Potential Chemical Oxo-precipitation (COP) for Remediating Wastewater with a High Boron Concentration using H2O2/Ba(OH)2 at Room Temperature

Abstract

Among current approaches for removing boron, chemical precipitation is widely used for treating wastewater that contain a high boron concentration. The need for heating and very large amounts of coagulant limits the efficiency of this method. Accordingly, this work developed a chemical oxo-preceipitation (COP) method, which uses hydrogen peroxide (H2O2) as the oxidant and barium hydroxide (Ba(OH)2) as the precipitant to improve considerably the chemical precipitation of wastewater with a high concentration of boron at room temperature. Under suitable conditions (pHi 9, mole ratio of H2O2/B = 2, and mole ratio of Ba/B = 0.8), boron can be efficiently removed from solution by forming amorphous precipitates of barium perborate. After four hours, amorphous barium perborate was transformed to a particular species with a crystalline phase. Consequently, the boron concentration was reduced from 1000 mg/L to 2 mg/L in six hours. The results of XRD, Raman spectroscopy and ICP prove that a dinuclear perborate with double peroxo bridges constituted the crystalline precipitate whose chemical formula was found to be BaB2(O2)2(OH)4-n (OOH)n.

Simultaneous Recovery of Display Panel Waste Glass and Wastewater Boron by Chemical Oxo-precipitation with Fluidized-Bed Heterogeneous Crystallization

“…The Raman spectra of the precipitates from the silica sand shows four distinct peaks at 745, 875, 1060, and 1553 cm –1 . The peak at 875 cm –1 is the contribution of the symmetric BO 3 stretching of B(OH) 3 and O–O stretching of H 2 O 2 13,39 and the band at 1553 cm –1 is attributed to the O–O stretching of oxygen. 14,15 Bands at 745 and 1060 cm –1 likely arise from the asymmetric [B(OH) 4 ] − stretching of metaborate due to the υ 1 symmetric (B–O(OH)) of metaborate 14 and symmetric (B–OH) stretching of H 3 BO 3 , 40 respectively.…”

“…Although the bands in the Raman spectra of the precipitates produced by MAS are similar to those by silica sand, the crystallization of MAS-based precipitates is more rapid and several sharp peaks at 711, 934, and 987 cm −1 associated with υ asym (B 2 (OO) 2 ), υ sym (O−O), and υ sym (B−O) are observed, respectively. 14,39 In addition, the peak intensity increases with increase in the reaction time from 8 to 216 h, which indicates that the reaction of perborate with peroxo groups produces cyclic dimeric peroxoborate (B 2 (OO) 2 (OH) 4 ) 2− by linking two peroxo bridges with two four-coordinated boron atoms. 14,39 It is noteworthy that the crystalline structure of barium peroxoborate (BaB 2 (OO) 2 (OH) 4 ) is rapidly formed in the presence of MAS carrier because of considerable absorbed amounts of barium onto the MAS surface.…”

“…14,39 In addition, the peak intensity increases with increase in the reaction time from 8 to 216 h, which indicates that the reaction of perborate with peroxo groups produces cyclic dimeric peroxoborate (B 2 (OO) 2 (OH) 4 ) 2− by linking two peroxo bridges with two four-coordinated boron atoms. 14,39 It is noteworthy that the crystalline structure of barium peroxoborate (BaB 2 (OO) 2 (OH) 4 ) is rapidly formed in the presence of MAS carrier because of considerable absorbed amounts of barium onto the MAS surface. These results clearly demonstrate the superiority of MAS to rapidly produce crystallized precipitates within 8 h in comparison with silica sand, which needs 216 h for crystallization.…”