CN101975779B - Method for rapidly evaluating performance of reverse osmosis antisludging agent by determining pH value of solution - Google Patents

Abstract

The invention relates to a method for rapidly evaluating the performance of a reverse osmosis antisludging agent by determining the pH value of a solution, comprising the following steps of: (1) adding a CaCl2 solution the concentration of which is C1 and the volume of which is V1 and an antisludging agent the dosage of which is W to a container; (2) making the container airtight at constant temperature under stirring, then dropwise adding a NaHCO3 solution the concentration of which is C2 and the volume of which is V2 and marking as the first time; (3) recording the pH value of the solution after t min, simultaneously dropwise adding the NaHCO3 solution the concentration of which is C2 and the volume of which is V2 and marking as the second time; (4) repeating the step (3) until the pH value of the solution falls, wherein the adding time of the NaHCO3 solution sums to n, and recording the pH value of the solution when the NaHCO3 solution is added for the (n-1)<th> time and the volume(n-1)V2 of the accumulatively consumed NaHCO3 solution; and (5) working out the supersaturation S of CaCO3 in the solution when the NaHCO3 solution is added for the (n-1)<th> time, and judging the performance of the antisludging agent according to the S magnitude. The method is rapid and accurate, has simple test condition and is easy to operate.

Description

A kind of based on the method for measuring pH value of solution value rapid evaluation performance of reverse osmosis antisludging agent

Technical field

The invention belongs to water-treatment technology field in the environmental engineering, be specifically related to a kind of static method that comes the rapid evaluation performance of reverse osmosis antisludging agent through mensuration pH value of solution value.

Background technology

Fouling is to influence one of subject matter of the normal operation of counter-infiltration, adds antisludging agent and has become one of effective means of control reverse osmosis membrane fouling.At present, domestic and international researcher is divided into static rating method and two big types of dynamic rating methods for the assessment method of reverse osmosis antisludging agent.

The static-state scale inhibition method mainly contains tosca method, Bubbling method, nephelometry, electrical conductivity method etc.Wherein tosca method and Bubbling method are that recirculated cooling water is bigger with antisludging agent assessment method and the dirty process difference that forms of counter-infiltration commonly used, and the test period is long, poor reproducibility.Nephelometry needs the sampling and measuring turbidity, and it is airtight to be not easy implement device during manually-operated, and complex operation.Electrical conductivity method is used CaCl ₂And Na ₂CO ₃Configuration test water sample, but the pH value of counter-infiltration water body is usually less than 8.3, and the carbonate composition is with HCO in the water ₃ ^-Be main, as shown in Figure 1.The pH value of counter-infiltration water body and carbonate are formed and electrical conductivity method configuration water sample has than big-difference.

Dynamically rating method is divided into feedwater single pass method, total recycle process, partial recycle process and discontinuous cycle method.Dynamically rating method can be simulated the operating condition of counter-infiltration well, the performance of accurate assessment of scale inhibitor, but dynamically the rating method effort is consuming time.In static rating method, be badly in need of a kind of method of research as the antisludging agent shaker test before the dynamic rating method, to increase work efficiency.

In counter-infiltration system, because the centrifugation of film, feedwater constantly concentrates, and difficulty soluble salt lime carbonate precipitates and separates out because of being in hypersaturated state, i.e. [Ca ²⁺] [CO ₃ ^2-]=SK _Sp, S is a degree of supersaturation, K _SpSolubility product for lime carbonate.After adding antisludging agent,, increased the degree of supersaturation of lime carbonate because antisludging agent suppresses or disturbs effects such as nucleus growth, complexing solubilising.Degree of supersaturation S value through lime carbonate behind the different antisludging agents of calculating adding can compare its scale-inhibiting properties.

In solution, generate CaCO ₃During deposition, the reaction of generation is as shown in the formula (1) and formula (2).

Because CaCO ₃The generation of deposition, CO in the solution ₃ ^2-Ion concentration reduces, and reaction (1) moves right H in the solution ⁺Concentration increases, and the pH value of solution value reduces significantly.

The carbonate of water distribution of the present invention is with HCO ₃ ^-Be main, near the characteristics that the pH value and the carbonate of counter-infiltration water body are formed, the pH value of monitoring solution reduces as the terminal point of judging with the pH value significantly.

Summary of the invention

The object of the invention is to overcome the deficiency in the present static qualification test, provide a kind of fast, accurately, test condition is simple, through measuring the method for pH value rapid evaluation performance of reverse osmosis antisludging agent.

For realizing above-mentioned purpose, the present invention adopts following technical scheme:

A kind of based on the method for measuring pH value of solution value rapid evaluation performance of reverse osmosis antisludging agent, may further comprise the steps:

1. in container, adding concentration is C ₁, volume is V ₁CaCl ₂Solution, dosage are the antisludging agent of W;

2. container is under airtight, constant temperature, the constant agitation velocity conditions, dropping concentration is C ₂, volume is V ₂NaHCO ₃Solution is designated as the 1st time;

3. the pH value of recording solution behind the tmin is (to guarantee CaCl ₂And NaHCO ₃Mix, sufficient reacting), simultaneously dripping concentration once more is C ₂, volume is V ₂NaHCO ₃Solution is designated as the 2nd time;

4. 3. repeating step (generates CaCO in the solution until the reduction of pH value of solution value at this moment ₃Deposition), NaHCO ₃The indegree that adds of solution amounts to n time, the NaHCO that the pH value of solution and accumulative total consumed when record (n-1) was inferior ₃Liquor capacity (n-1) V ₂

5. calculate (n-1) inferior adding NaHCO ₃The time solution in CaCO ₃Degree of supersaturation S judges the antisludging agent scale-inhibiting properties according to the S size.

Said C ₁Be 0.005～0.015mol/l, V ₁Be 100～200ml, C ₂Be 0.1～0.6mol/l, V ₂Be 0.2～5ml, t is 0.5～3.

The mensuration of said pH value is used the numeric type pH meter, and the resolution of pH meter is 0.01.

Said pH value is reduced to measured pH value and reduces more than 0.03 than preceding-pH value numerical value.

Work as CaCl ₂And NaHCO ₃Solution fully reacts but does not generate CaCO ₃Before the deposition, the pH value of solution value is mild ascendant trend; In case generated CaCO in the solution ₃Deposition because the balance of reaction (1) and (2) is broken, makes the pH value of solution value obviously to descend.With the NaHCO that adds ₃Liquor capacity is a horizontal ordinate, and the pH value of solution value is an ordinate mapping (see figure 2), and the pH value is with NaHCO ₃Liquor capacity increases curve and is slow ascendant trend earlier, and the back descends (the pH value reduces more than 0.03 than preceding-pH value numerical value) suddenly, and an obvious flex point appears in curve.

With CaCO in the solution before the deposition ₃The foundation judged as performance of antisludging agent of degree of supersaturation S, the S value is big more, explains that the resistance carbonate scale effect of antisludging agent is good more.According to the data of putting down in writing in the experimentation, computation process is following:

$\left[{\mathrm{Ca}}^{2+}\right]=\frac{C_1{V}_1}{{\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="HSA00000259867300013.png"\; state="\{\{state\}\}">V</figure-callout>}}_1+(n-1)V_2}---\left(3\right)$

$\left[{{\mathrm{HCO}}_3}^{-}\right]=\frac{C_2{V}_2}{V_1+(n-1)V_2}---\left(4\right)$

$\left[{{\mathrm{CO}}_3}^{2-}\right]=\frac{K_2\&times;\left[{{\mathrm{HCO}}_3}^{2-}\right]}{\left[H^{+}\right]}---\left(5\right)$

$S=\frac{\left[{\mathrm{Ca}}^{2+}\right]\left[{{\mathrm{CO}}_3}^{2-}\right]}{K_{\mathrm{sp}}}---\left(6\right)$

In the formula: [Ca ²⁺], [HCO ₃ ^-], [CO ₃ ^2-]-calcium ion, bicarbonate ion, carbon acid ion concentration, the mol/L of unit;

K ₂The secondary ionization equilibrium constant of-carbonic acid; K ₂=10 ^-10.33

K _Sp-CaCO ₃Solubility product, under 25 ℃, K _SpBe 4.8 * 10 ^-9

Beneficial effect of the present invention:

The present invention is based on the water body characteristics configuration water sample of counter-infiltration; The pH value of water sample, carbonate ion are formed more near the water body characteristics in the counter-infiltration operational process; Provide a kind of with the pH value as the test endpoint judge index, the static assessment method of rapid evaluation performance of antisludging agent., highly sensitive with the pH value as endpoint.Test method is simple, quick, accurate, easy to operate, and test condition and equipment are prone to realize.

Description of drawings

Fig. 1: the graph of a relation of various carbonate compound relative contents and pH value in the water;

NaHCO when adding 1mg/L antisludging agent TPTO-150 among Fig. 2: the embodiment 1 ₃Addition and pH value of solution graph of a relation;

Fig. 3: NaHCO when adding different antisludging agent ₃Addition and pH value of solution graph of a relation.

Embodiment

Through embodiment the present invention is further specified below, but protection scope of the present invention is not limited thereto.

Embodiment 1

A kind of based on the method for measuring pH value of solution value rapid evaluation performance of reverse osmosis antisludging agent, may further comprise the steps:

1. in container, add 150ml (V ₁), 0.009mol/l (C ₁) CaCl ₂Solution, dosage are the antisludging agent TPTO-150 (production of U.S. Tang Na company) of 1mg/L;

2. container is under airtight, (25 ± 1) ℃ temperature constant state, the constant electromagnetic agitation velocity conditions, drips 2ml (V ₂), 0.3mol/l (C ₂) NaHCO ₃Solution.Be designated as the 1st time;

3. measure the pH value of solution behind the 2min with the numeric type pH meter, the while drips the NaHCO of 2ml, 0.3mol/l once more ₃Solution is designated as the 2nd time;

4. repeating step 3., totally 11 times, the pH value of solution value reduced and (generated CaCO in the solution this moment ₃Deposition), write down the 10th time and drip NaHCO ₃Back pH value of solution value is 8.23, the NaHCO that this moment, accumulative total consumed ₃Liquor capacity is 20ml, sees Fig. 2 for details;

5. CaCO in the solution before calculating deposition generates ₃Degree of supersaturation S, judge the scale-inhibiting properties of antisludging agent according to the size of S.

In addition; Antisludging agent TPTO-150 is replaced by PTP-0100, ATMP (ATMP) or the HPMA (HPMA) of the U.S. Argo of GE-Betz company reverse osmosis antisludging agent MDC220, the clear power of the U.S. respectively; Addition is 1mg/L, and other condition is constant, according to 1. making an experiment to 3. step among the embodiment 1; And repeating step writes down each required data 3. until the reduction of pH value of solution value.Do blank test (being not add antisludging agent in the container) simultaneously and come contrast effect.Write down the NaHCO of the n-1 time (being before the pH value reduces) accumulative total adding ₃The pH value of volume and solution, the result sees table 1.

The test findings that table 1 antisludging agent does not write down simultaneously

Antisludging agent	TPTO-150	MDC220	PTP-0100	ATMP	HPMA	Blank
							Drip frequency n	11	17	7	13	7	4
?NaHCO 3Volume (n-1) V 2(ml)	20	32	12	24	12	6
							(n-1) inferior adding NaHCO 3The time pH value of solution	8.23	8.17	8.28	8.11	8.11	8.18

The comparison of different antisludging agent scale-inhibiting properties:

Antisludging agent TPTO-150 to add 1mg/L is an example, the NaHCO that adds before the pH value reduces ₃Volume is 20ml, and the pH value is 8.23.Computation process is following:

$\left[{\mathrm{Ca}}^{2+}\right]=\frac{C_1{V}_1}{{\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="HSA00000259867300013.png"\; state="\{\{state\}\}">V</figure-callout>}}_1+(n-1)V_2}=\frac{0.009\&times;150}{150+(11-1)\&times;2}0.0079\mathrm{mol}/L$

$\left[{{\mathrm{HCO}}_3}^{-}\right]=\frac{C_2{V}_2}{{\mathrm{<figure-callout\; id="1"\; label="V"\; filenames="HSA00000259867300013.png"\; state="\{\{state\}\}">V</figure-callout>}}_1+(n-1)V_2}=\frac{0.3\&times;20}{150+(11-1)\&times;2}=0.035\mathrm{mol}/L$

$\left[{{\mathrm{CO}}_3}^{2-}\right]=\frac{K_2\&times;\left[{{\mathrm{HCO}}_3}^{2-}\right]}{\left[H^{+}\right]}=\frac{4.69\&times;{10}^{-11}\&times;0.035}{{10}^{-8.23}}=2.80\&times;{10}^{-4}$

$S=\frac{\left[{\mathrm{Ca}}^{2+}\right]\left[{{\mathrm{CO}}_3}^{2-}\right]}{K_{\mathrm{sp}}}=\frac{0.0079\&times;2.80\&times;{10}^{-4}}{4.8\&times;{10}^{-9}}=461$

According to the test data in the table 1, calculate the degree of supersaturation value S that adds above-mentioned antisludging agent and blank test, see Table 2.

The degree of supersaturation value S that table 2 antisludging agent does not calculate simultaneously

Antisludging agent	TPTO-150	MDC220	PTP-0100	ATMP	HPMA	Blank
							Degree of supersaturation value S	461	563	346	405	232	148

With CaCO in the water sample before the deposition ₃Degree of supersaturation S as the basis for estimation of performance of antisludging agent, the S value is big more, explains that the resistance carbonate scale effect of antisludging agent is good more.Can find out that from table 2 the scale-inhibiting properties ordering of antisludging agent is: MDC220＞TPTO-150＞ATMP＞PTP-0100＞HPMA＞blank.

Annotate: when performance of antisludging agent near the time, can be through reduce to add NaHCO at every turn ₃Volume or reduce CaCl ₂And NaHCO ₃Concentration, distinguish scale-inhibiting properties.In the process of the test, after the pH value reduces, promptly can be observed the solution becomes muddiness in the several seconds, explain with the pH value and judge that terminal point is sensitive more, quick.

Claims (3)

1. the method based on mensuration pH value of solution value rapid evaluation performance of reverse osmosis antisludging agent is characterized in that, may further comprise the steps:

1. in container, adding concentration is C ₁, volume is V ₁CaCl ₂Solution, dosage are the antisludging agent of W;

2. container is under airtight, constant temperature, the constant agitation velocity conditions, dropping concentration is C ₂, volume is V ₂NaHCO ₃Solution is designated as the 1st time;

3. write down the pH value of solution value behind the t min, dripping concentration simultaneously is C ₂, volume is V ₂NaHCO ₃Solution is designated as the 2nd time;

4. 3. repeating step reduces NaHCO until the pH value of solution value ₃The indegree that adds of solution amounts to n time, the NaHCO that the pH value of solution and accumulative total consumed when record (n-1) was inferior ₃Liquor capacity (n-1) V ₂

5. calculate (n-1) inferior adding NaHCO ₃The time solution in CaCO ₃Degree of supersaturation S judges the antisludging agent scale-inhibiting properties according to the S size; Said C ₁Be 0.005～0.015mol/l, V ₁Be 100～200ml, C ₂Be 0.1～0.6mol/l, V ₂Be 0.2～5ml, t is 0.5～3.

2. evaluate the method for performance of reverse osmosis antisludging agent according to claim 1, it is characterized in that, the mensuration of said pH value is used the numeric type pH meter, and the resolution of pH meter is 0.01.

3. like the method for the said evaluation performance of reverse osmosis antisludging agent of claim 2, it is characterized in that said pH value is reduced to measured pH value and reduces more than 0.03 than last pH value numerical value.

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