One pot green synthesis of Al doped zinc ferrite nanoparticle decorated with reduced graphene oxide for photocatalytic remediation of organic pollutants: 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.