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This work demonstrated that Enteromorpha biochar with introduced iron (SFB900-3) could activate peroxymonosulfate (PMS) efficiently for NTP remediation. It removed 83.9%–95.1% of NTP in 60 min under a wide pH range from 3.15 to 8.95. Density functional theory (DFT) calculations revealed the synergistic relationship between internal Fe single atoms and introduced Fe compounds—Fe3C. The adsorption capacity of SFB900-3 for persulfate improved from −0.953 eV to −4.214 eV, and the Bader charge analysis showed that Fe atoms as active sites (0.658 e) enhanced the adsorption capacity more than carbon (0.050 e). Moreover, the energy barrier for PMS dissociation reduced from 0.072 eV to −5.372 eV due to the longer length of O–O bond under the synergistic effect of Fe single atom and Fe3C which increased from 1.467 Å to 3.890 Å. The quenching experiment confirmed that 1O2 was the main active substance in NTP degradation and its contribution rate was 88.2%, which was further verified by EPR detection. The effect factor experiments proved that the SFB900-3/PMS system had stable and efficient activity for NTP removal, which remained at 73.6% removal rate after three rounds of tests. This work provided novel guidance for constructing efficient and stable biochar-based materials for organic pollutant remediation. Highlights: Improved PMS activation by synergy of single Fe atom and Fe3C was proposed. Variations in electron distribution and energy barrier enhance PMS activation The prepared SFB900 exhibited excellent stability. The degradation pathways of nitenpyram were explained in detail. [ABSTRACT FROM AUTHOR]

[Display omitted] • The synergistic effect of enhanced electron-donating, and piezoelectricity. • Catalyst/PMS system under piezoelectric potential are calculated by DFT. • l -Cysteine enhanced biochar's hydrophilicity and electron donating ability. • Singlet oxygen dominated on atrazine removal. In this study, pyrolysis and hydrothermal methods were used for Enteromorpha biochar that was co-modified with l -cysteine and barium titanate (LBCBa). It has great environmental tolerance and can remove 93.0 % of atrazine (ATZ, 10 mg·L−1) within 60 mins of ultrasonic treatment. The enhanced hydrophilicity, electron-donating capability, and piezoelectricity of LBCBa are considered to induce excellent performance. The apparent reaction rate of the LBCBa-2/PMS/ATZ system with ultrasonic was 2.87 times that without ultrasonic. The density functional theory points out that, introducing l -cysteine to carbon edges improves the adsorption of ATZ and peroxymonosulfate (PMS), making PMS easier to activate. This work offered unique insights for fabricating effective catalysts and demonstrated the combination of hydrophilic functional groups and piezoelectricity in improving catalytic performance and stability. [ABSTRACT FROM AUTHOR]

Over the past few years, high-valent iron oxo species (Fe(IV)) have shown considerable promise. However, an improved solution is needed for the bottleneck of unsatisfactory electron transfer efficiency in Fe-based catalyst/PMS systems. In this study, Enteromorpha-derived biochar was pyrolyzed with iron and barium titanate (FeBCBa). Under ultrasonic treatment, it removes 94.5% of atrazine (10 mg/L) within 60 min, and is environmentally friendly. BaTiO 3 ′s piezoelectricity enhances Fe(IV) production in FeBCBa, resulting in superior performance. In the ultrasonic condition, the apparent reaction rate was 1.42 times higher than in the non-ultrasonic condition. Using density functional theory calculations, it can be shown that due to the Fe dopant, electrons in ATZ's LUMO are more easily transferred to the catalyst's HOMO, which is beneficial for ATZ removal. The results of this study provide new guidance for constructing stable and efficient catalysts for environmental remediation. [Display omitted] • The generation of Fe(IV) was enhanced by the piezoelectricity of BaTiO 3. • DFT calculations are used to fully comprehend the degradation of ATZ. • The toxicity of atrazine and its intermediates are detailed. • The electron transfer is described using the LUMO and HOMO of each component. • Biochar acts as a support for significantly reduced iron ions leaching. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synergy of Co(IV) with piezoelectricity of BaTiO 3 was proposed. • DFT calculations are adopted for in-depth understanding of synergy. • Variation in energy barrier improve PMS activation. • Biochar as a supporting greatly reduced Co ion leaching. • The degradation pathway and toxicity of atrazine and intermediates are described. Co-based catalysts, especially the role of high-valent cobalt oxo species (Co(IV)) have made considerable progress in the field of the advanced oxidation process based on peroxymonosulfate. Nevertheless, the unsatisfactory efficiency drives to find of a suitable method to enhance the electron transfer for the improved performance of Co-based catalyst/PMS systems. Here, Enteromorpha-derived biochar modified with cobalt and barium titanate (CoBCBa) was prepared by pyrolysis. It can completely remove atrazine (10 mg/L) within 30 min under ultrasonic, and exhibited strong environmental tolerance. The superior performance of CoBCBa is attributed to the synergistic effect of Co(IV) and the piezoelectricity of BaTiO 3. The apparent reaction rate under the ultrasonic condition was 1.61 times higher than that non-ultrasonic condition. The density functional theory calculation indicates that the reduction of the energy barrier in the CoBCBa/PMS system is beneficial to the production of Co(IV). This work provides novel guidance for constructing piezoelectricity assisted high-valent cobalt oxo species to treat organic pollutants in environmental remediation. [ABSTRACT FROM AUTHOR]

Herein, in-situ N -doped Enteromorpha prolifera derived magnetic biochar (MBC) was prepared by loading Fe 3 O 4. It can effectively activate peroxodisulfate (PDS) to degrade tetracycline (TC) and easy recycling. The removal rate of TC reached 87.2%, and its possible degradation pathway was revealed through a liquid chromatography-mass spectrometer. This work first proposes the mechanism of in-situ N -doping and Fe synergistic effect on PDS activation. Unlike the well-reported role of N doping in activating PDS, except for the edge pyridine N plays a significant role in the activation of PDS. After the load of Fe, the synergistic effect of Fe and graphite N induces a non-radical path dominated by singlet oxygen (1O 2) due to the excellent electron transfer function. Through chemical quenching experiment, electron spin detection, and electrochemical analysis, the mechanism of PDS activation by MBC was thoroughly investigate. This research will deepen the understanding of the mechanism of transition metals and carbon materials in synergistically driving PDS activation, and guide biochar-mediated PDS activation in environmental remediation. [Display omitted] • The important role of graphite N in the non-radical pathway was firstly proposed. • The synergy of Fe and N -doping enhanced PDS activation was firstly proposed. • The synergy improved electron transfer to induce 1O 2. • Using natural biomass to achieve environment conversation and resource recycling. [ABSTRACT FROM AUTHOR]

• The important role of pore accessibility was studied. • The bigger specific surface area does not always mean higher adsorption capacity. • Simultaneous treatment of Enteromorpha prolifera and butachlor hazards. • The prepared biochar can recycle utilization for butachlor removal. In this work, Enteromorpha prolifera derived magnetic biochar (MBC) is prepared for the removal of butachlor (BTR) and characterized. The NaOH added during the magnetic loading process has an activating effect and enhancing the accessibility of the pores. Based on the BET result, the importance of pore accessibility rather than the specific surface area has been proposed. The maximum adsorption capacity of BTR for MBC is 158.5 mg/g. Then, the batch experiment shows that the adsorption of MBC to BTR fitted with the quasi-second-order kinetic model. The effect factors on the BTR removal were studied. Through the result of BET, Raman, XPS and FT-IR, the mechanism of MBC adsorption of butachlor was explored. After 3 cycles, the prepared MBC has a negligible reduction in the removal capacity of BTR, which provides a reference scheme for the large-scale application of Enteromorpha prolifera and the water treatment of BTR. [ABSTRACT FROM AUTHOR]

• Properties of biochars derived from common agriculture wastes were characterized. • Bamboo, coconut shell and sawdust-coal biochar have better performance. • Specific surface area of biochar played an important role on adsorption capacity. • Adsorption capacity increased with increasing in concentration and temperature. • The adsorption mechanism was discussed in detail. Biochar has acquired increasing attention in waste utilization and the treatment of environmental pollutants. In this study, the physicochemical properties of five types of biochars include straw biochar (SWB), coconut shell biochar (CSB), sawdust-coal biochar (SCB), bamboo biochar (BOB), rice husk biochar (RHB), and their adsorption of epoxiconazole (EPC) is discussed. The effects of initial concentration of EPC, solution temperature and pH level to these biochars were investigated. Besides, this work also analyzed the adsorption kinetics, adsorption isotherm, and thermodynamics of EPC removal in five biochar. Freundlich isotherm shows that the adsorption capacity decreased in the order SCB > BOB > CSB > SWB > RHB. The removal efficiency of EPC by SCB, BOB and CSB are much higher than SWB and RHB, and SCB has the best performance in EPC removal. The adsorption capacity of SCB is 19.0 g/kg, and its removal rate is nearly 97 %. The adsorption capacity of RHB is only 10.8 g/kg, with the removal rate of about 51 %. According to the characterization results of BET, SEM, XRD, and FT-IR, it is speculated that the adsorption capacity of five biochars to EPC is closely related to the total pore volume and specific surface area (SSA). [ABSTRACT FROM AUTHOR]