Utilisation of immobilised activated sludge for the biosorption of chromium (VI)

Abstract

The objective of this investigation was to study the biosorption of Cr (VI) on immobilised activated sludge (IAS) and calcium alginate (CA) using batch system. The optimal pH for Cr (VI) biosorption by IAS and CA was 2.0 and 4.0, respectively. Equilibrium was attained at approximately 120 min for both biosorbents. For both biosorbents, the equilibrium biosorption capacity (mg/g) increased as the initial metal ion concentration increased and the concentration of biosorbent decreased. The rate of biosorption onto IAS and pure CA (as mg/g) increased from 5.02 to 87.66 and 4.97 to 79.09 as the concentration of Cr (VI) ions increased from 10 to 1000 mg/L, respectively. In the case of biosorbent concentration, as the concentration of IAS and pure CA increased from 1 to 20 g/L, the equilibrium uptake (qe) decreased from 21.33 to 1.57 and 19.41 to 1.38 mg/g, respectively. The biosorption data showed that the Langmuir model was more suitable than the Freundlich model. Also, the results indicated that the pseudo‐second order model was the most suitable for Cr (VI) biosorption onto IAS and CA. © 2011 Canadian Society for Chemical Engineering

Interactions of the dye, C.I. direct orange 34 with natural clay

“…Negative values of this quantity would indicate the feasibility and spontaneous nature of the adsorption process under the conditions and the temperatures range (298e333 K) covered by the research. Although this is the first investigation of adsorption thermodynamics for DO34, the DG value obtained in the research is in agreement with research for sorption of other azo dyes [30,38,39]. The increase in DG with increasing temperatures complies the assumptions of an (Table 6) indicates the increase in randomness during the adsorption process, probably because the number of desorbed water molecules is larger than that of adsorbed DO34 molecules.…”

“…As it is obvious from Fig. 5c, the plot of experimental data is not perfectly linear and the line did not cross the origin, indicating that external diffusion is the rate-limiting step in the adsorption of DO34 onto HC [39].…”

Ultrasound-assisted adsorption of textile dyes using modified nanoclay: Central composite design optimization

“…To interpret the FT-IR spec- tra, the absorption peaks were compared with the standard FT-IR patterns [36][37][38][39]. The asymmetric stretching band of the structural OH groups of the modified nanoclay sample appeared at 3,642 cm −1 [13,36,40]. The position of this band was not changed after the adsorption of AO7 and AR17, while its transmittance (%) was increased from 32.96% to 61.91% and 52.29% for AO7 and AR17, respectively.…”

“…Among available treatment techniques used for dye removal, such as coagulation and flocculation, membrane filtration, ozonation, and biological processes [1][2][3]5,6], the adsorption process has proven to be effective and reliable for removing dyes from aqueous solutions [7][8][9][10][11]. The adsorption process has ease of operation, cost efficiency, availability of adsorbents and no sludge formation [1][2][3]5,6,12,13]. However, the application of activated carbon as the most widely used adsorbent has decreased due to its high operational and capital costs, the necessity of regeneration and the reduction of activity after regeneration [7,14].…”

Application of Nanocrystalline Iranian Diatomite in Immobilized Form for Removal of a Textile Dye

“…Anyway, the separation of nanostructured adsorbents from aqueous solutions is difficult due to their fine size; thus, the immobilization of nano-crystalline diatomite within an appropriate support is suggested as a fundamental step for the process scale-up [5]. Among different support materials, polymeric matrixes such as alginate are widely used for the immobilization of fine adsorbent materials [19,30,31]. Alginate is a biopolymer extracted from the cell wall of brown algae, which has been extensively used for the immobilization of adsorbent materials because of its ease of preparation, hydrophilicity, biodegradability and availability [19,31].…”