Abstract
In this paper, the gallium (III) ions’ adsorption onto protonated clinoptilolite (H-CLP) was investigated both in batch and fixed-bed column experiments. Regarding batch experiments, the influence of some parameters such as adsorbent dosage, size particle, and temperature was studied, determining that a dosage of 10 g/L for an initial pollutant concentration of 40 mg/L leads to a removal percentage over 85% regardless of particle size and temperature. On the other hand, adsorption of gallium onto H-CPL is an endothermic and spontaneous process in the studied temperature range, concluding that the maximum adsorption capacity was 16 mg/g for 60 °C. Concerning to the effect of the presence of other cations in solution, such as Na+, K+, or Ca2+, gallium adsorption capacity only drops by 20%, although the initial concentration of other cations in the solution is 50 times higher than gallium concentration. This means that clinoptilolite has a high affinity for gallium which can be very favorable for further selectivity tests. A crucial factor for this high selectivity could be the protonation of clinoptilolite which allows working without modifying the pH of the aqueous solution with acid. In the fixed-bed experiments, breakthrough curves were obtained, and the effect of operation variables was determined. A breakpoint value of 254 min for 64 g of adsorbent and flow rate of 9.0 mL/min (7.0 BV/h) were obtained, when treating a pollutant volume of 33 BV. Additionally, the breakthrough curves were fitted to different models to study the particle size effect, being the best fit corresponding to the Adams–Bohart model. This fact confirmed the influence of particle size on adsorption kinetics.Graphical
Highlights
Gallium is a rare and valuable metal which has found significant applications in the semiconductor industry
The opposite situation occurs with the adsorption capacity (q), because when the H-CPL dosage is increased there is an increase in the number of active adsorption sites, but the concentration of ions remains the same; the adsorbed quantity per weight unit decreases
The results previously shown have been related to kinetics, but the effect of temperature has been studied at equilibrium conditions by means of isotherms obtained for gallium initial concentrations ranging from 10 to 200 mg/L
Summary
Gallium is a rare and valuable metal which has found significant applications in the semiconductor industry It is classified as a strategic metal due to its relative scarcity and increasing use. It has no minerals of its own so it must be recovered as a byproduct from other metallurgical processes, mostly associated with ores of zinc and aluminum [1]. These previous facts, together with the increasing demand of this metal, have led to a strong interest in the recovery of gallium from wastes. The removal of gallium from aqueous solutions has become an important objective
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
