## 3 Sulfur Cake
### Processing and Modification Technologies
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Treatment** & **Mechanism** & **Key Advantages** & **Limitations** & **Quantitative Data** & **Ref.** \\ \hline Thermal activation & Heating above 120 & & Simple and & & Reduces moisture & \\  & moisture and & scalable— & & incomplete & from \textgreater{}5\% to & \\  & decompose unstable & & enhances purity & impurity removal & \textless{}0.5\%; improves & \\  & compounds & & and reactivity & & purity by \textasci{}15–20\% & \\ \hline Chemical & Dissolution of & & & & & \\   treatment (Acid & & & & & \\   washing) & Ca(OH)\({}_{2}\), CaSO\({}_{4}\)) & & Targeted impurity removal— & Requires neutralization— & Sulfur content & \\  & impurities (e.g., & & significant sulfur & generates acidic & improved by up to & \\  & with acids & enrichment & waste & & 20\% & \\ \hline Cyclodextrin & & Host-guest & Highly & & & \\   polymer inclusion & complexation with & selective-efficient & & & \\  & organic sulfur & for trace organic & materials—limited & & \\  & compounds & pollutants & to specific organics & & \\ \hline Mechanochemical & Ball milling with & & Simultaneous & & \\   activation & chemical agents to & mechanical and & & & \\  & enhance surface area & & chemical & & \\  & and reactivity & action—improves & & generation risks & pollutant binding & \\ \hline Activated carbon & Adsorption of & & reusable— & Lower efficiency & & \\   filtration & impurities using & applicable to & for solid sulfur & & purification; \\  & bio-derived carbon & liquid phase & cake & & potential analog & \\  & & purification & & & for sulfur \\ \hline Thermal vacuum & Melting and & & High-purity & & & \\   fusion (patented) & separation under & & output— & & \\  & reduced pressure & applicable to & & & \\  & industrial scale & & & \\ \hline Membrane— & Combination of & & & & \\  & dynamic membrane & & & & \\   sulfur bed systems & filtration with & & & \\  & sulfur-based & & & & \\  & bioreaction & efficiency & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Critical analysis of sulfur cake processing and modification methods, comparing thermal, chemical, and additive-based techniques in terms of mechanisms. Biomass coke modification that uses mechanical activation, named mechano-chemical activation, increases both surface area and reactivity, with the possibility of simultaneous physical and chemical purification [34]. It has also been used as an absorbent in purifying ethyl ester using activated carbon prepared using de-oiled seed cake, implying the similar potential in sulfur cake refinement [35]. The combination of high-temperature fusion and vacuum condensation in the separation of impurities is supported in the patent literature [36]. Furthermore, integrated treatment systems involving the use of the dynamic membrane and elemental sulfur beds have been promising in processes such as denitrification and management of sulfur-based pollutants, with an efficiency of more than 95% treatment [37]. The combination of chemical, thermal, and mechano-chemical processes provides a powerful set of mechanisms to purify the sulfur cake, which has been demonstrated to reduce the moisture content, clean the impurities, and activate the product.