Engineered nanoparticles for removal of pollutants from wastewater: Current status and future prospects of nanotechnology for remediation strategies

Significant aspects of the world\u27s water scenario, primarily associated with global population growth and climate change, necessitate new technology implementation to ensure a supply of drinking water and prevent global water contamination. In light of this, the incorporation of state-of-the-art nanotechnology in conventional process engineering opens new paths for improved wastewater treatment technologies. Nano-based materials techniques, such as disinfection, desalination, sensing and monitoring, photocatalysis, membrane process, adsorption, biological treatment, coagulation/precipitation, and oxidation are discussed in this overview of current breakthroughs in nanotechnologies for removal of pollutants from wastewater. The benefits of these nano-based materials for wastewater treatment approaches, as well as the technical challenges are discussed in this review. The current state of commercialization, as well as future research opportunities in nano-based materials and technologies are highlighted. Additionally, the anticipated scientific breakthroughs, the constraints of nanotechnology for desalination processes, such as rules and regulations, and potential health risks are addressed. The regulation of nanoengineered materials and technologies used in wastewater treatment is being addressed in both Europe and United States of America

High interfacial charge separation in visible-light active Z- scheme g-C3N4/MoS2 heterojunction: Mechanism and degradation of sulfasalazine

Examination of highly proficient photoactive materials for the degradation of antibiotics from the aqueous solution is the need of the hour. In the present study, a 2D/2D binary junction GCM, formed between graphitic-carbon nitride (g-C3N4) and molybdenum disulphide (MoS2), was fabricated using facile hydrothermal method and its photo-efficacy was tested for the degradation of sulfasalazine (SUL) from aqueous solution under visible-light irradiation. Morphological analysis indicated the nanosheets arrangement of MoS2 and g-C3N4. The visible-light driven experiments indicated that 97% antibiotic was degraded by GCM-30% within 90 min which was found to be quite high than pristine g-C3N4 and MoS2 at solution pH of 6, GCM-30% dose of 20 mg, and SUL concentration of 20 mgL-1. The degradation performance of GCM-30% was selectively improved due to enhanced visible-light absorption, high charge carrier separation, and high redox ability of the photogenerated charges which was induced by the effective Z-scheme 2D/2D heterojunction formed between g-C3N4 and MoS2. The reactive radicals as determined by the scavenging study were •O2-, and h+. A detailed degradation mechanism of SUL by GCM-30% was also predicted based on the detailed examination of the band gaps of g-C3N4 and MoS2

Emerging contaminants of high concern for the environment: Current trends and future research

Wastewater is contaminated water that must be treated before it may be transferred into other rivers and lakes in order to prevent further groundwater pollution. Over the last decade, research has been conducted on a wide variety of contaminants, but the emerging contaminants are those caused primarily by micropollutants, endocrine disruptors (EDs), pesticides, pharmaceuticals, hormones, and toxins, as well as industrially-related synthetic dyes and dye-containing hazardous pollutants. Most emerging pollutants did not have established guidelines, but even at low concentrations they could have harmful effects on humans and aquatic organisms. In order to combat the above ecological threats, huge efforts have been done with a view to boosting the effectiveness of remediation procedures or developing new techniques for the detection, quantification and efficiency of the samples. The increase of interest in biotechnology and environmental engineering gives an opportunity for the development of more innovative ways to water treatment remediation. The purpose of this article is to provide an overview of emerging sources of contaminants, detection technologies, and treatment strategies. The goal of this review is to evaluate adsorption as a method for treating emerging pollutants, as well as sophisticated and cost-effective approaches for treating emerging contaminants

Constructing Z-scheme LaTiO\u3csub\u3e2\u3c/sub\u3eN/g-C\u3csub\u3e3\u3c/sub\u3eN\u3csub\u3e4\u3c/sub\u3e@Fe\u3csub\u3e3\u3c/sub\u3eO\u3csub\u3e4\u3c/sub\u3e magnetic nano heterojunctions with promoted charge separation for visible and solar removal of indomethacin

© 2020 Elsevier Ltd Pharmaceutical effluents in water bodies pose hazards to the ecosystem because of their potent biological toxicity. Focusing on the removal of such toxic complicated pharmaceutical residues, an innovative LaTiO2N/g-C3N4@Fe3O4 heterojunction photocatalyst was assembled by a simplistic route for visible and solar light degradation of anti-inflammatory drug indomethacin (IDM). The LCF-20 catalyst (with LaTiO2N:g-C3N4 -0.2:1) shows excellent performance for visible light photodegradation of IDM, as evidenced by 97.3 % removal in just 45 min exposure which is about 13 times faster than bare g-C3N4. 83.4 % of total organic carbon removal was achieved by LVF-20 under visible light. Also, with natural sunlight, nearly 80 % of IDM was removed in 90 min irradiation. The heterojunction\u27s extensive intimate interfacial interactions amid LaTiO2N and g-C3N4 reduce the shortcomings of the two for a better photo-activity. The high visible activity, diminished recombination, high charge transfer is attributed to effective Z-scheme transfer facilitated by Fe3O4 nanoparticles. Scavenging experiments prove the importance of superoxide radicals as the dominant species responsible for photodegradation reaction. By mass spectrometry and total organic carbon analysis, a reaction mechanism was also reasonably proposed. The photocatalytic mechanism was discussed in light of conventional and Z-scheme transfer for better insight. The catalyst is stable, recyclable and magnetically separable. This investigation offers a new perspective in the rational design and manufacture of organic-inorganic nitrides based magnetically recoverable heterojunctions as LaTiO2N/g-C3N4@Fe3O4. Such heterojunctions present a new class of robust hierarchical photocatalytic materials which are capable of remediation of pharmaceutical residues under practical conditions

Designing of bentonite based nanocomposite hydrogel for the adsorptive removal and controlled release of ampicillin

© 2020 In pharmacy, semisynthetic antibiotics with beta-lactam ring are the most prominently used drugs. The use of these drugs for humans and animals is continuously expanding. Their presence in the water system even at low concentrations can prove to be fatal to living beings. Also, they can even grow antibiotic-resistant bacteria and thus elimination of such drugs becomes very essential. Our study is focused on batch experiments for adsorptive removal of ampicillin (AMP) and its cumulative release in different solutions using xanthan gum-cl-poly(itaconic acid)/bentonite (XG-cl-poly(IA)/BN) nanocomposite hydrogel. It was synthesized by facile microwave method. The adsorption data of AMP was analyzed using various isotherm models such as Langmuir, Freundlich, Temkin and kinetic models such as Pseudo-first order, Pseudo-second order and Intraparticle diffusion. The maximum adsorption capacity as determined from Langmuir model was 245.09 mg/g at 318 K and solution pH 7. Also, XG-cl-poly(IA)/BN nanocomposite hydrogel was evaluated for AMP release in distilled water and at different pH solutions (2.2, 5.4, 7.4 and 9.4). The maximum AMP release was observed at pH 2.2 (37%)

Construction of dual Z-scheme g-C3N4/Bi4Ti3O12/Bi4O5I2 heterojunction for visible and solar powered coupled photocatalytic antibiotic degradation and hydrogen production: Boosting via I−/I3− and Bi3+/Bi5+ redox mediators

© 2020 Elsevier B.V. Inspired by waste to energy production, we report construction of dual Z-scheme advanced photocatalyst g-C3N4/Bi4Ti3O12/Bi4O5I2 heterojunction for coupled photocatalytic H2 evolution and degradation of antibiotics with high efficiency. The optimal CTBT-30 i.e (40 %g-C3N4/Bi4Ti3O12)/30 % Bi4O5I2 photocatalyst exhibited an excellent rate of H2 production under visible light (56.2 mmol g−1 h−1) along with simultaneous 87.1 % ofloxacin (OFL) removal. The H2 production rate is manifolds higher than in ultrapure water, sulfadiazine, rhodamine B and higher in hole scavenging triethanolamine. The interfacial intimate coupling with well-matched energy bands, foster the charge separation with effective Z-scheme transfer facilitated by I3−/I− and Bi3+/Bi5+ and redox mediators. The scavenging of majority of holes for direct oxidation or via [rad]OH radical formation leaves photogenerated electrons (at CB of g-C3N4 and Bi4O5I2) free for H2 evolution from H2O. Such work is promising for designing high photo-absorbing heterojunction photocatalysts for dual functionalities of clean energy production and environmental detoxification

Silicate glass matrix@Cu\u3csub\u3e2\u3c/sub\u3eO/Cu\u3csub\u3e2\u3c/sub\u3eV\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e7\u3c/sub\u3e p-n heterojunction for enhanced visible light photo-degradation of sulfamethoxazole: High charge separation and interfacial transfer

© 2020 Elsevier B.V. Focusing on the treatment of pharmaceuticals contaminated water by advanced oxidation processes, a novel three dimensional silicate glass matrix (3-DG) coupled Cu2O/Cu2V2O7 p-n heterojunction was constructed by in-situ hydrothermal technique. The optimal Cu2O/Cu2V2O7 with 30 wt % Cu2V2O7 (CV-30) degrades 90.1 % sulfamethoxazole (SMX) in 60 min and nearly 100 % removal in 45 min via coupling with 3-DG. Under natural sunlight ∼ 80 % SMX removal was observed. The internal electric field of the p-n junction facilitates the electron flow via the interface. 3-D silicate glass increases the visible light absorption dramatically via internal reflection which facilitates higher exposure for the junction and shortens the diffusion length of charge carriers. The effect of reaction parameters suggests that HCO3− and CO32− ions substantially escalate the SMX removal rate. Scavenging experiments and ESR probe suggest [rad]O2− as the main active species followed by [rad]OH radicals. The degradation products were detected by LC–MS analysis and a degradation mechanism was also predicted. The photocatalytic mechanism was explained in terms of the electron transfer facilitated by conventional transfer and Z-scheme. This strategy to construct such highly visible and solar active p-n heterojunctions will pave way for future opportunities for the degradation of recalcitrant pharmaceutical pollutants

Sustainable green nanoadsorbents for remediation of pharmaceuticals from water and wastewater: A critical review

In the last three decades, pharmaceutical research has increased tremendously to offer safe and healthy life. However, the high consumption of these harmful drugs has risen devastating impact on ecosystems. Therefore, it is worldwide paramount concern to effectively clean pharmaceuticals contaminated water streams to ensure safer environment and healthier life. Nanotechnology enables to produce new, high-technical material, such as membranes, adsorbent, nano-catalysts, functional surfaces, coverages and reagents for more effective water and wastewater cleanup processes. Nevertheless, nano-sorbent materials are regarded the most appropriate treatment technology for water and wastewater because of their facile application and a large number of adsorbents. Several conventional techniques have been operational for domestic wastewater treatment but are inefficient for pharmaceuticals removal. Alternatively, adsorption techniques have played a pivotal role in water and wastewater treatment for a long, but their rise in attraction is proportional with the continuous emergence of new micropollutants in the aquatic environment and new discoveries of sustainable and low-cost adsorbents. Recently, advancements in adsorption technique for wastewater treatment through nanoadsorbents has greatly increased due to its low production cost, sustainability, better physicochemical properties and high removal performance for pharmaceuticals. Herein, this review critically evaluates the performance of sustainable green nanoadsorbent for the remediation of pharmaceutical pollutants from water. The influential sorption parameters and interaction mechanism are also discussed. Moreover, the future prospects of nanoadsorbents for the remediation of pharmaceuticals are also presented

A comprehensive review on the removal of noxious pollutants using carrageenan based advanced adsorbents

Rapid industrial development is associated with high discharge of toxic pollutants into the environment. The industries discharge their wastewater containing organic pollutants directly into the water system without treating them that has posed many serious threats to environmental protection. The use of bioadsorbents for the removal of such toxic pollutants from the waste water due to its simple synthesis, easy operation, effectiveness, and economic viability have emerged a new dimension in the wastewater treatment approaches. Various adsorbents have been prepared to examine their adsorption capacity against different adsorbates, but, to attain sustainability, biocompatibility, and biodegradation, bio-adsorbents have been found to won the battle. Seaweed derived polysaccharide; Carrageenan (CR) has been proven to be an excellent adsorbent for the wastewater treatment. It has been successfully modified with various components to form CR based-magnetic composites, hydrogels, nanoparticle modified CR composites and many others to enrich and diversify its properties. In this review, we have explained the adsorption behaviour of various carrageenan based adsorbents for the removal of different dyes. The influence of various parameters such as the effect of initial concentration, adsorbent dosage, contact time, pH, temperature, and ion concentration on dye adsorption is well explained. This paper also summarizes the structure, morphology, swelling ability, and thermal stability of carrageenan. The data also expounds on the adsorption capacity, kinetic model, isotherm model, and nature of the adsorption process. Different types of solvents are used for the regeneration and reusability of carrageenan adsorbents and their regeneration studies and desorption efficiency is well-explained. The adsorption mechanism of dyes onto carrageenan based adsorbents has been well described in this review. This review provides a deep insight about the use of carrageenan based adsorbents for the wastewater treatment