Ligy Philip

The high carcinogenic risk associated with chloroform (CF) consumption makes the development of on-site detection and removal technologies an important task. The role of nanomaterials (NMs)-based sensors and treatment methods is a promising option owing to their diverse structural and functional merits. In this line, the present review article is designed to highlight the recent development in the applications of NMs for sensing and eliminating aqueous CF. Numerous NMs, including metal oxides, carbon nanotubes, metal-organic frameworks, and graphitic structures, have been investigated as selective and sensitive (0.003–15.5 mg/L) sensors for CF. Likewise, to remove aqueous CF biochar, zerovalent iron, and silver nanoparticles have been explored as effective adsorbents (4.73−4.69х104mg/g) or reducing agents. Accordingly, selection criteria and performance evaluation of NMs with respect to structural advances (functional groups and polarity) and physiochemical property (hydrophobicity and volatility) of CF is provided. The limitations of the available methods, hindrances in upscaling, recommendations related to the use of non-toxic precursors, simple fabrication techniques, and regeneration possibilities are also discussed. Overall, the review summarizes the available sensing and treatment methods for the effective abatement of aqueous chloroform.

Phosphorus is one of the vital nutrients for sustenance; however, its excess concentration can cause adverse impacts on the ecosystem. Numerous sensors have been developed and deployed to monitor phosphate ions (Pi) in the environment in the past decade. However, their high cost, non-portability, and lengthy and complex fabrication processes are detrimental to their widespread use. Accordingly, the objective of the study was to develop a low-cost, convenient paper-based colorimetric sensor with brilliant green (BG) as the probe. The use of triarylmethane dye as a colouring reagent allows naked eye-visible detection of Pi in the range of 13.6–0.27 mg L−1 with the limit of detection as 0.07 mg L−1. Moreover, the proposed sensor resolves the challenges of traditional methods like the formation of insoluble complexes, the requirement of surfactants, poor reagents storability, dependence on time and temperature. The sensitivity and selectivity of BG toward Pi was verified in the aqueous phase. Later, the paper-based sensor (W-BG) was developed via dip coating as a portable detection tool. The storability, stability, and applicability of the developed strips were tested and validated using FT-IR, UV-DRS, and XRD. Additionally, the performance of the strips was compared with a microfluid paper-based device to ensure the feasibility and versatility of the strips. The sensing mechanism is deduced as the formation of the phosphomolybdate complex, which was responsible for the delocalization of the lone pair of electrons on BG, thus rendering a distinct endpoint. The selectivity and sensitivity of the sensor were maintained in real water and wastewater samples. Overall, with affordable cost (0.08 $) and portability, W-BG can be considered as a smart and environmentally friendly water quality monitoring tool.

The development of affordable and modular water/wastewater treatment technologies is highly desirable to counter the adverse effects of antibiotics. Electrochemical treatment, especially electrocatalysis, has a vast potential to degrade antibiotics due to its higher treatment efficiency, low power consumption, and flexible design. Correspondingly, the current review broadly discusses the present status and future trends regarding the electrocatalytic degradation of antibiotics. At the beginning, antibiotic distribution and the merits and demerits of conventional treatment technologies are briefly conveyed. Later, the electrocatalytic removal of antibiotics is discussed in detail with a special focus on catalyst type (e.g., metal-based and carbon-based nanomaterials), oxidative/reductive degradation pathways, and reaction mechanisms. A comprehensive assessment of removal efficiency, operational cost, environmental toxicity of nanomaterials, and residual by-product management has also been carried out. Overall, the feasibility of electrocatalysis technology for antibiotic removal and the critical strategies required for its development have been summarized to provide a roadmap for future research.

Benzene, toluene, ethylbenzene, and xylene (BTEX) are commonly encountered industrial contaminants. The high consumption and unregulated discharge of carcinogenic BTE and neurotoxic X have heavily impacted the environment and water quality. Sorptive separation of BTEX from the aqueous phase is cost-effective and easy to operate; however, slower uptake, adsorbent saturation, and complexity in sorbent regeneration are primary limitations. Advanced oxidation processes (AOPs) offer faster kinetics, reusability, and better efficiency to eliminate BTEX. However, the economics, sustainability, and large-scale extensibility of AOPs need to be verified. In this context, the current review discusses recent developments in aqueous BTEX removal by sorption and AOPs. Life cycle assessment (LCA) analysis of various treatment technologies was carried out to verify the environmental compliances of the process. Based on the single point score, the sustainability ranking of the treatment technologies was: adsorption (Ads.) (0.48), ozonation (1.90), electrochemical oxidation (EO) (4.82), photocatalysis (5.43), Fenton's (7.87), ultrasound-peroxymonosulphate (US-PMS) (31.8), acoustic cavitation (AuC) (228), and hydrodynamic cavitation (HdC) (245). The lower the impact score, the higher is the sustainability of the technology to treat BTEX. Overall, this review identifies the research gaps and boosts the researchers to find out the feasibility of the proposed suggestion to minimize the pollution of hazardous BTEX.

BRICS countries represent some of the fastest-growing world's economies and populations. At the same time, the five nations face the challenge of poor health-hygiene and water quality crisis. The rapid industrialization and reforms to provide substantial health systems have resulted in the ubiquitous presence of emerging contaminants, mostly pharmaceutical and personal care products (PPCPs), in the different ecosystem matrices. Furthermore, antimicrobial resistance (AMR) is advancing global health concerns. Thus, evaluating the ecological, human health, and microbial risks associated with PPCPs is necessary. With this aim, the study was designed to assess the risk of PPCPs and AMR in the surface water. The application of point of use (POU) technologies as a plausible option to reduce the risk associated was determined. The most frequently detected PPCPs in five regions from the secondary data included ibuprofen (IBP), diclofenac (DCF), carbamazepine (CBZ), caffeine (CAF), ciprofloxacin (CIP), trimethoprim (TMP), sulfamethoxazole (SMX), and methylparaben (MPB). However, the risk associated with the above-mentioned PPCPs was not estimated in any case. The widespread presence of CAF enabled the detection of anthropogenic pollution. Similarly, the dominance of antibiotics was attributed to the overuse of antibiotics or non-astringent regulation. In terms of spatial variation, the PPCP concentration was in the order: India > China > Brazil > South Africa. We determined the ecological risk for surface water samples, and high risk (RQ > 1) was found for algae, daphnia, and fish for almost all PPCPs. For chronic human health risk, high carcinogenic (5×10-6-1.8×10-1) and non-carcinogenic risk coefficients (HQ = 2.5×10-4-11.5) were determined for various age groups. The age groups 16-21 years and 21-50 years depicted the least overall risk between 0.9 and 10. The probability of AMR risk was carried out using the quantitative microbial risk assessment (QMRA) method. Human exposure via accidental and incidental ingestion was obtained in the range of 50-106CFU/100 mL E. coli, with the variation in the probability of illness greater than 0.9. On evaluating the POU technologies for microbial reduction, maximum risk drop was obtained for carbon filter combined with UV with a reduction of probability of illness by 0.007. Overall, the study aids in fulfilling the large gap in PPCPs' monitoring and risk in the emerging countries (BRICS) compared with North American and European countries.

In the present study, sorptive and electro-sorptive capture of phosphate using NH2-MIL-101(Al), NH2-MIL-101(Fe), and UiO-66-NH2 was investigated. Additionally, the selectivity, desorption efficiency, role of the amino linker in adsorption, and molecular-level understanding of the phosphate sorption mechanism were discerned. MOFs exhibited high adsorption capacity (NH2-MIL-101(Al): 82.58 ± 1.92 mg P g−1, NH2-MIL-101(Fe): 89.13 ± 6.14 mg P g−1, and UiO-66-NH2: 81.42 ± 2.32 mg P g−1) and fast kinetics (60-120 min). However, the poor desorption efficiency (5-20%) indicated irreversible phosphate sorption. The use of a strong base (0.01 M NaOH) for desorption compromised the stability of the MOFs. The electrosorption process aided in achieving faster kinetics (30-60 min) but failed to recover adsorbed phosphate. The amino linker allowed the removal of more than 80% of the humic acid and co-existing ions without affecting phosphate sorption. Furthermore, DFT calculations demonstrated that high adsorption energy (−265.4 to −124 kJ mol−1) and metal-phosphate interaction (inner-sphere complexation) were responsible for effective phosphate adsorption. It was established that the adsorption of a single phosphate molecule per metal-oxide core was energetically more favourable than the saturation of all-metal centres. Thus, the presence of multiple functional groups in the MOFs did not assist in the phosphate capture. Overall, NH2-MIL-101(Fe) showed the highest stability, while UiO-66 NH2 depicted the lowest phosphate adsorption energy. The selected MOFs can selectively capture phosphate present in real water samples. Nonetheless, recovering adsorbed phosphate without disrupting the MOF structure is not possible.

The increased consumption of parabens and associated health hazards has necessitated the development of water treatment technologies capable of removing parabens to desired levels. Among the various available treatment options, catalytic degradation has the advantages of faster reaction kinetics, increased reactive species formation, and no sludge disposal problem. Accordingly, an overview of recent advances in catalytic systems briefing removal, mineralization, and performance comparison between catalysts is essential to scale up and transfer lab-scale results to real-scale applications. The current review highlights the superiority of photocatalysis, Fenton's, persulfate, and ozonation/catalytic ozonation systems to eliminate parabens. The performance evaluation and economic feasibility of catalytic treatment systems were identified using mathematical models. Additionally, density functional theory calculations were carried out to assess the fundamental mechanism associated with paraben degradation by TiO2and to develop a molecular-level understanding of synthesizing catalysts that can effectively degrade parabens. In a nutshell, this review acts as a roadmap to show the feasibility of catalytic treatment technologies to eliminate parabens from the water environment.

An economically feasible, readily accessible colorimetric probe based on basic fuchsin (BF) was developed to detect NO2- in water and wastewater systems. The study is divided into two phases; liquid phase and solid phase (colorimetric strip). Initially, the parameter optimization was carried out in the liquid phase, followed by sensing via colorimetric strips. Naked eye-colorimetric detection of NO2- in liquid phase was in the range of 0.92-9.2mgL-1 whereas for strips detection range was observed as 0.005-9.2mgL-1. Proper diffusion of BF on the Whatmann filter paper (W) enhanced the sensitivity of colorimetric strip. The investigation also showed high selectivity towards NO2- in the presence of several anions and cations. The colorimetric strips prior to and after interaction with NO2- were characterized using FT-IR, Raman, UV-DRS, and XRD. Results confirmed that diazotization reaction between secondary amine portion of the BF and NO2- was responsible for the specific color change (pink to colorless). The leaching test reported no leachable fraction from the coating, and this was accompanied by the use of Tween-80 as a surface coating agent. The solid colorimetric probe was showed potential selectivity towards NO2- over several interfering ions. Furthermore, the applicability of the prepared strip for detecting NO2- in real water samples indicated satisfactory performance. Cost analysis confirmed that the synthesized BF@W strip is a low-cost (0.01$/strip) and a portable colorimetric sensor for the detection of aqueous NO2-.

This study investigated the adsorption behavior and sustainability of biochar to remove four pharmaceutical and personal care products (PPCPs). The biochar (PEBC) was prepared via slow pyrolysis of empty palm bunch (PEB) at three temperatures (250-750 °C). To improve the adsorption capacity further, PEBC450 was acid treated with H2SO4 to develop PEBC450-A. The adsorption behavior of target pollutants (methyl paraben (MPB), carbamazepine (CZP), ibuprofen (IBP), and triclosan (TCS)) onto PEBC450-A was studied in batch experiments, and phenomenological and statistical models were applied to understand the sorption mechanism. Results demonstrated that the adsorption system was able to achieve fast equilibrium (in 4 h), with maximum adsorption capacities as 60.2 mg/g (MPB), 51.7 mg/g (CZP), 38.8 mg/g (IBP), 35.4 mg/g (TCS). The modeling results showed heterogeneous adsorption of PPCPs involving the participation of multiple functional groups in parallel and non-parallel orientations. The mass transfer kinetic models identified the internal mass transfer resistance as the rate-limiting step. The PPCPs adsorption was significantly affected by the change in solution pH and the presence of humic acid. However, no substantial change in PPCPs removal was observed in the presence of co-existing ions and different ionic strengths. In multi-pollutant systems and real water samples, PEBC450-A maintained more than 75% removal of target pollutants, indicating the developed material as a promising adsorbent for wastewater treatment. The sorption mechanism was found to be channel diffusion, hydrogen bonding, n-πand π-πinteractions, and van der Waals force. The comparative life cycle assessment of PEBC450-A and commercial activated carbon showed that the total impact contribution of PEBC450-A was 20 times less than commercial activated carbon. The overall finding makes PEBC450-A a low-cost and sustainable adsorbent for water treatment.