[Application of Iron and Sulfate-Modified Biochar in Phosphorus Removal from Water].

The excessive discharge of phosphate into natural water has caused serious environmental problems. Adsorption is an efficient technology for phosphorus removal from water. In this study, a novel biochar modified by chitosan, ferrous sulfate, and sodium sulfide was synthesized and performed well in phosphorus adsorption. The results of batch experiments showed that the optimum synthesized composite could adsorb 49.32 mg·g-1 of phosphate at 298 K. Meanwhile, the simulation results showed better fitting with the pseudo-second-order model and Langmuir model. The adsorption rate was dominated by three-dimensional diffusion within the inner pores. The adsorption process was defined as physic/chemisorption, while the adsorption mechanism was concluded to be electrostatic adsorption, porous filling, surface chemical precipitation, hydrogen binding, and the ligand effect. This study showed that the composite is effective in phosphorus removal from water, and we anticipate that our research will offer guidelines for adsorbent design and reveal the adsorption mechanism.

[Synthesis of Magnetic Iron Modifying Biochar for Ammonia Nitrogen Removal from Water].

A significant factor for eutrophication is the excessive discharge of ammonia nitrogen. Unfortunately, traditional methods to remove ammonia nitrogen are ineffective when facing gradually strict rules. Recently, adsorption has gained interest from scholars due to its efficiency and safety in ammonia nitrogen treatment. In this study, a novel biochar, modified with magnetic iron, was synthesized through co-precipitation, which performed well in ammonia nitrogen removal. The maximum adsorption amount at 293 K of the composite that was synthesized at 80℃(MB80) was 17.52 mg·g-1. Meanwhile, the simulation results displayed a good fitting with the pseudo second order model and Langmuir model. Additionally, the adsorption mechanism could be attributed to electrostatic adsorption, porous filling, ion exchange, and hydrogen bonding. Noticeably, MB80 maintained a good performance after 5 cycles, with desirable adsorption amount of 3.18 mg·g-1. This study aimed to provide an efficient method to treat ammonia nitrogen as well as a new way to dispose of municipal sludge.