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1.
Food Chem ; 284: 259-263, 2019 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-30744855

RESUMO

In this work, an analytical method for the determination of Cd and Pb in natural coconut water samples, industrialized coconut water samples and coconut milk using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS), after minimum treatment of the sample was developed. The analytical method was applied to 46 samples collected in Salvador, Bahia (Brazil). The ranges of concentrations obtained were: 0.42-18.72 µg L-1 Cd and <0.70-36.32 µg L-1 Pb for natural coconut water samples (n = 14); <0.06-1.49 µg L-1 Cd and 6.57-29.02 µg L-1 Pb for industrialized water coconut samples (n = 16); and <0.10-5.93 ng g-1 Cd and <0.85-22.41 ng g-1 Pb for coconut milk samples (n = 16). For all samples, Cd and Pb concentrations were below the maximum tolerated values recommended by Brazilian Health Surveillance Agency (Agência Nacional de Vigilância Sanitária, ANVISA).


Assuntos
Cádmio/análise , Cocos/química , Sucos de Frutas e Vegetais/análise , Chumbo/análise , Espectrofotometria Atômica/métodos , Brasil , Cocos/metabolismo , Grafite/química , Limite de Detecção , Reprodutibilidade dos Testes , Águas Residuárias/análise
2.
Anal Bioanal Chem ; 411(3): 659-667, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30515537

RESUMO

There are increasing concerns regarding the risks arising from the contamination of manipulators of antineoplastic drugs promoted by occupational exposure or even in the dosage of drugs. The present work proposes the use of an electrochemical sensor based on a biopolymer extracted from the babassu coconut (Orbignya phalerata) for the determination of an antineoplastic 5-fluorouracil (5-FU) drug as an alternative for the monitoring of these drugs. In order to reduce the cost of this sensor, a flexible gold electrode (FEAu) is proposed. The surface modification of FEAu was performed with the deposition of a casting film of the biopolymer extracted from the babassu mesocarp (BM) and modified with phthalic anhydride (BMPA). The electrochemical activity of the modified electrode was characterized by cyclic voltammetry (CV), and its morphology was observed by atomic force microscopy (AFM). The FEAu/BMPA showed a high sensitivity (8.8 µA/µmol/L) and low limit of detection (0.34 µmol/L) for the 5-FU drug in an acid medium. Electrochemical sensors developed from the babassu mesocarp may be a viable alternative for the monitoring of the 5-FU antineoplastic in pharmaceutical formulations, because in addition to being sensitive to this drug, they are constructed of a natural polymer, renewable, and abundant in nature. Graphical abstract ᅟ.


Assuntos
Antimetabólitos Antineoplásicos/análise , Cocos/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Fluoruracila/análise , Ouro/química , Custos e Análise de Custo , Monitoramento de Medicamentos/instrumentação , Eletrodos/economia , Limite de Detecção , Microscopia de Força Atômica , Oxirredução , Anidridos Ftálicos/química , Solubilidade
3.
Water Sci Technol ; 75(9-10): 2225-2236, 2017 May.
Artigo em Inglês | MEDLINE | ID: mdl-28498135

RESUMO

The coconut residual fiber (CRF) is the major byproduct obtained during production of virgin coconut oil. Its application as a biosorbent for adsorption of Congo red was investigated. The CRF was subjected to different pretreatments, namely, pressure cooking, hexane treatment, acid treatment and their combinations. The pretreatment of CRF with the combination of hexane, acid, and pressure cooking resulted in the highest degree of adsorption. The equilibrium data were analyzed and found to fit best to both Langmuir and Freundlich isotherms. Thermodynamic parameters such as standard free energy (ΔG0 kJ mol-1), standard enthalpy (ΔH0, kJ mol-1) and standard entropy (ΔS0, kJ mol-1 K-1) of the systems were calculated by using the Langmuir constant. The ΔG0, ΔH0 and ΔS0 were found to be 16.51 kJ mol-1, -19.39 kJ mol-1 and -0.12 kJ mol-1 K-1, respectively, at 300 K. These thermodynamic parameters suggest the present adsorption process to be non-spontaneous and exothermic. The adsorption process was observed to follow pseudo-second-order kinetics. The results suggest that CRF has potential to be a biosorbent for the removal of hazardous material (Congo red dye) with a maximum adsorption capacity of 128.94 mg g-1 at 300 K.


Assuntos
Cocos/química , Vermelho Congo/química , Poluentes Químicos da Água/química , Purificação da Água/economia , Purificação da Água/métodos , Água/química , Adsorção , Corantes/química , Cinética , Termodinâmica
4.
Bioresour Technol ; 209: 220-7, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26970925

RESUMO

Expression of pRSETA manb-1601 construct in Hi-Control Escherichia coli BL21 (DE3) cells improved recombinant endo-mannanase (ManB-1601) production by 2.73-fold (1821±100U/ml). A low-cost, agro-industrial residue supplemented industrial medium for enhanced and economical production of ManB-1601 was developed in two mutual phases. Phase-I revealed the potential of various pre- (induction time: 5h, induction mode: lactose 0.5mM) and post-induction [peptone supplementation: 0.94%(w/v), glycerol 0.123%(v/v)] parameters for enhanced production of ManB-1601 and resulted in 4.61-fold (8406±400U/ml) and 2.53-fold (3.30g/l) higher ManB-1601 and biomass production, respectively. Under phase-II, economization of phase-I medium was carried out by reducing/replacing costly ingredients with solubilized-defatted flax seed meal (S-DFSM), which resulted in 3.25-fold (5926U/ml) higher ManB-1601 production. Industrial potential of ManB-1601 was shown in oil extraction from copra as enzyme treatment led to cracks, peeling, fracturing and smoothening of copra, which facilitated higher (18.75%) oil yield.


Assuntos
Cocos/química , Escherichia coli/metabolismo , Manosidases/biossíntese , Óleos de Plantas/isolamento & purificação , Proteínas Recombinantes/biossíntese , Biomassa , Óleo de Coco , Cocos/efeitos dos fármacos , Meios de Cultura , Manosidases/genética , Manosidases/farmacologia , Proteínas Recombinantes/farmacologia
5.
Artif Cells Nanomed Biotechnol ; 44(8): 1878-1882, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26855063

RESUMO

The present study reports the simple, inexpensive, eco-friendly synthesis of silver nanoparticles (AgNPs) using coconut oil cake extract. Scanning electron microscopy-energy dispersive spectroscopy peak at 3 keV confirmed the presence of silver. Transmission electron micrograph showed that nanoparticles are mostly circular with an average size of 10-70 nm. The results of the X-ray powder diffraction analysis (2θ = 46.2, 67.4 and 76.8) indicated the crystal nature of the AgNPs. Fourier transform infrared spectroscopy analysis indicates that proteins present in the oilcake extract could be responsible for the reduction of silver ions. The synthesized AgNPs (1-4 mm) reduced the growth rate of multi-antibiotic-resistant bacteria such as Aeromonas sp., Acinetobacter sp. and Citrobacter sp. isolated from livestock wastewater.


Assuntos
Antibacterianos , Cocos/química , Bactérias Gram-Negativas/crescimento & desenvolvimento , Nanopartículas Metálicas/química , Extratos Vegetais/química , Prata , Antibacterianos/química , Antibacterianos/farmacologia , Prata/química , Prata/farmacologia
6.
Environ Sci Technol ; 49(11): 7063-70, 2015 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-25961379

RESUMO

The objective of this research is to develop a cost-effective carbonaceous CO2 sorbent. Highly nanoporous N-doped carbons were synthesized with coconut shell by combining ammoxidation with KOH activation. The resultant carbons have characteristics of highly developed porosities and large nitrogen loadings. The prepared carbons exhibit high CO2 adsorption capacities of 3.44-4.26 and 4.77-6.52 mmol/g at 25 and 0 °C under atmospheric pressure, respectively. Specifically, the sample NC-650-1 prepared under very mild conditions (650 °C and KOH/precursor ratio of 1) shows the CO2 uptake 4.26 mmol/g at 25 °C, which is among the best of the known nitrogen-doped porous carbons. The high CO2 capture capacity of the sorbent can be attributed to its high microporosity and nitrogen content. In addition, the CO2/N2 selectivity of the sorbent is as high as 29, higher than that of many reported CO2 sorbents. Finally, this N-doped carbon exhibits CO2 heats of adsorption as high as 42 kJ/mol. The multiple advantages of these cost-effective coconut shell-based carbons demonstrate that they are excellent candidates for CO2 capture.


Assuntos
Amônia/química , Dióxido de Carbono/química , Cocos/química , Análise Custo-Benefício , Hidróxidos/química , Nitrogênio/química , Compostos de Potássio/química , Adsorção , Oxirredução , Espectroscopia Fotoeletrônica , Porosidade , Propriedades de Superfície , Temperatura
7.
Mem. Inst. Oswaldo Cruz ; 110(1): 138-141, 03/02/2015. tab
Artigo em Inglês | LILACS | ID: lil-741607

RESUMO

Human respiratory syncytial virus (HRSV) is an important respiratory pathogens among children between zero-five years old. Host immunity and viral genetic variability are important factors that can make vaccine production difficult. In this work, differences between biological clones of HRSV were detected in clinical samples in the absence and presence of serum collected from children in the convalescent phase of the illness and from their biological mothers. Viral clones were selected by plaque assay in the absence and presence of serum and nucleotide sequences of the G2 and F2 genes of HRSV biological clones were compared. One non-synonymous mutation was found in the F gene (Ile5Asn) in one clone of an HRSV-B sample and one non-synonymous mutation was found in the G gene (Ser291Pro) in four clones of the same HRSV-B sample. Only one of these clones was obtained after treatment with the child's serum. In addition, some synonymous mutations were determined in two clones of the HRSV-A samples. In conclusion, it is possible that minor sequences could be selected by host antibodies contributing to the HRSV evolutionary process, hampering the development of an effective vaccine, since we verify the same codon alteration in absence and presence of human sera in individual clones of BR-85 sample.


Assuntos
Óxido de Alumínio/química , Cocos/química , Produtos Agrícolas/crescimento & desenvolvimento , Frutas/química , Monoterpenos/análise , Óleos Voláteis/química , Pelargonium/crescimento & desenvolvimento , Dióxido de Silício/química , Produtos Agrícolas/química , Produtos Agrícolas/economia , Produtos Agrícolas/metabolismo , Indústria de Processamento de Alimentos/economia , Irã (Geográfico) , Resíduos Industriais/análise , Resíduos Industriais/economia , Monoterpenos/metabolismo , Óleos Voláteis/economia , Óleos Voláteis/isolamento & purificação , Óleos Voláteis/metabolismo , Pelargonium/química , Pelargonium/metabolismo , Perfumes/química , Perfumes/economia , Perfumes/isolamento & purificação , Perfumes/metabolismo , Folhas de Planta/química , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Silicatos/química , Solo/química , Terpenos/análise , Terpenos/metabolismo
8.
Waste Manag Res ; 33(1): 81-8, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25492720

RESUMO

The preparation of chars and activated carbon as low-cost elemental mercury adsorbents was carried out through the carbonisation of coconut husk (pith and fibre) and the activation of chars with potassium hydroxide (KOH), respectively. The synthesised adsorbents were characterised by using scanning electron microscopy, Fourier transform infrared spectroscopy and nitrogen adsorption/desorption analysis. The elemental mercury removal performance was measured using a conventional flow type packed-bed adsorber. The physical and chemical properties of the adsorbents changed as a result of the carbonisation and activation process, hence affecting on the extent of elemental mercury adsorption. The highest elemental mercury (Hg°) adsorption capacity was obtained for the CP-CHAR (3142.57 µg g(-1)), which significantly outperformed the pristine and activated carbon adsorbents, as well as higher than some adsorbents reported in the literature.


Assuntos
Carvão Vegetal/química , Cocos/química , Hidróxidos/química , Mercúrio/química , Compostos de Potássio/química , Gerenciamento de Resíduos/métodos , Gerenciamento de Resíduos/normas , Adsorção , Microscopia Eletrônica de Varredura , Nitrogênio/química , Espectroscopia de Infravermelho com Transformada de Fourier , Gerenciamento de Resíduos/economia
9.
J Sci Food Agric ; 94(5): 905-10, 2014 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-23913545

RESUMO

BACKGROUND: Using proper growing medium is known to be an effective way to improve crop growth and yield. However, the effects of growing media on geranium essential oil have scarcely ever been examined in detail. In this research, the effects of different growing media (soil, sand, pumice, perlite and perlite + cocopeat) on growth, oil yield and composition of geranium were studied. RESULTS: Growth was significantly improved in soilless-grown plants compared with soil-grown plants. Oil yield of soilless-grown plants (except for pumice) was about threefold higher than that of soil-grown plants. The increase in oil yield was correlated with higher leaf dry weight (r² = 0.96), as oil content was not affected. The citronellol/geranium ratio of oil was clearly affected by growing media, ranging from 5:1 in soil culture to 3:1 in soilless culture. The latter is acceptable for perfumery. CONCLUSION: Compared with soil, soilless media could produce higher yields of high-quality geranium oil that fits market requirements. Growth, oil yield and composition of plants grown in sand (a cheap and abundant growing medium) were not significantly different from those of plants grown in perlite and perlite + cocopeat.


Assuntos
Óxido de Alumínio/química , Cocos/química , Produtos Agrícolas/crescimento & desenvolvimento , Frutas/química , Monoterpenos/análise , Óleos Voláteis/química , Pelargonium/crescimento & desenvolvimento , Dióxido de Silício/química , Monoterpenos Acíclicos , Produtos Agrícolas/química , Produtos Agrícolas/economia , Produtos Agrícolas/metabolismo , Indústria de Processamento de Alimentos/economia , Resíduos Industriais/análise , Resíduos Industriais/economia , Irã (Geográfico) , Monoterpenos/metabolismo , Óleos Voláteis/economia , Óleos Voláteis/isolamento & purificação , Óleos Voláteis/metabolismo , Pelargonium/química , Pelargonium/metabolismo , Perfumes/química , Perfumes/economia , Perfumes/isolamento & purificação , Perfumes/metabolismo , Folhas de Planta/química , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Silicatos/química , Solo/química , Terpenos/análise , Terpenos/metabolismo
10.
BMC Biotechnol ; 13: 70, 2013 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-24004578

RESUMO

BACKGROUND: Escherichia coli is most widely used prokaryotic expression system for the production of recombinant proteins. Several strategies have been employed for expressing recombinant proteins in E.coli. This includes the development of novel host systems, expression vectors and cost effective media. In this study, we exploit tender coconut water (TCW) as a natural and cheaper growth medium for E.coli and Pichia pastoris. RESULT: E.coli and P.pastoris were cultivated in TCW and the growth rate was monitored by measuring optical density at 600 nm (OD(600nm)), where 1.55 for E.coli and 8.7 for P.pastoris was obtained after 12 and 60 hours, respectively. However, variation in growth rate was observed among TCW when collected from different localities (0.15-2.5 at OD(600nm)), which is attributed to the varying chemical profile among samples. In this regard, we attempted the supplementation of TCW with different carbon and nitrogen sources to attain consistency in growth rate. Here, supplementation of TCW with 25 mM ammonium sulphate (TCW-S) was noted efficient for the normalization of inconsistency, which further increased the biomass of E.coli by 2 to 10 folds, and 1.5 to 2 fold in P.pastoris. These results indicate that nitrogen source is the major limiting factor for growth. This was supported by total nitrogen and carbon estimation where, nitrogen varies from 20 to 60 mg/100 ml while carbohydrates showed no considerable variation (2.32 to 3.96 g/100 ml). In this study, we also employed TCW as an expression media for recombinant proteins by demonstrating successful expression of maltose binding protein (MBP), MBP-TEV protease fusion and a photo switchable fluorescent protein (mEos2) using TCW and the expression level was found to be equivalent to Luria Broth (LB). CONCLUSION: This study highlights the possible application of TCW-S as a media for cultivation of a variety of microorganisms and recombinant protein expression.


Assuntos
Cocos/química , Meios de Cultura/química , Escherichia coli/crescimento & desenvolvimento , Proteínas Recombinantes/biossíntese , Sulfato de Amônio/química , Biomassa , Carboidratos/química , Carbono/química , Expressão Gênica , Nitrogênio/química , Pichia/crescimento & desenvolvimento
11.
Pak J Biol Sci ; 15(1): 1-9, 2012 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-22530436

RESUMO

Proximate composition, extraction, characterization and comparative assessment of Cocos nucifera and Colocynthis citrullus seeds and seed oils were evaluated in this work using standard analytical techniques. The results showed the percentage (%) moisture, crude fibre, ash, crude protein, lipids and total carbohydrate contents of the seeds as 7.51 and 4.27, 7.70 and 5.51, 1.02 and 2.94, 10.57 and 11.67, 47.80 and 50.42 and 32.84 and 29.47 while the calorific values were 553.99 and 567.32 Kcal/100 g for C. nucifera and C. citrullus, respectively. The two seed oils were odourless and at room temperature (30 degrees C) liquids, with a pale yellow to yellowish colouration. Lipid indices of the seed oils indicated the Acid Values (AV) as 2.06-6.36 mg NaOH g(-1) and 2.99-6.17 mg NaOH g(-1), Free Fatty Acids (FFA) as 1.03-3.18 and 1.49-3.09%, Saponification Values (SV) as 252.44-257.59 and 196.82-201.03 mg KOH g(-1), Iodine Values (IV) as 9.73-10.99 and 110.93-111.46 mg of I2 g(-1) of oil and Peroxide Values (PV) as 0.21-0.21 and 1.53-2.72 mg O2 kg(-1) for soxhlet-mechanical extracted C. nucifera and C. citrullus seed oils, respectively. The studied characteristics of the oil extracts in most cases compared favourably with most conventional vegetable oils sold in the Nigeria markets; however, there were some observed levels of significant differences in the values at p < or = 0.05. These results suggest that the seeds examined may be nutritionally potent and also viable sources of seed oils judging by their oil yield. The data also showed that the seed oils were edible inferring from their low AV and their corresponding low FFA contents. Industrially, the results revealed the seed oils to have great potentials in soap manufacturing industries because of their high SV. They were also shown to be non-drying due to their low IV which also suggested that the oils contain few unsaturated bonds and therefore have low susceptibility to oxidative rancidity and deterioration as confirmed by their low PV which also serves as indicators of the presence or high levels of anti-oxidants in the oils.


Assuntos
Cocos/química , Cucurbitaceae/química , Óleos de Plantas/análise , Sementes/química , Carboidratos/análise , Cocos/citologia , Cucurbitaceae/citologia , Ácidos Graxos/análise , Humanos
12.
Int J Toxicol ; 30(3 Suppl): 5S-16S, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21772024

RESUMO

Cocos nucifera (coconut) oil, oil from the dried coconut fruit, is composed of 90% saturated triglycerides. It may function as a fragrance ingredient, hair conditioning agent, or skin-conditioning agent and is reported in 626 cosmetics at concentrations from 0.0001% to 70%. The related ingredients covered in this assessment are fatty acids, and their hydrogenated forms, corresponding fatty alcohols, simple esters, and inorganic and sulfated salts of coconut oil. The salts and esters are expected to have similar toxicological profiles as the oil, its hydrogenated forms, and its constituent fatty acids. Coconut oil and related ingredients are safe as cosmetic ingredients in the practices of use and concentration described in this safety assessment.


Assuntos
Cocos/química , Cosméticos/efeitos adversos , Cosméticos/química , Óleos de Plantas/efeitos adversos , Animais , Óleo de Coco , Qualidade de Produtos para o Consumidor , Humanos , Óleos de Plantas/química , Testes de Toxicidade
13.
PLoS Negl Trop Dis ; 4(11): e879, 2010 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-21085467

RESUMO

BACKGROUND: Tungiasis, an ectoparasitosis caused by the female sand flea Tunga penetrans, is an important health problem in many impoverished communities in the tropics. Sand flea disease is associated with a broad spectrum of clinical pathology and severe sequels are frequent. Treatment options are limited. METHODOLOGY/PRINCIPAL FINDINGS: We assessed the effectiveness of the intermittent application of the plant-based repellent Zanzarin to reduce infestation intensity and tungiasis-associated morbidity in a resource-poor community in Brazil, characterized by a very high attack rate. The study population was randomized into three cohorts. Initially, during a period of four weeks, the repellent was applied twice daily to the feet of all cohort members. This reduced the number of embedded sandfleas to 0 in 98% of the participants. Thereafter members of cohort A applied the repellent every second week twice daily for one week, members of cohort B every fourth week for one week, and members of cohort C served as controls. Infestation intensity and tungiasis-associated morbidity were monitored during five months. The intermittent application of Zanzarin for one week every second week significantly reduced infestation intensity from a median 4 lesions (IQR 1-9) during the whole transmission season. In contrast, in cohort B (application of the repellent every fourth week) the infestation intensity remained twice as high (median 8 lesions, IQR 9-16; p = 0.0035), and in the control cohort C 3.5 times as high (median 14 lesions; IQR 7-26; p = 0.004 during the transmission season). Tungiasis-related acute pathology remained very low in cohort A (median severity score 2; IQR 1-4) as compared to cohort B (median severity score 5; IQR 3-7; p<0.001), and control cohort C (median severity score 6.5; IQR 4-8; p<0.001). CONCLUSIONS/SIGNIFICANCE: Our study shows that in a setting with intense transmission, tungiasis-associated morbidity can be minimized through the intermittent application of a plant-based repellent.


Assuntos
Controle de Doenças Transmissíveis , Repelentes de Insetos/administração & dosagem , Preparações de Plantas/administração & dosagem , Tunga/efeitos dos fármacos , Tungíase/prevenção & controle , Adolescente , Adulto , Aloe/química , Animais , Brasil/epidemiologia , Criança , Pré-Escolar , Cocos/química , Estudos de Coortes , Ectoparasitoses/epidemiologia , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Óleos de Plantas/administração & dosagem , Pobreza , Tungíase/tratamento farmacológico , Tungíase/economia , Tungíase/parasitologia , Adulto Jovem
14.
J Hazard Mater ; 159(2-3): 252-6, 2008 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-18367331

RESUMO

A high cost-effective treatment of sulphochromic waste is proposed employing a raw coconut coir as biosorbent for Cr(VI) removal. The ideal pH and sorption kinetic, sorption capacities, and sorption sites were the studied biosorbent parameters. After testing five different isotherm models with standard solutions, Redlich-Peterson and Toth best fitted the experimental data, obtaining a theoretical Cr(VI) sorption capacity (SC) of 6.3 mg g(-1). Acid-base potentiometric titration indicated around of 73% of sorption sites were from phenolic compounds, probably lignin. Differences between sorption sites in the coconut coir before and after Cr adsorption identified from Fourier transform infrared spectra suggested a modification of sorption sites after sulphochromic waste treatment, indicating that the sorption mechanism involves organic matter oxidation and chromium uptake. For sulphocromic waste treatment, the SC was improved to 26.8+/-0.2 mg g(-1), and no adsorbed Cr(VI) was reduced, remaining only Cr(III) in the final solution. The adsorbed material was calcinated to obtain Cr(2)O(3,) with a reduction of more than 60% of the original mass.


Assuntos
Compostos de Cromo/isolamento & purificação , Cocos/química , Eliminação de Resíduos Líquidos/métodos , Absorção , Análise Custo-Benefício , Concentração de Íons de Hidrogênio , Cinética , Laboratórios , Potenciometria , Compostos de Enxofre/química , Termodinâmica
15.
J Hazard Mater ; 158(1): 65-72, 2008 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-18308467

RESUMO

In this paper, the ability of coconut bunch waste (CBW), an agricultural waste available in large quantity in Malaysia, to remove basic dye (methylene blue) from aqueous solution by adsorption was studied. Batch mode experiments were conducted at 30 degrees C to study the effects of pH and initial concentration of methylene blue (MB). Equilibrium adsorption isotherms and kinetics were investigated. The experimental data were analyzed by the Langmuir, Freundlich and Temkin models of adsorption. The adsorption isotherm data were fitted well to Langmuir isotherm and the monolayer adsorption capacity was found to be 70.92 mg/g at 30 degrees C. The kinetic data obtained at different concentrations have been analyzed using a pseudo-first-order, pseudo-second-order equation and intraparticle diffusion equation. The experimental data fitted very well the pseudo-second-order kinetic model.


Assuntos
Cocos/química , Azul de Metileno/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Modelos Químicos , Termodinâmica
16.
J Environ Sci Eng ; 50(2): 137-40, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19295098

RESUMO

The application of adsorption for removal of heavy metals is quite popular and activated carbon is universally used as an adsorbent. However, high cost of its preparation and regeneration has led to a search for alternative sorbents, especially in the developing countries. A number of sorbents are used to remove metals by adsorption from industrial effluents, which include insoluble starch, xanthates, modified cotton and wool, tree barks, activated carbon, plant leaves and agricultural products. Therefore, as an alternative, coconut shell carbon (CSC), a low cost sorbent derived from organic waste material, was used in the present work, for removal of lead from aqueous effluents. The results of the batch sorption studies indicated that the efficiency of lead removal by coconut shell carbon is comparable to that of commercially available activated carbon. From the kinetic and equilibrium studies, the sorptive capacity of coconut shell carbon for lead was found to be 30 mg/g. Desorption and subsequent recovery of the metal from the surface of the sorbent was successfully demonstrated. Parameters affecting the sorption were evaluated.


Assuntos
Carbono/química , Cocos/química , Chumbo/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Cinética , Purificação da Água/economia
18.
J Hazard Mater ; 138(1): 116-24, 2006 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-16806675

RESUMO

Adsorptive removal of parachlorophenol (PCP) and 2,4,6-trichlorophenol (TCP) from aqueous solutions by activated carbon prepared from coconut shell was studied and compared with activated carbon of commercial grade (CAC). Various chemical agents in different concentrations were used (KOH, NaOH, CaCO(3), H(3)PO(4) and ZnCl(2)) for the preparation of coconut shell activated carbon. The coconut shell activated carbon (CSAC) prepared using KOH as chemical agent showed high surface area and best adsorption capacity and was chosen for further studies. Batch adsorption studies were conducted to evaluate the effect of various parameters such as pH, adsorbent dose, contact time and initial PCP and TCP concentration. Adsorption equilibrium reached earlier for CSAC than CAC for both PCP and TCP concentrations. Under optimized conditions the prepared activated carbon showed 99.9% and 99.8% removal efficiency for PCP and TCP, respectively, where as the commercially activated carbon had 97.7% and 95.5% removal for PCP and TCP, respectively, for a solution concentration of 50mg/L. Adsorption followed pseudo-second-order kinetics. The equilibrium adsorption data were analysed by Langmuir, Freundlich, Redlich-Peterson and Sips model using non-linear regression technique. Freundlich isotherms best fitted the data for adsorption equilibrium for both the compounds (PCP and TCP). Similarly, acidic pH was favorable for the adsorption of both PCP and TCP. Studies on pH effect and desorption revealed that chemisorption was involved in the adsorption process. The efficiency of the activated carbon prepared was also tested with real pulp and paper mill effluent. The removal efficiency using both the carbons were found highly satisfactory and was about 98.7% and 96.9% as phenol removal and 97.9% and 93.5% as AOX using CSAC and CAC, respectively.


Assuntos
Carvão Vegetal/química , Clorofenóis/isolamento & purificação , Cocos/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Concentração de Íons de Hidrogênio , Resíduos Industriais , Cinética , Hidróxido de Sódio/química , Termodinâmica , Eliminação de Resíduos Líquidos/economia
19.
J Environ Manage ; 81(3): 286-95, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16713064

RESUMO

Coconut (Cocos nucifera) husk, an agricultural waste, has been thoroughly investigated for the removal of toxic Cd(II), Cr(III) and Hg(II) ions from aqueous media. The parameters like nature and composition of electrolyte, concentration of toxic ions, dosage of coconut husk, and equilibration time between the two phases were optimized for their maximum accumulation onto the solid surface. The effect of common ions on the uptake of metal ions has been monitored under optimal conditions. The variation of retention of each metal ion with temperature was used to compute the thermodynamic quantities DeltaH, DeltaS and DeltaG. The values 18.1+/-0.6 kJmol(-1), 74+/-2 Jmol(-1)K(-1), and -3.8+/-0.04 kJmol(-1) at 298 K; 10.8+/-0.8 kJmol(-1), 48.8+/-2.7 Jmol(-1)K(-1), and -4.6+/-0.3 kJmol(-1) at 298 K; and -37.4+/-2k Jmol(-1), 105+/-7 Jmol(-1)K(-1) and -2.58+/-0.5 kJmol(-1) at 298 K were obtained for Cd(II), Cr(III) and Hg(II) ions, respectively. The sorption data were analysed by applying different sorption isotherms. The sorption capacity and energy were evaluated for each metal ion. The values of the Freundlich constants 1/n and C(m) were 0.92+/-0.04 and 52.6+/-22.2 mmolg(-1); 0.85+/-0.05 and 56.0+/-0.03 mmolg(-1); and 0.88+/-0.03 and 6.84+/-0.45 mmolg(-1) for Cd(II) Cr(III) and Hg(II) ions, respectively. Similarly, the Dubinin-Radushkevich (D-R) constants beta, X(m,) and E were evaluated for the three metal ions. To check the selectivity of the sorbent, sorption of a number of elements was measured under similar conditions. Separation of Zn(II) from Cd(II); Cr(III) from I(I), Zr(IV), Se(IV), and Hg(II) from Se(IV) and Zn(II) can be achieved using this sorbent. This cheap material has potential applications in analytical chemistry, water decontamination, industrial effluent treatment and in pollution abatement.


Assuntos
Cocos/química , Metais Pesados/isolamento & purificação , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Cátions , Concentração de Íons de Hidrogênio , Cinética , Temperatura , Eliminação de Resíduos Líquidos/economia , Purificação da Água/economia
20.
J Hazard Mater ; 98(1-3): 257-74, 2003 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-12628792

RESUMO

Adsorption of 2-chlorophenol (2-CP) by coir pith carbon was carried out by varying the parameters such as agitation time, 2-CP concentration, adsorbent dose, pH and temperature. Adsorption equilibrium reached at 40, 60, 80 and 100 min for 2-CP concentration of 10, 20, 30 and 40 mg/l, respectively. Adsorption followed second-order kinetics. The adsorption equilibrium data obeyed Freundlich isotherm. Acidic pH was favorable for the adsorption of 2-CP. Desorption studies showed that chemisorption plays a major role in the adsorption process.


Assuntos
Clorofenóis/farmacocinética , Cocos/química , Resíduos Industriais , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Agricultura , Estudos de Viabilidade
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