Removal of Dyes from Wastewater Using Flyash, a Low-Cost Adsorbent

Abstract

The use of low-cost adsorbent has been investigated as a replacement for the current expensive methods of removing dyes from wastewater. As such, fly ash generated in National Thermal Power plant was collected and converted into a low-cost adsorbent. The prepared adsorbent was characterized and used for the removal of dyes from wastewater. Adsorption studies were carried out for different temperatures, particle sizes, pH's, and adsorbent doses. The adsorption of each dye was found to increase with increasing temperature, thereby indicating that the process is endothermic in nature. The removal of each dye was found to be inversely proportional to the size of the fly ash particles, as expected. Both the linear and nonlinear forms of the Langmuir and Freundlich models fitted the adsorption data. The results indicate that the Freundlich adsorption isotherm fitted the data better than the Langmuir adsorption isotherm. Further, the data were better correlated with the nonlinear than the linear form of this equation. Thermodynamic parameters such as the free energies, enthalpies, and entropies of adsorption of the dye-fly ash systems were also evaluated. The negative values of free energy indicate the feasibility and spontaneous nature of the process, and the positive heats of enthalpy suggest the endothermic nature of the process. The adsorptions of crystal violet and basic fuschin follow first-order rate kinetics. In comparison to other low-cost adsorbents, the sorption capacity of the material under investigation is found to be comparable to that of other commercially available adsorbents used for the removal of cationic dyes from wastewater.

Organic xenobiotics removal in constructed wetlands, with emphasis on the importance of the support matrix

“…Some research has been focusing on the study of its sorbent properties and has explored the application of fly ash for treating wastewater (Table 2). Many adsorption studies point to the suitability of fly ash use for retention of hazardous organic pollutants commonly found in many industrial wastewaters such as phenolic compounds [258,259], dyes [260][261][262][263], pesticides [264], petroleum hydrocarbons [265], PAHs [266] and PCBs [266,267].…”

“…The polarities and water solubilities of the pollutants, fly ash particle sizes and its unburned carbon content, as well as pH of the media are specified as the main factors with significant effect on the adsorption processes [184,[258][259][260][263][264][265][267][268][269]. Depending on the balance between the composition on metal oxides or the residual carbon content, adsorption of polar or mostly non-polar molecules, respectively, may be favored.…”

Factor Affecting Microwave Assisted Preparation of Activated Carbon from Local Raw Materials

“…With the increasing demand for cleaner water, attention has been focused on improvements to existing treatments and the development of new techniques and materials [2,3].…”

“…Many investigators have studied the feasibility of using inexpensive alternative materials like pearl millet husk, date pits, saw dust, buffing dust of leather industry, coir pith, crude oil residue, tropical grass, olive stone, almond shells, pine bark, wool waste, coconut shell etc., as carbonaceous precursors for the removal of dyes from water and wastewater [3,5,[9][10][11].…”

Kinetic mechanism of competitive adsorption of disperse dye and anionic dye on fly ash

“…Great efforts are therefore being made to explore other applications prior to disposal. Since fly ash is enriched with SiO 2 and contains a portion of unburned carbon, this waste possesses a potentiality of a low-cost adsorbent to remove various hazardous materials from wastewater (Dizge et al 2008;Hsu 2008;Janoš and Buchtová 2003;Kao et al 2000;Mohan et al 2002;Ramakrishna and Viraraghavan 1997;Wang et al 2005;Wang and Wu 2006). Recently, the technical feasibilities were reviewed by Ahmaruzzaman (2010) and Saka et al (2012).…”