Influence of boron on rejection of trace nuclides by reverse osmosis

2019

Self Cite

BACKGROUND Reverse osmosis (RO), which is widely utilized in wastewater treatment, has been proven to be an effective tool for ion separation with high salts rejection. However, owing to the extremely low concentration of nuclides in boron‐containing low‐level radioactive wastewaters (LRWs), there is a significant reduction in rejection of nuclides by using commercial RO membranes. In this study, in order to obtain higher nuclides rejection under trace‐level condition, novel polyamide RO membranes were fabricated by grafting polyethylenimine (PEI) with different molecular weights on commercial RO membrane surfaces. RESULTS The properties of PEI‐modified membranes were analyzed, such as surface charge, morphology and hydrophilicity. The results showed that zeta potential at pH 7 increased from −22.89 mV to 20.19 mV, which indicated that surface charge altered from negative to positive. Meanwhile, hydrophilicity of membranes was improved since the contact angle decreased from 65° to 36°. The decontamination factor (DF) of cesium(I) increased from 11.69 to 114.23 and the DF of cobalt(II) increased from 28.62 to 3306.88. CONCLUSION The laboratory‐scale experiments with cross‐flow demonstrated the effective rejection of nuclides without obvious membrane flux loss of PEI‐modified membranes. In addition, PEI‐modified membranes offered a stable nuclides removal under high‐level background boron and various pH conditions, which demonstrated a possible application in boron‐containing LRW treatment. © 2019 Society of Chemical Industry

“…The nuclides DF of PEI‐modified RO membrane was much higher than conventional RO modules. For example, the three‐stage RO system of commercial RO membranes could reach 200–1400 …”

Section: Resultsmentioning

confidence: 99%

Section: The Influence Of Background Solutionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The application of polyethylenimine grafting reverse osmosis membrane in treating boron‐containing low‐level radioactive wastewaters

Chen

Ding

2019

Self Cite

“…Normally, the wastewater contains 500–2000 mg L −1 boron, and the radioactive concentration of radioactive nuclides is 10 4 –10 6 Bq L −1 . Using RO, these trace nuclides such as cesium, cobalt and strontium can be removed efficiently with rejections ranging from 90% to 99%, while 50–70% of boron can be removed . The different rejections among nuclides and boron have attracted lots of attention, so that to find the main influencers is particularly important.…”

Section: Introductionmentioning

confidence: 99%

The influence of salts on the reverse osmosis performance treating simulated boron‐containing low level radioactive wastewater

Ding

et al. 2018

Self Cite

BACKGROUND: With the rapid development of nuclear energy in China, a broad spectrum of low level radioactive wastewater (LLRW) has been generated and must be purified prior to discharging to the environment. Reverse osmosis (RO) has been proved an effective technology in the treatment of high boron-containing LLRW in nuclear power plants (NPPs). However, there is always a large amount of salts in the LLRW as background compounds. It is important to understand the influences of salts on the rejection of nuclides and boron.RESULTS: A lab-scale cross-flow membrane filtration unit was used. With the increase of ion concentration, the permeate flux decreased by 15% and 25% for BW30XFR and LE, respectively. Nuclides rejection increased by 2-8% and boron rejection increased by 5-10% when raising salts concentration to 2.5 mmol L -1 . Divalent ions such as Mg 2+ and SO 4 2− had a stronger impact than monovalent ions such as Na + and Cl − on nuclides and boron rejection. CONCLUSION: Increasing ion strength promoted the rejection of trace nuclides and boron, but at the cost of membrane flux loss.The results of dealing with simulated wastewater would give us information to better understand how to treat real radioactive wastewater.

Boron removal with modified polyamide RO modules by cross‐linked glutaric dialdehyde grafting

Chen

2020

Self Cite

BACKGROUNDReverse osmosis (RO) plays an increasingly important role in boron removal. In this study, novel polyamide RO membranes and modules with high boron rejection were fabricated by cross‐linked glutaric dialdehyde (GA) grafting. To evaluate the influence of GA grafting on membrane materials, the surface properties before and after modification were analyzed.RESULTSThe results showed that the membrane morphology changed distinctly after GA modification. All modified membranes became more hydrophilic as the water contact angle decreased from 60° to 35°. The zeta potential of RO membrane surface increased from −6.23 mV to 17.27 mV, which indicated that the surface charge altered from negative to positive. The rejection of boron increased from 76.65% to 90.14% and the boron permeability coefficient decreased from 3.71 to 0.79. Furthermore, the rejection of boron for modified module was >90% over a 5–22 ppm range of boron concentration. The rejection of boron also stabilized at ≈90% beyond 3000 min.CONCLUSIONThe modified RO membrane modules with high boron rejection and acceptable flux could be used in boron removal. The approach in this study can improve the separation properties of boron for commercially available modules without disassembling. © 2020 Society of Chemical Industry (SCI)