In in-situ chemical oxidation (ISCO) soil remediation projects, the selection parameters of sodium persulfate directly determine the oxidation efficiency of the reagent, construction feasibility and remediation compliance rate. Improper selection tends to cause insufficient oxidation capacity, poor construction adaptability and incomplete degradation of pollutants, which further impair the overall project quality and treatment performance. Product purity, active oxygen content and adaptability to activation processes serve as three core indicators for sodium persulfate selection. They form a complete evaluation system covering basic reagent quality, treatment efficiency and on-site implementability, acting as important guidelines for project quality control.
Ⅰ Product Purity: Core Guarantee for Fundamental Reagent Quality
Product purity determines the content of effective components, which is a prerequisite for stable performance of remediation reagents across multiple batches. High-purity products can steadily supply sufficient oxidative active substances; while low-purity products contain high proportions of inert impurities, leading to drastic fluctuations in effective oxidizing components and unstable compliance results for complex contaminated sites.
During project selection, it is critical to verify purity compliance and batch consistency, so as to avoid risks including uneven treatment at remediation points and incomplete pollutant removal caused by non-standard inferior products. Meanwhile, close attention shall be paid to the content of transition metal impurities, especially iron, manganese, heavy metals (lead-based) and other indicators. High-purity and low-impurity products introduce fewer exogenous by-products, minimize disturbance to the original soil structure and soil microecological environment, comply with the principles of harmless treatment and low disturbance for remediation projects, and facilitate subsequent ecological restoration of site soil.
Supported by a full-process standardized testing system, Fujian Zhanhua Chemical steadily produces qualified sodium persulfate with effective content ≥ 99.0%, together with strict impurity control: iron ≤ 0.001%, manganese ≤ 0.0001%, heavy metals (calculated as Pb) ≤ 0.001%, moisture ≤ 0.10%. Index fluctuations of each batch are well controlled, meeting the stability requirements for large-scale continuous material feeding of remediation projects.
Ⅱ Active Oxygen Content: Critical Support for Pollutant Treatment Efficiency
Active oxygen content is a quantitative core index characterizing the oxidation capacity and treatment potential of sodium persulfate, directly governing the degradation efficiency of soil pollutants, effective action duration and oxidation persistence. Sodium persulfate realizes oxidative decomposition of organic pollutants via activated sulfate radicals (SO₄•⁻). The total amount and sustained release stability of active oxygen are important criteria to judge product adaptability to site conditions.
Researches and practical cases on contaminated soil remediation in recent years prove that sodium persulfate with sufficient and slowly released active oxygen can maintain long-lasting oxidation activity in complex soil featuring high organic matter and high clay fraction. On the contrary, products with low active oxygen or excessively fast decomposition have shortened effective oxidation windows and frequently result in incomplete pollutant degradation. Therefore, active oxygen content and release stability are core screening benchmarks for reagent efficiency, ensuring precise matching between oxidation capacity and site pollution load. Through continuous process iteration and optimization, Fujian Zhanhua Chemical precisely regulates the retention and release characteristics of active oxygen, with stable active oxygen content ≥ 6.65%, fully satisfying the demand for long-term oxidative treatment in soil remediation.
Note: Sodium persulfate consumes active oxygen not only for target pollutants but also for endogenous soil substances such as organic matter. In practical projects, endogenous oxygen consumption by soil matrix shall be fully considered, and reasonable reagent dosage surplus shall be reserved.
Ⅲ Adaptability to Activation Processes: Important Basis for On-Site Implementation
Adaptability to activation processes acts as a key link connecting the physicochemical properties of products with field construction conditions, directly affecting activation efficiency, reaction stability and overall treatment effect. Sodium persulfate reacts mildly under ambient temperature. The industry commonly adopts thermal activation, alkaline activation and transition metal ion activation to stimulate its strong oxidation potential. The compatibility of physical and chemical parameters (including pH value, particle size and dissolution rate) of the reagent with the selected activation system determines the operating efficiency of the whole oxidation system.
Incompatibility between reagent physicochemical properties and activation schemes easily triggers insufficient activation efficiency, invalid reagent decomposition and reaction passivation, which weaken pollutant removal effects. In engineering practice, it is recommended to confirm the activation technical route first, then select sodium persulfate with corresponding physical and chemical specifications. The product pH range (normally 4.0~7.0) is compatible with mainstream activation pathways, reducing process adaptation defects and leaving greater flexibility for on-site scheme adjustment.
The three indicators — product purity, active oxygen content and activation process adaptability — form a mutually complementary selection logic, jointly influencing site applicability and treatment reliability of the reagent. It should be clarified that the above parameters are core references at the selection stage, while actual remediation performance is also affected by multiple factors such as soil pH, moisture content, organic matter content, spatial distribution of pollutant concentration and hydrogeological conditions. Before finalizing reagent selection and dosing schemes, laboratory bench-scale tests and field pilot tests on representative soil samples from the target site are recommended to determine the optimal reagent dosage ratio, activator proportion and reaction duration.