# Efficient Inorganic Stabilization Materials for Chromium and Arsenic Pollution in Water and Soil
## 4 Factors Affecting the Stabilization Process of Chromium and Arsenic Stabilized Materials
### The Influence of Stabilization Time on the Stabilization Process of Chromium and Arsenic  
In the initial stage of adding stabilization materials, due to sufficient active sites on the surface of the material, chemical reactions (such as ion exchange, surface complexation, and chemical precipitation) occur rapidly between the material and chromium or arsenic ions. Next, the active sites on the surface of the material are occupied, and the reaction rate gradually slows down. Finally, the adsorption and chemical reactions of pollutants reach dynamic equilibrium. [PERSON] et al. [100] combined montmorillonite with glucose to generate carbon-coated montmorillonite nanocomposite (CMt) under acidic conditions. Adsorption equilibrium can be quickly reached within 48 h. However, the stabilization products formed by short-term remediation are prone to re-release with environmental changes. [PERSON] et al. [101] used SIF as a stabilizer for As. The process of SIF stabilizing As is divided into three stages. The first stage is from 0 d to 2 d, where F4 (crystalline hydrous oxides-bound As) is converted to F3 (amorphous hydrous oxides bound As). As a result of the reductive dissolution of the Fe-As co-precipitate, As is released. In the second stage from 2 d to 90 d, the transition from F3 to F5 (residual As) mainly occurs. Through diffusion within the particles, a stable complex or mineral is finally formed. The third stage occurs between 90 d and 180 d, featuring mainly transition from F3 to F4, where the crystallization process of iron oxides and hydroxides is performed (Figure 12d). [PERSON] et al. [102] selected Ca(OH)\({}_{2}\) as the core material and zeolite as the coating to prepare core-coating wrapping balls. Then, FeSO\({}_{4}\).7H\({}_{2}\)O was added to obtain a novel granular half-wrapping structured amendment (HWA). When the ratio of FeSO\({}_{4}\).7H\({}_{2}\)O:zeolite:Ca(OH)\({}_{2}\)  
Figure 11: The chemical forms of As (**a**) and Cr (**b**) at different pH values [96].  
is 6.5:1:1, the stabilization rate of As is 95.5%. After 365 days, the stability rate decreases to 92.1%. The stabilization rate is calculated as the percentage decrease in the leaching concentration of heavy metals after stabilization compared to the leaching concentration before stabilization. Specifically, it is determined using the following formula:  
\[\text{Stabilization Rate}=\frac{C_{0}-C_{t}}{C_{0}}\times 100 \tag{1}\]  
Among them, \(C_{t}\) represents the heavy metal leaching concentration after t days of the stabilization process, while \(C_{0}\) represents the heavy metal leaching concentration before the stabilization treatment. However, current research primarily focuses on short-term stabilization effects, with relatively limited research on long-term stabilization. For instance, studies have found that iron-modified graphene oxide can maintain a Cr(VI) removal rate of over 70% even after five repeated uses [103]. Additionally, the ability of modified zero-valent iron to capture pollutants decreases by only 4.8% after six cycles. These findings indicate that these materials hold significant potential for long-term stabilization [104]. Therefore, further exploration of the application of such materials in long-term stabilization could contribute to the development of more efficient and sustainable pollution control technologies.