## 4 Conclusions  
Based on the aforementioned research findings, it is evident that the pyrolysis temperature plays a significant role in shaping the pore structure and surface properties of biochars, thereby impacting their adsorption capabilities. Analysis using scanning electron microscopy (SEM) indicated that higher pyrolysis temperatures lead to the development of intricate pore structures and rougher surfaces, thereby enhancing the adsorption capacity of the biochars. Furthermore, Raman spectroscopy analysis revealed that elevated pyrolysis temperatures result in increased levels of graphitization and disorder in the biochars. Additionally, the application of the Boehm method demonstrated that basic functional groups are predominant across all biochar samples, although intensified pyrolysis conditions resulted in a reduction of alkaline groups and an increase in acidic groups, phenolic hydroxyl groups, and carboxyl groups. As a result, the adsorption of SMX onto the biochars is influenced by specific surface area and pore volume roughness, leading to significantly higher adsorption rates and equilibrium capacities for biochars with more pronounced pore structures and rougher surfaces. Kinetic modeling further affirmed the preference for the Elovich model in describing the chemisorption process of SMX onto the biochars, with the 700 HSBC biochar displaying the highest adsorption rate, attributable to its amorphous structure. Furthermore, notable disparities were observed in the adsorption of SMX onto the biochars when comparing PBS solution and hydrolysis urine, indicating the differential impact of ions present in urine on the adsorption process. It is pertinent to note that our previous research validated that similar pore size distributions negate their influence on the adsorption results. Nevertheless, this study underscores the necessity for additional exploration using fractal theory to comprehensively expound on the impact of pore shape and distribution on adsorption. The comprehensive findings underscore the critical role of pyrolysis temperature and surface properties of biochars in influencing their adsorption capacities, offering valuable insights for potential environmental remediation applications.  
Conceptualization, R.H. and K.H.; methodology, R.H.; software, R.H.; validation, R.H. and K.H.; formal analysis, R.H.; investigation, R.H.; resources, H.Y.; data curation, R.H.; writing--original draft preparation, R.H.; writing--review and editing, X.Z. and H.Y.; visualization, R.H.; supervision, X.Z. and H.Y.; project administration, H.Y.; funding acquisition, H.Y. All authors have read and agreed to the published version of the manuscript.  
This work was supported by the National Key Research and Development Program of China (2023 YFC3207700).  
Not applicable.  
Data Availability Statement: The data presented in this study are available on request from the corresponding author. The data are not publicly available due to that we will use these original data to do other analyses.  
The authors thank [PERSON], Horticulture Branch, Heilongjiang Academy of Agricultural Sciences for assisting with the Raman testing.  
The authors declare no competing financial interests.