Development of a fixed‐bed column with cellulose/chitin beads to remove heavy‐metal ions

Abstract

Environmental friendly cellulose/chitin beads, having relatively high mechanical properties, were successfully prepared from a blend of cellulose and chitin in 6 wt % NaOH/5 wt % thiourea aqueous solution by coagulating with 5% H 2 SO 4 aqueous solution. The ability of the beads to adsorb Pb 2ϩ in an aqueous solution was measured with a fixed-bed column. The effects of important parameters, to design an adsorption column of the cellulose/chitin beads for fixed-bed columns, were investigated. The breakthrough curves for the adsorption behavior indicated that the column performance was improved with decreasing initial lead concentration, ionic strength, flow velocity or bead size, as well as increasing pH dependence and bed height. Column studies showed that constants, calculated from the experimental data, and the Bed Depth Service Time (BDST) model had a good correlation. The columns were easily regenerated by treating with 0.1 mol/L HCl aqueous solution after the adsorption of metals, providing a simple and economical method for removal and recovery of heavy metals. After four adsorption-desorption cycles, the efficiency of column for the removal of lead was not significantly reduced (not more than 5%). It is shown that heavymetal biosorption processes in fixed-bed columns could give a broad range of potential industrial applications.

Antioxidant Polymers: Metal Chelating Agents

“…Biosorption is a complementary, inexpensive, and easy method in such applications [35,36]. To this end, chitin has been known to chelate heavy metal ions for wastewater treatment purposes [28,30,[36][37][38][39]. Barriada et al, have reported on the removal of cadmium and lead from contaminated effluents by chitin chelation [40].…”

“…Similarly, vanadate and chromium cations, in addition to cadmium, copper, lead, and zinc have been adsorbed by chitin [35,41]. Moreover, it was also reported that lead as well as iron cations are adsorbed on chitin [37]. It should be mentioned here that cadmium, chromium, mercury, zinc, copper, lead, iron, silver, molybdenum, and nickel are major pollutants in industrial wastewater and are of particular interest for removal given the serious problems these metals can cause in the environment [28].…”

Design of Pilot Plant Packed Column for the Dehydration of Water from Ethanol-Water Mixtures

“…[7] reported column diameters of 30 mm, 2.0 -2.5 cm was reported by [4] [8] 5 cm was reported [9] and 20 cm by [10] have been employed. To minimize possible wall and axial dispersion effects in fixed columns, it is recommended that the bed length-to-particle diameter ratio be greater than 20 [4]. It could be deduced that the axial dispersion effects could be avoided if the adsorbent particle size is larger by using a deeper column or adsorbent with smaller particle size diameter.…”

“…From this, the concept of breakthrough can be defined as the amount of influent solution passing through the bed before a maximum effluent concentration is reached [3] [4]. Breakthrough and exhaustion are defined as the phenomena when the ratios of effluent-to-influent concentrations are 5% and 95% respectively [4]. Values of column breakthrough and exhaustion are often used to evaluate adsorption parameters in column adsorption systems.…”

“…As the equilibrium zone approaches the bottom of the column bed, the concentration of adsorbate in the effluent increases, and finally equals the influent adsorbate concentration. From this, the concept of breakthrough can be defined as the amount of influent solution passing through the bed before a maximum effluent concentration is reached [3] [4]. Breakthrough and exhaustion are defined as the phenomena when the ratios of effluent-to-influent concentrations are 5% and 95% respectively [4].…”