Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990-2021: a systematic analysis for the Global Burden of Disease Study 2021

BACKGROUND

Regular, detailed reporting on population health by underlying cause of death is fundamental for public health decision making. Cause-specific estimates of mortality and the subsequent effects on life expectancy worldwide are valuable metrics to gauge progress in reducing mortality rates. These estimates are particularly important following large-scale mortality spikes, such as the COVID-19 pandemic. When systematically analysed, mortality rates and life expectancy allow comparisons of the consequences of causes of death globally and over time, providing a nuanced understanding of the effect of these causes on global populations.

METHODS

The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 cause-of-death analysis estimated mortality and years of life lost (YLLs) from 288 causes of death by age-sex-location-year in 204 countries and territories and 811 subnational locations for each year from 1990 until 2021. The analysis used 56 604 data sources, including data from vital registration and verbal autopsy as well as surveys, censuses, surveillance systems, and cancer registries, among others. As with previous GBD rounds, cause-specific death rates for most causes were estimated using the Cause of Death Ensemble model-a modelling tool developed for GBD to assess the out-of-sample predictive validity of different statistical models and covariate permutations and combine those results to produce cause-specific mortality estimates-with alternative strategies adapted to model causes with insufficient data, substantial changes in reporting over the study period, or unusual epidemiology. YLLs were computed as the product of the number of deaths for each cause-age-sex-location-year and the standard life expectancy at each age. As part of the modelling process, uncertainty intervals (UIs) were generated using the 2·5th and 97·5th percentiles from a 1000-draw distribution for each metric. We decomposed life expectancy by cause of death, location, and year to show cause-specific effects on life expectancy from 1990 to 2021. We also used the coefficient of variation and the fraction of population affected by 90% of deaths to highlight concentrations of mortality. Findings are reported in counts and age-standardised rates. Methodological improvements for cause-of-death estimates in GBD 2021 include the expansion of under-5-years age group to include four new age groups, enhanced methods to account for stochastic variation of sparse data, and the inclusion of COVID-19 and other pandemic-related mortality-which includes excess mortality associated with the pandemic, excluding COVID-19, lower respiratory infections, measles, malaria, and pertussis. For this analysis, 199 new country-years of vital registration cause-of-death data, 5 country-years of surveillance data, 21 country-years of verbal autopsy data, and 94 country-years of other data types were added to those used in previous GBD rounds.

FINDINGS

The leading causes of age-standardised deaths globally were the same in 2019 as they were in 1990; in descending order, these were, ischaemic heart disease, stroke, chronic obstructive pulmonary disease, and lower respiratory infections. In 2021, however, COVID-19 replaced stroke as the second-leading age-standardised cause of death, with 94·0 deaths (95% UI 89·2-100·0) per 100 000 population. The COVID-19 pandemic shifted the rankings of the leading five causes, lowering stroke to the third-leading and chronic obstructive pulmonary disease to the fourth-leading position. In 2021, the highest age-standardised death rates from COVID-19 occurred in sub-Saharan Africa (271·0 deaths [250·1-290·7] per 100 000 population) and Latin America and the Caribbean (195·4 deaths [182·1-211·4] per 100 000 population). The lowest age-standardised death rates from COVID-19 were in the high-income super-region (48·1 deaths [47·4-48·8] per 100 000 population) and southeast Asia, east Asia, and Oceania (23·2 deaths [16·3-37·2] per 100 000 population). Globally, life expectancy steadily improved between 1990 and 2019 for 18 of the 22 investigated causes. Decomposition of global and regional life expectancy showed the positive effect that reductions in deaths from enteric infections, lower respiratory infections, stroke, and neonatal deaths, among others have contributed to improved survival over the study period. However, a net reduction of 1·6 years occurred in global life expectancy between 2019 and 2021, primarily due to increased death rates from COVID-19 and other pandemic-related mortality. Life expectancy was highly variable between super-regions over the study period, with southeast Asia, east Asia, and Oceania gaining 8·3 years (6·7-9·9) overall, while having the smallest reduction in life expectancy due to COVID-19 (0·4 years). The largest reduction in life expectancy due to COVID-19 occurred in Latin America and the Caribbean (3·6 years). Additionally, 53 of the 288 causes of death were highly concentrated in locations with less than 50% of the global population as of 2021, and these causes of death became progressively more concentrated since 1990, when only 44 causes showed this pattern. The concentration phenomenon is discussed heuristically with respect to enteric and lower respiratory infections, malaria, HIV/AIDS, neonatal disorders, tuberculosis, and measles.

INTERPRETATION

Long-standing gains in life expectancy and reductions in many of the leading causes of death have been disrupted by the COVID-19 pandemic, the adverse effects of which were spread unevenly among populations. Despite the pandemic, there has been continued progress in combatting several notable causes of death, leading to improved global life expectancy over the study period. Each of the seven GBD super-regions showed an overall improvement from 1990 and 2021, obscuring the negative effect in the years of the pandemic. Additionally, our findings regarding regional variation in causes of death driving increases in life expectancy hold clear policy utility. Analyses of shifting mortality trends reveal that several causes, once widespread globally, are now increasingly concentrated geographically. These changes in mortality concentration, alongside further investigation of changing risks, interventions, and relevant policy, present an important opportunity to deepen our understanding of mortality-reduction strategies. Examining patterns in mortality concentration might reveal areas where successful public health interventions have been implemented. Translating these successes to locations where certain causes of death remain entrenched can inform policies that work to improve life expectancy for people everywhere.

FUNDING

Bill & Melinda Gates Foundation.

Flower shaped Bi2O2.33/Bi2WO6 composite: An efficient photocatalyst for degradation of methylene blue from aqueous solution in direct solar light

Herein, we synthesized a Bi2O2.33/Bi2WO6 heterostructure as a platform for the degradation of methylene blue (MB) dye in an aqueous phase. The heterostructure was synthesized by facile ultrasonicated assisted solvothermal method. Various structural, morphological and other techniques such as XRD, FTIR, PL, EIS, UV-DRS, FESEM, HRTEM, XPS, EPR, TGA, BET surface area were used to analyze the characteristics of as-synthesized Bi2O2.33/Bi2WO6. The morphological studies revealed the deposition of Bi2O2.33 flowers in high density on Bi2WO6. Under solar irradiation, 98.6% degradation of MB was achieved in 190 min at optimal conditions (pH = 5, catalyst dose = 0.35 gL-1 and MB concentration = 10 mgL-1). The improved photocatalytic ability of composite in contrast to Bi2O2.33 and Bi2WO6 could be usually ascribed to the interface created between them, assisting the charge transfer. Based on the findings of radical trapping experiments, the charge transfer process over the photocatalyst was completely studied. Additionally, the present heterostructure demonstrated good recyclability over five runs. In nutshell, this study provided a facile approach for synthesizing solar light driven photocatalyst for degradation of methylene blue in aqueous phase and can further explored to be utilized for varied environmental remediation.

Solar-light-driven photocatalytic degradation of pharmaceutical pollutants utilizing 2D g-C3N4/BiOCl composite

Pharmaceuticals, which have been praised for protecting countless lives, have become a new category of environmental pollutants in recent decades as most of these pharmaceutical compounds are discovered in water bodies in concentrations ranging from ng/L to mg/L. Recently, metal-free g-C₃N₄ (GCN)-based composites have received considerable attention for the degradation of pharmaceutical compounds. In this study, GCN/BiOCl composite was prepared using a simple ultrasonication-assisted stirring method and characterized using various analytical and spectroscopic techniques including XRD, FTIR, PL, Elemental mapping, UV-DRS, FESEM, HRTEM, and TGA. The as-prepared composite was utilized to degrade levofloxacin (LVX) under solar light irradiation and showed excellent stability for the degradation of LVX. Furthermore, the universality of the GCN/BiOCl composite was investigated by degrading diverse pharmaceuticals such as ofloxacin (OFX), norfloxacin (NOX), ciprofloxacin (COX), and ketorolac tromethamine (KTC) in an aqueous phase. Therefore, this work provides an effective method to degrade pharmaceutical contaminants simultaneously in water using GCN/BiOCl composite.

Highly fluorescent nickel based metal organic framework for enhanced sensing of Fe3+ and Cr2O72- ions

Heavy metal contamination has sparked widespread concern among the populace. The significant issues necessitate the creation of high-performance fluorescent pigments that can identify harmful elements in water. The present study deals with metal organic framework [MOF] based on nickel [Ni-BDC MOF]. The Ni-BDC MOF was prepared by facile solvothermal method using nickel nitrate hexahydrate and terephthalic acid ligand as precursors. The MOF was characterized by various techniques in order to examine the crystal, morphological, structural, composition, thermal and optical properties. The detailed characterizations revealed that the synthesized Ni-BDC MOF are well-crystalline with high purity and possessing 3D rhombohedral microcrystals with rough surface. The MOF demonstrate good luminescence performance and excellent water stability. According to the Stern Volmer plot, the tests set up under optimized conditions demonstrate a linear correlation between the fluorescence intensity and concentration of both ions, i.e. Fe³⁺, and Cr₂O₇^2- ions. The linear range and detection limit for Fe³⁺ and Cr₂O₇^2- were found to be 0-1.4 nM and 0.159 nM, and 0-1 nM and 0.120 nM, respectively. The mechanisms for the selective detection of cations and anions were also explored. The recyclability for the prepared MOF was checked up to five cycles which showed excellent stability with just a slight reduction in efficiency. The constructed sensor was also used to assess the presence of Fe³⁺ and Cr₂O₇^2- ions in actual water samples. The results of the different experiments revealed that the prepared MOF is a good material for detecting Fe³⁺ and Cr₂O₇^2- ions.

Construction of multifunctional NH2-UiO-66 metal organic framework: sensing and photocatalytic degradation of ketorolac tromethamine and tetracycline in aqueous medium

Existence of pharmaceutical residues in water has endangered environmental pollution worldwide, which makes it ineludible to develop prospective bifunctional materials which not only possess excellent fluorescence behaviour to monitor pharmaceuticals but also exhibit simultaneous photocatalytic removal efficiency. Strengthened by functionalized metal organic framework (MOF) materials, we present here an amine functionalized zirconium-based MOF NH₂-UiO-66 which has been successfully synthesized using solvothermal approach. The as prepared MOF was subjected to numerous structural, morphological and compositional characterizations. Interestingly, featured by the excellent fluorescent intensity of MOF modulated by LMCT effect, NH₂-UiO-66 was screened to detect pharmaceutical compounds with KTC and TC in aqueous solution. The prepared functionalized MOF showcased excellent sensing platform with magnificent response range (0‒3 µM), lower limit of detection (160 nM; KTC and 140 nM; TC), excellent selectivity and influential anti-interference capability. More importantly, the practical utility of the proposed sensor was further explored for the determination of pharmaceutical drugs in real water samples with suitable recoveries. Simultaneously, the synthesized MOF also exhibited high photocatalytic efficiency towards the removal of KTC and TC under solar light irradiation. The degradation efficiency for KTC and TC was found to be 68.3% and 71.8% within 60 and 280 min of solar light, respectively. Moreover, excellent recyclability was demonstrated by the current synthesized system over five cycles. Overall, this study presents a feasible route for the utilization of functionalized MOFs as potential dual functional materials towards the simultaneous detection and degradation of specific pharmaceuticals from aqueous medium.

Adsorptive removal of antibiotic ofloxacin in aqueous phase using rGO-MoS2 heterostructure

This paper reports the synthesis, characterization and detailed adsorption studies of rGO-MoS₂ heterostructure. The heterostructure was explored for the adsorption of ofloxacin from the aqueous phase. Detailed studies were conducted to study the effect of crucial parameters such as pH of drug solution, adsorbent dose, temperature and initial drug concentration on the adsorption capacity. Even with a low surface area of 17.17 m²/g, the adsorbent exhibited maximum removal efficiency of 95% at a dose of 0.35 g/L and an initial drug concentration of 10 mg/L in 240 min. Thermodynamic study revealed the values for ∆H⁰ and ∆G⁰ to be - 101.15 and - 7.47 kJ/mol respectively, indicating that the process is spontaneous and exothermic in nature. The heterostructure adsorbent exhibited remarkable reusability and stability up to five cycles. The heterostructure combines excellent adsorption capabilities arising from the two-dimensional structures of rGO and MoS₂ with the stronger and more specific interaction with the drug molecules which results in better performance towards the removal of the drug. The excellent performance of the heterostructure indicates that combining 2D materials can be a good strategy for producing highly efficient materials towards the adsorptive removal of pollutants.

Dataset on aqueous solid-liquid extraction of gossypol from defatted cottonseed in acidic medium using green solvent, its kinetics and thermodynamics study and mass transfer effects

Extraction of gossypol from cottonseed is essentially required to produce cottonseed free from gossypol for animal feed and or human applications. The focus of the present research was to determine the percentage gossypol extraction after extracting the defatted cottonseed using environment friendly green solvent ethanol-water (95:5 v/v) acidified with 0.5 M oxalic acid. The cottonseed samples were taken according to the fixed solvent to seed ratio and were extracted in batch process using round bottom flasks maintained at required temperatures for different extraction times ranging from 5 to 180 mins. After extraction the samples were filtered and dried and subjected to total gossypol analysis using BIS method. One factor at a time (OFAT) experimental design was employed to optimize the different process parameters like acid type and concentration, solvent to seed ratio, temperature and contact time. The obtained data was studied for analysis of kinetics of extraction using three different kinetic models, calculation of activation energy, evaluating values of kinetic parameters and thermodynamic parameters. The data was also analyzed for evaluation of mass transfer effects viz. liquid film diffusion and internal solid diffusion and calculation of diffusion rate constants for the extraction of gossypol from cottonseed. The present dataset demonstrated the analysis of experimental data for determining the type of kinetics, thermodynamic parameters and mass transfer effects of the solvent extraction for future researchers.

Highly photoluminescent and pH sensitive nitrogen doped carbon dots (NCDs) as a fluorescent sensor for the efficient detection of Cr (VI) ions in aqueous media

Fluorescent carbon dots (CDs) are contemporary class of fluorescent materials that has emerged recently and have gathered increasing attention due to its excellent properties as compared to traditional semiconductor quantum dots. CDs have lucrative benefits of less toxicity, biocompatibility, eco friendliness, tunable fluorescence, high chemical and photostability, effortless synthesis routes and uncomplicated surface modifications and functionalization. In the present work, nitrogen-doped carbon dots (NCDs) were prepared by a facile hydrothermal process using l-ascorbic acid and ethylene diamine as precursors. The as-prepared NCDs were hydrophilic in nature and could remain stable for several weeks. NCDs displayed bright blue fluorescence under UV light irradiation and also exhibited an extensive range of emission spectra in the visible region to infra-red region based upon the excitation wavelength. NCDs possessed quasi-spherical morphology and high density growth. NCDs were further utilized as nanoprobes for the pH sensing and proficient sensitive and selective detection of chromium (VI) ions present in aqueous phase. Under augmented modifications and conditions, the photoluminescence intensity of NCDs against various micromolar concentration of chromium (VI) ions presented a linear relationship, as per Stern-Volmer equation. The calibration curve was found to be linear in the range of 0-4 μM and from the slope of the linear curve, the limit of detection (LOD) was calculated to be 2.598 nM. The Stern-Volmer calibration curve was also plotted against different temperatures, verifying static quenching mechanism. Therefore, the as synthesized NCDs can be successfully demonstrated for the efficient pH sensing and the detection of Cr (VI) ions.

Efficient Conversion of Glucose into Fructose via Extraction-Assisted Isomerization Catalyzed by Endogenous Polyamine Spermine in the Aqueous Phase

In the present study, natural polyamine spermine is demonstrated as a potential basic catalyst for glucose-to-fructose isomerization. For instance, spermine achieves a decent fructose yield (30% wt) and selectivity (74%) during the single-step aqueous phase isomerization under the modest operating conditions (100 °C for 15 min). In addition to the expected reaction byproduct monosugar mannose, spermine also assists in the synthesis of rare and important monosugar, that is, psicose up to 4% wt. Psicose is a zero calorie rare sugar, exhibits a low caloric value, and possesses anti-adipogenic property. A comparative study involving other polyamines concluded that the presence of 20 amines tends to exhibit the most significant impact in improving the target product yield by releasing a higher number of OH- ions, which are responsible for isomerization through the formation of an enediol anion. An attempt was made to further improve the fructose yield through the addition of neutral salts, but it promoted a meager achievement. In an alternate study, a selective extraction strategy was followed for the isolation of fructose from the reaction mixture. The employed aryl monoboronic acid remarkably improved the net fructose concentration, that is, fructose productivity up to 75% wt (cumulative) and 70% selectivity within three consecutive extractions and isomerization cycles, which is comparatively three times shorter than that reported in the literature. Notably, spermine itself provided the essential and necessary basic environment for selective fructose extraction and glucose isomerization, ruling out the use of any external reagents and thus establishing itself as a versatile material suitable for a typical isomerization reaction in an upscaled reactor.

Untangling the active sites in the exposed crystal facet of zirconium oxide for selective hydrogenation of bioaldehydes

A quantitative yield of furfuryl alcohol from furfural in isopropanol was achieved with ZrO₂ having monoclinic phase with a maximum exposed (−111) facet, whereas ZrO₂ possessing predominantly tetragonal phase yielded only 8.0% of furfuryl alcohol.

Solar light active silver/iron oxide/zinc oxide heterostructure for photodegradation of ciprofloxacin, transformation products and antibacterial activity

This paper reports on the multitasking potential of a silver/iron oxide/zinc oxide (Ag/Fe₂O₃/ZnO) heterostructure, which was used for the photocatalytic decomposition of ciprofloxacin (CPX) and bacterial disinfection. The Ag/Fe₂O₃/ZnO heterostructure was successfully prepared using a facile precipitation method, and characterization results showed interesting structural, morphological, compositional and luminescent properties. The morphological results of the prepared heterostructure confirmed the deposition of Ag nanoparticles onto the surface of ZnO nanoplates and Fe₂O₃ nanorods. Treatment studies showed that the Ag/Fe₂O₃/ZnO heterostructure had superior solar light driven photocatalytic activity towards CPX degradation (76.4%) compared to bare Fe₂O₃ nanorods (43.2%) and ZnO nanoplates (63.1%), Ag/Fe₂O₃ (28.2%) and Ag/ZnO (64.5%) under optimized conditions (initial CPX concentration: 10 mg/L; pH 4; catalyst loading: 0.3 g/L). Reactive species study confirmed the roles of e^-, h⁺, OH and O₂^- in the photocatalytic degradation process. This photocatalytic behaviour of the Ag/Fe₂O₃/ZnO heterostructure could be attributed to the improved full solar spectrum harvesting capacity, separation of charge carriers and migration of e^-/h⁺ across the heterostructure interface. In addition, the Ag/Fe₂O₃/ZnO heterostructure also showed good antibacterial activity against Escherichia coli (E. coli) under both dark and visible light conditions. This might be due to generation of reactive oxygen species during the reaction. To the best of our knowledge, this is the first study till date on the utilization of Ag/Fe₂O₃/ZnO heterostructure for the photocatalytic degradation of CPX and E. coli bacteria disinfection. Therefore, this work offers an attractive path to design ZnO-based ternary heterostructures for solar-driven applications in wastewater remediation.

Rapid Solar-Light Driven Superior Photocatalytic Degradation of Methylene Blue Using MoS₂-ZnO Heterostructure Nanorods Photocatalyst

Herein, MoS₂-ZnO heterostructure nanorods were hydrothermally synthesized and characterized in detail using several compositional, optical, and morphological techniques. The comprehensive characterizations show that the synthesized MoS₂/ZnO heterostructure nanorods were composed of wurtzite hexagonal phase of ZnO and rhombohedral phase of MoS₂. The synthesized MoS₂/ZnO heterostructure nanorods were used as a potent photocatalyst for the decomposition of methylene blue (MB) dye under natural sunlight. The prepared MoS₂/ZnO heterostructure nanorods exhibited ~97% removal of MB in the reaction time of 20 min with the catalyst amount of 0.15 g/L. The kinetic study revealed that the photocatalytic removal of MB was found to be in accordance with pseudo first-order reaction kinetics with an obtained rate constant of 0.16262 min-1. The tremendous photocatalytic performance of MoS₂-ZnO heterostructure nanorods could be accredited to an effective charge transportation and inhibition in the recombination of photo-excited charge carriers at an interfacial heterojunction. The contribution of active species towards the decomposition of MB using MoS₂-ZnO heterostructure nanorods was confirmed from scavenger study and terephthalic acid fluorescence technique.

Expeditious isomerization of glucose to fructose in aqueous media over sodium titanate nanotubes

Isomerization reaction of glucose to fructose over sodium titanate nanotubes (Na-TNTs) as a Lewis base catalyst was studied. Analytical instruments recorded the specific structural, textural and basic properties of the as-synthesized Na-TNTs. Furthermore, studying the catalytic isomerization performance of the Na-TNTs confirmed their high catalytic efficiency and suitability in aqueous media. The catalyst prompted rapid glucose isomerization within 2 min by achieving nearly half of the maximum yield, whereas with a prolonged reaction up to 15 min the maximum glucose conversion could be reached with 31.26% fructose yield and 65.26% selectivity under relatively lower operating conditions (100 °C and 10% wt catalyst dose). However, the recyclability performance of the catalyst was not impressive due to the accelerated leaching of cations and surface retention of carbonaceous content, resulting in ∼16% reduced yield after 4 runs. A simple regeneration technique using NaOH led to the initial catalytic activity being totally regained. Overall, a titania-based catalyst (preferably nanotube structured sodium titanate) was shown as a potential catalyst for large-scale demonstration of glucose isomerization to achieve high fructose productivity.

Recycling of Waste Poly(ethylene terephthalate) Bottles by Alkaline Hydrolysis and Recovery of Pure Nanospindle-Shaped Terephthalic Acid

Poly(ethylene terephthalate) (PET) is a versatile engineering plastic which exhibits exceptional mechanical and thermal properties. Huge amounts of PET are consumed in various industries such as food packaging industry, textile industry, in the manufacturing of audio, video tapes and X-ray films and so on. But due to its substantial fraction by volume in water bodies and its high persistence to the atmospheric and biological agents, it could be considered as a hazard substance. Thereby chemical recycling of PET serves as a solution to solid waste problem as it transforms PET into its monomers via hydrolysis. Chemical recycling of post consumed waste PET bottles via alkaline hydrolysis is the main aim of this paper. Operating parameters such as reaction time and temperature were optimized for the conversion of PET into nanospindle-shaped terephthalic acid (TPA). Depolymerization of PET was carried out via alkaline hydrolysis by varying reaction time and temperature and maximum yield of 92% was obtained at 200 °C with reaction time of 25 minutes. The formed TPA nanospindles were further characterized in detail which exhibited high crystallinity, purity and fascinating thermal and surface properties.

Nanocuboidal-shaped zirconium based metal organic framework for the enhanced adsorptive removal of nonsteroidal anti-inflammatory drug, ketorolac tromethamine, from aqueous phase

Nanocuboidal-shaped zirconium based metal organic framework (UiO-66) was synthesized and used for enhanced adsorptive removal (729.92 mg g⁻¹) of ketorolac tromethamine drug.

Solar light driven photocatalytic degradation of levofloxacin using TiO2/carbon-dot nanocomposites

This paper reports the synthesis of TiO₂ quantum dots, carbon dots (C-dots), and TiO₂/C-dots using facile sol–gel and hydrothermal methods.

A fluorescent probe based on nitrogen doped graphene quantum dots for turn off sensing of explosive and detrimental water pollutant, TNP in aqueous medium

This paper reports the carbonization assisted green approach for the fabrication of nitrogen doped graphene quantum dots (N-GQDs). The obtained N-GQDs displayed good water dispersibility and stability in the wide pH range. The as synthesized N-GQDs were used as a fluorescent probe for the sensing of explosive 2,4,6-trinitrophenol (TNP) in aqueous medium based on fluorescence resonance energy transfer (FRET), molecular interactions and charge transfer mechanism. The quenching efficiency was found to be linear in proportion to the TNP concentration within the range of 0-16μM with detection limit (LOD) of 0.92μM. The presented method was successfully applied to the sensing of TNP in tap and lake water samples with satisfactory results. Thus, N-GQDs were used as a selective, sensitive and turn off fluorescent sensor for the detection of perilous water contaminant i.e. TNP.

Visible light driven photocatalytic degradation of fluoroquinolone levofloxacin drug using Ag2O/TiO2 quantum dots: a mechanistic study and degradation pathway

Ag₂O/TiO₂ QDs exhibited a photocatalytic activity of 81% for the degradation of levofloxacin under visible light, which is higher than those of commercially available catalysts.

Removal of ofloxacin from aqueous phase using Ni-doped TiO2 nanoparticles under solar irradiation

Ni-doped TiO2 nanoparticles were prepared using hydrothermal method and characterized by means of XRD, TEM, and TGA. The detailed characterization results revealed that the catalyst possessed spherical morphology and excellent crystalline and thermal properties. Photocatalytic capability of Ni-doped TiO2 nanoparticles was estimated by means of ofloxacin degradation under solar light. About 70% degradation of ofloxacin (25 mg/L, natural pH) was obtained with 1 g/L catalyst dose. The microbiological analysis was carried by examining its antibacterial activity against E. coli culture on agar plate. The results indicated a decrease in antibacterial activity of drug solution with increase in irradiation time, which further supported the excellent catalytic behavior of the prepared Ni-doped TiO2.

Metal assisted approach to develop molecularly imprinted mesoporous material exhibiting pockets for the fast uptake of diethyl phthalate as copper complex

A new molecularly imprinted mesoporous material (MIM) containing specific pockets for the extraction of diethyl phthalate (DEP) as copper complex has been prepared for the first time. The mesoporous material was developed by utilizing copper-phthalate complex (Cu-DEP) as the template molecule, 3-aminopropyltriethoxysilane (APS) as a functional monomer and tetraethoxyorthosilicate (TEOS) as the silica source for polymer network formation. The mesoporous material showed fast uptake kinetics, and equilibrium was obtained within 30 min due to the introduction of copper, which provides an additional site for interaction with the functional monomer. Synthesized polymer was well characterized using UV-Vis spectrophotometry, IR spectroscopy, TGA studies, and TEM. To achieve efficient extraction of the template molecule, various factors including sorption kinetics, quantity of MIM, time required for equilibrium set-up, sorption isotherm and reuse of MIM were optimized. The extracted DEP samples were analyzed quantitatively at 310 nm using an HPLC-DA system. The prepared material is robust and can be reused. In addition, it was found to be selective for DEP as compared to other phthalates.

The visible light-driven photocatalytic degradation of Alizarin red S using Bi-doped TiO2 nanoparticles

Ultrasonic assisted sol–gel synthesized Bi-doped TiO₂ mesoporous nanoparticles with a good crystallinity and high surface area were prepared. The 1% Bi-doped TiO₂ catalyst showed the highest photocatalytic activity under visible light.

Photocatalytic degradation of the antibiotic levofloxacin using highly crystalline TiO2 nanoparticles

Highly crystalline TiO₂ (anatase) nanoparticles were synthesized by a facile sol–gel method for the photocatalytic degradation and inhibition of the commonly used antibiotic drug, levofloxacin.

Facile growth and characterization of TiO2 nanoparticles for photocatalytic degradation of 2,3-dichlorophenol: experimental optimization and comparison with commercial TiO2

This paper reports the facile synthesis and characterizations of TiO2 nanoparticles by simple sol-gel ultrasonication followed by annealing process. The prepared nanoparticles were characterized in terms of their morphological and structural properties and utilized as efficient photocatalyst for the photocatalytic degradation of 2,3-dichlorophenol (2,3-DCP). The as-synthesized TiO2 nanoparticles were annealed at 350 degrees C for various time intervals (3-5 h) and by morphological and photocatalytic performances, it was found that the nanoparticles annealed for 5 hrs exhibits best morphological and photocatalytic properties. To optimize the photocatalytic reaction parameters, several experiments based on catalyst dose (0.25-1.00 g/L), pH of the solution (pH = 3-11) and initial concentration (10-100 mg/L) have been performed using commercially available TiO2 (PC-105). Under optimized conditions, the photocatalytic performance of synthesized TiO2 nanoparticles and TiO2 (PC-105) was compared and it was found that the synthesized nanoparticles exhibits better photocatalytic properties as compared to the commercially available TiO2 (PC-105).

Studies on TiO(2)/ZnO photocatalysed degradation of lignin

The photocatalytic degradation of lignin obtained from wheat straw kraft digestion has been investigated by using TiO(2) and ZnO semiconductors. ZnO has been found to be a better photocatalyst than TiO(2). The different variables studied, include catalyst dose, solution pH, oxidant concentration and initial concentration of the substrate. The degradation of lignin was favorable at pH 11. Optimum values of catalyst dose and oxidant concentration were found to be 1g/l and 12.2 x 10(-6) M, respectively. The degradation of the organic compound was also evaluated as COD removal and increase in the COD removal was observed with increase in degradation rate. An attempt has also been made to explore the applicability of ZnO in immobilized mode for the degradation of lignin under solar light for industrial scale application. Further the comparative evaluation of ZnO in slurry/immobilized mode has been carried out.

Studies on photodegradation of two commercial dyes in aqueous phase using different photocatalysts

The present study involves the photocatalytic degradation of Methyl Orange (MO) and Rhodamine 6G (R6G), employing heterogeneous photocatalytic process. Photocatalytic activity of various semiconductors such as titanium dioxide (TiO(2)), zinc oxide (ZnO), stannic oxide (SnO(2)), zinc sulphide (ZnS) and cadmium sulphide (CdS) has been investigated. An attempt has been made to study the effect of process parameters viz., amount of catalyst, concentration of dye and pH on photocatalytic degradation of MO and R6G. The experiments were carried out by irradiating the aqueous solutions of dyes containing photocatalysts with UV and solar light. The rate of decolorization was estimated from residual concentration spectrophotometrically. Similar experiments were carried out by varying pH (2-10), amount of catalyst (0.25-2.0g/l) and initial concentration of dye (5-200mg/l). The experimental results indicated that the maximum decolorization (more than 90%) of dyes occurred with ZnO catalyst and at basic pH and the maximum adsorption of MO was noticed at pH 4 and of R6G at pH 10. The percentage reduction of MO and R6G was estimated under UV/solar system and it was found that COD reduction takes place at a faster rate under solar light as compared to UV light. In case of R6G, highest decolorizing efficiency was achieved with lower dose of catalyst (0.5g/l) than MO (1g/l) under similar conditions. The performance of photocatalytic system employing ZnO/solar light was observed to be better than ZnO/UV system.