Abstract
The paper presents a studies on decreasing boron and arsenic concentrations in processed geothermal water. Reverse osmosis leads to obtain permeate and concentrate characterized by concentrations of 3.99 and 9.82 mg B L−1, as well as 2.93 and 120 μg As L−1, respectively. This disqualifies the possible use of forth streams for irrigation and makes them inacceptable to be discharged to the surface aquifers. Hence, they have to be treated using chelating resins to further decrease concentrations of boron and arsenic. The new chelating resins 1PTN and 2PTN were synthesized by polymerization of vinylbenzyl chloride (VBC) within a matrix of Amberlite XAD-4 followed by the modification with N-methyl-D-glucamine (NMDG). The so-synthesized NMDG-functionalized resins were evaluated for the removal of boron and arsenic from RO streams and compared to commercial boron selective chelating resin (Diaion CRB 05). Removals and its kinetics followed the pseudo-second order model. Based on diffusional and reactional kinetic models, it was determined that diffusion in pores of the chelating resins was the critical step and the boron sorption rate of epidermal-activated resin was mostly controlled by the reacted layer mechanism.Based on the obtained results, it was found that the resin 2PTN, characterized by macroporous, epidermal-like structure revealed 94% removal of boron and 97% removal of arsenic from RO concentrate. These performances allowed to effectively decrease concentrations of both species to the permissible levels for drinking and irrigation water. What is more, the synthesized resins successfully competed with the commercial boron selective resin Diaion CRB 05 in the boron removal, and outperformed the commercial resin in the arsenic removal, making them a very attractive alternative for reclamation of geothermal water.
Published Version
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