Efficient removal of plastic additives by sunlight active titanium dioxide decorated Cd-Mg ferrite nanocomposite: Green synthesis, kinetics and photoactivity

Synthesis and characterization of novel guar gum based waste material derived nanocomposite for effective removal of hexabromocyclododecane and lindane

Herein, efficient degradation of hexabromocyclododecane (HBCD) and Lindane, a persistent organic pollutant using guar gum based calcium oxide doped silicon dioxide (GG-CaO@SiO2) has been reported. The nanocomposite was prepared by waste egg shell (CaO) and rice husk (SiO2) was well characterized. The maximum degradation of HBCD and Lindane were observed at 8 mg catalyst loading, neutral pH, and 2 mg L-1 of pollutant amount. The photocatalytic performance of GG-CaO@SiO2 for HBCD and Lindane photodegradation was evaluated, and it was found that the rate constant increased in the order of GG-CaO@SiO2 > CaO@SiO2 > GG. The polymeric GG-CaO@SiO2 nanocomposite showed maximum removal of both pollutants due to higher surface area (70 m2 g-1) and synergistic interactions among GG moieties. It achieved HBCD and Lindane elimination rates of 94 % and 90 % by photo-adsorptive degradation within 150 min. Meanwhile, the leaching of HBCD from expanded polystyrene (EPS) materials (0.14 ± 0.05 ppm) underwater with different time intervals and degradation of leachate HBCD were also assessed. The eradication of the pollutant manifested first-order kinetics, with the Langmuir adsorption. LC-MS analysis confirmed that GG-CaO@SiO2 effectively breaks down complex structure toxic pollutants into safer metabolites under natural sunlight exposure. The polymeric GG-CaO@SiO2 nanocomposite showed notable reusability up to ten cycle promotes sustainability.

Green construction of biochar@NiFe2O4 nanocomposite for highly efficient photocatalytic remediation of pesticides from agriculture wastewater

The world's attention is drawn to the widespread ingestion, toxicity, and bioaccumulation of the Atrazine (AT) and Endosulfan (ES). Pesticides have been proven to have endocrine-disrupting, genotoxic, and persistent characteristics. In this work, the structural design of green synthesized NiFe2O4 is incorporated in rice husk biochar to form BC@NiFe2O4 nanocomposite. Powder X-ray diffraction and microscopic analysis confirmed the semi-crystalline nature of BC@NiFe2O4 reduced due to the incorporation of amorphous BC. The green BC@NiFe2O4 nanocomposite degraded AT and ES up to 98 % and 92 %, respectively. The maximum degradation achieved by BC@NiFe2O4 nanocomposite with minimum pollutants concentration (50 mg L-1) with 10 mg catalyst dose at acidic pH in natural sunlight because of the higher negative value of zeta potential (-26.4 mV) and lower band gap (2.5 eV). The degradation process involves first-order kinetics followed by initial Langmuir adsorption. The presence of various radical quenchers (t-BuOH, p-BZQ, Na2EDTA) has led to the conclusion that hydroxyl radicals play a significant role in the degradation of the toxic substances AT and ES. Additionally, a green-fabricated BC@NiFe2O4 nanocomposite has exhibited exceptional efficiency in degrading AT and ES pollutants in actual wastewater samples. Furthermore, this nanocomposite has demonstrated outstanding sustainability and cost-effectiveness, maintaining its effectiveness for up to eight cycles without a noticeable reduction in activity. In summary, due to its favorable surface characteristics, the environmentally friendly BC@NiFe2O4 nanocomposite holds excellent promise as a unique and potential photocatalyst for various industrial applications.

Formulation Controls the Potential Neuromuscular Toxicity of Polyethylene Photoproducts in Developing Zebrafish

Sunlight transforms plastic into water-soluble products, the potential toxicity of which remains unresolved, particularly for vertebrate animals. We evaluated acute toxicity and gene expression in developing zebrafish larvae after 5 days of exposure to photoproduced (P) and dark (D) leachates from additive-free polyethylene (PE) film and consumer-grade, additive-containing, conventional, and recycled PE bags. Using a "worst-case" scenario, with plastic concentrations exceeding those found in natural waters, we observed no acute toxicity. However, at the molecular level, RNA sequencing revealed differences in the number of differentially expressed genes (DEGs) for each leachate treatment: thousands of genes (5442 P, 577 D) for the additive-free film, tens of genes for the additive-containing conventional bag (14 P, 7 D), and none for the additive-containing recycled bag. Gene ontology enrichment analyses suggested that the additive-free PE leachates disrupted neuromuscular processes via biophysical signaling; this was most pronounced for the photoproduced leachates. We suggest that the fewer DEGs elicited by the leachates from conventional PE bags (and none from recycled bags) could be due to differences in photoproduced leachate composition caused by titanium dioxide-catalyzed reactions not present in the additive-free PE. This work demonstrates that the potential toxicity of plastic photoproducts can be product formulation-specific.

Effect of green synthesized nano-titanium synthesized from Trachyspermum ammi extract on seed germination of Vigna radiate

The current work investigates the conditional influence on Vigna radiate seed germination in vitro and in vivo using the green chemistry approach for the manufacture of titanium dioxide nanoparticles (TiO₂ NPs) from seed extract of Trachyspermum ammi (T. ammi). Ultraviolet spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to analyze the TiO₂ NPs produced. The crystalline nature of TiO₂ NP was revealed by XRD data, and TEM investigation revealed an irregularity in TiO₂ NP shape with a size of 17.5 nm. UV absorbance at 315 nm for the TiO₂ NPs was observed using Ultraviolet-visible spectrophotometer. The antioxidant potential of the synthesized nanoparticle was discovered to be good. In case of seed germination studies, six concentrations (25, 50 100, 150, 200, and 250 μg mL^{- 1}) of TiO₂ NPs were examined along with the control on Vigna radiata seeds. Germination parameters such as seed vigor index (SVI), germination percentage (GP), germination value (GV) root length (RL) and shoot length (SL) of the Vigna radiata seedlings were observed and results revealed that the green synthesized TiO₂ NPs were significantly improved. The results indicated that the TiO₂ NP affected the plant growth more specifically at lower concentration (50 μg mL^-1) of TiO₂ NPs. Overall, the findings of this present study stipulated that the green TiO₂ NP production can enhance the growth of Vigna radiate under in vitro and in vivo conditions.

Comment on "Efficient removal of plastic additives by sunlight active titanium dioxide decorated Cd-Mg ferrite nanocomposite: Green synthesis, kinetics and photoactivity"

In this comment paper, some critical shortcomings and errors in the original paper [Chemosphere, 290, 133,307] are discussed. The authors have not adhered to the 12 Principles of Green Chemistry by incorporating the highly toxic metal Cd in their ferrite nanocomposite photocatalyst, despite its synthesis being described as green. Neither the necessity nor the effectiveness of Cd addition in relation to catalytic activity were explained. Although adsorption of the substrates on the catalyst is necessary for the photocatalytic process, excessive adsorption may give a false impression of efficient removal as opposed to true degradation or mineralization. This issue is extremely important for experimental design when the solubility of the substances is very low. The authors have disregarded the solvent effect of organic scavengers for the reactive species, potentially attributing a greater contribution of the degradation of substances to hydroxyl radicals. Some suggestions are also provided to improve their work in the field of photocatalysis.