Degradation of atrazine in aqueous solution through peroxymonosulfate activated by Co-modified nano-titanium dioxide

Electrochemically enhanced activation of Co3O4/TiO2 nanotube array anode for persulfate toward high catalytic activity, low energy consumption, and long lifespan performance

Advanced oxidation processes (AOPs) can directly degrade and mineralize organic pollutants (OPs) in water by generating reactive oxygen species with strong oxidizing ability. The development of advanced electrode materials with high catalytic performance, low energy consumption, no secondary pollution, and long lifespan has become a challenge that must be addressed in this field. A heterojunction catalyst loaded with Co3O4 on TDNAs (Co3O4/RTDNAs) was designed and constructed by a simple and efficient pyrolysis (Co3O4/TDNAs) and electrochemical reduction. Co3O4 can be uniformly distributed on the inner wall and surface of the TiO2 nanotubes, enhancing the specific surface area while forming a tight conductive interface with TiO2. This facilitates rapid transmission of electrons, thereby assisting Co3O4 in quickly activating PS to form reactive oxygen species. The Ti3+ and Ov generated in Co3O4/RTDNAs can significantly improve the electrocatalytic degradation of OPs. Also, the interface formed by Co3O4 and RTDNAs will effectively suppress Co2+ leakage, thereby reducing the risk of secondary pollution. When the reaction conditions were 1 mM PMS (PDS) and a current density of 5 mA/cm2 in the EA-PMS (PDS)/Co3O4/RTDNA system, 30 mg/L TC can achieve 83.24 % (81.89 %) removal in 120 min, with very low cobalt ion leaching, while the energy consumption was reduced significantly. Therefore, EA-PS/Co3O4/RTDNA system has strong stability and a high potential for treating the OPs in AOPs.

Investigation of the Persistence, Toxicological Effects, and Ecological Issues of S-Triazine Herbicides and Their Biodegradation Using Emerging Technologies: A Review

S-triazines are a group of herbicides that are extensively applied to control broadleaf weeds and grasses in agricultural production. They are mainly taken up through plant roots and are transformed by xylem tissues throughout the plant system. They are highly persistent and have a long half-life in the environment. Due to imprudent use, their toxic residues have enormously increased in the last few years and are frequently detected in food commodities, which causes chronic diseases in humans and mammals. However, for the safety of the environment and the diversity of living organisms, the removal of s-triazine herbicides has received widespread attention. In this review, the degradation of s-triazine herbicides and their intermediates by indigenous microbial species, genes, enzymes, plants, and nanoparticles are systematically investigated. The hydrolytic degradation of substituents on the s-triazine ring is catalyzed by enzymes from the amidohydrolase superfamily and yields cyanuric acid as an intermediate. Cyanuric acid is further metabolized into ammonia and carbon dioxide. Microbial-free cells efficiently degrade s-triazine herbicides in laboratory as well as field trials. Additionally, the combinatorial approach of nanomaterials with indigenous microbes has vast potential and considered sustainable for removing toxic residues in the agroecosystem. Due to their smaller size and unique properties, they are equally distributed in sediments, soil, water bodies, and even small crevices. Finally, this paper highlights the implementation of bioinformatics and molecular tools, which provide a myriad of new methods to monitor the biodegradation of s-triazine herbicides and help to identify the diverse number of microbial communities that actively participate in the biodegradation process.

Efficient degradation of atrazine from synthetic water through photocatalytic activity supported by titanium dioxide nanoparticles

The oxidation of atrazine herbicide from water was performed by using titanium dioxide (TiO2) nanoparticles synthesized via the sol-gel method. A batch-scale photocatalytic reactor was designed for experimental work. The process was monitored using a UV–visible spectrophotometer. Operational parameters such as catalyst loading and pollutant concentration were investigated. The X-ray diffraction confirmed the anatase phase and high purity of the synthesized particles. Fourier transform infrared showed the functional group of titanium (Ti–O–Ti). The morphology of synthesized nanoparticles was characterized by scanning electron microscopy and transmission electron microscopy, which exhibited the irregular shape of nanoparticles along with aggregations. The average size of TiO2 was found to be 56.92 nm as measured from dynamic light scattering analysis. UV–visible spectrometry showed an absorbance of 0.13 (<1). The nanoparticles displayed UV light-responsive catalytic ability with a bandgap energy of 3.14 eV. Furthermore, atrazine was discovered using mass spectrometry, which revealed a clear and sharp peak at 173, 95, and 76 m/z, respectively, at collision energies of 16 and 24 eV. The photocatalytic activity of the TiO2 nanoparticles was examined for the degradation of atrazine. Overall, the obtained results displayed the great efficiency of TiO2 nanoparticles towards ultra-violet light, which was 92.56% at 100 mg of dosages, highlighting the great potential of the photocatalysis process for atrazine degradation. Furthermore, the process followed pseudo-first-order kinetics and the rate was seen to depend on catalyst loading.