Highly porous cerium oxide prepared via a one-step hard template method as an extremely effective adsorbent for arsenic species removal from water

The Removal of Arsenic and Its Inorganic Forms from Marine Algae—A Base for Inexpensive and Efficient Fertilizers

“…[ 14 ], with the conditions given in the Materials and Chemicals section, the method leads to the production of highly porous ceria (the specific surface area, S BET = 187 m 2 g −1 , and pore volume, V p = 0.49 cm 3 g −1 ) in the form of easy-to-handle micro particles built of ceria nanocrystallites (<10 nm), with a surface concentration ratio Ce 3+ :Ce 4+ equal to 0.26. The ceria selected for this study was a solid of higher porosity to a similar material whose potential for As species adsorption was proven [ 13 ]. The comparison of various CeO 2 materials is presented in Table S1 .…”

“…Therefore, the adsorption process was optimized in the initial pH range from 2.0 to 9.9 ( Figure 1 and Figure 2 ). Since the adsorbent was prepared by calcining the XAD7-Ce(NO 3 ) 3 -CH 3 OH system in the air at 300 °C, the pH PZC likely equals 8.86 [ 13 ]. Hence, in the given conditions, the ceria surface is protonated and positively charged, the inorganic As(III) species exist in a non-ionic form of H 3 AsO 3 , while the inorganic As(V) species can be in two predominant forms in pH < 6.7 in the form of the monovalent anion H 2 AsO 4 − and above pH = 7 in the form of the divalent anion HAsO 4 2− [ 15 , 16 , 17 ].…”

“…The maximum adsorption capacity of the adsorption of inorganic As(III) and As(V) species equals 92 mg g −1 and 66 mg g −1 , respectively. These values are high, and the material presented here is within the group of superb inorganic As species adsorbents [ 13 , 33 , 34 , 35 , 36 , 37 ]. The Langmuir adsorption and Freundlich adsorption models were fitted into experimental points of the adsorption isotherm ( Table 2 ).…”

“…Cerium oxide is an inorganic porous material which is well known for its catalytic (automotive catalysts, ethanol reforming) and sorptive (dextran [ 9 ], histidine [ 10 ], U [ 11 ], phosphates [ 12 ], As [ 13 ]) properties. They are strictly connected to the surface chemistry of the CeO 2 : the surface oxygen vacancies, Ce(III) and Ce(IV) cations.…”

“…The As adsorption capacity of CeO 2 is also related to its active surface area, which increases and causes the presence of more active sites for As. Unfortunately, it is hard to synthesize this porous solid with the specific surface area exceeding 170 m 2 g − 1 [ 13 ].…”