Equilibrium and kinetics studies of Direct blue 71 adsorption from aqueous solutions using modified zeolite

Abstract

This study deals with the application of Iranian zeolite as a low cost adsorbent for the removal of the Direct blue 71 (DB 71) from colored solution. Important parameters including equilibrium and contact time, initial dye concentration, effect of pH, and zeolite dosage were evaluated. Maximum dye removal was obtained at about 99.8% for 25 mg/L at 120 min of equilibrium. Higher adsorption efficiency of direct dye was obtained at higher dose and acidic pH. To analyze the adsorption equilibrium and kinetic, Langmuir, Freundlich, and Temkin isotherms as well as four kinetic models encompassing pseudo first-order, pseudo second-order, intraparticle diffusion, and Elovich were evaluated. The Langmuir isotherm (R 2 ¼ 0.995) and pseudo second-order models, gave the best fit to equilibrium experimental data. In Langmuir analysis, the maximum adsorption capacity (q m) by 13.66 mg/g was determined. Finally, the characteristics of zeolite including both natural and modified, such as compositions, surface morphology by X-ray diffraction technique (XRD), X-ray fluorescence (XRF), and scanning electron microscopy (SEM) were obtained. According to XRF analysis, it was

Synthesis, Characterization, and Utilization of a Lignin-Based Adsorbent for Effective Removal of Azo Dye from Aqueous Solution

“…Adsorption is considered as an alternative method to the traditional combination of chemical and biological processes for the removal of dyes from aqueous solutions. , Dye adsorption by various adsorbents is considered to occur primarily via π interaction, hydrogen bonding, and electrostatic interactions. Several organic and inorganic materials including zeolite, , lignocellulosic substrate, , activated carbon, graphite, and graphene oxide have been all tested and shown to have different adsorption activities toward organic dyes in wastewater. , Some of these adsorbents have a rather high dye-removal efficiency; however, low-cost renewable green bioadsorbents are still rare for this field of application, and further studies are urgently required …”

Removal of diazo-dye Direct Blue 2 (DB2) in aqueus solution by P(HEMA) nanoparticles

“…Son yıllarda yapılan çalışmalarda buğday kabuğu [58], çok duvarlı karbon nanotüp [59], Carica papaya yaprağı [60], fıstık kabuğu atığı [61] ve modifiye zeolit [62] gibi farklı adsorbentlerin kullanılabilirliği rapor edilmiştir. Biyo-uyumlu ve ekonomik olan bu tür adsorbentlerin kullanılan adsorbent miktarının fazla olması [58] ve uzun adsorpsiyon süresi [58,61], adsorpiyon kapasitesinin düşük olması [59,60,62]…”

“…Özellikle maliyetinin düşük olması, kolay hazırlanıyor olması ve uygulanan işlemin basit olması nedeniyle Direct Blue türü azo boyaların atık sulardan gideriminde adsorpsiyon yöntemi sıklıkla kullanılmaktadır [54,55,56,57,58]. Son yıllarda yapılan çalışmalarda buğday kabuğu [58], çok duvarlı karbon nanotüp [59], Carica papaya yaprağı [60], fıstık kabuğu atığı [61] ve modifiye zeolit [62] gibi farklı adsorbentlerin kullanılabilirliği rapor edilmiştir. Biyo-uyumlu ve ekonomik olan bu tür adsorbentlerin kullanılan adsorbent miktarının fazla olması [58] ve uzun adsorpsiyon süresi [58,61], adsorpiyon kapasitesinin düşük olması [59,60,62] ve desorpsiyon ajanı olarak aseton gibi organik ürünlerin kullanılması [63] gibi bazı dezavantajları mevcuttur.…”