The effects of scale inhibitor ATMP in water on nanofiltration

Abstract

As a kind of advanced water purification technology, nanofiltration (NF) has been widely used in the treatment of water. In the NF process, scale inhibitor such as aminotris (methylenephosphonic acid) (ATMP, H 6 atmp, H 6 L) is commonly added to control scale deposition. However, the impact of ATMP on the separation performance of NF has up to now been unknown. In this study, the impact of ATMP on calcium ion (Ca 2+) rejection rate and permeate flux of NF 270 membrane were investigated by permeate experiments with different ATMP concentrations. The results showed that ATMP had a significant impact on Ca 2+ rejection rate, as well as the feed pH. Both a local minimum in rejection rate and a slight maximum in permeate flux appeared at 10 mg•L-1 ATMP, corresponding to the feed pH about 5.5, which may be close to the isoelectric point (IEP) of membrane. When ATMP concentration was below 8 mg•L-1 and above 10 mg•L-1 , increasing ATMP concentration would both dramatically enhance Ca 2+ rejection rate. The main mechanism affecting the performance of NF was electrostatic effect caused by ATMP rather than its chelation effect. Our work demonstrated that in addition to the scale inhibition effect, ATMP in water also had a certain impact on the performance of NF membrane, especially for treating low alkalinity water (contain hardness and SO 4 2−), and aminotris (methylene phosphonic acid) (ATMP, H 6 atmp, H 6 L) is preferred to avoid precipitation and improve NF softening and desalination performance.

Pilot-Scale Field Demonstration of Environmental Nanotechnology for Groundwater Defluoridation

“…Groundwater is often characterized by high hardness and high alkalinity, e.g ., groundwater in the present study contained total dissolved solids (TDS) as high as 1500 mg/L, among which the content of Ca, Mg, and Si reached ∼320 mg/L, and carbonate was around 100 mg/L (Table S2). To prevent scaling in pipelines, pretreatment has become a requisite step prior to pumping groundwater into the advanced water treatment units. − For instance, acidic scale inhibitor ( e.g ., amino trimethylene phosphonic acid, ATMP) was added to groundwater before membrane filtration . The circulating fluidization crystallization process has been extensively studied to reduce hardness and alkalinity of groundwater prior to further purification .…”

“…63−66 For instance, acidic scale inhibitor (e.g., amino trimethylene phosphonic acid, ATMP) was added to groundwater before membrane filtration. 65 The circulating fluidization crystallization process has been extensively studied to reduce hardness and alkalinity of groundwater prior to further purification. 66 Among these, acidification might be one of the most feasible methods to retard the scale in terms of easy operation, relatively low dosage (∼250 mL of 30% H 2 SO 4 per ton of groundwater in this study), and low cost.…”

Nanofiltration Membrane Fouling and Control Caused by Residual Aluminum in Feed Water

“…Therefore, this kind of membrane fouling belongs to colloidal particle fouling. The pH of the experimental water was 7.0, which was higher than the isoelectric point of NF270 membrane with about pH 5.0 ~ 6.0 (Han et al, 2019;Mänttäri et al, 2006). In this case, the surface of membrane is negatively charged because the carboxyl groups of membrane can be deprotonated (solid-COOH → solid-COO-) (Zeng et al, 2017).…”

Removal of cerium ions by Amino Cyclohexyl Phosphonic Acid (ACHPA) intercalated into layered double hydroxide (Ni/Al-LDH)

“…Amino-Phosphonic acids have shown an inherent advantage in being used as an effective adsorbent and chelating ligand [1] in the adsorption of toxic heavy metals due to their remarkable physicochemical properties [2]. Amino phosphonic acids are chelating agents [3,4] which are synthesised by a Mannich reaction (Figure 1), this reaction is one of the best methods for introducing the amine function into organic molecules [5][6][7].…”