The third junior high school chemical waste liquid treatment topic, how to deal with chemical waste

If a factory wants to treat a waste liquid containing sulfuric acid, if the same amount of waste liquid is neutralized, the least amount of substance required is:

The relative molecular mass of H2SO4 is: 2 2+(32+16 4)=98Ca(OH)2 The relative molecular mass is: 40+(16+1) 2=74CaCO3 The relative molecular weight is:

40 + (12 + 16 3) = 10098 parts of H2SO4 requires 74 parts of Ca(OH)2 for a complete reaction.

98 parts of H2SO4 require 100 parts of CaCO3 to react completely.

So the answer is A.

NaOH crystals are purified from NaOH containing Na2CO3.

Ba(OH)2 is added first, then filtered, then heated, filtered, cooled, and the crystals are precipitated and then dried.

I made it up: 1After the reaction of CuSO4 with NaOH in the solution, after adding CO2 (gas), how to deal with it?

Analysis: In the reaction of CuSO4+2NaOH=Cu(OH)2(precipitation)+Na2SO4, copper hydroxide is toxic, and sodium sulfate is non-toxic;

When CO2 is added, Cu(OH)2 becomes Cu2CO3(OH)2, which is also toxic.

Answer: Filtration, the filter residue is placed in a rigid glass tube, passed into the CO, heated. (Causes Cu2CO3(OH)2 to decompose into Cuo and eventually to copper).

In chemistry class, pour into the waste tank. Otherwise, it can be removed by converting it into precipitate, gas, and water with chemical reagents, and then filtering the precipitate.

Steps and methods for solving process problems.

First, go through the whole question and determine the purpose of the process. ——What raw materials obtain what products (by-products), compare raw materials and products.

Secondly, read the local part intensively and clarify the reaction principle - determine the reactants and products of each step.

Third, re-read the diagram for the problem, and clarify the requirements - scientific expression and standardized writing.

Key Points of Examination: The properties of matter and their mutual transformation.

Transformation networks of elements and their compounds.

Methods for separating and purifying substances.

Crystallization – the process by which solid matter is precipitated from a solution.

Evaporation solvents, cooling hot saturated solutions, concentrated evaporation).

Filtration – solid-liquid separation.

Distillation – liquid, liquid separation.

Separation – the separation of immiscible liquids from each other.

Extraction – The solute is extracted from another solvent with one solvent.

Sublimation – the separation of solids that can be directly gasified.

Salting-out - the addition of inorganic salts reduces the solubility of the solute and precipitates.

Basic theory of electrolyte solution.

Ionization of weak acids and bases.

Ionization of water. Hydrolysis of salts.

Redox reactions.

Raw materials products.

Method: Conservation of Elements Method.

The coarse salt contains soluble impurities such as magnesium chloride and sodium sulfate and insoluble impurities such as sediment. In order to extract pure table salt from coarse salt, a research team designed the following experiments: in order to completely convert impurities such as magnesium chloride and sodium sulfate in coarse salt into precipitate, all each reagent added was excessive; White precipitate A is known to be soluble in acid, while white precipitate B is insoluble in dilute nitric acid.

The reagent is a soluble base, then the white precipitate a is the reagent that is

Add the reagent to the chemical equation where the reaction takes place is:

Operation M is

Answer: mg(OH)2 BACL2 or BA(OH)2

na2co3+2hcl=2nacl+h2o+co2↑

naoh+hcl=nacl+h2o

Evaporation crystallization or evaporation of solvents or evaporation.

The waste liquid discharged from a factory contains Zn(NO3)2 and AGNo3, which is ** metal AG, and the following scheme is designed:

b contains gas c is

zn, ag (2 points, 1 point for writing the correct one), h2

2l (8 points) The process of treating source water into tap water in a waterworks is as follows:

1) The effect of adding activated carbon is; In rural areas, there is no activated charcoal, and it is often added to purify water.

2) In the laboratory, the water hardness can be reduced in the operations of standing, adsorption, filtration, distillation, etc.

3) If there is a high amount of MgCl2 in the source water in the area, please write down the chemical formula when adding CAO to the source water treatment process. Programs:

2l (8 points) (1) (2 points) adsorbed impurities alum (2) (2 points) distilled.

3) (4 points) Cao + H2O = Ca(OH)2 (2 points) Ca(OH)2 + MgCl2 = mg(OH)2 + CaCl2 (2 points).

Buy a set of "Five-Three", there is a detailed summary in that book.

Waste Disposal Principles:

The high-concentration waste acid and waste lye should be discharged when neutralized to neutral. For high concentrations of organic solvents containing a small amount of analytes and other reagents, they should be reused. The high-concentration waste liquid used for ** should be stored centrally in order to **; The low concentration is discharged after treatment, and the storage container and storage conditions should be determined according to the nature of the waste liquid, and different waste liquids are generally not allowed to be mixed, protected from light, away from heat sources, so as to avoid adverse chemical reactions.

Waste liquid storage containers must be labeled, indicating the type, storage time, etc.

Precautions for Laboratory Waste Disposal:

1).Try to ** the solvent and reuse it repeatedly without hindering the experiment.

2).In order to facilitate disposal, its collection classification is often divided into: a) flammable substances b) flame retardant substances c) aqueous waste liquid d) solid substances, etc.

3).Substances that are soluble in water are easily lost as aqueous solutions. Therefore, it is important to pay attention to it.

However, solvents such as methanol, ethanol and acetic acid can be easily decomposed by bacteria. Therefore, the dilute solution of this type of solvent can be discharged after diluting it with a large amount of water.

4).Waste liquid containing heavy metals, etc., decomposes its organic matter and treats it as inorganic waste liquid.

There are three types of waste liquid treatment methods: physical treatment, chemical treatment and biological treatment. Chemical treatment is also generally combined with physical processes, also known as physicochemical treatment.

1.Physical treatment method refers to the use of physical or mechanical separation to treat waste liquid, and the commonly used methods are: filtration, sedimentation, floating, oil separation and centrifugal separation.

2.The chemical treatment method is a wastewater treatment method that separates, removes or converts pollutants in a dissolved and colloidal state in wastewater into harmless substances through chemical reactions and mass transfer.

3.Biological treatment is through the metabolic action of microorganisms.

This is a wastewater treatment method that converts organic pollutants in the state of solution, colloid, and micro-suspended organic pollutants into stable and harmless substances.

The ways to deal with it are:

1. Enterprises handle it by themselves. It is necessary to have a sewage discharge permit (with sewage discharge qualification), and secondly, the sewage treatment process is required.

The equipment must meet national or industry emission standards. Traditional sewage treatment processes are difficult to meet the standards.

2. Outsourcing. Outsourcing is handled by qualified environmental protection departments, which is costly (in some coastal areas.

The processing cost has been as high as 6,000 yuan to send more than Wang tons).

3. Waste liquid emission reduction and reuse technology. Anmei waste liquid emission reduction and reuse technology uses thermal cycle to evaporate and separate water from waste liquid, and the final purification of the purified liquid can reach more than that, and the cost is low.

1. Treatment of exhaust gas.

Experiments that produce a small amount of toxic gas should be carried out in a fume hood, and a small amount of toxic gas should be discharged to the outside through exhaust equipment and diluted by air.

Experiments that produce large quantities of toxic gases must have absorption or treatment devices. Acid gases such as nitrogen oxides and sulfur dioxide are absorbed by lye. The flammable organic waste liquid can be completely burned with oxygen in the combustion furnace.

2. Disposal of waste liquid.

1. Each laboratory should be equipped with containers for storing waste residue and waste liquid, and the waste residue and waste liquid polluting the environment generated by the experiment should be classified and poured into the designated container for storage.

2. Acidic and alkaline waste liquids are neutralized and post-treated respectively according to their chemical properties. Discharge after reaching pH between 6 and 9.

3. The organic waste liquid is treated after concentration, conversion, combustion and other treatments.

4. Try not to use or use less chemical reagents containing heavy metals for experiments.

3. Waste destruction.

1. Toxic wastes that can be naturally degraded are buried in a centralized and deep manner.

2. Waste chemicals that are insoluble in water are forbidden to be thrown into the wastewater pipeline, and must be concentrated in the incinerator for incineration or chemically treated into harmless substances.

3. Broken glass and other sharp wastes with edges and corners should not be thrown into the waste paper basket, but should be collected in a special waste box for disposal.

Wastewater: Put barbed wire in the wastewater to remove copper ions (**copper) in the wastewater, the reaction principle Fe + Cu (2 +) = Fe (2 +) + Cu

Exhaust gas: In the combustion process, limestone (caCO3) is added to the furnace to remove sulfur dioxide (acid rain substance) from the flue gas, reaction principle: caCO3====cao CO2 (high temperature conditions), cao SO2====CASO CASO3 O2====2CASO4

Solid waste: Incineration of solid waste with high organic matter to produce carbon dioxide and water.

Solution: (1) Both sodium carbonate and sodium hydroxide can react with dilute sulfuric acid, and the solution is neutral pH when the treatment is completed.

According to the law of conservation of mass.

m=10g；（

3) The mass of sulfuric acid participating in the reaction is:

10g set, the mass of sodium sulfate produced is x;

h2so4na2so

x x = solute mass fraction of the resulting solution is:, Answer: (1

3) When the waste liquid is just finished, the solute mass fraction of the resulting solution is

Then there must be something in the filter residue: ag may be there is: cu and there must be no is: fe

Hypothetical method: first add hydrochloric acid without bubbles, then there must be no iron in the filter residue, and then judge copper and silver, assume that copper is replaced first, copper will also react with silver nitrate, and silver is replaced, so zinc must react with silver nitrate first, so there must be silver, and whether there is copper depends on the amount of zinc).

There must be Zn(NO3)2 in the filtrate, Fe(NO3)2 and possibly: Cu(NO3)2, AGNo3

Zinc must react with the solution, so there must be Zn(NO3)2, there is no iron in the filter residue, then the iron must exist in the solution in the form of ions, so there must be Fe(NO3)2, and the presence or absence of Cu(NO3)2, AGNo3 depends on the amount of zinc).

If there are bubbles, then there must be Fe, Cu, Ag in the filter residue and there must be Zn in the filtrate

zn(no3)2。There may be: fe(no3)2 must not be :

cu(no3)2,agno3

The method is the same as above, and the hypothetical method (high school will know the reason) shows that zinc reacts with agno3 first, then with cu(no3)2, and finally with cu(no3)2......）

1. There must be AG in the filter residue; may have cu;

There must be Zn2+ and Fe2+ in the filtrate; There may be Cu2+, Fe3+, Ag+

2. There must be Ag, Cu and Fe in the filter residue; There may be zn;

There must be Zn2+ in the filtrate; There may be fe2+; What must not be AG+ and Cu2+ and Fe3+ are not.

No bubbles means that there is no pre-hydrogen metal, so there is no Fe and Zn, Ag is the least active, it will be replaced, there is Ag, Fe is gone and becomes Fe2+, Zn is gone and becomes Zn2+, so there must be Fe2+, Ag, Zn2+, Ag+ If there is a lot, the Fe, Zn reaction is finished, Cu2+ does not react, Ag+ is insufficient, Cu2+ is a lot, Cu2+ reacts, there will be Cu2+, Cu, so there may be Cu, Cu2+, Ag+

If there are bubbles, it means that there is a pre-hydrogen metal, so there must be no Cu2+, Ag+, there must be Cu, Ag, Zn2+, after the reaction is completed, there will be Fe reaction, there is Fe, Fe2+. In excess of Zn, Fe2+ reacts, Fe2+ is gone, Fe remains. There may be Fe2+, Zn

1. The addition of hydrochloric acid to the filter residue without bubbles means that there is no Fe and Zn Zn is replaced by AG first, and whether there is Cu is related to the amount of Zn. Therefore, there must be AG in the filter residue, there may be Cu, and there must be no Zn and Fe in the filtrate. The answer you know.

2.If there are bubbles, there must be Zn, and Fe may or may not be excessive, and with Zn, there must be Ag and Cu, and that's how the analysis process is.

According to the composition of the substances in the waste liquid, the general treatment methods are:

1. Precipitation method, the ion precipitation in the waste liquid is treated.

2. Neutralization method, according to the acidity or alkalinity of the waste liquid, neutralize with alkali or acid.

3. Oxidation method, using oxidant to oxidize the toxic ions in the waste liquid into CO2 or non-toxic ions.