Adsorption of hazardous dye crystal violet from wastewater by waste materials.

The adsorption performance of the materials bottom ash (BA), a power plant waste, and de-oiled soya (DOS), a soya bean industry waste for removal of crystal violet dye, has been investigated through batch and column experiments. Batch studies have been performed to describe the impact of parameters such as pH, amount of adsorbent, dye concentration, temperature, and contact time on the removal of the dye. Experimental data have been modeled by using Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich (D-R) isotherms. Thermodynamic parameters (DeltaG(o), DeltaH(o), and DeltaS(o)) were evaluated for the dye-adsorbent systems, which revealed that the adsorption process is endothermic in nature. Pseudo-first- and second-order kinetic models have been applied to the experimental data and pseudo-second-order kinetics was found to describe the adsorption of the dye (crystal violet) on the adsorbents. In order to achieve bulk removal of the dye, column operations were made. Recovery of the dye was made by eluting HCl solution through the exhausted columns and almost 95% and 78% of the dye was recovered from BA and DOS columns, respectively.

Decoloration treatment of a hazardous triarylmethane dye, Light Green SF (Yellowish) by waste material adsorbents.

An agricultural industry waste, deoiled soya, and a waste of thermal power plants, bottom ash, have been tested for their adsorption ability to remove Light Green SF (Yellowish) dye from wastewaters. The effects of various essential experimental parameters (dye concentration, mesh size, temperature, and pH) have been investigated. A study of four isothermal models, Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich, has been made and important thermodynamic parameters have been calculated. The decreasing values of enthalpy show that the adsorption process is endothermic. Mechanistic studies reveal the involvement of a pseudo-second-order mechanism to drive the adsorption process in dye-bottom ash and dye-deoiled soya systems. It has been observed that a particle diffusion mechanism was prominent in the case of adsorption of the dye on bottom ash and deoiled soya. Column adsorption and desorption experiments further confirmed the practical application of the present research. The percentage adsorption has been obtained as 88.74% and 89.65% with percentage recovery of 99.82% and 99.08% for bottom ash and deoiled soya, respectively. The experimental results confirmed that triarylmethane dye Light Green SF (Yellowish) can be successfully removed and recovered from aqueous solutions economically and efficiently.

Adsorption studies on the removal of coloring agent phenol red from wastewater using waste materials as adsorbents.

Bottom ash, a waste of thermal power plants, and deoiled soya, an agricultural waste material, were employed for successful removal and recovery of hazardous phenol red dye from wastewaters. The adsorption characteristics and operational parameters were determined by monitoring different parameters such as effect of pH, effect of concentration of the dye, amount of adsorbents, contact time, and temperature. The equilibrium data were analyzed on the basis of various adsorption isotherm models, namely Langmuir, Freundlich, Tempkin, and Dubinin-Radushkevich. The highest monolayer adsorption capacity has been obtained for the phenol red-bottom ash system (2.6x10(-5) mol/g) at 50 degrees C. Different thermodynamic parameters such as free energy, enthalpy, and entropy have been calculated and it was concluded that with the increase in temperature adsorption increases, indicating the endothermic nature of the process for both adsorbent materials. Kinetic parameters were derived from pseudo-first-order and pseudo-second-order kinetics. Differentiation between particle and film diffusion mechanisms operative in the present study has been carried out. The column regeneration characteristic has been also investigated and recovery percentage greater than 90% was obtained for both adsorbents by utilizing acidic eluent.

Batch and bulk removal of a triarylmethane dye, Fast Green FCF, from wastewater by adsorption over waste materials.

De-Oiled Soya, an agricultural waste material and Bottom Ash a waste of power plants, have been used as adsorbents for the removal and recovery of a triarylmethane dye Fast Green FCF from wastewater. Batch studies have been carried by observing the effects of pH, temperature, concentration of the dye, amount of adsorbents, sieve size of adsorbent, contact time, etc. Graphical correlation of various adsorption isotherm models like, Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich have been carried out for both the adsorbents. The adsorption over both the materials has been found endothermic and feasible in nature. Various thermodynamic parameters, such as, Gibb's free energy, entropy and enthalpy of the on-going adsorption process have been calculated. The kinetic studies suggest the process following pseudo first order kinetics and involvement of particle diffusion mechanism. The bulk removal of the dye has been carried out by passing the dye solution through columns of Bottom Ash and De-Oiled Soya and saturation factor of each column has been calculated. Attempts have also been made to recover the dye by eluting dilute NaOH through the columns.

Applicability of waste materials--bottom ash and deoiled soya--as adsorbents for the removal and recovery of a hazardous dye, brilliant green.

Deoiled soya, an agricultural waste material, and bottom ash, a waste of power plants, have been successfully used for the removal and recovery of the hazardous water-soluble dye brilliant green from water. To remove the dye from water, batch adsorption studies have been carried out by observing the effects of pH, concentration, amounts of adsorbents, size of adsorbent particles, etc. Attempts have also been made to monitor the adsorption process through Langmuir, Freundlich, Tempkin, and D-R adsorption isotherm models. Relevant thermodynamic parameters have also been calculated from these models. The adsorption process has been found endothermic and feasible at all the temperatures. The kinetics of the adsorption was also recorded and indicates pseudo-second-order kinetics in both cases. Kinetic operations also reveal the involvement of a film diffusion mechanism for the deoiled soya adsorption at all the temperatures, while bottom ash undergoes through a particle diffusion mechanism at only 30 degrees C and at higher temperatures a film diffusion mechanism operates. Bulk removal of the dye has been carried out through column studies for both adsorbents. Attempts have also been made to recover the dye from exhausted columns by eluting sulfuric acid of pH 3.

Studies on the adsorption kinetics and isotherms for the removal and recovery of Methyl Orange from wastewaters using waste materials.

De-Oiled Soya a waste of Soya oil industries and Bottom Ash a waste of thermal power plants have been used as effective adsorbent for recovery and removal of hazardous dye Methyl Orange from wastewater. During the studies effects of amount of dye and adsorbents, pH, sieve sizes, column studies etc. have been carried out. Adsorption of the dye over both the adsorbents has been monitored through Langmuir and Freundlich adsorption isotherm models and feasibility of the process is predicted in both the cases. Different thermodynamic parameters like Gibb's free energy, enthalpy and entropy of the undergoing process are also evaluated through these adsorption models. The kinetic studies confirm the first order process for the adsorption reaction and also play an important role in finding out half-life of the adsorption process and rate constants for both the adsorbents. It is also found that over the entire concentration range the adsorption on Bottom Ash takes place via particle diffusion process, while that of De-Oiled Soya undergoes via film diffusion process. In order to establish the practical utility of the developed process, attempts have been made for the bulk removal of the dye through column operations. For the two columns saturation factors are found as 98.61 and 99.8%, respectively, for Bottom Ash and De-Oiled Soya with adsorption capacity of each adsorbent as 3.618 and 16.664 mg/g, respectively. The dye recovery has been achieved by eluting dil. NaOH through the exhausted columns.