Antibiotic sulfamethoxazole (SMX) has been commonly found in various water matrices, therefore effective decontamination method is urgently needed. Metal-free pristine coconut-shell-derived biochar (CSBC), synthesized by thermochemical conversion at 700 °C, was used for activating peroxymonosulfate (PMS), an oxidant, to degrade SMX, a sulfonamide antibiotic, in water. SMX degradation, maximized at 0.05 mM concentration, was 85% in 30 min at pH 5.0 in the presence of 150 mg L-1 of CSBC. Remarkably, SMX removal reached 99% in a chloride-rich CSBC/PMS system. SMX degradation was mainly attributed to the role of CSBC in enhancing PMS activation to produce combined radical (SO4•-/HO•) and nonradical (1O2) reaction pathways. The most abundant genus in the CSBC/PMS system was Methylotenera, which belonged to the Proteobacteria phylum. Thus, from a perspective of biowaste-to-resource recycling and circular bioeconomy view point, CSBC is a potential catalytic activator of PMS for the removal of sulfonamide antibiotics from aqueous environments.
In this study, biochar derived from chestnut shells was synthesized through pyrolysis at varying temperatures from 300 °C to 900 °C. The study unveiled that the pyrolysis temperature is pivotal in defining the physical and chemical attributes of biochar, notably its adsorption capabilities and its role in activating peracetic acid (PAA) for the efficient removal of acetaminophen (APAP) from aquatic environments. Notably, the biochar processed at 900 °C, referred to as CN900, demonstrated an exceptional adsorption efficiency of 55.8 mg g-1, significantly outperforming its counterparts produced at lower temperatures (CN300, CN500, and CN700). This enhanced performance of CN900 is attributed to its increased surface area, improved micro-porosity, and a greater abundance of oxygen-containing functional groups, which are a consequence of the elevated pyrolysis temperature. These oxygen-rich functional groups, such as carbonyls, play a crucial role in facilitating the decomposition of the O-O bond in PAA, leading to the generation of reactive oxygen species (ROS) through electron transfer mechanisms. This investigation contributes to the development of sustainable and cost-effective materials for water purification, underscoring the potential of chestnut shell-derived biochar as an efficient adsorbent and catalyst for PAA activation, thereby offering a viable solution for environmental cleanup efforts.
Polycyclic aromatic hydrocarbons (PAHs) are critical environmental concerns due to their intrinsic toxic aromatic nature and concomitant circumstances that potentially harm the ecological and human health. In this study, converting mahogany (Swietenia macrophylla King) pericarps to value-added biochar by pyrolysis for evaluating the potential formation/destruction of biochar-bound PAHs was studied for the first time. This study designed and optimized the thermal processing conditions at 300-900 °C in the CO2 or N2 atmosphere, and heteroatoms (N, O, B, NB, and NS) were modified for mahogany pericarps biochar (MPBC) production. The MPBC500 exhibited significantly higher pyrolysis products of PAHs (2780 ± 38 ng g-1) than that of MPBC900 (78 ± 6 ng g-1) under N2 without introducing modified elements. Specifically, the inhibition capacity of MPBC500 for PAHs under CO2 was improved most efficiently by the active nitrogen species of the pyridinic N and pyrrolic N groups. The pyrolysis conditions and heteroatom modification of MPBC altered its physicochemical properties, that is, aromaticity and hydrophobicity, affecting the PAH concentration and composition in the pyrolysis products. This study reveals sustainable approaches to reduce the environmental footprint of biochar by focusing on increases in PAHs pollution in sustainable biochar produced from a low-carbon bioeconomy perspective.
In this study, biochar produced from sunflower seeds husk was activated through ZnCl2 to support the NiCo2O4 nanoparticles (NiCo2O4@ZSF) in catalytic activation of peroxymonosulfate (PMS) toward tetracycline (TC) removal from aqueous solution. The good dispersion of NiCo2O4 NPs on the ZSF surface provided sufficient active sites and abundant functional groups for the adsorption and catalytic reaction. The NiCo2O4@ZSF activating PMS showed high removal efficiency up to 99% after 30 min under optimal condition ([NiCo2O4@ZSF] = 25 mg L-1, [PMS] = 0.04 mM, [TC] = 0.02 mM and pH = 7). The catalyst also exhibited good adsorption performance with a maximum adsorption capacity of 322.58 mg g-1. Sulfate radicals (SO4•-), superoxide radical (O2•-), and singlet oxygen (1O2) played a decisive role in the NiCo2O4@ZSF/PMS system. In conclusion, our research elucidated the production of highly efficient carbon-based catalysts for environmental remediation, and also emphasized the potential application of NiCo2O4 doped biochar.
The objective of this study is to comprehensively characterize persistent organic pollutants (POPs) in seawater at Kaohsiung Harbor, focusing on their concentrations, partitioning behaviors, and profiles in both particle and liquid phases. We analyzed 100 L seawater for each sample, finding total dioxin-like toxicity (PCDD/Fs + PCBs + PBDD/Fs) ranging from 0.00936 to 0.167 pg WHO-TEQ/L, with PCDD/Fs accounting for 68 % of total toxicity. POPs predominantly appeared in the particle phase, observed in over 80 % of samples, except for PCBs. The observed correlations between particulate matter (PM) and chlorinated POPs at sites receiving river effluents suggest shared pollution sources. The liquid partition of PCDD/Fs, PCBs, and PBDEs in the seawater shows an inverse relationship with log Kow and a direct proportionality with solubility, particularly above 0.1 μg/L. Furthermore, PBDEs in seawater can transform into PBDD/Fs upon UV light exposure, highlighting another potential pathway for the persistence and spread of these harmful contaminants in the environment. These findings emphasize the need for field-based investigations to assess PBDF formation in aquatic environments and underscore the importance of stronger mitigation strategies, including better wastewater treatment and stricter discharge regulations to reduce POPs in marine ecosystems.
In this study, process optimization for the microalgae-based piggery wastewater treatment was carried out by growing Chlorella sorokiniana AK-1 on untreated piggery wastewater with efficient COD/BOD/TN/TP removal and high biomass/protein productivities. Integration of the immobilization carriers (sponge, activated carbon) and semi-batch cultivation resulted in the effective treatment of raw untreated piggery wastewater. With 100% wastewater, 0.2% sponge and 2% activated carbon, the semi-batch cultivation (90% media replacement every 6 days) exhibited a COD, BOD, TN and TP removal efficiency of 95.7%, 99.0%, 94.1% and 96.9%, respectively. The maximal protein content, protein productivity, lutein content, and lutein productivity of the obtained microalgal biomass was 61.1%, 0.48 g/L/d, 4.56 mg/g, and 3.56 mg/L/d, respectively. The characteristics of the treated effluent satisfied Taiwan Piggery Wastewater Discharge Standards (COD