Removal Of Environmental Pollutants Research Articles

Preparation of silica nanoparticle based polymer composites via mussel inspired chemistry and their enhanced adsorption capability towards methylene blue

The highly efficient removal of environmental pollutants from aqueous solution using low cost adsorbents has recently attracted great research attention.

Synthesis, Characterization, Fluorescence, Photocatalytic and Antibacterial Activity of CdS Nanoparticles Using Schiff Base.

Cadmium sulfide nanoparticles (CdS NPs) were successfully prepared using sonochemical method by employing Schiff-base, (2-[(4-methoxy-phenylimino)-methyl]-4-nitro phenol) as a complexing agent. Here, SB is used as a ligand to control the morphology of NPs. XRD patterns and TEM images show that the synthesized CdS NPs have cubic structures with a diameter of about 2-10 nm. The formation of CdS NPs and their optical, structure, thermal and morphologies were studied by means of UV-vis DRS, fluorescence, FTIR, zeta potential, XRD, SEM and TEM. The interactions between CdS NPs and SB were investigated in an aqueous solution using fluorescence spectroscopy. The fluorescence quenching studies suggest that SB quenches the fluorescence of CdS NPs effectively. The degradation kinetics of methyl red (MR) by the photocatalyst was followed by Langmuir-Hinshelwood model. The results revealed that photocatalytic degradation of MR by SB capped CdS NPs could be considered as a practical and reliable technique for the removal of environmental pollutants. The antibacterial activity of samples was evaluated against E. coli, S. aureus and P. aeruginosa and the results were compared. SB and SB capped CdS NPs could be a potential antibacterial compounds after further investigation.

ChemInform Abstract: Black Titanium Dioxide (TiO2) Nanomaterials

AbstractReview: 191 refs.

Photoelectrochemical Degradation of 17-β Estradiol Using a Photoanode Prepared with RuO2 Nanoparticles Supported over Graphene

The development of photoelectroactive materials has been a target of several researches on the removal of environmental pollutants. In this sense, the use of semiconductors materials with small band gap energies has been used as modifiers materials with photoelectrochemical properties providing visible light activation and decreasing the electron-hole recombination. Reduced graphene oxide (RGO) is a single layer of hybridized carbon atoms that has attracted attention due to their electronic and structural characteristics as a semiconductor type p. Besides RGO can act as a support for immobilization of several species. One special substance used as a RGO modifier is ruthenium oxide (RuO2) nanoparticles. These oxide are recognized for their excellent electrocatalytic activity for oxygenated species, and can be easily adsorb over RGO basal plane. It has been observed that RGO/RuO2 has the excellent catalytic properties for degradation of organic pollutants and can convert the solar light into hydrogen, as the concept of water splitting. Also, the system RGO/RuO2 makes a heterojunction p-n, decreasing the recombination electron-hole. The objective of this work is the synthesis, characterization and application of a photoanode based on a RuO2 supported on RGO for the photoelectrochemical degradation of 17β-estradiol. The material was prepared by a single mixture of RGO and ruthenium chloride in purified water. The mixture was kept under hydrothermal system assisted by microwave at 160 ºC during 15 minutes. Thus, a suspension containing 5.0 mg RGO/RuO2 in 1.0 mL of ethanol with 0.5 % of Nafion was dropped over a glassy carbon plate. The structural and morphologic characteristics of the RGO/RuO2 nanoparticles were carried out using transmission microscopy (TEM), X ray diffraction (DRX) and microanalysis using EDX. The structural and morphological characterization demonstrated that the RuO2 nanoparticles was well-dispersed over the RGO surface and the nanoparticles with monoclinic phase have an average diameter at 4.0 nm. The prepared material was electrochemical characterized using linear sweep voltammetry (LSV) in phosphate buffer solution pH 7.0 containing 50 µmol L-1 of 17β-estradiol. The LSV demonstrated that the RGO/RuO2 surface allowed a 17β-estradiol oxidation peak at 0.65 V vs. Ag/AgCl. The observed value of the current peak in presence of solar light increased in almost 2-fold compared with the photoanode in dark. The photoanodes were then used in a photoelectrochemical system on the oxidation 17β-estradiol under visible irradiation by a high Xe lamp (250 W). The hormone degradation was monitored by spectrophotometric, total organic carbon (TOC) measurements and liquid chromatography (HPLC). The best experimental conditions promoted a removal at 90.5 % of the 17β-estradiol after 180 minutes of photoelectrocatalytic treatment under pseudo first order kinetics. Therefore, the use of RGO/RuO2 as a material for development of photoelectrochemical method could be a promising alternative for the remediation of endocrine disruptor in environmental. Aknowledge: FAPESP

Synthesis of zeolite from marble powder waste: a greener approach and its application for the removal of inorganic metals from wastewater

The wastewater containing heavy metals, produced at various stages of operation in textile, printing, plastic, and paper-making industries, pose major hazards to the environment and the public health. Therefore, it is necessary that the pollutants should be treated before discharge by using highly efficient adsorbents. Zeolite is a potential material and can conveniently be processed as adsorbents for the removal of environmental pollutants. A wide range of commercial zeolite has been marketed but due to high cost it is of limited use. The present research offers a green approach for the application of zeolite synthesized by using marble powder waste as a precursor. The significance rests on the conversion of waste into a useful adsorbent marble zeolite (MZ). Zeolite is an environmental friendly, novel, and cost-effective adsorbent. In the current study, remediation of heavy metals in industrial wastewater is done using zeolite. The marble waste contains metals like Zn, Ni, Pb, Cr, Cd, and Cu in it and this waste itself also used as an adsorbent for removal of metals and its efficiency is ≥85%. The batch method has been employed for metal removal using different standard solutions at concentrations of 50–200 mg/L of individual metals (Zn, Ni, Pb, Cr, Cd, and Cu). The optimum removal efficiency is determined at 50 mg/L and the results depicted the performance of MZ (1 mg/kg) in removing inorganic pollutants upon adsorbate–adsorbent contact for 30 min, at lower dose of MZ. It was also found that the higher the induced concentration, the lesser the removal efficiency. It may be due to the limiting factor of adsorbent dose. The adsorbent was also applied on industrial effluents taken from textile and plastic factories at optimum studied conditions. The removal mechanism of metal ions followed adsorption and ion exchange processes. These results show that the MZ holds a great potential to remove heavy metals from industrial wastewater. The study recommends the reutilization of MZ as a potential adsorbent, which can greatly enhance the sustainability of useful resources.

New method for the adsorption of organic pollutants using natural zeolite incinerator ash (ZIA) and its application as an environmentally friendly and cost-effective adsorbent

Rapid development of civilization together with the evolution of industry has caused deep changes in the quality of the environment in which the human beings live. The enhancing demands for a healthy environment, particularly for the removal of pollutants from industrial and municipal wastewater, are a major reason to search for new materials. Zeolites are potential materials and can conveniently be used as adsorbents for the removal of environmental pollutants. The present research offers a green approach to investigate the removal efficiency of polyaromatic hydrocarbons and azo dyes from wastewater using zeolite derived from incinerator waste (ash) as an effective, economical, and environmentlly friendly suitable material as an adsorbent. The significance rests on the use of hazardous waste into a useful resource (adsorbent). Batch adsorption studies are conducted and results are analyzed by UV–vis spectrophotometer. The results depicted the performance of zeolite incinerator ash (1 mg/kg) in removing 98, 97, and 96% of anthracene, phenanthrene, and pyrene, respectively, and up to 90% removal of the dyes upon adsorbate–adsorbent contact for 10 min. Thus, the zeolite made from natural waste materials possess unique porous properties and offer promise for the removal of organic pollutants. The recovery ability can also be tested and evaluated to determine the reusability of the adsorbent. This is an additional benefit which reduces the need for extracting materials from the environment to be used in the industrial processes.

MICROEMULSIONS: COMPONENTS, CHARACTERISTICS, POTENTIALITIES IN FOOD CHEMISTRY AND OTHER APPLICATIONS

Microemulsions (MEs) are thermodynamically stable systems consisting of nanosized droplets dispersed in a solvent continuous medium (known as pseudo-phase), which is immiscible with the dispersed phase. These systems consist of water, a hydrophobic solvent called oil, an amphiphile and often, a co-surfactant that is normally a medium chain alcohol. A large number of publications describe the importance of MEs in many branches of chemistry, and there is an intensive search for new applications. In addition, MEs have been applied in many areas, including oil extraction, removal of environmental pollutants from soils and effluents, dissolution of additives in lubricants and cutting oils, cleaning processes, dyeing and textile finishing, as nanoreactors to obtain nanoparticles of metals, semiconductors, superconductors, magnetic and photographic materials, and latex. However, only some studies indicate the potential applications of MEs in food and even fewer evaluate their chemical behavior. Potential applications of MEs in food comprise dissolution of lipophilic additives, stabilization of nutrients and biologically active compounds, using as an antimicrobial agent and to maximize the efficiency of food preservatives. This work consists of a literature review focusing on composition and physical and chemical characteristics of microemulsions. Despite the small number of studies on the subject reported in the literature, we demonstrate some potential applications of MEs in food chemistry.

Black titanium dioxide (TiO2) nanomaterials.

In the past few decades, there has been a wide research interest in titanium dioxide (TiO2) nanomaterials due to their applications in photocatalytic hydrogen generation and environmental pollution removal. Improving the optical absorption properties of TiO2 nanomaterials has been successfully demonstrated to enhance their photocatalytic activities, especially in the report of black TiO2 nanoparticles. The recent progress in the investigation of black TiO2 nanomaterials has been reviewed here, and special emphasis has been given on their fabrication methods along with their various chemical/physical properties and applications.

Use of microalgae for the removal of environmental pollutants

In this mini review it is to focus that how can pollutants be removed from the environment by utilizing microalgae which are deliberately increasing and causing hazardous effects to our environment. Microalgae are sunlight-driven cell factories that convert carbon dioxide to potential biofuels, foods, feeds and high-value bioactives. Various types of pollutants continuously causing damage to the environment and after a long-term observation it is found that there is a best option of using microalgae in different techniques for reducing environmental pollutants. Since, versatile species of microalgae has been a part in reduction and removal of environmental pollutants as we observed in different bioremmedial techniques such as in waste water treatment plants, heavy metal removal techniques, bio-degradation of azo-dyes, phenol and other organic aromatic compounds which are dangerous to the environment. It is reappraised that one of microalgae specie which is named as chlorella vulgaris is found to be very effective in removing of heavy metals, waste water treatment and also in biodegradation of azo-dyes. This article basically explained the usefulness of using microalgae for the remediation of pollutants.

Efficient visible-light-driven photocatalytic degradation of nitrophenol by using graphene-encapsulated TiO2 nanowires

In this work, a new hybrid nanocatalyst, namely titanium dioxide (TiO2) composite nanowires, encapsulated with graphene (G) and palladium nanoparticles (Pd NPs) (designated as G-Pd@TiO2-CNWs), was prepared. In preparing the nanowires, a combination of electrospinning and hydrothermal approaches was employed. The visible-light-driven photocatalytic performance of G-Pd@TiO2-CNWs was investigated using the reduction of 4-nitrophenol (4-NP) as a model reaction. The results showed that G-Pd@TiO2-CNWs converted nearly 100% of 4-NP under visible light irradiation. The reaction kinetics of the photocatalytic reduction of 4-NP was studied by UV–vis spectrophotometry and the apparent rate constant was determined and compared with those for other supported TiO2 catalysts. Furthermore, the spent G-Pd@TiO2-CNWs could be recovered by simple centrifugation and reused. The work is expected to shed new light on the development of G-incorporated hybrid nanostructures for harvesting light energy and on the development of new photocatalysts for the removal of environmental pollutants.

Enhancing microwave absorption of TiO2 nanocrystals via hydrogenation

Abstract

Uncovering results in electro-scrubbing process toward green methodology during environmental air pollutants removal

Present findings uncovered the electro-scrubbing process as a green methodology. This green methodology was assessed by an analysis of electrode dissolution into an electrolyte and acid fumes emission to the atmosphere. As an initial experiment oxidation effect of Co(II) by PbO2 electrode revealed an enhanced oxidation efficiency of ∼20% compared to a Pt-coated Ti electrode. The mist concentration from the first scrubber test was approximately 30 times lower than that of the indoor air particles. In addition, molar mass of Co(II) and SEM analyses revealed no Co(II) or PbO2 from the first scrubber. An analysis of the second scrubber showed no Co(II), PbO2 or pH changes during a 24h study confirming that no sulphuric acid escaped from the first scrubber or mediator containing electrolyte solution. This electro-scrubbing process was applied to the air pollutants removal process, in which a definite ratio between Co(III) and odor gases at given concentrations were identified. These results show that this electro-scrubber can maintain its initial concentration of Co(II) and H2SO4 by just adding water, and is become a highly sustainable and green methodology system without a loss of H2SO4 and Co catalysts to the environment.

Optimized cryopreservation of mixed microbial communities for conserved functionality and diversity.

The use of mixed microbial communities (microbiomes) for biotechnological applications has steadily increased over the past decades. However, these microbiomes are not readily available from public culture collections, hampering their potential for widespread use. The main reason for this lack of availability is the lack of an effective cryopreservation protocol. Due to this critical need, we evaluated the functionality as well as the community structure of three different types of microbiomes before and after cryopreservation with two cryoprotective agents (CPA). Microbiomes were selected based upon relevance towards applications: (1) a methanotrophic co-culture (MOB), with potential for mitigation of greenhouse gas emissions, environmental pollutants removal and bioplastics production; (2) an oxygen limited autotrophic nitrification/denitrification (OLAND) biofilm, with enhanced economic and ecological benefits for wastewater treatment, and (3) fecal material from a human donor, with potential applications for fecal transplants and pre/probiotics research. After three months of cryopreservation at −80°C, we found that metabolic activity, in terms of the specific activity recovery of MOB, aerobic ammonium oxidizing bacteria (AerAOB) and anaerobic AOB (AnAOB, anammox) in the OLAND mixed culture, resumes sooner when one of our selected CPA [dimethyl sulfoxide (DMSO) and DMSO plus trehalose and tryptic soy broth (DMSO+TT)] was added. However, the activity of the fecal community was not influenced by the CPA addition, although the preservation of the community structure (as determined by 16S rRNA gene sequencing) was enhanced by addition of CPA. In summary, we have evaluated a cryopreservation protocol that succeeded in preserving both community structure and functionality of value-added microbiomes. This will allow individual laboratories and culture collections to boost the use of microbiomes in biotechnological applications.

Preparation of zeolite from incinerator ash and its application for the remediation of selected inorganic pollutants: A greener approach

Zeolites are potential materials and can conveniently be processed as adsorbents for the removal of environmental pollutants. A wide range of commercial zeolites have been marketed but due to high cost are of limited use. The present research offers a green approach for the synthesis of zeolite using Incinerator waste (ash) as precursor. The significance rests on the conversion of hazardous waste into a useful resource (adsorbent).Incinerator ash (IA) was converted hydrothermally under strongly alkaline conditions into zeolite (ZIA). The synthesized ZIA was applied as virgin adsorbent in batch mode for the removal of primary metal pollutants of Cadmium, Chromium and Lead. The residual concentration of each metal was analyzed on Flame Atomic Absorption Spectrophotometer. Each series of batch was conducted at four varying induced concentration of metal salts as a function of time. The synthesized adsorbent was characterized on FTIR spectrophotometer to assess the involvement of functional group in metal binding to adsorbent surface. The results depicted the performance of ZIA (1mg/Kg) in removing 99.5 %, 84% and 78% of Cadmium, Chromium and Lead, respectively, upon adsorbate-adsorbent contact for 30 minutes, at lower dose of ZIA. It was also found that higher is the induced concentration, less is the removal efficiency. It may be due to limiting factor of adsorbent dose. Correlation matrix suggests positive relationship of Pb and Cr, Pb and Cd, Cr and Cd. No negative correlation was found. The study recommends the reutilization of Incinerator ash as a potential adsorbent, which can greatly enhance the sustainability of useful resources.

Ionic liquids and deep eutectic mixtures: sustainable solvents for extraction processes.

In recent years, ionic liquids and deep eutectic mixtures have demonstrated great potential in extraction processes relevant to several scientific and technological activities. This review focuses on the applicability of these sustainable solvents in a variety of extraction techniques, including but not limited to liquid- and solid-phase (micro) extraction, microwave-assisted extraction, ultrasound-assisted extraction and pressurized liquid extraction. Selected applications of ionic liquids and deep eutectic mixtures on analytical method development, removal of environmental pollutants, selective isolation, and recovery of target compounds, purification of fuels, and azeotrope breaking are described and discussed.

Synthesis and application of TiO2 nanotubes in environmental pollutant removal

Abstract TiO2 nanotubes were synthesized at different hydrothermal temperatures: 110 °C, 130 °C, 150 °C, and 180 °C. The calcination of the titanate precursors at various temperatures governs TiO2 nanotube formation; the calcination temperatures were 300 °C, 500 °C, 700 °C, and 800 °C. It was observed that with the sample prepared at 130 °C and calcined at 500 °C only anatase formed, but with the sample calcined at 800 °C, both anatase and rutile formed. The obtained TiO2 nanotubes were characterized by means of X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, and Raman spectroscopy. Brunauer–Emmett–Teller analysis suggests that the TiO2 nanotubes prepared at a hydrothermal temperature of 130 °C and calcined at 500 °C have the highest surface area of 316.2 m2 g−1 of all samples. The synthesized TiO2 nanotubes were used as photocatalysts in the removal of the organic dye methylene blue from aqueous solution by UV irradiation.

Structural evolution from TiO2nanoparticles to nanosheets and their photocatalytic performance in hydrogen generation and environmental pollution removal

The rapid depletion of the fossil fuel reserves, and the increase of green-house gas emissions and other environmental pollutants, bring up an urgent need for the development of clean energy and sustainable environmental solutions. The ability to use sunlight to produce fuels such as H2 from abundant, non-toxic resources, and to decompose environmental pollutants with benign photocatalysts, would revolutionize our civilization. TiO2 has attracted substantial interest due to its activity for generating hydrogen from water under ultraviolet (UV) light irradiation. The discovery of (001) facet control with the fluoride additive in the reactants has triggered intensive studies for model photocatalysis. Here, we found that small TiO2 nanoparticles were formed at the very beginning stage of the reaction, then were transformed into large TiOF2 crystals, and finally turned into (001)-faceted TiO2 nanosheets. TiOF2 acted as a metastable intermediate medium in the transformation from TiO2 nanoparticles into (001)-faceted TiO2 nanosheets. The (001) face showed higher activity for the photocatalytic generation of hydrogen and the photodecomposition of methylene blue and rhodamine B. The synergic effect between TiOF2 and TiO2 nanosheets or nanoparticles further improved the photocatalytic activities. This study provides us with a promising solution for solving the energy and environment problems.

Hydrothermal Synthesis and Characterization of POM-Based Photocatalyst for Degradation of Pollutant Organic Dyes

The activated photocatalysts are urgently needed for the application of photocatalytic techniques in environmental pollutant removal. A POM - based photocatalyst with the chemical formula of (4, 4’-H2bpy)( 4, 4’-Hbpy)2[SiW12O40]·4H2O (1) has been hydrothermally synthesized and structurally characterized by the elemental analysis, and single crystal X-ray diffraction. Compound 1 consists of 4, 4’-bipyridine unit and keggin type polyoxometalates [SiW12O40]4-. There are hydrogen-bonding interactions between polyoxometalates, 4, 4’-bipyridine and water molecules in 1, forming a new 3-D networks. The degradation of rhodamine B (RhB) under UV-vis irradiation with 1 as the heterogeneous photocatalyst has been investigated, showing a good photocatalytic property of 1 for RhB degradation.

Sorption of nalidixic acid onto micrometric and nanometric magnetites: Experimental study and modeling

The sorption of nalidixic acid (NA) was studied onto three kinds of magnetite characterized by different particle sizes (from micrometric to nanometric) and surface properties. Experiments were performed under static batch and dynamic flow conditions. Obtained results indicate that kinetics and extent of sorption was strongly affected by the particle size of tested magnetites. Ionic strength effect was less significant suggesting that aggregation state of the magnetite particles did not affect the sorption. During kinetic sorption experiments, apparent rate constant normalized to solid mass was faster for nanosized magnetite while an opposite trend was observed for the surface area-normalized rate constants. Infrared data suggested the possibility of similar surface interactions on both microsized and nanosized magnetites. Transport of NA in magnetite-packed column was found associated to the instantaneous sorption without any significant effect of kinetic limitation. Breakthrough curves (BC) and sorption extent in columns were calculated by using Thomas, Yan and Yoon–Nelson models. Sorption capacities predicted by Thomas or Yan model were in good agreement with that determined by integrating total area above BC. However, Thomas model failed particularly to predict an accurate concentration at lower and higher time points of the BC. These findings have strong implications in relation to the transport and removal of environmental pollutants in natural and engineered systems.

Environmental pollutants removal from composting leachate using anaerobic biological treatment process

Aims: The main purpose of this study was to make an initial assessment on the possibility of anaerobic treatment of an extremely high strength leachate streams generated at Isfahan composting plant. Materials and Methods: In this interventional study, the pretreated composting leachate was fed intermittently to a anaerobic sequencing batch reactor (ASBR) at increasing steps of 6 g chemical oxygen demand (COD)/l.day (hydraulic retention time [HRT] =23 h), 33 g COD/l.day (HRT = 18 h), and finally 36.5 g COD/l.day (HRT = 12 h) for about 10 months. Reactor performance was investigated by measuring pH, total suspended solids (TSS), electrical conductivity, biogas production, COD, and TSS removal twice a week. Results: In pretreated composting leachate, biochemical oxygen demand 5/COD ratio was ranged 0.64-0.8. The pH value in ASBR was between 7.47 and 8.15 without any pH adjustment throughout the study. Conclusion: Although in loading rate of 11 g/l.day, most of the pollutants were decreased significantly, but aerobic process is required to ensure achieving national standard values for discharge in receiving waters.