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1.
Int J Biol Macromol ; 262(Pt 2): 130239, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38367788

RESUMO

Herein, cellulose nanocrystals were synthesized from oil palm fronds (CNC-OPF) involving two pretreatment approaches, viz. autohydrolysis and soda pulping. The pretreatments were applied individually to OPF fibers to assess their influence on CNCs' physicochemical and thermal properties. CNC-OPF samples were assessed using complementary characterization techniques, which confirmed their purity and characteristics. CP/MAS 13C NMR and TEM studies revealed that autohydrolysis pretreatment yielded CNCs with effective hemicellulose and extractives removal compared to that of soda pulping. XRD analysis demonstrated that autohydrolysis-treated CNC-OPF contained a much higher crystallinity index compared to soda pulping treatment. BET measurement disclosed a relatively higher surface area and wider pore diameter of autohydrolysis-treated CNC-OPF. Autohydrolysis-treated CNCs were applied as a reinforcement filler in alginate-based hydrogel beads for the removal of 4-chlorophenol from water, which attained a qmax of 19.168 mg g-1. BET analysis revealed the less porous nature of CNC-ALG hydrogel beads which could have contributed to hydrogel beads' relatively lower adsorption capacity. The point of zero charge of CNC-ALG hydrogel beads was 4.82, suggesting their applicability only within a short solution pH range. This study directs future studies to unveil the possibilities of functionalizing CNCs in order to enhance the adsorption performance of CNC-immobilized hydrogel beads towards 4-chlorophenol and other organic contaminants.


Assuntos
Clorofenóis , Nanopartículas , Celulose/química , Hidrogéis/química , Nanopartículas/química
2.
Photochem Photobiol Sci ; 23(2): 245-256, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38105417

RESUMO

In photocatalytic removal of organic pollutants, adsorption and degradation are two important processes that take place. Various instrumental techniques and trapping experiments have been used to identify the reactive species and the mechanism of photodegradation. The present work focuses on investigating the mechanism of photo-induced degradation from the comparative characterization of fresh and used samples, isotherm models, competitive adsorption, and desorption studies of pure and Ag+-modified TiO2 NPs. The comparative characterizations of fresh and used NPs were carried out with FT-IR, EDX, and XRF analyses after methylene blue (MB) degradation. The Ag+ doped TiO2 used in this study was fabricated using simple impregnation technique. The prepared NPs were characterized using techniques including XPS, XRD, SEM/EDX, XRF, UV-DRS, and pH point-zero charge analyses (pHPZC). The Ag+-modified TiO2 NPs showed improved efficiency compared to pure TiO2 NPs using normal compact fluorescent light (CFL). The Langmuir and Freundlich isotherm models were applied to test the adsorption behavior on the surface photocatalysts. The investigational data finest fitted to the Langmuir isotherms model compared to Freundlich model, suggesting the homogeneous monolayer adsorption followed by degradations. The competitive removal of MB in the presence of a photo-generated electrons trapper (Cd2+) was enhanced almost 3-folds (115 mg/L) compared to the removal from a single MB solution (40 mg/L). The characterization of the used samples as well as adsorption in the dark and negligible desorption of used samples support the involvement of the proposed photo-induced degradation mechanism.

3.
Appl Microbiol Biotechnol ; 107(5-6): 1503-1513, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36719432

RESUMO

Viruses have spread throughout the world and cause acute illness or death among millions of people. There is a growing concern about methods to control and combat early-stage viral infections to prevent the significant public health problem. However, conventional detection methods like polymerase chain reaction (PCR) requires sample purification and are time-consuming for further clinical diagnosis. Hence, establishing a portable device for rapid detection with enhanced sensitivity and selectivity for the specific virus to prevent further spread becomes an urgent need. Many research groups are focusing on the potential of the electrochemical sensor to become a key for developing point-of-care (POC) technologies for clinical analysis because it can solve most of the limitations of conventional diagnostic methods. Herein, this review discusses the current development of electrochemical sensors for the detection of respiratory virus infections and flaviviruses over the past 10 years. Trends in future perspectives in rapid clinical detection sensors on viruses are also discussed. KEY POINTS: • Respiratory related viruses and Flavivirus are being concerned for past decades. • Important to differentiate the cross-reactivity between the virus in same family. • Electrochemical biosensor as a suitable device to detect viruses with high performance.


Assuntos
Técnicas Biossensoriais , Flavivirus , Vírus , Humanos
4.
Environ Sci Pollut Res Int ; 30(2): 4462-4484, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-35969341

RESUMO

The purpose of this research is to synthesize environmentally friendly nanosorbents for the novel adsorption of diesel range organics (DRO) from contaminated water. Central composite design (CCD) analysis of response surface methodology (RSM) was employed in a model fitting of the variables predicting the adsorption efficiency of Moringa oleifera-functionalized zerovalent iron particles (ZINPs) for the removal of DRO. The effects of the reaction parameters on the response were screened using 24 factorial designs to determine the statistically significant independent variables. A quadratic model predicting the DRO adsorption efficiency of ZINPs with an F value of 276.84 (p value < 0.0001) was developed. Diagnostic plots show that the predicted values were in excellent agreement with actual experimental values (R2 = 0.99). The maximum percentage removal of DRO of 92.6% was achieved after optimization, using the synthesized ZINPs after 8 h of contact between DRO substrates and ZINPs at pH of 8, the temperature of 25 °C, with an adsorbent dosage of 2 g/L and at composite desirability of 1. Characterization of ZINPs revealed the formation of quasi nanospheres and nanocubes with an average particle diameter of 50.9 ± 9.7, a crystallite size of 15.31 nm, a crystallinity index of 32.47% and a pore width of 75.69-88.59 nm. The adsorption equilibrium data modelling of ZINPs for adsorption of DRO was best described by Langmuir isotherm with the maximum monolayer coverage capacity of 7.194 mg/g. The separation factor [Formula: see text], indicated favourable adsorption. The adsorption kinetic data were consistent with pseudo-second-order kinetics indicating probable chemisorption.


Assuntos
Moringa oleifera , Poluentes Químicos da Água , Purificação da Água , Poluentes Químicos da Água/química , Temperatura , Adsorção , Cinética , Ferro , Água/química , Concentração de Íons de Hidrogênio , Purificação da Água/métodos , Termodinâmica
5.
Int J Biol Macromol ; 229: 838-848, 2023 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-36586654

RESUMO

The primary aim of this study is to develop an economical, stable, and effective heterogeneous catalyst for wastewater remediation via the Fenton oxidation process. For this purpose, Fe3O4-montmorillonite alginate (FeMA) composite beads were synthesized by entrapping Fe3O4-montmorillonite in calcium alginate beads. The performance of the catalysts was evaluated via the Fenton degradation of ofloxacin (OFL), an antibiotic that is frequently detected in water bodies. The physiochemical properties of the FeMA composite beads were characterized using X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope/energy dispersive X-ray (FESEM/EDX), Brunauer-Emmett-Teller (BET) analysis, Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). FeMA composite beads were found to have a higher surface area, higher porosity, and better thermal stability compared to pristine alginate beads. The composite beads were subsequently used for Fenton degradation of ofloxacin (OFL) in an aqueous solution. The effects of Fe3O4-montmorillonite loading on alginate, FeMA composite beads dosage, initial solution pH, initial OFL concentration, different oxidants, H2O2 dosage, reaction temperature, and inorganic salts on Fenton degradation of OFL in aqueous solution was investigated. The results revealed that the percentage of OFL degradation reached about 80 % under optimized conditions, while the total organic carbon (TOC) removal reached about 53 %. The entrapment of Fe3O4-montmorillonite in alginate beads results in less iron ions leaching compared to previous observation, and the efficiency remains constant over the five cycles investigated. The kinetics of the Fenton degradation process are best fitted to the pseudo-first-order kinetic model. It is therefore believed that FeMA composite beads can be a promising material for wastewater remediation via the Fenton oxidation process.


Assuntos
Antibacterianos , Ofloxacino , Antibacterianos/farmacologia , Bentonita , Peróxido de Hidrogênio/química , Águas Residuárias , Alginatos/química , Catálise
6.
Environ Sci Pollut Res Int ; 29(27): 40403-40414, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35347628

RESUMO

Ceramics-based filter for water treatment is an ancient technology to procure potable water at the household level. The traditional clay pots (vessels or hollow cylindrical container) have been used since long in the developing countries. The ceramic material (CaCu3Ti4O12 or CCTO) is a hetero-junction of titanium oxide, a well-known UV-active photocatalyst, and visible light absorbing CuO materials. This hetero-junction is able to overcome the limitations such as high bandgap, poor stability, low efficiency, and high photo-generated charge (e-/h+) recombination rate, associated with the other commonly used metal oxide semiconductor photocatalysts. Moreover, the low-cost, viable and facile synthesis routes for CCTO triggered its potential applications in photoelectrochemical and photocatalytic processes. This review will elaborate on the available literature demonstrating the visible light activity of CCTO photocatalysts in water treatment technologies. Furthermore, the mechanism of photocatalysis and synthesis routes are presented in this work for broader impact of the CCTO potential applications. The extended porous character and excellent surface texture have made the ceramic materials as an ideal choice to combat the bacteria, pathogens and turbidity in aqueous medium at household level. Specifically, the controlled size and shape make the CaCu3Ti4O12 (CCTO) an excellent visible light-driven photocatalyst, involving highly reactive species such as •OH, •O2- anions, h+, and e-, for the removal of organic and inorganic pollutants from water.


Assuntos
Águas Residuárias , Purificação da Água , Catálise , Luz , Titânio
7.
Turk J Chem ; 46(6): 1946-1955, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-37621338

RESUMO

The increase in new cases of drug resistance to first-line drugs such as ethambutol (ETB) makes it necessary to develop improvements for antituberculosis drugs. A new method for improving the bioavailability of active pharmaceutical ingredient (API) was investigated for preventing drug resistance and side-effects of antituberculosis drugs. In this study, an antituberculosis drug delivery system using ß-cyclodextrin (ß-CD) as the supramolecular carrier of ETB was prepared using the kneading method. The inclusion behaviour of ß-CD/ETB inclusion complex in solid and liquid state was investigated. The inclusion complex was characterized using Fourier transform infrared spectroscopy, thermogravimetric analysis, nuclear magnetic resonance (NMR) spectroscopy, and UV-visible spectroscopy. The 1H and nuclear Overhauser effect spectroscopy NMR results indicated the hydrophobic interaction between ß-CD and ETB. Meanwhile, the Benesi-Hildebrand equation was used to calculate the formation constant (K) of ß-CD/ETB complex in natural condition, pH4, and pH9, which were 105.43, 107.06, and 119.11, respectively. The stoichiometry ratio of ß-CD/ETB complex was proven to be 1:1.

8.
Nanomaterials (Basel) ; 11(10)2021 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-34685183

RESUMO

The influence of variable reaction time (tr) on surface/textural properties (surface area, total pore volume, and pore diameter) of carbon-encapsulated magnetite (Fe3O4@C) nanocomposites fabricated by a hydrothermal process at 190 °C for 3, 4, and 5 h was studied. The properties were calculated using the Brunauer-Emmett-Teller (BET) isotherms data. The nanocomposites were characterised using Fourier transform infrared spectroscopy, X-ray diffraction analysis, thermogravimetry, and scanning and transmission electron microscopies. Analysis of variance shows tr has the largest effect on pore volume (F value = 1117.6, p value < 0.0001), followed by the surface area (F value = 54.8, p value < 0.0001) and pore diameter (F value = 10.4, p value < 0.001) with R2-adjusted values of 99.5%, 88.5% and 63.1%, respectively. Tukey and Fisher tests confirmed tr rise to have caused increased variations in mean particle sizes (11-91 nm), crystallite sizes (5-21 nm), pore diameters (9-16 nm), pore volume (0.017-0.089 cm3 g-1) and surface area (7.6-22.4 m2 g-1) of the nanocomposites with individual and simultaneous confidence limits of 97.9 and 84.4 (p-adj < 0.05). The nanocomposites' retained Fe-O vibrations at octahedral (436 cm-1) and tetrahedral (570 cm-1) cubic ferrite sites, modest thermal stability (37-60 % weight loss), and large volume-specific surface area with potential for catalytic application in advanced oxidation processes.

9.
Front Chem ; 9: 752276, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34621725

RESUMO

Sustainable water processing techniques have been extensively investigated and are capable of improving water quality. Among the techniques, photocatalytic technology has shown great potential in recent years as a low cost, environmentally friendly and sustainable technology. However, the major challenge in the industrial development of photocatalyst technology is to develop an ideal photocatalyst which must have high photocatalytic activity, a large specific surface area, harvest sunlight and shows recyclability. Keeping these views, the present review highlighted the synthesis approaches of graphene/metal oxide nanocomposite, characterization techniques and their prominent applications in photocatalysis. Various parameters such as photocatalyst loading, structure of photocatalyst, temperature, pH, effect of oxidizing species and wavelength of light were addressed which could affect the rate of degradation. Moreover, the formation of intermediates during photo-oxidation of organic pollutants using these photocatalysts is also discussed. The analysis concluded with a synopsis of the importance of graphene-based materials in pollutant removal. Finally, a brief overview of the problems and future approaches in the field is also presented.

10.
Front Chem ; 8: 376, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32582621

RESUMO

Herein, the role of metal-based nanoparticles (NPs) in biomedical analysis and the treatment of critical deceases been highlighted. In the world of nanotechnology, noble elements such as the gold/silver/palladium (Au/Ag/Pd) NPs are the most promising emerging trend to design bioengineering materials that could to be employed as modern diagnostic tools and devices to combat serious diseases. NPs are considered a powerful and advanced chemical tool to diagnose and to cure critical ailments such as HIV, cancer, and other types of infectious illnesses. The treatment of cancer is the most significant application of nanotechnology which is based on premature tumor detection and analysis of cancer cells through Nano-devices. The fascinating characteristic properties of NPs-such as high surface area, high surface Plasmon resonance, multi-functionalization, highly stable nature, and easy processing-make them more prolific for nanotechnology. In this review article, the multifunctional roles of Au/Ag/Pd NPs in the field of medical science, the physicochemical toxicity dependent properties, and the interaction mechanism is highlighted. Due to the cytotoxicity of Ag/Au/Pd NPs, the conclusion and future remarks emphasize the need for further research to minimize the toxicity of NPs in the bio-medicinal field.

11.
RSC Adv ; 9(61): 35401-35416, 2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-35541022

RESUMO

4-Hydroxytamoxifen (4-OHT), the most common hormone used for the treatment of breast cancer, is a selective estrogen receptor modulator (SERM) inhibitor that acts as an antagonist in breast tissue and a partial agonist in the endometrium. However, the detailed molecular mechanism of 4-OHT structure modification has not been well investigated to date. Herein, molecular docking, molecular dynamics simulations and free energy calculations were performed to explore the mechanisms of the molecular interactions between newly designed benzophenone imines (BIs) and the three forms apo, antagonist and agonist of the human estrogen receptor hERα. The proposed inhibitors were designed by replacing the triarylethylene estrogenic scaffold found in 4-OHT with Schiff base triarylimine derivatives. The antiestrogen scaffold i.e. the O-alkyl side chain in 4-OHT was developed by incorporating an alanine amino acid side chain functionality into the triarylimine scaffold. Docking results reveal that the newly designed BIs bind to the hydrophobic open pocket of the apo and antagonist hERα conformations with higher affinity as compared to the natural and synthetic estrogen estradiol (E2) and 4-OHT. The analysis of the molecular dynamics simulation results based on six different systems of the best docked BI (5c) with hERα receptors demonstrates stable interactions, and the complex undergoes fewer conformational fluctuations in the open apo/antagonist hERα receptors as compared to the case of the closed agonist. In addition, the calculated binding free energies indicate that the main factor that contributes to the stabilization of the receptor-inhibitor complexes is hydrophobic interactions. This study suggests that the development of these Schiff base derivatives may be worth exploring for the preparation of new 4-OHT analogues.

12.
Int J Biol Macromol ; 118(Pt A): 640-648, 2018 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-29894784

RESUMO

Magnetic nanocellulose alginate hydrogel beads are produced from the assembly of alginate and magnetic nanocellulose (m-CNCs) as a potential drug delivery system. The m-CNCs were synthesized from cellulose nanocrystals (CNCs) that were isolated from rice husks (RH) by co-precipitation method and were incorporated into alginate-based hydrogel beads with the aim of enhancing mechanical strength and regulating drug release behavior. Ibuprofen was chosen as a model drug. The prepared CNCs, m-CNCs and the alginate hydrogel beads were characterized by various physicochemical techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and vibrating sample magnetometer studies (VSM). Besides the magnetic property, the presence of m-CNCs increased the integrity of the alginate hydrogel beads and the swelling percentage. The drug release study exhibited a controlled release profiles and based on the drug release data, the drug release mechanism was analyzed and discussed based on mathematical models such as Korsmeyer-Peppas and Peppas-Sahlin.


Assuntos
Alginatos/química , Portadores de Fármacos/química , Hidrogéis/química , Microesferas , Nanopartículas/química , Liberação Controlada de Fármacos , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Oryza/química
13.
Environ Sci Pollut Res Int ; 24(26): 20959-20971, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28726220

RESUMO

The effects of dry biomass density in cryogel beads, shaking speed and initial concentration ratio of phenol to 4-chlorophenol (4-CP) on the bioregeneration efficiencies of binary phenol and 4-CP-loaded granular activated carbon (GAC) for phenol and 4-CP, respectively, were investigated under the simultaneous adsorption and biodegradation approach. The results revealed higher bioregeneration efficiencies of binary-loaded GAC for phenol and 4-CP at higher dry biomass density but moderate shaking speed. The optimum dry biomass density in cryogel beads and shaking speed for use in bioregeneration were found to be 0.01 g/mL and 250 rpm, respectively. With respect to the initial phenol to 4-CP concentration ratio, the bioregeneration efficiencies were lower under increasing phenol and 4-CP initial concentrations, respectively, with the effect being more conspicuous under increasing 4-CP concentration. Higher bioregeneration efficiencies were achieved with the use of immobilized rather than suspended biomasses.


Assuntos
Biodegradação Ambiental , Carvão Vegetal , Clorofenóis/química , Criogéis , Fenol/química , Adsorção , Biomassa
14.
Environ Sci Pollut Res Int ; 23(16): 15941-51, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27335012

RESUMO

Titanium dioxide (TiO2) has been considered a useful material for the treatment of wastewater due to its non-toxic character, chemical stability and excellent electrical and optical properties which contribute in its wide range of applications, particularly in environmental remediation technology. However, the wide band gap of TiO2 photocatalyst (anatase phase, 3.20 eV) limits its photocatalytic activity to the ultraviolet region of light. Besides that, the electron-hole pair recombination has been found to reduce the efficiency of the photocatalyst. To overcome these problems, tailoring of TiO2 surface with rare earth metals to improve its surface, optical and photocatalytic properties has been investigated by many researchers. The surface modifications with rare earth metals proved to enhance the efficiency of TiO2 photocatalyts by way of reducing the band gap by shifting the working wavelength to the visible region and inhibiting the anatase-to-rutile phase transformations. This review paper summarises the attempts on modification of TiO2 using rare earth metals describing their effect on the photocatalytic activities of the modified TiO2 photocatalyst.


Assuntos
Recuperação e Remediação Ambiental/métodos , Metais Terras Raras/química , Processos Fotoquímicos , Titânio/química , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Catálise , Luz
15.
Prep Biochem Biotechnol ; 46(4): 321-7, 2016 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-25830286

RESUMO

This study aimed to work out a simple and high-yield procedure for the immobilization of horseradish peroxidase on silver nanoparticle. Ultraviolet-visible (UV-vis) and Fourier-transform infrared spectroscopy and transmission electron microscopy were used to characterize silver nanoparticles. Horseradish peroxidase was immobilized on ß-cyclodextrin-capped silver nanoparticles via glutaraldehyde cross-linking. Single-cell gel electrophoresis (Comet assay) was also performed to confirm the genotoxicity of silver nanoparticles. To decrease toxicity, silver nanoparticles were capped with ß-cyclodextrin. A comparative stability study of soluble and immobilized enzyme preparations was investigated against pH, temperature, and chaotropic agent, urea. The results showed that the cross-linked peroxidase was significantly more stable as compared to the soluble counterpart. The immobilized enzyme exhibited stable enzyme activities after repeated uses.


Assuntos
Técnicas Biossensoriais , Enzimas Imobilizadas/metabolismo , Peroxidase do Rábano Silvestre/metabolismo , Nanopartículas Metálicas/química , Prata/química , beta-Ciclodextrinas/química , Dano ao DNA , Concentração de Íons de Hidrogênio , Microscopia Eletrônica de Transmissão
16.
PLoS One ; 10(4): e0122603, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25849291

RESUMO

In this study, iron impregnated activated carbon (FeAC) was synthesized following an oxidation and iron impregnation of activated carbon (AC). Both the AC and FeAC were characterized by pHZPC and FTIR spectroscopy. The removal of Methylene Blue (MB) by AC and FeAC was examined under various experimental conditions. The FeAC showed up to 95% (higher than AC) MB removal in the pH range of 7-10. Although the reaction kinetics was pseudo-second order, the overall rate was controlled by a number of processes such as film diffusion, pore diffusion and intraparticle diffusion. The activation energy values for the MB uptake by AC and FeAC (21.79 and 14.82 kJ/mol, respectively) revealed a physisorption process. In the regeneration study, FeAC has shown consistently ≥ 90% MB removal even up to 10 repeated cycles. The reusable characteristic of the spent FeAC improved the practical use of activated carbon and can be a breakthrough for continuous flow system applications where it can work effectively without any significant reduction in its performance.


Assuntos
Carvão Vegetal/química , Ferro/química , Azul de Metileno/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Azul de Metileno/química , Concentração Osmolar , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica , Poluentes Químicos da Água/química , Purificação da Água
17.
J Environ Manage ; 147: 349-55, 2015 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-25284799

RESUMO

Horizontal subsurface-flow (HSF) constructed wetland incorporating baffles was developed to facilitate upflow and downflow conditions so that the treatment of pollutants could be achieved under multiple aerobic, anoxic and anaerobic conditions sequentially in the same wetland bed. The performances of the baffled and conventional HSF constructed wetlands, planted and unplanted, in the removal of azo dye Acid Orange 7 (AO7) were compared at the hydraulic retention times (HRT) of 5, 3 and 2 days when treating domestic wastewater spiked with AO7 concentration of 300 mg/L. The planted baffled unit was found to achieve 100%, 83% and 69% AO7 removal against 73%, 46% and 30% for the conventional unit at HRT of 5, 3 and 2 days, respectively. Longer flow path provided by baffled wetland units allowed more contact of the wastewater with the rhizomes, microbes and micro-aerobic zones resulting in relatively higher oxidation reduction potential (ORP) and enhanced performance as kinetic studies revealed faster AO7 biodegradation rate under aerobic condition. In addition, complete mineralization of AO7 was achieved in planted baffled wetland unit due to the availability of a combination of aerobic, anoxic and anaerobic conditions.


Assuntos
Compostos Azo/isolamento & purificação , Benzenossulfonatos/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Áreas Alagadas , Aerobiose , Anaerobiose , Compostos Azo/análise , Benzenossulfonatos/análise , Biodegradação Ambiental , Corantes/análise , Corantes/isolamento & purificação , Cinética , Fatores de Tempo , Águas Residuárias/química , Poluentes Químicos da Água/análise
18.
Bioresour Technol ; 160: 52-6, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24630369

RESUMO

To enhance the potential of activated carbon (AC), iron incorporation into the AC surface was examined in the present investigations. Iron doped activated carbon (FeAC) material was synthesized and characterized by using surface area analysis, energy dispersive X-ray (EDX), temperature programmed reduction (TPR) and temperature programmed desorption (TPD). The surface area of FeAC (543 m(2)/g) was found to be lower than AC (1043 m(2)/g) as a result of the pores widening due to diffusion of iron particles into the porous AC. Iron uploading on AC surface was confirmed through EDX analysis, showing up to 13.75 wt.% iron on FeAC surface. TPR and TPD profiles revealed the presence of more active sites on FeAC surface. FeAC have shown up to 98% methylene blue (MB) removal from the aqueous media. Thermodynamic parameters indicated the spontaneous and exothermic nature of the sorption processes.


Assuntos
Carvão Vegetal/química , Corantes/isolamento & purificação , Ferro/química , Compostos Orgânicos/isolamento & purificação , Adsorção , Cinética , Azul de Metileno/isolamento & purificação , Temperatura
19.
Environ Sci Pollut Res Int ; 21(1): 485-94, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-23807562

RESUMO

The feasibility of using dried attached-growth biomass from the polyurethane (PU) foam cubes as a solid carbon source to enhance the denitrification process in the intermittently aerated moving bed sequencing batch reactor (IA-MBSBR) during the treatment of low COD/N containing wastewater was investigated. By packing the IA-MBSBR with 8% (v/v) of 8-mL PU foam cubes saturated with dried attached-growth biomass, total nitrogen removal efficiency of 80% could be achieved for 10 consecutive cycles of operation when the intermittent aeration strategy of consecutive 1 h of aeration followed by 2 h of non-aeration period during the REACT period of the IA-MBSBR was adopted. Negligible release of ammonium nitrogen (NH4(+)-N) and slow-release of COD from the dried biomass would ensure that the use of this solid carbon source would not further burden the treatment system. The slow-releasing COD was found to have no effect in promoting the assimilation process and would also allow the carbon source to be used for many cycles of operation. The 'carbon-spent' PU foam cubes could be reused by merely drying at 60 °C at the end of the operational mode. Thus, the dried attached-growth biomass formed on the PU foam cubes could be exploited as an alternative solid carbon source for the enhancement of denitrification process in the IA-MBSBR.


Assuntos
Reatores Biológicos/microbiologia , Carbono/metabolismo , Nitrogênio/metabolismo , Biomassa , Desnitrificação , Poliuretanos/química , Eliminação de Resíduos Líquidos/métodos
20.
ScientificWorldJournal ; 2013: 641420, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24311980

RESUMO

Calcium oxide (CaO) nanoparticles are known to exhibit unique property due to their high adsorption capacity and good catalytic activity. In this work the CaO nanocatalysts were prepared by hydrothermal method using anionic surfactant, sodium dodecyl sulphate (SDS), as a templating agent. The as-synthesized nanocatalysts were further used as substrate for the synthesis of alumina doped calcium oxide (Al2O3·CaO) nanocatalysts via deposition-precipitation method at the isoelectric point of CaO. The Al2O3·CaO nanocatalysts were characterized by FTIR, XRD, TGA, TEM, and FESEM techniques. The catalytic efficiencies of these nanocatalysts were studied for the photodegradation of 2,4,6-trinitrophenol (2,4,6-TNP), which is an industrial pollutant, spectrophotometrically. The effect of surfactant and temperature on size of nanocatalysts was also studied. The smallest particle size and highest percentage of degradation were observed at critical micelle concentration of the surfactant. The direct optical band gap of the Al2O3·CaO nanocatalyst was found as 3.3 eV.


Assuntos
Óxido de Alumínio/química , Compostos de Cálcio/química , Óxidos/química , Picratos/química , Picratos/isolamento & purificação , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção/efeitos da radiação , Óxido de Alumínio/efeitos da radiação , Compostos de Cálcio/efeitos da radiação , Catálise , Luz , Micelas , Óxidos/efeitos da radiação , Picratos/efeitos da radiação , Dodecilsulfato de Sódio/química , Dodecilsulfato de Sódio/efeitos da radiação , Água/química , Poluentes Químicos da Água/efeitos da radiação
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