into silica. It's been asserted that natural silica is entirely harmless to handle and inexpensive and easy to produce with readily available materials. Using waste biomass to create mesoporous SiO2 for removing contaminants from aqueous solutions aids in both preserving an eco-friendly environment and repurposing waste streams to treat additional waste streams (Rahman et al. 2015).
Meanwhile, mesoporous bio-silica, an inorganic substance consisting of Si and oxygen, has gained a lot of interest since it is safe to use, stable, biocompatible, and easy to produce (Niculescu 2020). Mesoporous materials, i.e., porous materials with pore size at 2–50 nm, have garnered significant interest in a wide range of scientific disciplines over the past two decades (Boissiere et al. 2011) (Kwon et al. 2010) (Liang et al. 2006) (Liu et al. 2011) (Ma et al. 2011) (Yang et al. 2011). These substances were used to purge waste solutions of Th(IV). Moreover, mesoporous silica nanomaterials are unique families of attractive porous silica featuring very large specific surface areas, mechanical and thermal durability, extremely consistent pore arrangement, strong sorption capacity, and extraordinarily wide prospects of functionalization (Thirumavalavan et al. 2011) (Walcarius & Mercier 2010) (Yousefi et al. 2009). Because of these benefits, mesoporous silica is a great substrate for thorium extraction from geological and environmental samples. Solid-phase extraction has been reported to be used for Th(IV) recovery and preconcentration (Ghasemi & Zolfonoun 2010) (Jiang et al. 2019) (Lin et al. 2010). Mesoporous molecular screens (Al-MCM-41) were investigated for their ability to adsorb Th(IV). According to the findings, Th(IV) sorption on Al-MCM-41 was an endothermic and spontaneous process that reached equilibrium in 12 hrs (Zuo et al. 2011). Correspondingly, the produced nanoporous ZnO was used to remove Th(IV) from waste solutions, whereas nano tin oxide was used to remove Th(IV) and U(VI) ions from water (Kaynar et al. 2015) (Nilchi et al. 2013).
This investigation intended to prepare mesoporous silica nanoparticles (Mes-Si-NPs) using sugarcane bagasse-produced lignin with sodium silicate. This technique provides improved Mes-Si-NPs with pores and inner cavities for Th(IV) uptake from its solution. Also, Mes-Si-NPs was utilized for assessing the best sorption parameters of Th(IV) using the batch adsorption technique. Also, the isotherms and kinetics studies are studied for Th(IV) sorption on the synthesized Mes-Si-NPs.