Highly effective degradation of ibuprofen by alkaline metal-doped copper oxides via peroxymonosulfate activation: Mechanisms, degradation pathway and toxicity assessments

Impact of ibuprofen on nitrogen removal performance and its biotransformation in a coupled sulfur autotrophic denitrification and anammox system

Ibuprofen (IBU), a commonly used non-steroidal anti-inflammatory drug, is frequently detected in wastewater treatment systems, where it can interfere with nitrogen removal. This study investigated the effects of IBU on nitrogen removal performance and its biotransformation in a coupled sulfur autotrophic denitrification and anammox (SAD/A) system. Moreover, key parameters, such as nitrogen removal efficiency, microbial activity, community structure, and IBU degradation products, were carefully monitored. While IBU concentrations of up to 1 mg/L had negligible impacts on nitrogen removal efficiency due to the counteracting effects of slight inhibition on anammox and enhancement of sulfur autotrophic denitrification, a significant inhibition of ammonia removal occurred when the concentration increased to 10 mg/L. Quantum chemical analyses revealed that IBU underwent biotransformation through decarboxylation and hydroxylation pathways, leading to the formation of two biotransformation products with high ecological toxicity. This study is the first to elucidate the mechanisms by which IBU influences microbial communities and metabolic activities in SAD/A systems. In addition, it highlights the resilience of these systems in maintaining nitrogen removal efficiency under varying IBU concentrations, as well as the environmental risks posed by the biotransformation products of IBU.

Cashew gum-assisted synthesis of Zn0.98Nd0.02O photocatalyst: pH-dependent green approach and photocatalytic degradation of ciprofloxacin and ibuprofen pharmaceutical pollutants

The presence of pharmaceutical residues in aquatic environments represents a serious environmental problem, with negative impacts on ecosystems and public health. The removal of these contaminants from wastewater is a challenge that requires innovative and sustainable strategies. In this study, a green synthesis approach, assisted by cashew gum, was employed to synthesize the Zn0.98Nd0.02O photocatalysts at varying pH levels (5, 7, 9, 11, and 13) via the sol-gel method. The effects of synthesis pH on structural, optical, and photocatalytic properties were systematically investigated. The structural analysis revealed a hexagonal wurtzite structure, with crystallite sizes ranging from 69 nm (pH 5) to 235 nm (pH 9). Micrography images showed that pH significantly influenced morphology, with particles ranging from agglomerates to more dispersed spherical shapes. Porosity analysis indicated mesoporous structures with surface areas varying between 2.2 and 5.2 m2/g, depending on pH. Photoluminescence (PL) spectra highlighted the presence of oxygen-related defects, with emission peaks shifting due to structural disorder induced by doping and pH variation. Optical studies also indicated a tunable bandgap (3.284-3.218 eV) and Urbach energy (50.96-75.30 meV), signifying increased structural disorder at higher pH. Photocatalytic performance was evaluated against Ciprofloxacin (CIP) and Ibuprofen (IBU), achieving degradation efficiencies of 97.5 % (CIP at pH 7) and 74.1 % (IBU at pH 13) under UV light. Kinetic studies confirmed pseudo-first-order behavior with rate constants of 2.14 × 10-2 min-1 for CIP and 8.99 × 10-3 min-1 for IBU. Reactive species analysis identified hydroxyl radicals (•OH) as dominant contributors to pollutant degradation. Reusability tests demonstrated >96 % CIP removal over four cycles and consistent structural stability, validated via XRD. This study highlights the potential of the Zn0.98Nd0.02O photocatalysts synthesized under eco-friendly conditions for addressing pharmaceutical pollutants in wastewater treatment.

Promoting effect of oxygen vacancies in CuZnOx-2/peroxymonosulfate system on the p-arsanilic acid degradation and secondary arsenic species immobilization

Combining chemical oxidation and adsorption is highly desirable but challenging to remove organoarsenic compounds for water purification. Herein, we prepared a Zn-doped CuO (CuZnOx-2) catalyst by incorporating Zn atoms into the CuO lattice, which results in abundant surface oxygen vacancies (OVs) and modulates the electronic structure of Cu-OVs-Zn sites for PMS activation to degrade p-arsanilic acid (p-ASA) and adsorb the secondary arsenic species simultaneously. The elevated d-band centers for Cu upward to the Fermi level can significantly strengthen the adsorption of PMS, p-ASA, and the generated arsenic species. The OVs cause the charge redistribution to form electron-rich centers, which accelerate the electron transfer from Cu-OVs-Zn sites to adsorbed PMS, facilitating the cleavage of peroxide bond to produce SO4•-, •OH. Furthermore, the PMS adsorbed on the local environment of OVs with different configurations can directly decompose to produce 1O2 without undergoing PMS → O2•- → 1O2 or O2 → O2•- → 1O2 processes. The evolution process of the main arsenic species in solution and catalyst surface with oxidation was clarified. The ultimate removal of the total As involves 20 % As(III), 60 % As(V), and 20 % organic arsenic intermediates via forming inner-sphere complexes or electrostatic interaction. This contribution provides a brand-new perspective for the remediation of organoarsenic pollution over designing highly active catalysts.

Sustainable upcycling of copper from waste printed circuit boards with the assistance of tannic acid and Fe3+ to a magnetic heterogeneous catalyst

The recovery and upcycling of metals from electronic waste into functional materials for wastewater treatment is a win-win strategy for simultaneously realizing electronic waste recycling and wastewater purification. This study focused on converting Cu from waste printed boards (PCBs), a common Cu-rich electronic waste, into CuFe2O4 supported on a mesoporous carbon framework (PCFT) with the assistance of Fe3+ and tannic acid (TA). Compared to the PCF prepared without TA, the resulting PCFT exhibited excellent magnetic properties, high crystallinity, lower interfacial transfer resistance, more abundant oxygen vacancies (OV), and lower metal leaching. Moreover, PCFT can serve as a superior heterogeneous catalyst to activate peroxymonosulfate to remove reactive brilliant blue KN-R from wastewater, and its catalytic activity was markedly higher than that of CFT synthesized with Cu(NO3)2·3H2O, which may be due to its higher specific surface area and more abundant OV. The combined results of scavenging experiments, electron paramagnetic resonance analysis, and electrochemical measurements implied that both radical and nonradical processes promoted the elimination of KN-R; however, •OH and SO4•- were not the major contributors. Furthermore, the PCFT exhibited high adaptability to pH and water matrices, confirming its practical application potential. These findings provide a novel strategy for the upcycling of metals from electronic waste.

Fabrication of sulfur doped exfoliated gCN photocatalyst for enhanced visible light degradation of pernicious organic pollutants and their photocatalytic antibacterial activity

The synthesis of sulfur-doped exfoliated graphitic carbon nitride (S-gCN) photocatalyst was achieved by the implementation of a two-step calcination technique. The XRD results revealed that all the fabricated photocatalytic materials were crystalline in nature. The inclusion of 5% sulfur in gCN led to a conspicuous escalation in the surface area of photocatalyst, rising from 10.294 to 61.185 m2g⁻1. Morphological scrutiny of the samples using FE-SEM revealed that pristine gCN exhibited tightly stacked small nanosheets, whereas inclusion of sulfur and exfoliation resulted in generation of loosely distributed large nanosheet. Furthermore, the inclusion of sulfur also induced a shift in the energy band gap (Eg) from 2.81 eV to 2.63 eV, making it felicitous for investigation as proficient visible light photocatalyst. Additionally, the photoluminescence photo-induced charge carrier recombination behavior revealed a reduced peak intensity for 5% S-gCN compared to other synthesized compositions. This observation can be directly linked to the minimized electron-hole pairs recombination during photocatalysis, underscoring its superior photocatalytic performance. Our findings revealed that the 5% S-gCN photocatalyst exhibit the most promising attributes, it degraded Tetracycline drug, Chlorpyrifos pesticide and Eriochrome Black T dye under visible light irradiation almost ∼4 times more efficiently than pristine gCN. Additionally, exceptional visible light photocatalytic antibacterial efficacy was also perceived by 5% S-gCN against S. aureus bacteria. Overall, the present research sheds light on how doping and exfoliation interact to modify the structure and catalytic properties of gCN, paving the way for the development of outstanding performance, visible light-responsive efficient photocatalysts for environmental restoration.

Tannic acid-assisted upcycling of Cu from waste printed circuit boards to an efficient peroxymonosulfate catalyst for the degradation of organic pollutants

The recovery of metals from solid waste for use as heterogeneous catalysts to activate peroxymonosulfate (PMS) for organic wastewater treatment is a promising, environmentally friendly and economical strategy. Herein, we present a facile and versatile strategy for upcycling copper (Cu) from waste printed circuit boards (PCBs) to Cu oxides supported on a three-dimensional carbon framework (10PCBs-Cu-TA) with the aid of tannic acid (TA). Compared to the PCBs-Cu synthesized without TA, introducing TA into 10PCBs-Cu-TA reduced Cu leaching, enhanced crystallinity, promoted electron transfer, and increased the number of oxygen vacancies. Moreover, 10PCBs-Cu-TA exhibited superior catalytic activity in activating PMS for the degradation of reactive brilliant blue KN-R, exceeding the activity of 10Cu-TA prepared using commercial Cu(NO3)2·3H2O. This enhanced performance may be attributed to the higher specific surface area and oxygen vacancies of 10PCBs-Cu-TA. The 10PCBs-Cu-TA/PMS system also exhibited broad catalytic universality and adaptability to various contaminants and water matrices. Quenching experiments, electron paramagnetic resonance analysis, and electrochemical measurements indicated that radical and non-radical processes jointly contributed to KN-R degradation. The proposed strategy for upcycling Cu from waste PCBs into functional materials provides novel insights into the utilization of solid waste and the development of PMS activators.