Enhanced photo-catalytic degradation of natural organic matters (NOMs) with a novel fibrous silica-copper sulfide nanocomposite (KCC1-CuS)

Dendritic mesoporous nanoparticles for the detection, adsorption, and degradation of hazardous substances in the environment: State-of-the-art and future prospects

Equipped with hierarchical pores and three-dimensional (3D) center-radial channels, dendritic mesoporous nanoparticles (DMNs) make their pore volumes extremely large, specific surface areas super-high, internal spaces especially accessible, and so on. Other entities (like organic moieties or nanoparticles) can be modified onto the interfaces or skeletons of DMNs, accomplishing their functionalization for desirable applications. This comprehensive review emphasizes on the design and construction of DMNs-based systems which serve as sensors, adsorbents and catalysts for the detection, adsorption, and degradation of hazardous substances, mainly including the construction procedures of brand-new DMNs-based materials and the involved hazardous substances (like industrial chemicals, chemical dyes, heavy metal ions, medicines, pesticides, and harmful gases). The sensitive, adsorptive, or catalytic performances of various DMNs have been compared; correspondingly, the reaction mechanisms have been revealed strictly. It is honestly anticipated that the profound discussion could offer scientists certain enlightenment to design novel DMNs-based systems towards the detection, adsorption, and degradation of hazardous substances, respectively or comprehensively.

A systematic review of photocatalytic degradation of humic acid in aqueous solution using nanoparticles

OBJECTIVES

Humic acid (HA) compounds in the disinfection processes of drinking water and wastewater are considered as precursors of highly toxic, carcinogenic and mutagenic disinfectant by-products. The aim of this study was to systematically review all research studies on the photocatalytic degradation of humic acid and to evaluate the laboratory conditions and results of these studies.

CONTENT

The present systematic review was performed by searching the Scopus, PubMed, and web of science databases until December 2021. The parameters of type of catalyst, catalyst size, optimum pH, optimum initial concentration of humic Acid, optimum catalyst concentration, optimum time, light used and removal efficiency were investigated.

SUMMARY

395 studies were screened and using the inclusion and exclusion criteria, in total, 20 studies met our inclusion criteria and provided the information necessary to Photocatalytic degradation of humic acid by nanoparticles. In the investigated studies, the percentage of photocatalytic degradation of humic acid by nanoparticles was reported to be above 70%, and in some studies, the removal efficiency had reached 100%.

OUTLOOK

From the results of this systematic review, it was concluded that the photocatalytic process using nanoparticles has a high effect on the degradation of humic acid.

Biosynthesis of MnFe2O4@TiO2 magnetic nanocomposite using oleaster tree bark for efficient photocatalytic degradation of humic acid in aqueous solutions

The presence of humic acid compounds in water resources, as one of the precursors of Trihalomethanes and Holoacetic acids, causes health problems for many communities. The aim of this research study was to investigate the photocatalytic degradation efficiency of humic acid using MnFe₂O₄@TiO₂ nanoparticles which produced by green synthesis method. The synthesis of metal nanoparticles using plant extracts and the study of their catalytic performance is a relatively new topic. Many chemical techniques have been proposed for the synthesis of MnFe₂O₄@TiO₂ nanoparticles, but green synthesis has received much attention due to its availability, simplicity, and non-toxicity. The properties of synthesized nanoparticles were determined by SEM, FT-IR, XRD, EDS, and DLS analysis. The results of the study showed that under optimal experimental conditions (pH = 3, nanocomposite dose = 0.03 g/L, humic acid initial concentration = 2 mg/L, and contact time = 20 min), it is possible to achieve maximum degradation of humic acid. Therefore; MnFe₂O₄@TiO₂ nanoparticles have high efficiency for removing of humic acid from aqueous solutions under UV light.

CuS-Based Nanostructures as Catalysts for Organic Pollutants Photodegradation

The direct or indirect discharge of toxic and non-biodegradable organic pollutants into water represents a huge threat that affects human health and the environment. Therefore, the treatment of wastewater, using sustainable technologies, is absolutely necessary for reusability. Photocatalysis is considered one of the most innovative advanced techniques used for pollutant removal from wastewater, due to its high efficiency, ease of process, low-cost, and the environmentally friendly secondary compounds that occur. The key of photocatalysis technology is the careful selection of catalysts, usually semiconductor materials with high absorption capacity for solar light, and conductivity for photogenerated charge carriers. Among copper sulfides, CuS (covellite), a semiconductor with different morphologies and bandgap values, is recognized as an important photocatalyst used for the removal of organic pollutants (dyes, pesticides, pharmaceutics etc.) from wastewater. This review deals with recent developments in organic pollutant photodegradation, using as catalysts various CuS nanostructures, consisting of CuS NPs, CuS QDs, and heterojunctions (CuS/ carbon-based materials, CuS/organic semiconductor, CuS/metal oxide). The effects of different synthesis parameters (Cu:S molar ratios, surfactant concentration etc.) and properties (particle size, morphology, bandgap energy, and surface properties) on the photocatalytic performance of CuS-based catalysts for the degradation of various organic pollutants are extensively discussed.