Analysis And Detection Of Trace PPCPs In Water And Their Separation Properties By High-performance Forward Osmosis Membrane

With the improvement of human living standards and the advancement of medical standards,pharmaceutical and personal care products（PPCPs）are widely used in many fields.Although PPCPs are present in trace amounts in water bodies,they are difficult to degrade and can be accumulated in living organisms,posing a great threat to human being’s health and the ecological environment.Conventional water treatment processes can not remove PPCPs effectively.Forward osmosis（FO）is a technology that relies on the osmotic pressure difference on both sides of the membrane as a driving force.It has low energy consumption and low membrane fouling,and the membrane pore size of the FO membrane is small,which has great potential in removing PPCPs safe and efficiently.Ibuprofen（IBU）,naproxen（NPX）,sulfamethoxazole（SMX）and triclosan（TCS）were selected according to the physicochemical properties（molecular weight,chargeability,hydrophobicity,etc.）of PPCPs in water.Four compounds were used as representative of PPCPs in water.For the double selective layered composite forward osmosis membrane developed by the research team,the rejection characteristics of PPCPs in water by composite forward osmosis membrane under different water quality conditions were investigated.The solid phase extraction as pretreatment method and liquid chromatography-triple quadrupole mass spectrometer（UPLC-MS/MS）detection method were established.Combined with solid phase Zeta potential meter,atomic force microscopy（AFM）and contact angle measuring instrument,the in-depth analysis of its interception mechanism was carried out.Finally,compared with the performance of commercial membranes,it provides direction for the low energy consumption and high efficiency removal of trace PPCPs in water..The main results are as follows:（1）Simultaneous detection technology of representative PPCPs in trace amounts.The effect of different conditions on the recovery rate of the extraction column was studied.It was concluded that the best method for the solid phase extraction of the sample was to use the HLB solid phase extraction column:methanol and deionized water were used as the activation solution,and the sample p H=3.Deionized water is used as eluent and washed with methanol as deliquoring.The recovery of four kinds of PPCPs was good,which provides support for the detection of trace PPCPs in water.UPLC-MS/MS was used to study the four compounds simultaneously,and the standard curve was drawn.The correlation was good（r²>0.998）.The limit of quantification of the four target compounds could reach ng/L.Simultaneous detection of four PPCPs in water is achieved.（2）Under the condition of four PPCPs blend together,the rejection characteristics of PPCPs in water by double selective layered composite forward osmosis membrane were studied under the condition of p H,ionic strength and complex pollutants in feed solution.The p H of the feed solution mainly affected the rejection rate of PPCPs by affecting the surface electrical properties of the forward osmosis membrane and the chargeability of PPCPs.p H=9,the rejection rates of the four PPCPs reached the highest level.When the ionic strength of the feed solution increased from 0 to 20 mmol/L,the electrostatic repulsion of the negatively charged IBU,NPX and SMX and the forward osmosis membrane decreased,the rejection decreased.And the ionic strength increased from 20 mmol/L to 100 mmol/L,the pores shrink and the screening effect increased,and the rejection rates of IBU,NPX and SMX continue to increase.For TCS,as the ionic strength increased,the forward diffusion increased and the rejection decreased.When the ionic strength reached 100 mmol/L,the pore shrinkage of the membrane led to an increase in the screening effect,which was greater than the forward diffusion of TCS and the rejection rate increased.In the feed solution,the organic substance represented by SA and the inorganic substance represented by Ca²⁺coexist to form membrane fouling,and the rejection rates of the four PPCPs are increased.The main rejection mechanisms of negatively charged IBU,NPX and SMX are electrostatic repulsion and size exclusion.The main rejection mechanism of the neutral hydrophobic compound TCS is size exclusion and hydrophobic interaction.The presence of a fouling layer promoted the rejection of the membrane.（3）Under the condition of four PPCPs blend together,the rejection characteristics of PPCPs in water by double selective layered composite forward osmosis membrane were studied under the condition of different type and concentration of the draw solution.The 1 mol/L Na Cl,Mg Cl₂,Mg SO₄ and glucose were used as the draw solution.The reverse salt flux and rejection rate of the forward osmosis membrane were:Na Cl>Mg Cl₂>Mg SO₄>glucose.The increase in reverse salt flux will inhibit the forward diffusion of the four PPCPs,resulting in an increase in rejection.With Na Cl as the draw solution,the rejection of the four PPCPs was the highest.The reverse salt flux increased with the concentration of the draw solution,and the rejection rate of the four PPCPs increased.However,when the concentration of the draw solution reached 5 mol/L,the negatively charged IBU,NPX and SMX are mainly electrostatically charged.The effect of repulsion,the surface electronegativity of the forward osmosis membrane decreased,the electrostatic repulsion decreased,and the rejection rate decreased.（4）Compared with commercial CTA membranes,the active layer of the self-made double selective layered composite forward osmosis membrane has a polyamide structure,so the membrane has a smaller effective pore size,and exhibits superior performance in terms of rejection of PPCPs in water.