Sunflower Stalks as Adsorbents for Color Removal from Textile Wastewater

Abstract

Sunflower stalks as adsorbents for two basic dyes (Methylene Blue and Basic Red 9) and two direct dyes (Congo Red and Direct Blue 71) in aqueous solutions were studied with equilibrium isotherms and kinetic adsorptions. The maximum adsorptions of two basic dyes on sunflower stalks are very high, i.e., 205 and 317 mg/g for Methylene Blue and Basic Red 9, respectively. The two direct dyes have relatively lower adsorption on sunflower stalks. The adsorptive behaviors of sunflower stalk components are different. The pith, which is the soft and porous material in the center of stalks, has twice the adsorptive capacity of the skin. Particle sizes of sunflower stalks also affect the adsorption of dyes. The adsorption rates of two basic dyestuffs are much higher than that of the direct dyes. Within 30 min about 80% basic dyes were removed from the solutions.

Adsorption of Malachite Green from Aqueous Solutions by PNSBP: Equilibrium, Kinetic and Thermodynamic Studies

“…The removal of dyes with temperatures would increase the mobility of the ions of dyes and produces a swelling effect within the internal structure of adsorbent, thus enabling the large molecules of dyes to penetrate further. The temperature affects the rate of removal of dyes by altering the molecular interactions and the solubility of dyes [20]. …”

Hexamine adsorption study on activated carbon from aqueous solutions for application in treatment of hexamine industrial wastewater

“…The equilibrium sorption capacity of activated carbon increased from 0.027 to 0.512 mg/g with an increase in the concentration of hexamine from 5 to 75 mg/L with an adsorbent dose of 1 g and pH of 13. This is due to the acceleration of hexamine diffusion from solutions at higher concentrations (Ozacar 2003;Sun and Xu 1997).…”

Adsorption Studies of Cd (II) from Water by Acid Modified Multiwalled Carbon Nanotubes

“…It can be seen that the adsorption of Cd(II) on CNT and MCNT-HNO 3 increased with the initial or equilibrium Cd(II) concentrations, due to the increase in the driving force of the concentration gradient as a result of increasing the metal ion initial concentration [38,39]. It is clear that the oxidized form MCNT-HNO 3 appeared to be more effective under a higher aqueous Cd (II) concentration as compared with raw CNT (CNT:11.5 mg/g , MCNT-HNO 3 : 26.88 mg/g ).…”