Synthesis and characterization of novel guar gum based waste material derived nanocomposite for effective removal of hexabromocyclododecane and lindane

Herein, efficient degradation of hexabromocyclododecane (HBCD) and Lindane, a persistent organic pollutant using guar gum based calcium oxide doped silicon dioxide (GG-CaO@SiO2) has been reported. The nanocomposite was prepared by waste egg shell (CaO) and rice husk (SiO2) was well characterized. The maximum degradation of HBCD and Lindane were observed at 8 mg catalyst loading, neutral pH, and 2 mg L-1 of pollutant amount. The photocatalytic performance of GG-CaO@SiO2 for HBCD and Lindane photodegradation was evaluated, and it was found that the rate constant increased in the order of GG-CaO@SiO2 > CaO@SiO2 > GG. The polymeric GG-CaO@SiO2 nanocomposite showed maximum removal of both pollutants due to higher surface area (70 m2 g-1) and synergistic interactions among GG moieties. It achieved HBCD and Lindane elimination rates of 94 % and 90 % by photo-adsorptive degradation within 150 min. Meanwhile, the leaching of HBCD from expanded polystyrene (EPS) materials (0.14 ± 0.05 ppm) underwater with different time intervals and degradation of leachate HBCD were also assessed. The eradication of the pollutant manifested first-order kinetics, with the Langmuir adsorption. LC-MS analysis confirmed that GG-CaO@SiO2 effectively breaks down complex structure toxic pollutants into safer metabolites under natural sunlight exposure. The polymeric GG-CaO@SiO2 nanocomposite showed notable reusability up to ten cycle promotes sustainability.

Recent updates on remediation approaches of environmentally occurring pollutants using visible light-active nano-photocatalysts

Photocatalysis emerges as a potential remedy for the issue of an unreliable light source. Recognized as the most dependable and potent energy source sustaining life on Earth, sunlight offers a promising solution. Sunlight is abundant and free, operational costs associated with running photocatalytic system using nanoparticles are often lower compared to system relying on artificial light source. The escalating problem of water pollution, particularly in highly industrialized nations, necessitates effective wastewater treatment methods. These methods aim to combat elevated pollution levels, encompassing pharmaceuticals, dyes, flame retardants, and pesticide components. Advanced oxidation processes within photocatalytic wastewater treatment exhibit substantial promise for removing complex organic pollutants. Doped nanomaterials, with their enhanced properties, enable efficient utilization of light. Coupled nanomaterials present significant potential in addressing both water and energy challenges by proficiently eliminating persistent pollutants from environment. Photocatalysis when exposed to sunlight can absorb photons and generate e- h + pairs. This discussion briefly outlines the wastewater treatment facilitated by interconnected nanomaterials, emphasizing their role in water-energy nexus. In exploring the capabilities of components within a functional photocatalyst, a comprehensive analysis of both simple photocatalysts and integrated photocatalytic systems is undertaken. Review aims to provide detailed explanation of the impact of light source on photon generation and significance of solar light on reaction kinetics, considering various parameters such as catalyst dosage, pH, temperature, and types of oxidants. By shedding light on these aspects, this review seeks to enhance our understanding of intricate processes involved in photocatalysis and its potential applications in addressing contemporary environmental challenges.

Green construction of biochar@NiFe2O4 nanocomposite for highly efficient photocatalytic remediation of pesticides from agriculture wastewater

The world's attention is drawn to the widespread ingestion, toxicity, and bioaccumulation of the Atrazine (AT) and Endosulfan (ES). Pesticides have been proven to have endocrine-disrupting, genotoxic, and persistent characteristics. In this work, the structural design of green synthesized NiFe2O4 is incorporated in rice husk biochar to form BC@NiFe2O4 nanocomposite. Powder X-ray diffraction and microscopic analysis confirmed the semi-crystalline nature of BC@NiFe2O4 reduced due to the incorporation of amorphous BC. The green BC@NiFe2O4 nanocomposite degraded AT and ES up to 98 % and 92 %, respectively. The maximum degradation achieved by BC@NiFe2O4 nanocomposite with minimum pollutants concentration (50 mg L-1) with 10 mg catalyst dose at acidic pH in natural sunlight because of the higher negative value of zeta potential (-26.4 mV) and lower band gap (2.5 eV). The degradation process involves first-order kinetics followed by initial Langmuir adsorption. The presence of various radical quenchers (t-BuOH, p-BZQ, Na2EDTA) has led to the conclusion that hydroxyl radicals play a significant role in the degradation of the toxic substances AT and ES. Additionally, a green-fabricated BC@NiFe2O4 nanocomposite has exhibited exceptional efficiency in degrading AT and ES pollutants in actual wastewater samples. Furthermore, this nanocomposite has demonstrated outstanding sustainability and cost-effectiveness, maintaining its effectiveness for up to eight cycles without a noticeable reduction in activity. In summary, due to its favorable surface characteristics, the environmentally friendly BC@NiFe2O4 nanocomposite holds excellent promise as a unique and potential photocatalyst for various industrial applications.

One pot green synthesis of Al doped zinc ferrite nanoparticle decorated with reduced graphene oxide for photocatalytic remediation of organic pollutants: Green synthesis, kinetics, and photoactivity

The world is drawn to the widespread use, toxicity, and bioaccumulation of the Atrazine (AT) and Auramine O (AO). Pesticides and dyes also have endocrine disruptors, genotoxic and persistent properties. Therefore, the photodegradation of AT and AO in water was investigated. Herein, the structural design of Al-ZnFe2O4 incorporated in rGO nanocomposite has been synthesized via facile precipitation and green synthesis methodology. PXRD and microscopic analysis confirmed the reduced crystallinity nature of Al-ZnFe2O4 due to the incorporation of amorphous rGO. The green Al-ZnFe2O4@rGO nanocomposite (AT: 90%; AO: 95%) showed maximum degradation as compared to native nanoparticles with minimum pollutants concentration of 10 mg catalytic dose at neutral pH in sunlight irradiation due to negative zeta potential (-36.0 mV), higher surface area (163 m2g-1) and tailored band gap (2.1 eV). First-order kinetics followed by initial Langmuir adsorption constituted the degradation process. The presence of different radical quenchers (t-BuOH, p-BZQ, Na2EDTA) concluded that hydroxyl radical plays a significant role in the degradation of toxic AT and AO. Green fabricated Al-ZnFe2O4@rGO also showed excellent efficiency for the degradation of AT and AO pollutant in real wastewater sample. Nanocomposite demonstrated remarkable sustainability and cost-effectiveness by remaining effective for up to nine cycles without experiencing any appreciable activity reduction. Due to its favorable surface features, Al-ZnFe2O4@rGO nanocomposite made via green process is a unique and potential photocatalyst for industrial applications.

Efficient photo-adsorptive eradication of endocrine disrupting pesticides by chitosan co- decorated metal oxide bio-nanocomposite

Extensive consumption, toxicity and bioaccumulation of malathion (MLT) and lindane (γ-HCH) pesticides collectively attract the world's attention. Herein, the nanocomposite of chitosan wrapped NiO@ZnO was synthesized by a green methodology using Azadirachta indica leaves extract. Structural and morphological analysis of chitosan-NiO@ZnO showed hollow sphere-flake shaped image adsorbed on a solid chitosan surface with a large surface area of 73 m²g^-1. A decrease in values of lattice strain, dislocation density and crystallite size described the imperfection in crystal geometry and new peaks in FT-IR spectra at 698 cm^-1 and 448 cm^-1 of Ni-N and Zn-N, which respectively confirm the coupling. Chitosan-NiO@ZnO and individual nanoparticles (NiO and ZnO) were well-characterized and utilized for degradation MLT and γ-HCH under direct sunlight and dark conditions. The highest degradation of pesticides (above 94%) resulted with 2 mg L^-1 and 10 mg L^-1 of MLT (π-π) and γ-HCH, respectively with a 20 mg catalyst dose, and pH of ~ 7 under daylight exposure (5 h). Chitosan-NiO@ZnO substantially suppressed the half-life of the targeted pesticides (MLT: 0.48 h; HCH 0.51 h) and demonstrated the first-order kinetics with a high adsorption capacity, X_m (MLT: 14.5 mg g^-1 and γ-HCH 20.7 mg g^-1), which also confirmed the strong binding with the pesticides, followed by their conversion into safer and smaller metabolites. The charge separation mechanism was elucidated by UV reflectance and photoluminescence data. Hydroxyl radicals were most frequently responsible for the degradation of pesticides as confirmed by scavenger analysis. The synthesized green-nano photocatalyst showed high reusability (up to 10^th cycles), sensitivity and stability within the degradation process, presumably making it suitable for industrial applications.

An updated review on environmental occurrence, scientific assessment and removal of brominated flame retardants by engineered nanomaterials

Due to the extensive manufacturing and use of brominated flame retardants (BFRs), they are known to be hazardous, bioaccumulative, and recalcitrant pollutants in various environmental matrices. BFRs make flame-resistant items for industrial purposes (textiles, electronics, and plastics equipment) that are disposed of in massive amounts and leak off in various environmental matrices. The consumption of plastic items has expanded tremendously during the COVID-19 pandemic which has resulted into the increasing load of solid waste on land and water. Some BFRs, such as polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDs), are no longer utilized or manufactured owing to their negative impacts, which promotes the utilization of new BFRs as alternatives. BFRs have been discovered worldwide in soil, sludge, water, and other contamination sources. Various approaches such as photocatalysis-based oxidation/reduction, adsorption, and heat treatment have been found to eradicate BFRs from the environment. Nanomaterials with unique properties are one of the most successful methodologies for removing BFRs via photocatalysis. These methods have been praised for being low-cost, quick, and highly efficient. Engineered nanoparticles degraded BFRs when exposed to light and either convert them into safer metabolites or completely mineralize. Scientific assessment of research taking place in this area during the past five years has been discussed. This review offers comprehensive details on environmental occurrence, toxicity, and removal of BFRs from various sources. Degradation pathways and different removal strategies related to data have also been presented. An attempt has also been made to highlight the research gaps prevailing in the current research area.

Long-Term Variation in Carbonaceous Components of PM2.5 from 2012 to 2021 in Delhi

Carbonaceous species [organic carbon (OC), elemental carbon (EC), elemental matter (EM), primary organic carbon (POC), secondary organic carbon (SOC), total carbon (TC), and total carbonaceous matter (TCM)] of PM_2.5 were analyzed to study the seasonal variability and long-term trend of carbonaceous aerosols (CAs) in megacity Delhi, India from January, 2012 to April, 2021. The average concentrations (± standard deviation) of PM_2.5, OC, EC, TC, EM, TCM, POC and SOC were 127 ± 77, 15.7 ± 11.6, 7.4 ± 5.1, 23.1 ± 16.5, 8.2 ± 5.6, 33.3 ± 23.9, 9.3 ± 6.3 and 6.5 ± 5.3 µg m^-3, respectively during the sampling period (10-year average). The average CAs accounted for 26% of PM_2.5 concentration during the entire sampling period. In addition, the seasonal variations in PM_2.5, OC, EC, POC, SOC, and TCM levels were recorded with maxima in post-monsoon and minima in monsoon seasons. The linear relationship of OC and EC, OC/EC and EC/TC ratios suggested that the vehicular emissions (VE), fossil fuel combustion (FFC) and biomass burning (BB) are the major sources of CAs at megacity Delhi, India.

Efficient removal of plastic additives by sunlight active titanium dioxide decorated Cd-Mg ferrite nanocomposite: Green synthesis, kinetics and photoactivity

Large use of flame retardants or additives in plastic industries have caused scientific attention as their leaching from consumer products is indicative of environmental concern. Moreover, plastic additives have proven features of endocrine disruptors, genotoxicity and persistence. Therefore, photodegradation of tetrabromobisphenol A (TBBPA) and bisphenol A (BPA) were explored in water. Seeing environmental safety, titanium dioxide decorated magnesium substituted cadmium ferrite (CdMgFe₂O₄@TiO₂) was synthesized by using plant extract of M. koenigii via co-precipitation. Sharp peaks obtained in PXRD ensured high crystallinity and purity of distorted spherical nanocomposite (5-25 nm). Subsequently, CdMgFe₂O₄@TiO₂ nanocatalyst was evaluated for the effective elimination of plastic additives at variable reaction parameters (pollutant: 2-10 mgL^-1; catalyst: 5-25 mg; pH: 3-7, dark-sunlight). With 20 mg of catalytic dose, CdMgFe₂O₄@TiO₂ showed maximum degradation of 2 mgL^-1 of TBBPA (91%) and BPA (94%) at neutral pH under sunlight. Considerable reduction in persistence of TBBPA (t_1/2:2.4 h) and BPA (t_1/2:2.1 h) indicated admirable photoactivity of CdMgFe₂O₄@TiO₂. Results were supported by BET, zeta potential, band reflectance and photoluminescence analysis that indicated for higher surface area (90 m²g^-1), larger particle stability (-20 mV), lower band gap (1.9 eV) and inhibited charge-pairs recombination in nanocomposite. Degradation consisted of initial Langmuir-adsorption followed by first order kinetics. Scavenger analysis revealed the role of hydroxyl radical in photodegradation studies. Nanocomposite was effective up to eight cycles without any significant loss of activity that advocated its high-sustainability and cost-effectiveness. Overall, with excellent surface characteristics, green synthesized CdMgFe₂O₄@TiO₂ nanocomposite is a promising and alternative photocatalyst for industrial applications.

Efficient degradation of organic pollutants by novel titanium dioxide coupled bismuth oxide nanocomposite: Green synthesis, kinetics and photoactivity

Herein, a green and facile methodology was used for the structural design of semiconductor nanomaterials and employed as efficient photocatalyst to resolve the environmental issues of water pollutants. Titanium oxide coupled with bismuth oxide (TiO₂@Bi₂O₃) nanocomposite was synthesized by employing the seed extract of Sapindus mukorossi (commonly found plant in India) and subsequently used for the elimination of toxic, and persistence industrial pollutants namely bisphenol A (BPA) and methylene blue (MB). Microscopic and spectroscopic techniques revealed particle size of synthesized nanocomposite found less than 50 nm along with high crystallinity. Appearance of stretching vibrations at 459 cm^-1 for Bi-O-Ti in the IR spectra of nanocomposite has established the coupling of TiO₂ with Bi₂O₃. The parameters of degradation were optimized by varying the pollutant concentration, catalytic amount and pH in the presence of natural sunlight. The nanocomposite TiO₂@Bi₂O₃ showed maximum degradation (MB: 94% and BPA: 91%) at a minimum concentration of pollutant (50 mgL^-1) with catalyst amount (35 mg), neutral pH and reduces half-life of pollutants (BPA: 1h, MB: 0.5h). Owing of higher surface area (80 m²g^-1), lower band gap (2.5 eV), and more negative zeta potential value (-40.3 mV) results into excellent photocatalytic properties. The breakage of S-N conjugated system in MB results into rapid degradation as compare to BPA. The degradation followed first-order kinetics and Langmuir adsorption in both the cases. Presence of active radicals during the photocatalysis process was responsible for quick degradation and strongly supported by scavenger analysis. GC-MS analysis revealed the degradation of toxic pollutants into safer metabolites and finally mineralized. Multiple times (n = 8) reusability of green photocatalyst advocated sustainability and appropriate for industrial applications.

Bioremediation: an alternative approach for detoxification of polymers from the contaminated environment

The industries and metropolitan wastes produced by anthropogenic activities are of great concern for nature as it causes soil contamination and deteriorate the environment. Plastic utilization is rapidly enhancing globally with passing days that last for a more extended period in the environment due to slow decomposition and natural degradation. Excessive use of polymer has risked the life of both marine, freshwater and terrestrial organisms. Lack of proper waste management and inappropriate disposal leads to environmental threats. Bioremediation processes involve microbes such as fungi, bacteria, etc. which contribute a crucial role in the breakdown of plastics. Extremophiles secrete extremozymes that are functionally active in extreme conditions and are highly crucial for polymer disaggregation in those conditions.

Sunlight-induced photocatalytic degradation of organic pollutants by biosynthesized hetrometallic oxides nanoparticles

Dyes and phenols are extensively used chemicals in petrochemicals, pharmaceuticals, textile, and paints industries. Due to high persistence, bioaccumulation, and toxicity, their removal from the environment is highly imperative by advanced techniques. Single metal oxide nanomaterials are generally associated with limitations of large bandgap (> 3eV) and charge recombination. Therefore, heterometallic oxides (HMOs) as CuFe₂O₄, CuMn₂O₄, and MnZn₂O₄ have been synthesized via green route by employing leaf extract of Azadirachta indica. XRD revealed the crystalline nature of HMOs nanospheres with particle size less than 100 nm. Subsequently, HMOs nanocatalysts were used as photocatalyst for removal of 3-amino phenols (3-AP) and eriochrome black T (EBT) from water under sunlight. Reaction parameters namely pollutant concentration (50-130 mgL^-1), catalyst dose (20-100 mg), and pH (3-11) were optimized in order to get best results. Substantial degradation (80-95%) of pollutants (50 mgL^-1) by HMOs (80 mg) was achieved at neutral pH under sunlight exposure. Highest removal by CuFe₂O₄ might be due to its high surface area (35.7 m²g^-1), low band gap (2.4 eV), larger particle stability (Zeta potential: -22.0 mV), and lower photoluminescence intensity. Sharp declines in curves were visually confirmed by color change and indicated for first-order kinetics of degradation with initial Langmuir adsorption. Spectrophotometric analysis revealed that half-life (t_1/2) of 3-AP (0.9-1.7 h) and EBT (0.6-0.8 h) were significantly reduced. Faster degradation of EBT than 3-AP was because of less electronegative N-atom at the diazo group. Scavenger analysis indicated the presence of active radicals in photo-catalytic degradation of 3-AP and EBT. All HMOs have shown high reusability (n=8) which ensures their stability, sustainability, and efficiency. Overall, green synthesized HMOs nanoparticles with prominent surface characteristics offer a viable alternative photocatalyst for industrial applications.

Insight in to sunlight-driven rapid photocatalytic degradation of organic dyes by hexacyanoferrate-based nanoparticles

Release of colouring agents into the environment alarms the need to design a cheap, quick and safe process. Owing to environmental safety concern, synthesis of two metal hexacyanoferrates (MHCFs) based on cadmium (CdHCF) and manganese (MnHCF) was carried out using natural plant extract of Azadirachta indica and water as a solvent. Synthesized MHCFs were utilized for the removal of an acid dye (fuchsin acid, FA) and a xanthenes dye (rhodamine B, RB). The reactions were optimized at various conditions of dye concentration, catalyst dose, reaction pH, time and source of light. The MHCFs showed excellent results with both the dyes within very limited span of time (2 h). Consequently, 98% of FA and 97% of RB were degraded with 10 mg of CdHCF, at neutral pH and under sunlight. The degradation process followed the first-order reaction kinetics having t_1/2 around 0.3 min. The MHCFs exhibited difference of only little percentage in degradation owing to a very slight difference between their surface areas (CdHCF: 54.1 m² g^-1; MnHCF: 49.7 m² g^-1). The synthesised nanocatalysts were stable as indicated by their higher negative zeta potential values. The adsorption of dyes was found to be maximum with CdHCF having X_m value 19.69 mg g^-1 and 18.15 mg g^-1 for FA and RB, respectively. Photocatalytic degradation involved the main role of hydroxyl radical as indicated by decline in activity of nanocatalyst in the presence of scavengers. All in all, this study presents highly active nanomaterials with higher surface area, stability and semiconducting properties under natural conditions.

Degradation of tricyclic polyaromatic hydrocarbons in water, soil and river sediment with a novel TiO2 based heterogeneous nanocomposite

Polycyclic aromatic hydrocarbons (PAHs), pervasive and precedence pollutants have potential to decimate the bionetwork and human health. Therefore, photocatalytic degradation of toxic three membered PAHs, namely acenaphthene (ACN), phenanthrene (PHN) and fluorene (FLU) was explored in water and soil. Titanium dioxide based zinc hexacyanoferrate framework (TiO₂@ZnHCF) nanocomposite was synthesized via a two step A. indica mediated co-precipitation method. Under sunlight, fall in concentration of PAHs (Water- 93%-96%, soil- 82%-86% and river sediment- 81.63%-85.43%) with time revealed superior activity of nanocomposite (TiO₂@ZnHCF) as compared to the bared one. Slower degradation in soil and sediment could be attributed to the reduced diffusion caused by the interaction between the organic content of soil/sediment with PAHs. Doping caused an increase in surface area (118.15 m²g^-1) with decrease in band gap energy (1.65 eV) and photoluminescence intensity. PAHs removal (X_m = 9.48 mg g^-1 of ACN, 9.35 mg g^-1 of PHN and 8.96 mg g^-1 of FLU) involved role of "cation- π" interaction with nanocomposite. Besides, it reduced t_1/2 values of ACN (1.88 h), PHN (2.09 h) and FLU (2.86 h) and resulted into smaller by-products. Smaller by-products like (Z)-prop-1-ene-1,2,3-triol (m/z = 91) and (E)-3-hydroxyacrylaldehyde (m/z = 71) identified in GC-MS, evidently braced e^- excitement from encapsulated nanocatalyst followed by OH (active species) based oxidation of PAHs. Lower photoluminescence intensity indicates the least charge carrier recombination with highest photocatalytic activity of nanocomposites. Inclusive of the present study provides promising photocatalyst with greater surface activity, low quantum yield with charge separation, reusable up to ten cycles deprived of substantial loss of its action and suppressing the cost of process.

Mineralization of carcinogenic anthracene and phenanthrene by sunlight active bimetallic oxides nanocomposites

Polycyclic aromatic hydrocarbons (PAHs) are causing environmental concerns due to their persistent nature and carcinogenicity. Hence, their removal through advanced nanomaterials with characteristics of low-cost and high efficiency is essential. In view of this, bimetallic oxides (BMOs) nanocomposites of NiO-ZnO, ZnCo₂O_4, MnCo₂O₄ and CoFe₂O₄ were synthesized via green route using leaf extract of Aegle marmelos. Subsequently, these BMOs were investigated for photocatalytic removal of selected PAHs like anthracene (ANTH) and phenanthrene (PHEN) from water. Nanospheres of NiO-ZnO, ZnCo₂O_4, and CoFe₂O₄ and nanosheets of MnCo₂O₄ with particle size range of 10-30 nm were confirmed by transmission electron microscopy. At neutral pH, nanocomposites showed excellent ability in degrading 2 mg L^-1 of PAHs (ANTH: 98%; PHEN: 93%) within 12 h under the exposure of sunlight. Among the synthesized BMOs, NiO-ZnO was found best followed by ZnCo₂O_4, MnCo₂O₄ and CoFe₂O_4. This fact is attributed to the highest surface area (129 m² g^-1) and particles stability (zeta potential: -30 eV) of NiO-ZnO. Photodegradation of PAHs by nanocomposites followed first order kinetics and fitted in Langmuir model for adsorption. Higher degradation under sunlight and lower removal efficiency with scavenger confirmed the photodegradation activity of nanocomposites. Overall, reusable (n = 10) nanocomposites with no loss of activity have high photocatalytic potential in the removal of carcinogenic PAHs.

Promoting sun light-induced photocatalytic degradation of toxic phenols by efficient and stable double metal cyanide nanocubes

Aromatic substituted phenols and their by-products discharged from numerous industries are of environmental concern due to their toxic, carcinogenic, recalcitrant, and bioaccumulating properties. Therefore, their complete removal from waters by low-cost, efficient, environmentally friendly nanomaterial-based treatment techniques is desirable. Double metal cyanide complexes (DMCC) are the extremely useful heterogeneous and recoverable catalyst. Hence, green route has been developed for several DMCC and their photocatalytic efficiency was evaluated for degradation of toxic phenols. Herein, nanocubes for hexacyanocobaltate of iron (FeHCC ~ 200 nm), nickel (NiHCC < 10 nm), and zinc (ZnHCC ~ 500 nm) were synthesized after employing Aegle marmelos. Subsequently, at neutral pH and sunlight irradiation, 15 mg of catalysts were able to degrade the maximum extent of phenols (1 × 10^-4 M) in the order: 3-aminophenol (96% ZnHCC > 94% FeHCC > 93% NiHCC) > phenol (94% ZnHCC > 92% FeHCC > 91% NiHCC) > 2,4-DNP (92% ZnHCC > 91% FeHCC > 90% NiHCC). This is attributed to highest basicity of 3-aminophenol containing excess of free electrons. Highest catalytic potential of ZnHCC (X_m = 0.54-0.43 mg/g) is because of its highest surface area and negative zeta potential along with sharp morphology and crystallinity. Adsorption of phenols over catalyst was statistically significant with Langmuir isotherms (R² ≥ 0.96; p value ≤ 0.05). Small and non-toxic by-products like oxalic acid, benzoquinone, (Z)-hex-3-enedioic acid, (Z)-but-2-enal, and (Z)-4-oxobut-2-enoic acid were identified in GC-MS. Degradation modes involving hydroxylation, oxidative skeletal rearrangement, and ring opening clearly supported enhanced oxidation of phenols by ^•OH. Overall, due to greater active sites, high surface activity, low band gap, and semiconducting nature, DMCC revealed promising potential for solar photocatalytic remediation of wastewater.

Removal of chlorpyrifos, thiamethoxam, and tebuconazole from water using green synthesized metal hexacyanoferrate nanoparticles

The low-cost and highly efficient pesticides are largely used in residential, agricultural, and commercial applications. Their prevalent occurrence, bioaccumulation, and chronic toxicity to living beings have raised environmental concern and call for their whole eradication, especially from water. By virtue of semiconducting nature and high surface area, nanomaterials have become efficient adsorbent and photocatalyst in removal of toxins. To confirm this, the potential of highly crystalline metal hexacyanoferrates (MHCFs) of Zn, Cu, Co, and Ni was evaluated in deprivation of selected hazardous pesticides, viz., chlorpyrifos (CP), thiamethoxam (TH), and tebuconazole (TEB). Sharp nanocubes of ZnHCF (~ 100 nm), distorted nanocubes of CuHCF (~ 100 nm), and nanospheres of CoHCF and NiHCF (< 10 nm) were synthesized via green route using Sapindus mukorossi (raw ritha). At 50 mg L^-1 of pesticide, 15 mg of MHCF photocatalyst, neutral pH and sunlight irradiation, selected agrochemicals were degraded to maximum extent (91-98%) by ZnHCF followed by CuHCF (85-91%), NiHCF (73-85%), and CoHCF (70-83%). This might be because of highest zeta potential and BET surface area of ZnHCF. The highest adsorption of CP (83-98%) followed by TH (76-95%) and TEB (70-91%) on acidic surface of catalysts might be related to access of free electrons in their structures. On treatment with MHCF photocatalyst, targets underwent mineralization along with formation of some minor and non-toxic by-products such as (Z) but-2-enal, 3-aminopropanoic acid, and pyridin-3-ol, identified after mass spectrometric analysis of reaction mixture. Based on them, degradation pathways have been proposed to reveal the potential of MHCF for solar photocatalytic removal of organic pollutants in environment.

Degradation of toxic PAHs in water and soil using potassium zinc hexacyanoferrate nanocubes

Polycyclic aromatic hydrocarbons (PAHs) the ubiquitous, persistent and carcinogenic environmental contaminants have raised concern worldwide. Recently, their removal methodologies are advanced after exploring nanomaterials. Therefore, degradation of selected toxic PAHs (3-5 rings) using potassium zinc hexacyanoferrate (KZnHCF) nanocubes was studied. Highly crystalline and sharp KZnHCF nanocubes (∼100 nm) were obtained by green route using sapindus mukorossi. In both water and soil, anthracene and phenanthrene were degraded to maximum extent (80-93%), whereas, the degradation of fluorene, chrysene and benzo (a) pyrene were ∼70-80%.Because of small size (lower molecular weight), large number of anthracene and phenanthrene molecules were adsorbed on catalyst as compared to other PAHs. Higher degradation of PAHs in water than in the soil is attributed to the easy absorption of PAHs on catalyst in water and slow diffusion of PAHs on organic content of soil. PAHs were degraded at the concentration of 50 mg/L, 25 mg catalyst dose, neutral pH and solar irradiation. Higher proficiency of the catalyst was revealed by degradation of PAHs into small and non-toxic by-products such as malealdehyde, 4-oxobut-2-enoic acid and o-xylene. Overall, the potential KZnHCF nanostructures open future scope for eradication of other pollutants from the environment.

Widespread detection of a brominated flame retardant, hexabromocyclododecane, in expanded polystyrene marine debris and microplastics from South Korea and the Asia-Pacific coastal region

The role of marine plastic debris and microplastics as a carrier of hazardous chemicals in the marine environment is an emerging issue. This study investigated expanded polystyrene (EPS, commonly known as styrofoam) debris, which is a common marine debris item worldwide, and its additive chemical, hexabromocyclododecane (HBCD). To obtain a better understanding of chemical dispersion via EPS pollution in the marine environment, intensive monitoring of HBCD levels in EPS debris and microplastics was conducted in South Korea, where EPS is the predominant marine debris originate mainly from fishing and aquaculture buoys. At the same time, EPS debris were collected from 12 other countries in the Asia-Pacific region, and HBCD concentrations were measured. HBCD was detected extensively in EPS buoy debris and EPS microplastics stranded along the Korean coasts, which might be related to the detection of a quantity of HBCD in non-flame-retardant EPS bead (raw material). The wide detection of the flame retardant in sea-floating buoys, and the recycling of high-HBCD-containing EPS waste inside large buoys highlight the need for proper guidelines for the production and use of EPS raw materials, and the recycling of EPS waste. HBCD was also abundantly detected in EPS debris collected from the Asia-Pacific coastal region, indicating that HBCD contamination via EPS debris is a common environmental issue worldwide. Suspected tsunami debris from Alaskan beaches indicated that EPS debris has the potential for long-range transport in the ocean, accompanying the movement of hazardous chemicals. The results of this study indicate that EPS debris can be a source of HBCD in marine environments and marine food web.

Releasing of hexabromocyclododecanes from expanded polystyrenes in seawater -field and laboratory experiments

Expanded polystyrene (EPS) is a major component of marine debris globally. Recently, hazardous hexabromocyclododecanes (HBCDDs) were detected in EPS buoys used for aquaculture farming. Subsequently, enrichment of HBCDDs was found in nearby marine sediments and mussels growing on EPS buoys. It was suspected that EPS buoys and their debris might be sources of HBCDDs. To confirm this, the release of HBCDDs from EPS spherules detached from a buoy to seawater was investigated under field (open sea surface and closed outdoor chambers with sun exposure and in the dark) and laboratory (particle-size) conditions. In all exposure groups, initial rapid leaching of HBCDDs was followed by slow desorption over time. Abundant release of HBCDDs was observed from EPS spherules exposed to the open sea surface (natural) and on exposure to sunlight irradiation or in the dark in controlled saline water. Water leaching and UV-light/temperature along with possibly biodegradation were responsible for about 37% and 12% of HBCDDs flux, respectively. Crumbled EPS particles (≤1 mm) in samples deployed on the sea surface for 6 months showed a high degree of weathering. This implies that surface erosion and further fragmentation of EPS via environmental weathering could enhance the leaching of HBCDDs from the surface of EPS. Overall, in the marine environment, HBCDDs could be released to a great extent from EPS products and their debris due to the cumulative effects of the movement of large volumes of water (dilution), biodegradation, UV-light/temperature, wave action (shaking), salinity and further fragmentation of EPS spherules.

Recent strategies for removal and degradation of persistent & toxic organochlorine pesticides using nanoparticles: A review

Organochlorines (OCs) are the most hazardous class of pesticides, therefore, banned or restricted in several countries. The major sources of OCs include food industries, agriculture and sewage wastes. Their effluents discharged into the water bodies contain extremely high concentration of OCs which ultimately causes environmental concern. Because of their high persistence, toxicity and potential to bioaccumulation, their removal from wastewater is imperative. The degradation techniques are now advanced using nanomaterials of various kinds. During the last few years, nanoparticles such as TiO₂ and Fe are found to be excellent adsorbents and efficient photocatalysts for degrading more or less whole OCs as well as their toxic metabolites, which opens the opportunities for exploring various other nanoparticles as well. It is noteworthy that such methodologies are economic, fast and very efficient. In this review, the detailed information on different types of OC pesticides, their metabolites, environmental concern and present status on degradation methods using nanoparticles have been reviewed. An attempt has also been made to highlight the research gaps prevailing in the current research area.

Benzotriazole-type ultraviolet stabilizers and antioxidants in plastic marine debris and their new products

Ultraviolet stabilizers (UVSs) and antioxidants are the most widely used additives in plastics to enhance the lifetime of polymeric materials. There is growing interest in the roles of plastic marine debris and microplastics as source or vector of toxic substances to marine environment and organisms. However, there is limited information available on plastic associated chemicals, particularly additive chemicals. Therefore, to evaluate their extent of exposure from plastics to the marine environment, we determined UVSs and antioxidants in plastic debris (n=29) collected from beaches along with their corresponding new plastic products in markets (n=27) belonging to food, fisheries, and general use. Antioxidants were present at higher concentrations than UVSs in both plastic debris and new plastics, indicative of their high use over UVSs. Irganox 1076 and Irganox 1010 were more commonly used than other chemicals investigated. The irregular use with high concentration of additive chemicals was observed in short-term use plastic products. Except for Irganox 1076 and UV 326, most antioxidants and UVSs were relatively high in new plastics compared to corresponding plastic marine debris, implying their potential leaching or degradation during use or after disposal. The present study provides quantitative information about additive chemicals contained in plastic marine debris and their new products. These results could be useful for better understanding of environmental exposure to hazardous chemicals through plastic pollution.

Styrofoam Debris as a Source of Hazardous Additives for Marine Organisms

There is growing concern over plastic debris and their fragments as a carrier for hazardous substances in marine ecosystem. The present study was conducted to provide field evidence for the transfer of plastic-associated chemicals to marine organisms. Hexabromocyclododecanes (HBCDs), brominated flame retardants, were recently detected in expanded polystyrene (styrofoam) marine debris. We hypothesized that if styrofoam debris acts as a source of the additives in the marine environment, organisms inhabiting such debris might be directly influenced by them. Here we investigated the characteristics of HBCD accumulation by mussels inhabiting styrofoam. For comparison, mussels inhabiting different substrates, such as high-density polyethylene (HDPE), metal, and rock, were also studied. The high HBCD levels up to 5160 ng/g lipid weight and the γ-HBCD dominated isomeric profiles in mussels inhabiting styrofoam strongly supports the transfer of HBCDs from styrofoam substrate to mussels. Furthermore, microsized styrofoam particles were identified inside mussels, probably originating from their substrates.

Styrofoam Debris as a Source of Hazardous Additives for Marine Organisms

There is growing concern over plastic debris and their fragments as a carrier for hazardous substances in marine ecosystem. The present study was conducted to provide field evidence for the transfer of plastic-associated chemicals to marine organisms. Hexabromocyclododecanes (HBCDs), brominated flame retardants, were recently detected in expanded polystyrene (styrofoam) marine debris. We hypothesized that if styrofoam debris acts as a source of the additives in the marine environment, organisms inhabiting such debris might be directly influenced by them. Here we investigated the characteristics of HBCD accumulation by mussels inhabiting styrofoam. For comparison, mussels inhabiting different substrates, such as high-density polyethylene (HDPE), metal, and rock, were also studied. The high HBCD levels up to 5160 ng/g lipid weight and the γ-HBCD dominated isomeric profiles in mussels inhabiting styrofoam strongly supports the transfer of HBCDs from styrofoam substrate to mussels. Furthermore, microsized styrofoam particles were identified inside mussels, probably originating from their substrates.

Safe transportation of biomedical waste in a health care institution

INTRODUCTION

The chances of health care waste (Biomedical waste) coming in contact with the health care workers, patients, visitors, sanitary workers, waste handlers, public, rag pickers and animals during transportation are high.

MATERIALS AND METHODS

The study was conducted over a period of seven months (April 2013-October 2013) in a 500-bedded hospital where the average quantum of biomedical waste is 0.8 kg/bed/day. The issues related to transportation of health care waste from 39 generation sites to the health care waste storage site inside the hospital (intramural transfer) were addressed and analysed in a predesigned proforma.

RESULTS

The biomedical waste management team inspected the generation sites in the hospital on a daily basis and conformance to the procedures was checked. It was found that waste was collected at scheduled timings in 99.6% occasions; however, compliance to wearing personal protective equipment (PPE) was poor and ranged from 1.22-1.84%.

CONCLUSION

Transportation of health care waste is a crucial step in its management. Regular training program for all the sections of health care workers with special emphasis on waste handlers is needed.

Catalytic removal of organic colorants from water using some transition metal oxide nanoparticles synthesized under sunlight

The novelty of the work lies in utilizing the sunlight irradiated, green synthesis of TMO nanoparticles, and their potential in simulated water treatment.

Qualitative Analysis of Additives in Plastic Marine Debris and Its New Products

Due to their formulation and/or processing, plastics contain additives and impurities that may leach out under conditions of use and accumulate in the environment. To evaluate their role as vectors of chemical contaminants in marine environment, plastic debris (n = 19) collected from coastal beaches along with new plastics (n = 25; same or same brand) bought from local markets were screened by gas chromatography-mass spectrometry in full scan mode. Detected peaks were identified using NIST library in different polymers (polypropylene (PP) > polyethylene (PE) > PP + PE > polyethyl terephthalate > poly(acylene:styrene) with different use (food, fishery, and general use). A database on the presence of 231 different chemicals were grouped into hydrocarbons, ultra-violet (UV)-stabilizers, antioxidants, plasticizers, lubricants, intermediates, compounds for dyes and inks, flame retardants, etc. The UV326, UV327, UV328, UV320, UvinualMC80, irganox 1076, DEHP, antioxidant no 33, di-n-octylisophthalate, diisooctyl phthalate, hexanoic acid 2-ethyl-hexadecyl ester, and hydrocarbons were most frequently detected. Finding of toxic phthalates and UV stabilizers in those products having moisture contact (like bottles with short use) raised concern to humans and indicated their irregular use. The comparison between new and debris plastics clearly indicated the leaching and absorption of chemicals and supports our assumption of plastic as media for transferring these additives in marine environment.

A comparison of microscopic and spectroscopic identification methods for analysis of microplastics in environmental samples

The analysis of microplastics in various environmental samples requires the identification of microplastics from natural materials. The identification technique lacks a standardized protocol. Herein, stereomicroscope and Fourier transform infrared spectroscope (FT-IR) identification methods for microplastics (<1mm) were compared using the same samples from the sea surface microlayer (SML) and beach sand. Fragmented microplastics were significantly (p<0.05) underestimated and fiber was significantly overestimated using the stereomicroscope both in the SML and beach samples. The total abundance by FT-IR was higher than by microscope both in the SML and beach samples, but they were not significantly (p>0.05) different. Depending on the number of samples and the microplastic size range of interest, the appropriate identification method should be determined; selecting a suitable identification method for microplastics is crucial for evaluating microplastic pollution.

Hexabromocyclododecane in polystyrene based consumer products: an evidence of unregulated use

Polystyrene (PS) is made flame retardant by combining with hexabromocyclododecane (HBCD). HBCD can release from consumer products during their production, use or disposal. As a result, it has become a ubiquitous contaminant in the environment with a high potential for bioaccumulation. Therefore, to evaluate the extent of exposure to HBCD from PS, we determined the concentration of HBCD in a variety of products (n=34) made from three types of commonly used PS: expanded PS (EPS), extruded PS foam (XPS), and extruded PS. The concentration of HBCD was highest in EPS, with a mean value and range of 475643±16710ngg(-1) and 106-960000ngg(-1), respectively. PS related to building construction and laboratory uses had a significantly higher concentration of HBCD (3300-905000ngg(-1)), except XPS styroboard (191±100ngg(-1)). Lower concentrations were measured in most food-related products (24.3-199ngg(-1)). However, a relatively high concentration of HBCD was detected in an ice box (960000±29000ngg(-1)), aquaculture buoy (53500±2100ngg(-1)), and disposable tray (8430±730ngg(-1)) used in fish market, raising concern for public health. Our data demonstrate a wide variation in the concentration of HBCD, suggesting a lack of proper controls for the addition of HBCD to PS products. Other brominated flame retardants (BFRs) were also detected in a majority of the XPS products (TBBPA=3.83-545ngg(-1), BTBPE=44-216ngg(-1) and DBDPE=215-4200ngg(-1)). Thus, HBCD is being added to PS along with other BFRs that cannot be ignored.

Levels and profiles of persistent organic pollutants in resident and migratory birds from an urbanized coastal region of South Korea

Persistent organic pollutants (POPs) levels in resident and migratory birds collected from an urbanized coastal region of South Korea were investigated. As target species, resident birds that reside in different habitats-such as inland and coastal regions-were selected and their POP contamination status and accumulation features evaluated. Additionally, winter and summer migratory species were analysed for comparison with resident birds. Black-tailed gull and domestic pigeon were selected as the coastal and inland resident birds, respectively, and pacific loon and heron/egret were selected as the winter and summer migratory birds, respectively. The overall POP concentrations (unit: ng/g lipid) in resident birds were 14-131,000 (median: 13,400) for PCBs, 40-284,000 (11,200) for DDTs, <1.0-2850 (275) for CHLs, 23-2020 (406) for HCHs, 2-1520 (261) for HCB, <0.2-48 (5) for pentachlorobenzene (PeCB), 71-7120 (1840) for PBDEs, and <1.8-2300 (408) for HBCDs. In resident birds, the overall level of POPs was higher in seagull compared to pigeon. The stable isotope ratio of nitrogen and carbon indicates that seagull occupies a higher trophic position in the environment than pigeon. However, the POP accumulation profiles in these species differed. Pigeon tends to accumulate more recently used POPs such as PBDEs than seagull. The high-brominated BDE congeners, γ-HBCDs and γ-HCH (also called lindane) were enriched in pigeon compared to seagull, implying the widespread use of Deca-BDE, technical HBCDs, and lindane in the terrestrial environment of South Korea. The different accumulation profile of POPs in both resident species would be related to their habitat difference and trophic positions. For urban resident bird such as pigeon, an intentional intake of dust or soils during feeding is likely to be an additional route of exposure to POPs. Resident birds generally accumulated higher POPs concentrations than migratory birds, the exceptions being relatively volatile compounds such as HCB, PeCB and HCHs.

Effect of yogic intervention on the autonomic nervous system in the patients with coronary artery disease: a randomized controlled trial

In this study 258 patients from the Department of Cardiology in Chhatrapati Shahuji Maharaj Medical University, Lucknow were selected to participate. All had been diagnosed with coronary artery disease. They were randomly divided into 2 groups, the yoga group and the non-yoga group, 129 in each group; 208 completed the study protocol. The yogic intervention consisted of 35-40 min/day, 5 days a week over a period of 18 months in the Department of Physiology. Autonomic function testing was done in both the groups at zero time and after 18 months. We observed a statistically significant reduction in body mass index, waist circumference, systolic and diastolic blood pressure, and heart rate (P < 0.05), i.e., a significant positive effect was observed when yoga therapy was used as an adjunct in patients with coronary artery disease.