Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 19 de 19
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Artigo em Inglês | MEDLINE | ID: mdl-32399875

RESUMO

Bio-evaluating of surface waters is not a new approach but is becoming more important since the application of the European Water Framework Directive (WFD). The present study was designed to evaluate the limno-ecological conditions of rivers in the West Mediterranean basin of Turkey using diatom metrics and multivariate approaches according to the WFD requirements. Canonical correspondence analysis (CCA) was used to assess the relationships of diatom species and environmental variables from 17 stations of 12 rivers sampled in two seasons. The CCA indicated that nitrite, chloride, electrical conductivity (EC), sulfate, temperature, and total phosphorus (TP) are the most explanatory factors on the distribution of the diatom species. Karasu River had the most deteriorated ecosystem, distinctly revealed by the CCA. Nutrient enrichment and high EC, biological oxygen demand (BOD5), and temperature values were noticed in this ecosystem. Karasu River was also characterized by pollution tolerant diatom species (e.g., Nitzschia inconspicua, Nitzschia pusilla, Halamphora normanii, and Rhoicosphenia abbreviata). Trophic index Turkey (TIT), eutrophication and/or pollution index-diatom (EPI-D), and trophic index (TI) showed poor ecological conditions in Karasu and Hamzabey rivers when a moderate environment quality in Dalaman River (at R6 station) and a good ecological state in Kocadere River. A high ecological status was found in Dalaman (at R5 station) concerning the results of TIT and TI, while a good condition was recorded based on EPI-D. This ecosystem was also associated with pollution-sensitive diatom taxa (Achnanthidium minutissimum, Cymbella excisa, Meridion circulare, and Gomphonema olivaceum). Results of CCA were corroborated with the bio-assessment of sampling stations based on diatom metrics. TIT, TI, and EPI-D had different indices' scores, but they showed significantly positive correlations with logTP. Spearman correlation coefficient value of TIT strengthens the suitability of it for the bio-assessment of the rivers in the West Mediterranean basin of Turkey.

2.
Environ Sci Pollut Res Int ; 26(8): 8028-8038, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30684177

RESUMO

This study is the first attempt to evaluate the limno-ecological status of freshwater ecosystems in Aras River system (Turkey) using diatom metrics and multivariate analyses according to the European Union Water Framework Directive requirements. Samples were collected using the standard protocols from 17 sampling stations in August and October of 2014, and June of 2015. Deterioration of water quality in the Aras River catchment was remarked from the downstream of Karakoyunlu, Sarisu, and Bozkus creeks, which showed higher values of trophic index Turkey (TIT), trophic index (TI), and eutrophication and/or pollution index-diatom (EPI-D). These sites were also characterized by pollution tolerant taxa e.g., Cocconeis placentula, Gomphonema parvulum, Navicula cryptocephala, Navicula trivialis, and Tryblionella angustata. Sites S14-S17 had high ecological status according to TIT, supported by the score of EPI-D which indicated a good ecological condition for S14. The occurrence of pollution-sensitive species (e.g., Hannaea arcus, Cymbella affinis, Didymosphenia geminata, Meridion circulare, and Encyonema silesiacum) and the low nutrients like total phosphorus, orthophosphate and nitrate, conductivity, and BOD5 supported the high ecological status of S14-S17. The relationships between diatom assemblages and environmental variables were also illustrated by multivariate analyses. Spearman correlation analysis revealed that TIT had positive important correlations with total phosphorus (p < 0.01, r = 0.768). Trophic index and EPI-D had also significant correlations with environmental variables, but they had lower correlation coefficient than that of TIT. It seems that TIT could be a suitable diatom metric for assessing the ecological status of sampling stations in Aras River system and Mediterranean region. Our findings showed also that ecological statuses of surface waters should be evaluated due to the indices developed in their ecoregions.


Assuntos
Diatomáceas/crescimento & desenvolvimento , Monitoramento Ambiental/métodos , Rios/química , Qualidade da Água , Ecologia , Eutrofização , Região do Mediterrâneo , Turquia
3.
Environ Sci Pollut Res Int ; 26(12): 11514-11523, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29423689

RESUMO

Heavy metal pollution in watercourses is a major environmental problem throughout the world due to rapid population growth, industrialization, and economic development. Considering this, the present study aimed to develop a new adsorbent from pumpkin husk (PH) by KOH modification to remove copper (Cu2+) ions and to explore its adsorptive potential. The sorption studies of Cu2+ on KOH-modified PH were carried out as functions of particle size, solution pH, adsorbent dose, temperature, initial metal concentration, and contact time. The sorption capacity of KOH-modified PH was found to be higher than that of raw PH, as 19.4 and 10.2 mg g-1, respectively. Morphology and surface structures of adsorbents were characterized by determination of zero point charge, a Fourier transform infrared spectrometer (FTIR-ATR) spectra, and a scanning electron microscopy (SEM) of PH powders before and after the sorption of Cu2+. The pHzpc of PH was found to be 5.0. FTIR-ATR analyses indicated that amino, amide, hydroxyl, carboxyl, and oxygenated groups of PH play an important role in the sorption process. Sorption isotherm, kinetic, and thermodynamic parameters of Cu2+ on KOH-modified PH were studied. The kinetic process was well represented by the Logistic model. The maximum sorption was found as 73.16 mg g-1 according to the well-fitting of Langmuir isotherm. Results of sorption and thermodynamic studies indicated that the process was exothermic, being feasible, and spontaneous. KOH-modified PH as an eco-friendly adsorbent had great potential to remove Cu2+ ions from aquatic system.


Assuntos
Cobre/química , Poluentes do Solo/química , Poluentes Químicos da Água/química , Adsorção , Cobre/análise , Cucurbita/química , Concentração de Íons de Hidrogênio , Hidróxidos/química , Íons , Cinética , Metais Pesados , Modelos Químicos , Tamanho da Partícula , Compostos de Potássio/química , Poluentes do Solo/análise , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Termodinâmica , Poluentes Químicos da Água/análise
4.
J Immunoassay Immunochem ; 39(2): 150-162, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-28686108

RESUMO

OBJECTIVE: Hypertrophic cardiomyopathy (HCM) is a genetic condition with the hallmark feature of left ventricular hypertrophy. Human Urotensin-II (hUT-II) is regarded as a cardiovascular autacoid/hormone, and it has cardiac inotropic and hypertrophic properties. Aims of this study were to elucidate the clinical significance of serum hUT-II levels as a potential new biomarker in patients with HCM. METHODS: This study included 40 HCM patients (60% males and 40% females) and were compared to 30 healthy control subjects (47% males and 53% females. All patients underwent extensive clinical, laboratory, and echocardiographic. Blood samples were taken to test for serum hUT-II levels by commercial ELISA Kit. RESULTS: Serum hUT-II was significantly higher (p < 0.01) in patients with HCM (15.8 ± 2.1 pmol/L) compared with healthy controls (3.3 ± 1.7 pmol/L). With regard to HCM patient, Serum hUT-II levels were significantly higher in the female with 16.3 ± 1.9 pmol/L than the male with 15.4 ± 2.2 pmol/L (p < 0.05). Among echocardiographic parameters, hUT-II was negatively associated with ejection fraction (r = -0.160, p = 0.324). CONCLUSION: Results of the first study indicated that serum hUT-II levels were markedly elevated in patients with HCM. Serum hUT-II is a novel biomarker parameter that has clinical use in patients with the severity of LVH.


Assuntos
Cardiomiopatia Hipertrófica/sangue , Urotensinas/sangue , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Biomarcadores/sangue , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
5.
Ecotoxicol Environ Saf ; 142: 171-180, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28411512

RESUMO

The present study prompted the second attempts to evaluate biochemical responses of filamentous algae under different physico-chemical variables in various water bodies in Turkey. These variables were investigated by use of multivariate approach in the years of 2013 (May and November) and 2014 (May and October). Studied ecoregions had the different geographic position, climate, land-use, and anthropogenic activities, could strongly affect physico-chemical variables of water bodies, which caused to change or regulate in algal biomass composition due to the different response of filamentous species. Besides, biochemical responses of species changed at different sampling times and stations. Multivariate analyses indicated that temperature, heavy metals, and nutrient contents of aquatic systems were found to be major variables driving the spatial and temporal occurrence and biochemical contents of filamentous species. Total protein and pigment production by filamentous algae were high in water bodies having high nutrients, whereas they were low in high heavy metal contents. Amount of malondialdehyde (MDA), H2O2, total thiol group, total phenolic compounds, proline, total carbohydrate, and bioaccumulation of metals by filamentous algae were closely related with heavy metal contents of water bodies, indicated by the multivariate approach. Significant increase in aforementioned biochemical compounds with a distinct range of habitats and sensitive-tolerance to environmental conditions could make them highly valuable indicators.


Assuntos
Clorófitas/crescimento & desenvolvimento , Monitoramento Ambiental/métodos , Água Doce/análise , Metais Pesados/análise , Spirogyra/crescimento & desenvolvimento , Poluentes Químicos da Água/análise , Biomassa , Ecossistema , Água Doce/química , Metais Pesados/metabolismo , Estações do Ano , Turquia , Poluentes Químicos da Água/metabolismo
6.
Ecotoxicol Environ Saf ; 133: 403-12, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27508982

RESUMO

To the best of our knowledge, any study about biochemical response of filamentous algae in the complex freshwater ecosystems has not been found in the literature. This study was designed to explore biochemical response of filamentous algae in different water bodies from May 2013 to October 2014, using multivariate approach in the South East of Turkey. Environmental variables were measured in situ: water temperature, oxygen concentration, saturation, conductivity, salinity, pH, redox potential, and total dissolved solid. Chemical variables of aqueous samples and biochemical compounds of filamentous algae were also measured. It was found that geographic position and anthropogenic activities had strong effect on physico-chemical variables of water bodies. Variation in environmental conditions caused change in algal biomass composition due to the different response of filamentous species, also indicated by FTIR analysis. Biochemical responses not only changed from species to species, but also varied for the same species at different sampling time and sampling stations. Multivariate analyses showed that heavy metals, nutrients, and water hardness were found as the important variables governing the temporal and spatial succession and biochemical compounds. Nutrients, especially nitrate, could stimulate pigment and total protein production, whereas high metal content had adverse effects. Amount of malondialdehyde (MDA), H2O2, total thiol groups, total phenolic compounds, proline, total carbohydrate, and metal bioaccumulation by filamentous algae could be closely related with heavy metals in the ecosystems. Significant increase in MDA, H2O2, total thiol group, total phenolic compounds, and proline productions by filamentous algae and chlorosis phenomenon seemed to be an important strategy for alleviating environmental factors-induced oxidative stress as biomarkers.


Assuntos
Ecossistema , Água Doce/química , Metais Pesados/farmacologia , Nitratos/farmacologia , Alga Marinha/efeitos dos fármacos , Poluentes Químicos da Água/farmacologia , Qualidade da Água , Animais , Biomassa , Exposição Ambiental , Estresse Oxidativo , Alga Marinha/metabolismo , Turquia , Água/química
7.
J Environ Sci (China) ; 45: 49-59, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27372118

RESUMO

The biosorption of phosphorus in the form of orthophosphate (Po) from wastewater using biomass as the sorbent is of potential importance because the Po-loaded biomass could be applied in the agricultural sector as fertilizer and soil conditioner. However, biomass generally displays a very low affinity for Po sorption and therefore biomass surface modification is required. In the present study, the biomass (as model grinded leaves of Phragmites sp. were used) was pretreated with Ca(OH)2 to enhance Po biosorption capacity (qe). The results indicate that the alkaline pretreatment resulted in a modification of surface functional groups. It was concluded that the main sorption mechanisms were ligand exchange and electrostatic attraction. A series of experiments were conducted to investigate the performance of the pretreated biomass for Po uptake under various conditions. Isotherm and thermodynamic studies were also applied and analyzed. The biosorption process was best described by the pseudo-second order kinetic model and Langmuir isotherm, which gave a qmax of 12.27mgP/g at 25°C and pH7. The Ca(OH)2 treated Phragmites biomass applied in this study for Po recovery may present some potential advantages in terms of costs and environmental impact.


Assuntos
Hidróxido de Cálcio/química , Fosfatos/metabolismo , Poaceae/metabolismo , Poluentes Químicos da Água/metabolismo , Adsorção , Biodegradação Ambiental , Biomassa , Termodinâmica
8.
Appl Biochem Biotechnol ; 180(4): 728-739, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27193256

RESUMO

The study was performed to investigate the effects of using cow effluent for the cultivation of Spirulina platensis on its biomass production and cell physiology. S. platensis was cultivated in three different cow effluents (CE) used as cultivation medium during 15 days. CE was prepared using dry cow manures, and it was further modified with supplement of NaNO3 (CEN) and NaNO3 + NaCl (CENS). High nitrate value stimulated chlorophyll-a and total protein content of the cyanobacterium and also biomass production in standards medium (SM) and CEN media. Total carbohydrate content of S. platensis grown in CE media was found to be higher (p < 0.05) than that of SM. Productions of biomass and biochemical compounds by the cyanobacterium grown on the CE and SM media were evaluated by using multivariate approach. Conductivity, oxidation reduction potential (ORP), salinity, pH, and TDS played important role (p < 0.01) in the biochemical composition. As an effective explanatory factor, ORP had a significant positive correlation with H2O2, whereas negatively correlated with chlorophyll-α, biomass production, filament length, and proline. Canonical correspondence analysis proposed that biochemical compounds of S. platensis were not only affected by salinity and nutrition of media but also by pH and ORP. The present study indicated that CEN as a low cost model medium had high potential for the production of biomass by S. platensis with high protein content.


Assuntos
Biomassa , Spirulina/crescimento & desenvolvimento , Spirulina/metabolismo , Estresse Fisiológico , Águas Residuárias , Animais , Bovinos , Método de Monte Carlo , Análise Multivariada , Espectroscopia de Infravermelho com Transformada de Fourier
9.
Environ Sci Pollut Res Int ; 21(7): 5086-97, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24374618

RESUMO

The use of effective disposal of redundant pumpkin husk (PH) to remove pollutants is an important issue for environmental protection and utilization of resource. The aim of this study was to remove a potentially toxic reactive azo dye, Reactive Red (RR) 120, by widespread PH as a low-cost adsorbent. Particle size, adsorbent dose, pH, temperature, initial dye concentration, and contact time affected the sorption process. Amine, amide, hydroxyl, and carboxyl groups of PH played significant roles on the sorption process. Rapid sorption occurred within the first 2 min and equilibrium was reached within 60 min. Sorption kinetic was well represented by logistic equation. Generated secondary logistic model can be used to describe effects of initial dye concentration, contact time, and temperature by a single equation with high R (2) value. Monolayer sorption capacity was found as 98.61 mg g(-1). Activation energy, thermodynamic, and desorption studies showed that this process was physical, endothermic, and spontaneous. This study indicated that redundant PH as a low-cost adsorbent had a great potential for the removal of RR 120 as an alternative eco-friendly process.


Assuntos
Compostos Azo/análise , Cucurbita/química , Modelos Químicos , Poluentes Químicos da Água/análise , Adsorção , Compostos Azo/química , Cinética , Tamanho da Partícula , Temperatura , Termodinâmica , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/química
10.
Bull Environ Contam Toxicol ; 91(5): 571-6, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24048218

RESUMO

Effects of cadmium (Cd(2+)) on biomass, pigmentation (chlorophyll a, b, and total carotene), malondialdehyde (MDA), and proline productions by Scenedesmus quadricauda var. longispina were investigated. Cadmium had inhibitory effect on the productions of biomass and pigmentation. Significant differences were found in pigment content among groups. On the other hand, Cd(2+) had a simulative effect on the production of MDA and proline by the alga. FTIR-ATR spectroscopy was used to examine active groups of algal biomass before and after Cd(2+) exposure. Results confirmed that amino, amide, and anionic groups had significant role on the biosorption of Cd(2+) by the alga. Increased accumulation of MDA and proline seemed to be an important strategy for alleviating metal-induced oxidative stress in S. quadricauda var. longispina.


Assuntos
Cádmio/toxicidade , Clorofila/metabolismo , Malondialdeído/metabolismo , Prolina/metabolismo , Scenedesmus/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Clorofila A , Scenedesmus/fisiologia
11.
Environ Sci Pollut Res Int ; 20(10): 7355-66, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-23625123

RESUMO

Effective disposal of pumpkin husk (PH) as a redundant waste is a significant work for environmental protection and full utilization of resource. Predictive modeling of sorption of Lanaset Red (LR) G on PH was investigated in a batch system as functions of particle size, adsorbent dose, pH, temperature, and initial dye concentration. Fourier transform infrared spectroscopy attenuated total reflectance spectra of PH powders before and after the sorption of LR G were determined. Sorption process was found to be dependent on particle size, adsorbent dose, pH, temperature, initial dye concentration, and contact time. Amine and amide groups of PH had significant effect on the sorption process. The pHzpc of PH was found as 6.4. Sorption process was very fast initially and reached equilibrium within 60 min. Dynamic behavior of sorption was well represented by logistic and Avrami models. The sorption of LR G on PH was excellently described by Langmuir model, indicating a homogeneous phenomenon. Monolayer sorption capacity decreased from 440.78 to 436.28 mg g(-1) with increasing temperature. Activation energy, thermodynamic, and desorption studies showed that this process was physical character, exothermic, and spontaneous. This study confirmed that PH as an effective and low-cost adsorbent had a great potential for the removal of LR G as an alternative eco-friendly process.


Assuntos
Compostos Azo/química , Corantes/química , Complexos de Coordenação/química , Modelos Químicos , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Adsorção , Cucurbita/química , Concentração de Íons de Hidrogênio , Resíduos Industriais , Cinética , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Termodinâmica , Águas Residuárias/química
12.
Environ Sci Pollut Res Int ; 20(7): 4647-58, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23288677

RESUMO

The effective disposal of redundant elephant dung (ED) is important for environmental protection and utilization of resource. The aim of this study was to remove a toxic-azo dye, Reactive Red (RR) 120, using this relatively cheap material as a new adsorbent. The FTIR-ATR spectra of ED powders before and after the sorption of RR 120 and zero point charge (pHzpc) of ED were determined. The sorption capacity of ED for removing of RR 120 were carried out as functions of particle size, adsorbent dose, pH, temperature, ionic strength, initial dye concentration, and contact time. Sorption isotherm, kinetic, activation energy, thermodynamic, and desorption parameters of RR 120 on ED were studied. The sorption process was found to be dependent on particle size, adsorbent dose, pH, temperature, ionic strength, initial dye concentration, and contact time. FTIR-ATR spectroscopy indicated that amine and amide groups have significant role on the sorption of RR 120 on ED. The pHzpc of ED was found to be 7.3. Sorption kinetic of RR 120 on ED was well described by sigmoidal Logistic model. The Langmuir isotherm was well fitted to the equilibrium data. The maximum sorption capacity was 95.71 mg g(-1). The sorption of RR 120 on ED was mainly physical and exothermic according to results of D-R isotherm, Arrhenius equation, thermodynamic, and desorption studies. The thermodynamic parameters showed that this process was feasible and spontaneous. This study showed that ED as a low-cost adsorbent had a great potential for the removal of RR 120 as an alternative eco-friendly process.


Assuntos
Compostos Azo/isolamento & purificação , Corantes/isolamento & purificação , Esterco , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Animais , Compostos Azo/química , Corantes/química , Elefantes , Monitoramento Ambiental/métodos , Cinética , Concentração Osmolar , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Termodinâmica , Águas Residuárias/análise , Águas Residuárias/química , Poluentes Químicos da Água/química
13.
Bioresour Technol ; 129: 396-401, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23262017

RESUMO

Artificial neural network (ANN), pseudo second-order kinetic, and gene expression programming (GEP) models were constructed to predict removal efficiency of Lanaset Red G (LR G) using lentil straw (LS) based on 1152 experimental sets. The sorption process was dependent on adsorbent particle size, pH, initial dye concentration, and contact time. These variables were used as input to construct a neural network for prediction of dye uptake as output. ANN was an excellent model because of the lowest error and the highest coefficient values. ANN indicated that initial dye concentration had the strongest effect on dye uptake, followed by pH. The GEP model successfully described the sorption kinetic process as function of adsorbent particle size, pH, initial dye concentration, and contact time in a single equation. Low cost adsorbent, LS, had a great potential to remove LR G as an eco-friendly process, which was well described by GEP and ANN.


Assuntos
Algoritmos , Compostos Azo/isolamento & purificação , Corantes/isolamento & purificação , Lens (Planta)/química , Modelos Químicos , Componentes Aéreos da Planta/química , Poluentes Químicos da Água/isolamento & purificação , Absorção , Compostos Azo/química , Biodegradação Ambiental , Corantes/química , Simulação por Computador , Metais/química , Metais/isolamento & purificação , Rede Nervosa , Água/química , Poluentes Químicos da Água/química
14.
Bioresour Technol ; 103(1): 64-70, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22018750

RESUMO

An artificial neural network (ANN) model was used to predict removal efficiency of Lanaset Red (LR) G on walnut husk (WH). This adsorbent was characterized by FTIR-ATR. Effects of particle size, adsorbent dose, initial pH value, dye concentration, and contact time were investigated to optimize sorption process. Operating variables were used as the inputs to the constructed neural network to predict the dye uptake at any time as an output. Commonly used pseudo second-order model was fitted to the experimental data to compare with ANN model. According to error analyses and determination of coefficients, ANN was the more appropriate model to describe this sorption process. Results of ANN indicated that pH was the most efficient parameter (43%), followed by initial dye concentration (40%) for sorption of LR G on WH.


Assuntos
Compostos Azo/isolamento & purificação , Corantes/isolamento & purificação , Complexos de Coordenação/isolamento & purificação , Juglans/química , Resíduos/análise , Adsorção , Compostos Azo/química , Corantes/química , Complexos de Coordenação/química , Concentração de Íons de Hidrogênio , Cinética , Modelos Químicos , Tamanho da Partícula , Análise de Regressão , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de Tempo
15.
Bioresour Technol ; 102(10): 5634-8, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21388806

RESUMO

A three-layer artificial neural network (ANN) was constructed to predict the removal efficiency of Lanaset Red (LR) G on Chara contraria based on 2304 experimental sets. The effects of operating variables (particle size, adsorbent dosage, pH regimes, dye concentration, and contact time) were studied to optimize the sorption conditions of this dye. The operating variables were used as the input to the constructed neural network to predict the dye uptake at any time as the output. This adsorbent was characterized by FTIR. Pseudo second-order model was also fitted to the experimental data. According to values of error analyses and determinations coefficient, the ANN was more appropriate to describe this adsorption process. Result of this model indicated that pH regimes had the highest importance effect (49%) on the dye uptake.


Assuntos
Chara/metabolismo , Corantes/isolamento & purificação , Modelos Químicos , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Tamanho da Partícula
16.
J Hazard Mater ; 173(1-3): 123-9, 2010 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-19748176

RESUMO

The adsorption of copper ions on Spirulina platensis was studied as a function of contact time, initial metal ion concentration, and initial pH regimes. Characterization of this adsorbent was confirmed by FTIR spectrum. Modified Gompertz and Logistic models have not been previously applied for the adsorption of copper. Logistic was the best model to describe experimental kinetic data. This adsorption could be explained by the intra-particle diffusion, which was composed of more than one sorption processes. Langmuir, Freundlich, and Redlich-Peterson were fitted to equilibrium data models. According to values of error functions and correlation coefficient, the Langmuir and Redlich-Peterson models were more appropriate to describe the adsorption of copper ions on S. platensis. The monolayer maximum adsorption capacity of copper ions was determined as 67.93 mg g(-1). Results indicated that this adsorbent had a great potential for removing of copper as an eco-friendly process.


Assuntos
Cobre/química , Spirulina/química , Poluentes Químicos da Água/análise , Adsorção , Algoritmos , Biomassa , Previsões , Concentração de Íons de Hidrogênio , Cinética , Modelos Logísticos , Modelos Estatísticos , Soluções , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica , Água , Purificação da Água
17.
Bioresour Technol ; 100(14): 3625-9, 2009 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19329296

RESUMO

Batch cultivations were performed to evaluate the influence of phosphate concentrations (0.25, 0.5, 0.75, and 1.0 g L(-1)) for pH regimes (9.5, 10.0, and 10.5) on the biomass production by Spirulina platensis. The best condition for cell growth (3.099 g L(-1)) was found at 0.5 g L(-1) phosphate and pH value of 10.0. Cultivation time, phosphate, and pH caused to increase significantly (p<0.01) in biomass production by S. platensis. Lag time was observed up to 4 h. After then, biomass production increased sharply (p<0.01) from 0.020 g L(-1) to 2.063, 2.213, 1.532, and 0.797 g L(-1) at 0.25, 0.5, 0.75, and 1.0 g L(-1) phosphate values, respectively. Modified Gompertz model could be regarded as sufficient to describe the biomass production by S. platensis with high determination coefficients and low sum of square value indicated that. Biological parameters for biomass production were successfully predicted by modified Gompertz model.


Assuntos
Biomassa , Biotecnologia/métodos , Clorofila/química , Nitratos/metabolismo , Fosfatos/metabolismo , Spirulina/crescimento & desenvolvimento , Clorofila/metabolismo , Clorofila A , Concentração de Íons de Hidrogênio , Modelos Biológicos , Modelos Estatísticos , Fosfatos/química
18.
Bioresour Technol ; 100(5): 1847-51, 2009 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18993057

RESUMO

Effects of nitrate (2.0, 2.5, and 3.0 g L(-1)) and salt (0.5, 1.0, 1.5, 2.0 g L(-1)) concentrations on biomass production by Spirulinaplatensis was examined in the Schlösser medium. The highest (p<0.001) biomass yields and chlorophyll a content was observed at 2.5 g L(-1) nitrate and 1.5 g L(-1) NaCl as 3.495 g L(-1) and 29.92 mg L(-1), respectively. Increment rate of biomass production was especially found between 72 and 216 h. Modified Richards, Schnute, Logistic and Gompertz models was successfully predicted (r(2)>0.96 and RSS0.003) biomass production by S.platensis as function of nitrate and salt concentrations. Low residual sum of squares (RSS) and high regression coefficients (r(2)) indicated that used models were well fitted to the experiment data and it could be regarded as sufficient to describe biomass production of Spirulina sp. Biological variables i.e. production rate (micro) and lag time (lambda) for S.platensis ranged 0.012-0.034 h(-1) and 2.43-5.85 h, respectively from biomass production were successfully predicted by modified Logistic model according to low RSS and F-testing value.


Assuntos
Biotecnologia/métodos , Nitratos/metabolismo , Cloreto de Sódio/metabolismo , Spirulina/crescimento & desenvolvimento , Biomassa , Clorofila/metabolismo , Clorofila A , Modelos Biológicos , Análise de Regressão
19.
Bioresour Technol ; 99(18): 8742-7, 2008 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-18501595

RESUMO

This study attempted to investigate variation in biovolume of Scenedesmus obliquus, in the modified Johnson medium at 20+/-2 degrees C, under 16kergcm(-2)s(-1) continuous illumination. The experiments were carried out at four nitrate (8, 12, 16, and 20mM) and four phosphate (0.1, 0.3, 0.5 and 0.7mM) concentrations at pH 7 and 8. The best response for algal growth was found at 0.3mM phosphate and 12mM nitrate at pH 7, as it was obtained from weight averaging method. Besides, optimum phosphate and nitrate concentrations significantly distinguished (p<0.01) from other concentrations according to Turkey's HSD test. Key features of the growth of S. obliquus under phosphate and nitrate influenced batch culture was successfully predicted by modified Gompertz model. Through the cultivations, specific growth rate (mu) ranged from 0.30 to 1.02 day(-1), while biovolume doubling time (td) varied from 0.68 to 2.30 days. There were important differences (p<0.05) for both mu and td among response variables. Both nutrients displayed noteworthy effect (p<0.01) on the algal biovolume.


Assuntos
Modelos Biológicos , Nitratos/farmacologia , Fosfatos/farmacologia , Scenedesmus/efeitos dos fármacos , Concentração de Íons de Hidrogênio , Análise de Regressão , Scenedesmus/crescimento & desenvolvimento , Fatores de Tempo
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA