Removal of Barium from Solution by Natural and Iron(III) Oxide-Modified Allophane, Beidellite and Zeolite Adsorbents

Abstract

Efficient capture of barium (Ba) from solution is a serious task in environmental protection and remediation. Herein, the capacity and the mechanism of Ba adsorption by natural and iron(III) oxide (FeO) modified allophane (ALO), beidellite (BEI) and zeolite (ZEO) were investigated by considering the effects of contact time, temperature, pH, Ba2+ concentration, adsorbent dosage, the presence of competitive ions and adsorption–desorption cycles (regenerability). Physicochemical and mineralogical properties of the adsorbents were characterized by XRD, FTIR, SEM with EDX and N2 physisorption techniques. The Ba2+ adsorption fitted to a pseudo-first-order reaction kinetics, where equilibrium conditions were reached within <30 min. BEI, ALO and ZEO with(out) FeO-modification yielded removal efficiencies for Ba2+ of up to 99.9%, 97% and 22% at optimum pH (pH 7.5–8.0). Adsorption isotherms fitted to the Langmuir model, which revealed the highest adsorption capacities for BEI and FeO-BEI (44.8 mg/g and 38.6 mg/g at 313 K). Preferential ion uptake followed in the order: Ba2+ > K+ > Ca2+ >> Mg2+ for all adsorbents; however, BEI and FeO-BEI showed the highest selectivity for Ba2+ among all materials tested. Barium removal from solution was governed by physical adsorption besides ion exchange, intercalation, surface complexation and precipitation, depending mainly on the absorbent type and operational conditions. BEI and FeO-BEI showed a high regenerability (>70–80% desorption efficiency after 5 cycles) and could be considered as efficient sorbent materials for wastewater clean-up.

Magnetic Mg-Fe/LDH Intercalated Activated Carbon Composites for Nitrate and Phosphate Removal from Wastewater: Insight into Behavior and Mechanisms

“…NaOH solutions with 0.1 and 0.5 M concentrations were used to regenerate the spent composite to be tested for the subsequent adsorption/desorption sequence. The magnitude of nitrate and phosphate anions removed after every adsorption/desorption cycle ( n ) is called the removal efficiency ( RE (%) ) and is computed using Equation (5) [ 62 ]: …”

Metal Removal from Nickel-Containing Effluents Using Mineral–Organic Hybrid Adsorbent

“…The final price of the hybrid adsorbent would constitute 530 USD per ton of sorbent. The price of the studied hybrid adsorbent would be comparable with the price of ALO sorbent (200–600 USD per ton) [ 6 ], higher than the price of activated charcoal (approximately 100 USD per ton) [ 45 ] but lower than the price of single-walled carbon nanotubes, multiwalled carbon nanotubes, and granular activated carbon (90,000, 12,000, and 1000 USD per ton, respectively) [ 37 ]. It should be mentioned that the zeolite used in the present study was purchased from a commercial company in a small amount; its procurement from the producer in large quantities would significantly decrease the price.…”

“…Zeolites are excellent ion exchangers which are characterized by a structural negative charge, which makes them perfect candidates for the removal of cations. Zeolites are readily available materials possessing excellent thermal and radiation stability and are characterized by a three-dimensional tetrahedral network and uniform porous structure [ 6 ]. At the same time, it should be mentioned that zeolites possess a low affinity for anions.…”

Zinc-Containing Effluent Treatment Using Shewanella xiamenensis Biofilm Formed on Zeolite

“…The emission of toxic elements in the environment presents a serious risk for the ecological systems and human health, due to the nonbiodegradability of metals and their tendency to accumulate in living organisms, causing different diseases [ 1 ]. Therefore, reduction of the concentration of metal ions released in the environment is a priority task in order to prevent natural water pollution [ 2 ].…”

“…Recently, a wide range of technologies has become available for wastewater treatment, among them chemical precipitation, flocculation, filtration, ion-exchange, coagulation, electrochemical treatment, membrane separation, oxidation-reduction, and adsorption [ 1 , 7 , 8 ]. However, these technologies are often low in terms of energy efficiency, as chemical product consumption is high, especially at metal concentrations of less than 100 mg/L, and some generate large volumes of sludge [ 7 , 8 ].…”