Batch and column test analyses for hardness removal using natural and homoionic clinoptilolite: breakthrough experiments and modeling

Abstract

Hard water causes many problems in domestic and industrial usage, which has to be removed using costeffective technologies. To achieve this, the main goal of this study is to assess and optimize the factors controlling water softening applications. The research approach included a combined use of batch and column experiments performed in laboratory conditions through the ion exchange process, evaluating the effectiveness of natural and homoionic clinoptilolite on the removal characteristics of divalent cations. The equilibrium data could be fitted by both the Langmuir and the Freundlich models, even though it was fitted better by the Langmuir model with a maximum adsorption capacity of 10.5 mg g -1 for homoionic clinoptilolite (HC) and 9.68 mg g -1 for the natural clinoptilolite (NC). The adsorption kinetics can be successfully fitted to pseudo-second order kinetic model and the results of the intraparticle diffusion model suggest intraparticle diffusion was not the only rate-controlling step. It was also observed that the statistics indices of agreements from non-linear Thomas model were higher than that linear Thomas model. Nevertheless, the slope of the breakthrough curve for the linearized method decreased with increasing time as compared to non-linear method, thereby resulting in a slightly steeper slope for the nonlinear method and reducing the adsorption capacity. The study also concludes that the non-linear method is slightly more effective in predicting the performance of the selective removal efficiency of hardness ions. Results illustrate that clinoptilolite may be used as an alternative to more costly materials, due to its low cost and high abundance.

Remoción de arsénico (V) utilizando zeolita natural: pruebas de columna de lecho fijo

“…El tratamiento ácido ha demostrado ser útil en la mejora de las propiedades de sorción de las zeolitas (Silva, Lecus, & Corrao, 2019). Por ello, en esta investigación se utilizaron zeolitas tipo clinoptilolita procedentes de un depósito sedimentario cercano a la región de Tehuacán en el estado de Puebla, México (Bibiano-Cruz et al, 2016).…”

“…Similares resultados de cercanía de los valores calculados de q y K fueron Utilizando un enfoque adicional al tema de la idoneidad de los modelos en la descripción del proceso de sorción, Radnia et al (2013) establecen como prioritaria la comparación del parámetro q. Este parámetro (Tabla 5), para los modelos TL, TNL y YNL, muestra, entre ellos, una tendencia de cuantificación bastante similar y además muy cercana al valor experimental (qe) (Tabla 3), lo que demostraría la aplicabilidad de dichos modelos en la explicación del fenómeno de sorción en la columna (Bibiano-Cruz et al, 2016). Aunque se observó una mayor idoneidad estadística para el modelo TNL (Tabla 5), la igualmente adecuada predicción del qe por los modelos TL y YNL no debería ser ignorada (Radnia et al, 2013).…”

Evaluation of Zeolite as a Potential Reactive Medium in a Permeable Reactive Barrier (PRB): Batch and Column Studies

“…In general, the Si/Al ratio is an important property of zeolites because it is theoretically related to the CEC and selectivity of this material. The lower the Si/Al ratio is, the higher the CEC observed for zeolite [27]; similarly, zeolite with a high aluminum concentration has a preference for small or highly charged cations, such as cadmium and lead [64].…”

“…Several types of reactive materials (natural and industrial) with different sorption characteristics have proven to be efficient in PRBs in terms of the removal of different groups of contaminants present in groundwater. Such materials include (1) modified natural materials, such as brown coal [23], modified montmorillonite [24], modified and treated zeolites [12,25] and zero-valent iron [26]; (2) natural materials, such as zeolites [27][28][29], limestones [30], laterites [13] and sericite [31]; and (3) combined materials, such as sand and zeolite [32,33] and zero-valent iron and zeolite [14,20].…”

Estudo De Meio Reativo Para Barreiras Reativas Permeáveis (Brp): Ensaios Laboratoriais

“…Ainda nos primeiros 15 minutos de ensaio, são atingidas significativas porcentagens de remoção, como por exemplo, da ordem de 42% e 45,3% para as concentrações de 500 e 2000 mg/L, respectivamente. Isto ocorre porque no início do ensaio grande parte dos sítios de adsorção está disponível, entretanto, à medida que o processo vai se desenvolvendo estes vão sendo ocupados, dificultando o acesso e causando um efeito de repulsão entre os íons adsorvidos e os remanescentes em solução (Bibiano-Cruz et al, 2016). Além disso, o processo de adsorção sofre outras influências decorrentes dos valores de concentração da solução, temperatura, tempo de contato e agitação (Nandi et al, 2009).…”