Removal of fluoride from aqueous solution by adsorption on hydroxyapatite (HAp) using response surface methodology

Mourabet, M.; Rhilassi, A. El; Boujaady, H. El; Bennani-Ziatni, M.; Hamri, R. El; Taïtaï, A.

doi:10.1016/j.jscs.2012.03.003

Cited by 144 publications

(65 citation statements)

References 19 publications

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“…Among the other design techniques based on RSM, BBD is one of the most powerful and efficient statistical tool (33). Based on the literatures review and results from prototype tests, a four-factor, three-level BBD was used to model the nitrate reduction.…”

Section: Experimental Designmentioning

confidence: 99%

Modeling Nitrate Removal by Nano-Scaled Zero-Valent Iron Using Response Surface Methodology

2014

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Background: Contamination of water resources with nitrate is a serious environmental problem in many regions of the world. In addition, this problem has been observed in some regions of Iran. As Nitrate is threatening for human health and environment, it must be decreased to standard levels in drinking water. Objectives: The purpose of this research was to model the nitrate removal from water by nano-scaled zero-valent iron (nZVI) using response surface methodology and to investigate the effects of the nZVI dose, nitrate concentration, contact time, and ionic strength on removal efficiency. Materials and Methods: Box-Behnken design was used. Response surface methodology was used for modeling nitrate removal. All experiments were conducted according to standard methods. Important assessed parameters included nZVI dose (0.5-2 g/L), nitrate concentration (50-150 mg/L), contact time (15-60 minutes), and ionic strength (1000-5000 μmho/cm). Results: Results indicated that there was a direct association between nitrate removal efficiency and time and nZVI dosage. Therefore, increasing of the contact time or nZVI dose would increase nitrate removal. On the other hand, the nitrate removal was decreased when ionic strength and initial concentration were increased. The analysis of variance revealed that the proposed regression model could be appropriately used to design experiments. The model correlation coefficient was 0.9992 and the adjusted value was 0.9982. Conclusions: Response surface methodology and Box-Behnken design were powerful statistical tools for navigating nitrate reduction process. The results showed that a high percentage of nitrate were reduced by nZVI and this method might be efficiently used for nitrate removal from water.

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Section: Experimental Designmentioning

confidence: 99%

Modeling Nitrate Removal by Nano-Scaled Zero-Valent Iron Using Response Surface Methodology

2014

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“…Interestingly, much higher constant values (1.45 and 5, respectively) have been determined by Mourabet et al (2012). In this study, the heterogeneity parameter (1/n) of 0.77, which depended on the nature and strength of the adsorption process, indicated a normal distribution of the energy sites; here 1/n denoted that 77 % of the active sites where adsorption took place had equal energy and the sorption process was favorable.…”

Section: Adsorption Isotherm Developmentmentioning

confidence: 60%

“…Adsoption onto HAP enhanced the fluoride removal by 6.2 %, achieving an overall fluoride removal of 94.5 %. Gao et al (2009) examined various HAP-based adsorbing materials, resulting in removal efficiencies of 88 to 90.9 %, while fluoride removal of 86.3 % was determined by Mourabet et al (2012) using HAP.…”

Section: Fluoride Removal By Adsorptionmentioning

confidence: 99%

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Fluoride Removal from Aluminium Finishing Wastewater by Hydroxyapatite

Melidis

2015

Environ. Process.

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The hexavalent chromium toxicity forces the aluminium finishing industry to use fluoride-containing chemicals in order to improve aluminium passivation. Disposal of industrial wastewaters containing excess concentration of fluoride to surface and ground waters can cause several health hazards. Effluents containing fluoride need treatment to reduce their concentration to disposable values before being discharged into public sewage. In this study, fluoride-containing wastewater from the aluminium finishing industry was firstly treated by precipitation at pH 12.5, achieving residual fluoride concentrations of 8.69±1.84 mg/L from an initial concentration of 74.5±4.6 mg/L, and then by adsorption of the remaining solution onto hydroxyapatite (HAP), resulting in fluoride effluent concentrations of 4.09±0.16 mg/L. The total fluoride removal efficiency was 94.5 %. The sorption onto HAP data fitted well the Freundlich (r 2 =0.992) and Langmuir (r 2 =0.994) models. The adsorption capacity indicator (K F ) was equal to 0.723. The dimensionless constant R L of 0.62 indicates favorable sorption of fluoride onto HAP. It is concluded that the adsorption step using HAP can be used as a posttreatment to remove fluoride from aluminium finishing industry wastewater.

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“…Sua utilização vai muito além das áreas médicas, sendo esse mineral Eclética Química, 39, 141-150, 2014. 142 muito utilizado como remediador ambiental em processos de adsorção de metais pesados [6][7][8][9] e outros íons indesejados de efluentes líquidos contaminados [10,11]. Na literatura, várias rotas de obtenção da hidroxiapatita são descritas, cada uma apresentando diferenças nas propriedades finais das matrizes cerâmicas obtidas.…”

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Avaliação da influência da razão Ca/P nos valores de cristalinidade e crescimento de cristalitos durante a sinterização de pós de hidroxiapatita

Azevedo

Strecker

2016

Eclet. Quim.

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ciências naturais (DCNat), Universidade Federal de São João del-Rei (UFSJ). 36301-160 -São João Del Rei, MG -Brasil.Resumo: Amostras de hidroxiapatita (HAp) foram sintetizadas por meio da precipitação de soluções aquosas contendo os íons precursores. Ao final das sínteses, amostras com diferentes razões Ca/P foram obtidas e submetidas a sinterização em diferentes temperaturas. A análise por difração de Raios X comprovou que a estequiometria final dos pós de HAp influenciou nas respostas à sinterização. As amostras deficientes em cálcio (Ca/P=1,47) apresentaram além dos picos de difração do composto hidroxiapatita, fases de tricálcio fosfato -TCP (Ca 3 (PO 4 ) 2 ). As intensidades dos picos de TCP aumentaram com o aumento da temperatura devido a decomposição da HAp. Os difratogramas das amostras com cálcio em excesso (Ca/P=1,73) apresentaram picos de pequena intensidade de Ca(OH) 2 e CaO. Os cristais do material Ca/P=1,47 tiveram uma diminuição do tamanho e cristalinidade com o aumento da temperatura e sua consequente decomposição, se diferenciando dos pós com Ca/P=1,73, que aumentaram seus tamanhos e a ordenação atômica devido ao processo de sinterização.Palavras-chave: Hidroxiapatita, Sinterização, Estequiometria, Decomposição. INTRODUÇÃOA hidroxiapatita (HAp) é um mineral da família das apatitas e possui fórmula química Ca 10 (PO 4 ) 6 (OH) 2 . É um mineral raramente encontrado livre na natureza, porém, é constituinte inorgânico majoritário nos tecidos ósseos [1,2]. O mineral apatítico pode ser obtido em laboratório e apresenta grande interesse nas pesquisas médicas devido sua similaridade aos tecidos ósseos naturais, podendo ser utilizado como material de partida na fabricação de próteses e enxertos [3][4][5]. Sua utilização vai muito além das áreas médicas, sendo esse mineral Eclética Química, 39, 141-150, 2014. 142 muito utilizado como remediador ambiental em processos de adsorção de metais pesados [6][7][8][9] e outros íons indesejados de efluentes líquidos contaminados [10,11]. Na literatura, várias rotas de obtenção da hidroxiapatita são descritas, cada uma apresentando diferenças nas propriedades finais das matrizes cerâmicas obtidas. A HAp pode ser fabricada a partir de precipitação de soluções aquosas contendo os íons precursores, reação de neutralização, reação em estado sólido, gelcasting, dip Coating, spin Coating, entre outros [6,9,[12][13][14][15]. Na maioria dos processos de síntese dos pós de hidroxiapatita se faz necessário um posterior tratamento térmico para consolidar a matriz cerâmica por meio de mecanismos de sinterização [12,16,17]. Os pós sinterizados possuem características que os diferem daqueles chamados "verdes", os quais não passaram por nenhum tratamento térmico [17]. A razão Ca/P das amostras de hidroxiapatita devem ser severamente controlada pra que a não estequiometria acarrete em decomposições com consequente aparecimento de novas fases, cinética de crescimento de grãos e cristalinidade das amostras. As amostras que possuem uma razão Ca/P final próxima de 1,667 são ditas como ...

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Removal of fluoride from aqueous solution by adsorption on hydroxyapatite (HAp) using response surface methodology

Cited by 144 publications

References 19 publications

Modeling Nitrate Removal by Nano-Scaled Zero-Valent Iron Using Response Surface Methodology

Modeling Nitrate Removal by Nano-Scaled Zero-Valent Iron Using Response Surface Methodology

Fluoride Removal from Aluminium Finishing Wastewater by Hydroxyapatite

Avaliação da influência da razão Ca/P nos valores de cristalinidade e crescimento de cristalitos durante a sinterização de pós de hidroxiapatita

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