Recent advances in visible light driven inactivation of bloom forming blue-green algae using novel nano-composites: Mechanism, efficiency and fabrication approaches.

Over the years, algae have proved to be a water pollutant due to global warming, climate change, and the unregulated addition of organic compounds in water bodies from diffused resources. Harmful algal blooms (HABs) are severely affecting the health of humans and aquatic ecosystems. Among available anti-blooming technologies, semiconductor photocatalysis has come forth as an effective alternative. In the recent past, literature has been modified extensively with a decisive knowledge regarding algal invasion, desired preparation of nanomaterials with enhanced visible light absorption capacity and mechanisms for algal cell denaturation. The motivation behind this review article was to gather algal inactivation data in a systematic way based on various research studies, including the construction of nanoparticles and purposely to test their anti-algal activities under visible irradiation. Additionally, this article mentions variety of starting materials employed for preparation of various nano-powders with focus on their synthesis routes, analytical techniques as well as proposed mechanisms for lost cellular integrity in context of reduced chlorophyll' a' level, cell rapture, cell leakage and damages to other physiological constituents; credited to oxidative damage initiated by reactive oxidation species (ROS). Various floating and recyclable composited catalysts Ag2CO3-N: GO, Ag/AgCl@ZIF-8, Ag2CrO4-g-C3N4-TiO2/mEP proved to be game-changers owing to their enhanced VL absorption, adsorption, stability, separation and reusability. An outlook for the generalized limitations of published reports, cost estimations for practical implementation, issues and challenges faced by nano-photocatalysts and possible opportunities for future studies are also proposed. This review will be able to provide vast insights for coherent fabrication of catalysts, breakthroughs in experimental methodologies and help in elaboration of damage mechanisms.

Application of conventional and emerging low-cost adsorbents as sustainable materials for removal of contaminants from water.

The impact of water pollution has led to the search for cost-effective and environmentally friendly treatment processes to alleviate the associated environmental hazards. Adsorption is identified as an advanced treatment technology that offers simplicity and cheap alternatives to water treatment technologies when low-cost adsorbents such as industrial by-products, waste, and agricultural waste are utilized. The utilization of these materials as low-cost adsorbents for the treatment of drinking water will bring them some value. Several practices have been done to improve the removal efficiencies of the low-cost adsorbents in order to achieve WHO standards of drinking water quality. The paper highlights some of the synthesis routes employed for the modification of low-cost adsorbents. This updated review provides information on the different applications of low-cost adsorbents in removing pollutants and their adsorption capacities in an attempt to deploy the recent sustainable low-cost adsorbents with high removal efficiencies for water treatment. Future research should focus on the fabrication of hybrid low-cost adsorbents with multifunctional and antimicrobial properties. In addition, life cycle assessment (LCA) should be conducted to reveal the environmental burdens associated with the modification of the low-cost adsorbent to improve their removal efficiencies.

Updated review on microplastics in water, their occurrence, detection, measurement, environmental pollution, and the need for regulatory standards.

The gravity of the impending threats posed by microplastics (MPs) pollution in the environment cannot be over-emphasized. Several research studies continue to stress how important it is to curb the proliferation of these small plastic particles with different physical and chemical properties, especially in aquatic environments. While several works on how to monitor, detect and remove MPs from the aquatic environment have been published, there is still a lack of explicit regulatory framework for mitigation of MPs globally. A critical review that summarizes recent advances in MPs research and emphasizes the need for regulatory frameworks devoted to MPs is presented in this paper. These frameworks suggested in this paper may be useful for reducing the proliferation of MPs in the environment. Based on all reviewed studies related to MPs research, we discussed the occurrence of MPs by identifying the major types and sources of MPs in water bodies; examined the recent ways of detecting, monitoring, and measuring MPs routinely to minimize projected risks; and proposed recommendations for consensus regulatory actions that will be effective for MPs mitigation.

Adsorption and photocatalytic scavenging of 2-chlorophenol using carbon nitride-titania nanotubes based nanocomposite: Experimental data, kinetics and mechanism.

Adsorption and interaction of pollutant species on surface of the catalyst materials play an important role on the photocatalysis process. Herein, experimental data on the adsorption behavior of 2-chlorophenol (2-CP) onto graphitic pure carbon nitride (C3N4), titania nanotubes (TiO2-NTs) and carbon nitride/titania nanotubes nanocomposite (C3N4/TiO2-NTs) from synthetic wastewater has been summarized. The data on photocatalytic degradation of the 2-CP under both ultraviolet (UV) and visible light irradiation is also presented. This work also evaluates the 2-CP scavenging efficiency of C3N4/TiO2-NTs nanocomposite prepared by calcination of 2 wt.% melamine with TiO2-NTs at 450 °C. The adsorption and photocatalysis experiments were conducted for 180 min at pH 7 with 100 mL solution of 2-CP (40 mg/L) and 0.05 g catalyst material. The acquired data can be valuable to identify the equilibrium time for 2-CP adsorption onto C3N4, TiO2-NTs, and C3N4/TiO2-NTs nanocomposite. Moreover, the obtained data can be useful to identify the suitable light source for the decomposition of 2-CP in the aquatic environment. The evaluated kinetic data might be significant for identifying the adsorption and photocatalysis reaction rate onto the applied catalyst materials. The obtained adsorption and photocatalysis data have been compared with that in literature to identify the adsorption and photocatalysis behavior of 2-CP on numerous catalysts at different experimental conditions.

Adsorptive removal of antibiotics from water over natural and modified adsorbents.

Various adsorbents including agricultural waste-based adsorbents, nanomaterials and layered double hydroxides have been reviewed for removal of antibiotics from water due to their unique properties. The adsorption mechanism is governed mostly by the affinity of a pollutant to adsorbent materials. However, the main adsorption mechanisms defined in this study for removal of antibiotics are the electrostatic attraction, π-π interaction and hydrogen bonding. The study highlighted the contribution of modification in the adsorption capacity of antibiotics. Some of the most important adsorbents discussed in this review are graphene-based adsorbents, binary layered double hydroxides and magnetic nanoparticles as well as the antibiotics sulfamethoxazole, tetracycline and metronidazole. The key factors for the selection of the suitable materials are the structure, characteristics and other physicochemical parameters such as pH and temperature. However, the most crucial factor is the adsorption capacity. Some of the adsorption kinetics models and isotherms for antibiotic sorption are also highlighted in this study. In addition, the review summarizes the future prospects and recent challenges faced with the adsorption techniques for removal of antibiotics from wastewater. This review will help readers understand the current trend in the adsorptive removal of antibiotics from water.

Fabrication of Novel Al(OH)3/CuMnAl-Layered Double Hydroxide for Detoxification of Organic Contaminants from Aqueous Solution.

A novel lamellar Al(OH)3/CuMnAl-layered double hydroxide (LDH) nanocomposite was successfully synthesized via the hydrothermal method and tested as a highly efficient adsorbent for the removal of Congo red (CR) dye from aqueous solution. Structural, morphological, and spectroscopic characterization of the Al(OH)3/CuMnAl-LDH nanocomposite were studied by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, photoluminescence (PL) analysis, and UV-visible spectroscopy analysis techniques. The CR dye adsorption performance of the prepared materials increased with an increase in functionality. The adsorption capacity of the Al(OH)3/CuMnAl-LDH nanocomposite (172 mg/g, pH 7, temp 30 °C) was found to be higher than that of pure Al(OH)3 (32 mg/g, pH 7, temp 30 °C) and CuMnAl-LDH (102 mg/g, pH 7, temp 30 °C). The results revealed that anion exchange and hydrogen bonding are mainly responsible for the adsorption of CR onto the Al(OH)3/CuMnAl-LDH nanocomposite. Moreover, the adsorption of CR in the presence of Cu(II) and NaCl salt showed a synergistic and antagonistic effect while the presence of anionic Cr(VI) ions had no significant effect. The adsorption thermodynamics, isotherm, and kinetics modeling analyses were also conducted to study the interactions between CR molecules and the Al(OH)3/CuMnAl-LDH nanocomposite. The adsorption of CR was found to be endothermic and followed by the pseudo-second-order kinetics and the Langmuir adsorption isotherm model. The developed nanocomposite showed excellent potential for treating industrial wastewater.