Microcolumn adsorption studies of acid/basic dyes related to the physicochemical properties of the adsorbent

Abstract

The adsorptive removal of cationic Methylene Blue and anionic Alizarin Red S was analysed in microcolumn tests. A detailed analysis of the influence of adsorbent surface acidity/basicity, elemental composition, Brunauer-Emmett-Teller area, pore distribution, and point-of-zero-charge pH on breakthrough properties was carried out. The characteristics of the mass transfer zone were used for evaluation of column performance. Four different activated carbons with different physical and chemical properties were analysed. It was concluded that, for adsorbents containing pores smaller than 1.7 times the solute molecular radius, the interactions between surface and solute have the greatest influence on the effective usage of column uptake capacity. A column packed with adsorbent characterised by large enough pores readily removed either anionic or cationic solutes. Partial correlation analysis revealed that the adsorption of cationic dye (Methylene Blue) was more sensitive to adsorbent textural properties in comparison with anionic dye (Alizarin Red S). Maximum column capacities were 3-4 times higher for cationic Methylene Blue than for anionic Alizarin Red S, with values of 494 and 107 mg/g respectively. The higher solubility of Alizarin Red S could be responsible for its lower and more even removal efficiencies. Finally, the surface chemistry of the adsorbent affected how the operating conditions influenced the column performance, as deduced from the opposite effect of flow rate on the adsorption of Methylene Blue by each adsorbent.

The adsorption of basic dye (Alizarin red S) from aqueous solution onto activated carbon/γ-Fe2O3 nano-composite: Kinetic and equilibrium studies

“…ARS is a water-soluble, widely used anthraquinone dye with pKa value of 4.5. Solubility in water for ARS is reported to be about 77 g L À 1 at 20°C [22]. [24,25].…”

Punica granatum husk (PGH), a powdered biowaste material for the adsorption of methylene blue dye from aqueous solution

“…(2014) [1][2][3][4][5][6][7][8][9][10][11] www.deswater.com doi: 10.1080/19443994.2014.984344 ability of activated carbon for dye removal is well known and undisputed, but its high cost precludes the practical use [11]. In this way, the search for cheaper and efficient adsorbents, such as, low-cost agricultural wastes, to replace activated carbon has gained attention in recent years [12].…”

“…Several traditional treatment processes have been applied for the removal of MB dye from waters and wastewaters in order to decrease their impact on the environment. The processes developed consist basically in decolorizing by electrochemical combined with biological treatment [4], photocatalytic oxidation [5], Fenton treatment [6], nanofiltration [7], sonocatalytic degradation [8], biological treatment [9], and adsorption on activated carbon [10]. Activated carbon is most popular adsorbent used for metals, pesticide, and dye removal.…”

Designing Metallic Iron Packed‐Beds for Water Treatment: A Critical Review

“…There are several transport phenomena taking place within the interstitial fluid elements and also within the pores of the adsorbent. The overall adsorption process includes axial dispersion in the direction of the liquid flow, film diffusion resistance, intra‐particle diffusion resistance, which may include both pore and surface diffusion, and sorption kinetics at the adsorbent surface . For all these reasons, adsorption packed‐beds are difficult to design and operate.…”

“…p K α , molecular size, redox properties) should be considered to optimize the efficiency of packed‐beds . Despite decades of intensive researches, a science‐based optimization of packed‐bed adsorption is yet to be established .…”