Chemical Engineer Article: Maret 2010

Anion exchanger resin

Ion exchange resins can be used in the separation method or concentration by using redemption equality. Ion exchange resin is an organic high polymer containing ionic functional group, resin, there is generally a polymer granules with various sizes. These pellets are placed in a glass tube long enough to produce the ion exchange column in which ions will happen leveling process.

resin manufacture is a way to enter that in the ionisation cluster into the organic polymer matrix, the most common is polystyrene which acts as adsorbent.

solution through a column called influent, while the solution is out of the column is called effluent. The process is the exchange resin absorption and returns that have been used to shape called regeneration. While spending the ions from the column with the appropriate reagent called elusi. total exchange capacity is the number of cluster-cluster that can be exchanged within the column is expressed in milleknalen, breakthrough capacity is defined as the number of ions that can be taken by the column on the separation conditions.

Elusi analysis has many benefits, for example all the ions are separated leaving the column as factions separate. Elusi process consists of two, the first is the fraction with some eluen and the second is still mengelusi active ions.

anionik resin is a substance that can replace menukaratau anions existing in the surrounding medium. Resin-resin (synthetic) can be derived from solid polymers that bind tightly in a cross with a large molecular weight can come from certain organic substances such as phenol and sterina associated with a particular group can be ionized and alkaline, such as amine or phenol groups or kuartener aluminum is added to the resin polifeniletana stable.

The basic principle is the anion exchange resin can trade for other anion anion hidroksiloleh happened to the ion exchange resin. There are two types of anion exchange resin having strongly basic groups (kuartener ammonium groups) and the resin which has a weak base group (cluster anions).

Surface of a strong base can be used over a pH range of 0 to 12, while the weak base resin exchanger only above a pH range of 0 to 9. Weak base exchanger groups will not let go of a very weak acid, but is preferred for strong acids that may be restrained by a strong base resin like sulfanol.

Ion exchange process is a process of competition between solut ions contained in ion phase with opponent cars are attached to the functional group on the matrix of opposite charge. This means that the solut ion should be able to replace one or more ions are bound by the opponent stationer phase (matrix). When we have exchange positively charged ions or cation exchanger that has bound ions in the phase opposite the car present in the solut ion ion exchange process can act.

Liquid propellants?

All the fuel that can drive called propellant rockets. Propellant is generally classified into 3 types, namely:

Solid propellant
Liquid propellant
Propellant hybrid

Each type of propellant on the advantages and disadvantages of each. However, for the current development, liquid propellant is more commonly used in the field of space.

Examples of liquid propellant please see here

So how rockets can fly into space?

Just like a conventional engine, a rocket of energy use arising from the oxidation reaction of fuel with the oxidant. Only the pressure of fuel in a rocket engine could reach more than 300 psi. Meanwhile, the air pressure outside the engine about 1 atm, sometimes even a vacuum.

Because there is this pressure difference results of the combustion gas velocity changes from slow to very fast. Changes in velocity than occurs because the pressure difference, as well as the results of the combustion gases flowing through the throat of diameter 4 times smaller than the diameter of the engine.

In accordance with the continuity equation, because the flow remains, while the narrower area, then the velocity changes.

Change in velocity per unit of time equal to the acceleration. After the laws of classical physics of Newton, the acceleration will result in the emergence of force (force). The force that drives this arise so that the rocket could be launched.

The Nitration of Benzene

Benzene reacts slowly with hot concentrated nitric acid in an electrophilic aromatic substitution reaction to form nitrobenzene. This reaction is potentially dangerous, however, because nitric acid is a strong oxidizing agent that often explodes in the presence of any material that readily oxidizes. A safer, faster, and more convenient synthesis employs a mixture of concentrated nitric acid and concentrated sulfuric acid. The concentrated sulfuric acid acts as a catalyst allowing nitration to take place more readily at more moderate temperatures.

The nitronium ion (⊕NO2) is the electrophile in the nitration of benzene to form nitrobenzene. Although concentrated nitric acid produces the nitronium ion by itself, the equilibrium is so far to the left that the process is slow. Adding concentrated sulfuric acid to the reaction mixture increases the concentration of the nitronium ion, thereby increasing the rate of the nitration reaction. The nitronium ion forms via a pathway similar to the first step in the dehydration of an alcohol.

After the nitronium ion forms, it reacts with benzene to form the σ complex, the first step of the electrophilic aromatic substitution reaction. This step is slow because the σ complex is not aromatic. Additionally, the σ complex is higher in energy than the benzene and the nitronium ion.

In the next step of the mechanism, the σ complex loses a proton to form nitrobenzene. This step is rapid because the loss of a proton allows the molecule to become aromatic again.

Chemists tested whether the loss of a proton is the fast step or the slow step of an electrophilic aromatic substitution by replacing the hydrogens in benzene with deuterium and then running the reaction. Deuterium (2H abbreviated as D) is an isotope of hydrogen (1H) that contains not only one proton in its nucleus but also one neutron. Thus, deuterium has twice the mass of hydrogen. Because the bond energy between a pair of atoms changes in proportion to the masses of the isotopes involved in that bond, the C—D bond is higher in energy than the C—H bond. This isotope effect is observable in the IR spectrum. The IR absorption of the C—H bond in benzene is approximately 3050 cm–1; whereas the C—D bond of deuteriobenzene is about 2150 cm–1.

Because breaking a C—D bond requires more energy than breaking a C—H bond, a reaction whose rate-determining step involves breaking a C—H bond proceeds more slowly when deuterium is present. Thus, replacing C6H6 with C6D6 results in a reduction of the nitration rate if the breaking of a C—H bond is the rate-determining step. With the electrophilic aromatic substitution reaction, chemists measured no difference in the rate of reaction between C6D6 and C6H6. This shows that the rate-determining step is the formation of the σ complex, not the step that breaks the C—H bond.

Batch Pan

Next to natural solar evaporation, the batch pan (Figure 1) is one of the oldest methods of concentration. It is somewhat outdated in today's technology, but is still used in a few limited applications, such as the concentration of jams and jellies where whole fruit is present and in processing some pharmaceutical products. Up until the early 1960's, batch pan also enjoyed wide use in the concentration of corn syrups. With a batch pan evaporator, product residence time normally is many hours. Therefore, it is essential to boil at low temperatures and high vacuum when a heat sensitive or thermodegradable product is involved. The batch pan is either jacketed or has internal coils or heaters. Heat transfer areas normally are quite small due to vessel shapes, and heat transfer coefficients (HTC’s) tend to be low under natural convection conditions. Low surface areas together with low HTC's generally limit the evaporation capacity of such a system. Heat transfer is improved by agitation within the vessel. In many cases, large temperature differences cannot be used for fear of rapid fouling of the heat transfer surface. Relatively low evaporation capacities, therefore, limit its use.

Titanium Dioxide

The production of titanium dioxide pigments involves reaction between sulfuric acid and the ore which contains iron, titanium sulfate and other compounds. After pretreatment, which includes the crystallization of iron as ferrous sulfate, the liquor is heated and hydrolyzed to precipitate Titanium dioxide. Prior to this operation, the concentration of liquor has to be adjusted by the evaporation of water. It is essential that this process takes place in an evaporator with short heat contact times in order to avoid the premature hydrolysis that occurs with prolonged heating, which subsequently causes fouling of the heat surface and blockage of the tubes. Although the liquor contains a high proportion of sulfuric acid, the presence of other ions in solution may inhibit corrosion, so that copper often can be used for heat transfer surfaces. Titanium is another material used for this application. Generally, single or multiple effect rising film evaporators are used for this duty, the number of effects being determined by throughput and by assessing the cost of operation against the increase in capital required for additional equipment. In some cases, it is economically attractive to operate the evaporator as a single effect unit at atmospheric pressure using the vapor given off for preheating. The liquor is discharged at a temperature in excess of 212°F (100°C), reducing the subsequent thermal load at the hydrolysis stage.

Acetaminophen

Acetaminophen, sold under the trade name Tylenol, is a widely used anal- gesic and antipyretic that is an over-the-counter drug. Combined with codeine it is one of the top five prescription drugs. Acetaminophen is pre- pared by treating p-aminophenol with a mixture of glacial acetic acid and acetic anhydride.

Chemical reaction engineering By Levenspiel O. (3ed., Wiley, 1998).pdf

Chemical Reaction Engineering Book Description

Publisher: John Wiley & Sons
Author: Octave Levenspiel, Cctave Levenspiel
Edition Number: 3
Language: English
ISBN:
047125424X
EAN:
9780471254249
No. of Pages: 688
Publish Date: 1998-08-31

Chemical Process and Design Handbook

Introduction to Chemical Reaction Engineering and Kinetics - RW Missen

Heat Transfer Handbook - Wiley Bejan 2003

Book: Heat Transfer (in SI Units) (SIE)
This hallmark text on Heat Transfer presents an elementary and classical treatment of principles of heat transfer With emphasis on physical understanding while relying on meaningful experimental data.
Key Features:

Analytical and Numerical treatment of Conduction-to gain insight into important tools of numerical analysis used in practice. (Chapter 2-4) Integral analysis of both free and forced convection boundary layers is used to present a physical picture of convection process. (Chapters 5-7) Heat Exchangers: Log mean temperature difference and effectiveness approaches are discussed. (Chapter 10) Important analogies between heat, mass and momentum transfer are discussed through a brief introduction to diffusion and mass transfer in chapter 11. Design is highlighted with over 100 open ended, design oriented homework problems. Emphasis on resistance capacity formulation in computer numerical methods. Large number of numerical examples on heat sources, radiation boundary conditions, non uniform mesh size and 3D nodal systems.

Table of Content:

Chapter 1. Introduction
Chapter 2. Steady-State Conduction-One Dimension
Chapter 3. Steady-State Conduction-Multiple Dimension
Chapter 4. Unsteady-State Conduction
Chapter 5. Principles of Convection
Chapter 6. Empirical and Practical Relation for Forced-Convection Heat Transfer
Chapter 7. Natural Convection Systems
Chapter 8. Radiation Heat Transfer
Chapter 9. Condensation and Boiling Heat Transfer
Chapter 10. Heat Exchange
Chapter 11. Mass Transfer
A. Tables
B. Exact Solutions of Laminar-Boundary-Layer Equations
C. Analytical Relations for the Heisler Charts
D. Use of Microsoft Excel for Solution of Heat- Transfer Problems

Process Heat Transfer - DQ Kern

This book is designed to provide fundamental instruction in heat transfer while employing the methods and language of industry.

Key Features:

Provides the rounded group of heat-transfer tools required in process engineering it has been necessary to present a number of empirical calculation methods which have not previously appeared in the engineering literature.

Considerable throught has been given to these methods, and the author has discussed them with numerious engineers before accepting and including them in the text.

About the Author:

DONALD KERN
DONALD Q.KERAN D.Q. Kern Associate and He is a Professorial Lecturer in Chemical Engineering Case Insitiue of Technology.

Table of Content:

Preface
Index to the Principal Apparatus Calculations
Chapter 1 Process Heat Transfer
Chapter 2 Conduction
Chapter 3 Convection
Chapter 4 Radiation
Chapter 5 Temperature
Chapter 6 Counterflow: Double-pipe Exchangers
Chapter 7 1-2 Parallel-Counterflow: Shell-And-Tube Exchangers
Chapter 8 Flow Arrangeements for Increased Heat Recovery
Chapter 9 Gases
Chapter 10 Streamline Flow and Free Convection
Chapter 11 Calculations for Process Condition
Chapter 12 Condensation of Single Vapors
Chapter 13 Condensation of Mixed Vapors
Chapter 14 Evaporation
Chapter 15 Vaporizers, Evaporators, and Reboilers
Chapter 16 Extended Surfaces
Chapter 17 Direct-Contact Transfer: Cooling Towers
Chapter 18 Batch and Unsteady State Processes
Chapter 19 Furnace Calculations
Chapter 20 Additional Applications
Chapter 21 The Control of Temperature and Related Process Variables
Appendix of Calculation Data
Author Index
Subject Index

Design of Distillation Column Control Systems

Design of Distillation Column Control Systems

By: Buckley, Page S.; Luyben, William L.; Shunta, Joseph P. © 1985 Elsevier

Description: It is the purpose of this book to indicate the range of technology, which has been developed for distillation control, to the point where it can be economically and reliably used for design.

Perry Chemical Engineering Handbooks

Perry's Chemical Engineers' Handbook (also known as Perry's Handbook or Perry's)[1] was first published in 1934 and the most current eighth edition was published in October 2007. It has been a source of chemical engineering knowledge for chemical engineers, and a wide variety of other engineers and scientists, through seven previous editions spanning more than seventy years.

The subjects covered in the book include: physical properties of chemicals and other materials; mathematics; thermodynamics; heat transfer; mass transfer; fluid dynamics; chemical reactors and chemical reaction kinetics; transport and storage of fluid; heat transfer equipment; psychrometry and evaporative cooling; distillation; gas absorption; liquid-liquid extraction; adsorption and ion exchange; gas-solid, liquid-solid and solid-solid operations; biochemical engineering; waste management, materials of construction, process economics and cost estimation; process safety and many others. An electronic version of this reference book is provided by Knovel.

KirkOthmer Encyclopedia of Chemical Technology

Kirk, Othmer: KirkOthmer Encyclopedia of Chemical Technology (Kirk-Othmer Encyclopedia of Chemical Technology) 5th Edition

The fifth edition of the Kirk-Othmer Encyclopedia of Chemical Technology builds upon the solid foundation of the previous editions, which have proven to be a mainstay for chemists, biochemists, and engineers at academic, industrial, and government institutions since publication of the first edition in 1949.

The new edition includes necessary adjustments and modernisation of the content to reflect changes and developments in chemical technology. Presenting a wide scope of articles on chemical substances, properties, manufacturing, and uses; on industrial processes, unit operations in chemical engineering; and on fundamentals and scientific subjects related to the field.

The Encyclopedia describes established technology along with cutting edge topics of interest in the wide field of chemical technology, whilst uniquely providing the necessary perspective and insight into pertinent aspects, rather than merely presenting information.

* Set began publication in January 2004
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Sulfonation

Sulfonation is the introduction of a sulfonic acid group (–SO3H) into an organic compound as, for example, in the production of an aromatic sulfonic acid from the corresponding aromatic hydrocarbon.

ArH + H2SO4 → ArSO3H + H2O

The usual sulfonating agent is concentrated sulfuric acid, but sulfur trioxide, chlorosulfonic acid, metallic sulfates, and sulfamic acid are also occasionally used. However, because of the nature and properties of sulfuric acid, it is desirable to use it for nucleophilic substitution wherever possible. For each substance being sulfonated, there is a critical concentration of acid below which sulfonation ceases. The removal of the water formed in the reaction is therefore essential. The use of a very large excess of acid, while expensive, can maintain an essentially constant concentration as the reaction progresses. It is not easy to volatilize water from concen- trated solutions of sulfuric acid, but azeotropic distillation can some- times help.

The sulfonation reaction is exothermic, but not highly corrosive, so sulfonation can be conducted in steel, stainless-steel, or cast-iron sulfona- tors. A jacket heated with hot oil or steam can serve to heat the contents sufficiently to get the reaction started, then carry away the heat of reaction. A good agitator, a condenser, and a fume control system are usually also provided.

1- and 2-naphthalenesulfonic acids are formed simultaneously when naphthalene is sulfonated with concentrated sulfuric acid. The isomers must be separated if pure α- or β-naphthol are to be prepared from the product mix. Variations in time, temperature, sulfuric acid concentration, and acid/hydrocarbon ratio alter the yields to favor one particular isomer, but a pure single substance is never formed. Using similar acid/hydrocar- bon ratios, sulfonation at 40oC yields 96% alpha isomer, 4% beta, while at 1600C the proportions are 15% α-naphthol, 8.5% β-naphthol.

The α-sulfonic acid can be hydrolyzed to naphthalene by passing steam at 160o C into the sulfonation mass. The naphthalene so formed passes out with the steam and can be recovered. The pure β-sulfonic acid left behind can be hydrolyzed by caustic fusion to yield relatively pure β- naphthol.

In general, separations are based on some of the following consideration:

1. Variations in the rate of hydrolysis of two isomers
2. Variations in the solubility of various salts in water
3. Differences in solubility in solvents other than water
4. Differences in solubility accentuated by common-ion effect (salt additions)
5. Differences in properties of derivatives
6. Differences based on molecular size, such as using molecular sieves or absorption.

Sulfonation reactions may be carried out in batch reactors or in continuous reactors. Continuous sulfonation reactions are feasible only when the organic compounds possess certain chemical and physical properties, and are practical in only a relatively few industrial processes. Most commercial sulfonation reactions are batch operations.

Continuous operations are feasible and practical (1) where the organic compound (benzene or naphthalene) can be volatilized, (2) when reaction rates are high (as in the chlorosulfonation of paraffins and the sulfonation of alcohols), and (3) where production is large (as in the manufacture of detergents, such as alkylaryl sulfonates). Water of reaction forms during most sulfonation reactions, and unless a method is devised to prevent excessive dilution because of water formed during the reaction, the rate of sulfonation will be reduced. In the interests of economy in sulfuric acid consumption, it is advantageous to remove or chemically combine this water of reaction. For example, the use of reduced pressure for removing the water of reaction has some technical advantages in the sulfonation of phenol and of benzene. The use of the partial-pressure distillation is predicated upon the ability of the diluent, or an excess of volatile reactant, to remove the water of reaction as it is formed and, hence, to maintain a high concentration of sulfuric acid. If this concentration is maintained, the necessity for using excess sulfuric acid is eliminated, since its only function is to maintain the acid concentration above the desired value. Azeotropic removal of the water of reaction in the sulfonation of benzene can be achieved by using an excess of vaporized benzene. The use of oleum (H2SO4 SO3) for maintaining the necessary sulfur trioxide concentration of a sulfonation mixture is a practical procedure. Preferably the oleum and organic compound should be added gradually and concurrently to a large volume of cycle acid so as to take up the water as rapidly as it is formed by the reaction. Sulfur trioxide may be added intermittently to the sulfonation reactor to maintain the sulfur trioxide concentration above the value for the desired degree of sulfonation.

Vinylation

Unlike ethynylation, in which acetylene adds across a carbonyl group and the triple bond is retained, in vinylation a labile hydrogen compound adds to acetylene, forming a double bond.

XH + HC≡CH → CH2=CHX

Catalytic vinylation has been applied to the manufacture of a wide range of alcohols, phenols, thiols, carboxylic acids, and certain amines and amides. Vinyl acetate is no longer prepared this way in many countries, although some minor vinyl esters such as vinyl stearate may still be man- ufactured by this route. However, the manufacture of vinyl-pyrrolidinone and vinyl ethers still depends on acetylene as the starting material.

Polymerization

Polymerization is a process in which similar molecules (usually olefins) are linked to form a high-molecular-weight product; such as the formation of polyethylene from ethylene

nCH2CH2 → H–( CH2CH2)n–H

The molecular weight of the polyethylene can range from a few thousand to several hundred thousand. Polymerization of the monomer in bulk may be carried out in the liquid or vapor state. The monomers and activator are mixed in a reactor and heated or cooled as needed. As most polymerization reactions are exothermic, pro- vision must be made to remove the excess heat. In some cases, the polymers are soluble in their liquid monomers, causing the viscosity of the solution to increase greatly. In other cases, the polymer is not soluble in the monomer and it precipitates out after a small amount of polymerization occurs. In the petroleum industry, the term polymerization takes on a different meaning since the polymerization processes convert by-product hydrocarbon gases produced in cracking into liquid hydrocarbons suitable (of limited or specific molecular weight) for use as high-octane motor and aviation fuels and for petrochemicals. To combine olefinic gases by polymerization to form heavier fractions, the combining fractions must be unsaturated. Hydrocarbon gases, particularly olefins, from cracking reactors are the major feedstock of polymerization.

(CH3)2C=CH2 → (CH3)3CH2C(CH3)=CH2
(CH3)3CH2C(CH3)=CH2 → C12H24

Vapor-phase cracking produces considerable quantities of unsaturated gases suitable as feedstocks for polymerization units. Catalytic polymerization is practical on both large and small scales and is adaptable to combination with reforming to increase the quality of the gasoline. Gasoline produced by polymerization contains a smog-producing olefinic bond. Polymer oligomers are widely used to make detergents.

Oxo reaction

The oxo reaction is the general or generic name for a process in which an unsaturated hydrocarbon is reacted with carbon monoxide and hydrogen to form oxygen function compounds, such as aldehydes and alcohols. In a typical process for the production of oxo alcohols, the feedstock comprises an olefin stream, carbon monoxide, and hydrogen. In a first step, the olefin reacts with CO and H2 in the presence of a catalyst (often cobalt) to produce an aldehyde that has one more carbon atom than the originat- ing olefin:

RCH=CH2 + CO + H2 → RCH2CH2CH=O

This step is exothermic and requires an ancillary cooling operation.

The raw aldehyde exiting from the oxo reactor then is subjected to a higher temperature to convert the catalyst to a form for easy separation from the reaction products. The subsequent treatment also decomposes unwanted by-products. The raw aldehyde then is hydrogenated in the pres- ence of a catalyst (usually nickel) to form the desired alcohol:

RCH2CH2CH=O + H2 → RCH2CH2CH2OH

The raw alcohol then is purified in a fractionating column. In addition to the purified alcohol, by-products include a light hydrocarbon stream and a heavy oil. The hydrogenation step takes place at about 150°C under a pressure of about 1470 psi (10.13 MPa). The olefin conversion usually is about 95 percent.

Among important products manufactured in this manner are substituted propionaldehyde from corresponding substituted ethylene, normal and iso-butyraldehyde from propylene, iso-octyl alcohol from heptene, and trimethylhexyl alcohol from di-isobutylene.

Fermentation

Fermentation processes produce a wide range of chemicals that complement the various chemicals produced by nonfermentation routes. For example, alcohol, acetone, butyl alcohol, and acetic acid are produced by fermentation as well as by synthetic routes. Almost all the major antibiotics are obtained from fermentation processes.

Fermentation under controlled conditions involves chemical conversions, and some of the more important processes are:

Oxidation, e.g., ethyl alcohol to acetic acid, sucrose to citric acid, and dextrose to gluconic acid
Reduction, e.g., aldehydes to alcohols (acetaldehyde to ethyl alcohol) and sulfur to hydrogen sulfide
Hydrolysis, e.g., starch to glucose and sucrose to glucose and fructose and on to alcohol
Esterification, e.g., hexose phosphate from hexose and phosphoric acid

Esterification

A variety of solvents, monomers, medicines, perfumes, and explosives are made from esters of nitric acid. Ethyl acetate, n-butyl acetate, iso-butyl acetate, glycerol trinitrate, pentaerythritol tetranitrate (PETN), glycol dini- trate, and cellulose nitrate are examples of such reactions.

Ester manufacture is a relatively simple process in which the alcohol and an acid are heated together in the presence of a sulfuric acid catalyst, and the reaction is driven to completion by removing the products as formed (usually by distillation) and employing an excess of one of the reagents. In the case of ethyl acetate, esterification takes place in a column that takes a ternary azeotrope. Alcohol can be added to the condensed over- head liquid to wash out the alcohol, which is then purified by distillation and returned to the column to react.

Amyl, butyl, and iso-propyl acetates are all made from acetic acid and the appropriate alcohols. All are useful lacquer solvents and their slow rate of evaporation (compared to acetone or ethyl acetate) prevents the surface of the drying lacquer from falling below the dew point, which would cause con- densation on the film and a mottled surface appearance (blushing). Other esters of importance are used in perfumery and in plasticizers and include methyl salicylate, methyl anthranilate, diethyl-phthalate, dibutyl-phthalate, and di-2-ethylhexyl-phthalate.

Unsaturated vinyl esters for use in polymerization reactions are made by the esterification of olefins. The most important ones are vinyl esters: vinyl acetate, vinyl chloride, acrylonitrile, and vinyl fluoride. The addition reac- tion may be carried out in either the liquid, vapor, or mixed phases, depending on the properties of the acid. Care must be taken to reduce the polymerization of the vinyl ester produced.

Esters of allyl alcohol, e.g., diallyl phthalate, are used as bifunctional polymerization monomers and can be prepared by simple esterification of phthalic anhydride with allyl alcohol. Several acrylic esters, such as ethyl or methyl acrylates, are also widely used and can be made from acrylic acid and the appropriate alcohol. The esters are more volatile than the cor- responding acids.

Condensation and Addition (Friedel-Crafts) reactions

There are only a few products manufactured in any considerable tonnage by condensation and addition (Friedel-Crafts) reactions, but those that are find use in several different intermediates and particularly in making high- quality vat dyes. The agent employed in this reaction is usually an acid chloride or anhy- dride, catalyzed with aluminum chloride. Phthalic anhydride reacts with chlorobenzene to give p-chlorobenzoylbenzoic acid and, in a continuing action, the p-chlorobenzoylbenzoic acid forms β-chloroanthraquinone. Since anthraquinone is a relatively rare and expensive component of coal tar and petroleum, this type of reaction has been the basis for making relatively inexpensive anthraquinone derivatives for use in making many fast dyes for cotton. Friedel-Crafts reactions are highly corrosive, and the aluminum-con- taining residues are difficult to dispose.

What is BOD and COD?

The life of microorganisms, such as fish and other aquatic animals, can not be separated from the dissolved oxygen content in water, no different from humans and other living things on the ground, which also requires oxygen from the air in order to stay viable. Water that does not contain oxygen can not give life to the micro-organisms, fish and other aquatic animals. Dissolved oxygen in water is vital for life. To fulfill her life, humans are not only dependent on food from the mainland only (rice, wheat, vegetables, fruit, meat, etc.), but also depends on the food that comes from water (fish, shellfish, squid, seaweed , etc.).

Existing plants in the water, with the help of sunlight, do photosynthesis that produces oxygen. Oxygen resulting from photosynthesis is going to dissolve in the water. Apart from that, oxygen in the air can also enter the water through a process of slow diffusion yag through the water surface. Concentration of dissolved oxygen in water depends on water saturation level itself. Water saturation can be caused by colloidal floating in the water by the amount of waste solvents dissolved in the water. Apart from that the water temperature also affects the concentration of dissolved oxygen in the water. Air pressure can also affect the solubility of oxygen in the water. Air pressure can also affect the solubility of oxygen in the water because the air pressure affect the speed of diffusion of oxygen from the air into the water.

Industrial and technological progress often also affect the state of water environment, both river water, sea water, lake water and ground water. This impact caused by the existence of water pollution caused by various things like that have been outlined in advance. One way to assess how much water has been contaminated environment is to look at the dissolved oxygen content in the water.

In general, the water is polluted environments very low oxygen content. That is because the oxygen dissolved in the water is absorbed by microorganisms to break down / degrade the organic waste so that the volatile material (which is marked with the stench). Furthermore, organic waste materials can also react with oxygen dissolved in the organic water in the water, the less the rest of the dissolved oxygen content in it. Organic waste is usually derived from paper industries, leather tanning industry, food processing industries (such as meat cutting industry, canning industry, freezing shrimp industry, the bread industry, dairy industry, cheese and butter industry), waste household waste, material agricultural waste, animal waste and human excrement, and so forth.

By looking at the dissolved oxygen content in water can be determined how far the level of environmental contamination has occurred. Way in which for the purpose is to test:

1. COD, chemical oxygen stands Demand, or chemical oxygen demand for oxidation of waste materials in the water.
2. BOD stands for Biological Oxygen Demand, or the biological oxygen demand to break up waste materials in the water by microorganisms.

Alkylation

Alkylation is usually used to increase performance of a product and involves the conversion of, for example, an amine to its alkylated homologs as in the reaction of aniline with methyl alcohol in the presence of sulfuric acid catalyst:

C6H5NH2 + 2CH3OH → C6H5N(CH3)2 + 2H2O

Thus, aniline, with a considerable excess of methyl alcohol and a catalytic amount of sulfuric acid, is heated in an autoclave at about 200o C for 5 or 6 hours at a high reaction pressure of 540 psi (3.7 MPa). Vacuum distillation is used for purification.

In the alkylation of aniline to diethylaniline by heating aniline and ethyl alcohol, sulfuric acid cannot be used because it will form ether; consequently, hydrochloric acid is employed, but these conditions are so corrosive that the steel used to resist the pressure must be fitted with replaceable enameled liners.

Alkylation reactions employing alkyl halides are carried out in an acidic medium. For example, hydrobromic acid is formed when methyl bromide is used in the alkylation leading, and for such reactions an autoclave with a replaceable enameled liner and a lead-coated cover is suitable.

In the petroleum refining industry, alkylation is the union of an olefin with an aromatic or paraffinic hydrocarbon:

CH2=CH2 + (CH3)3CH → (CH3)3CCH2CH3

Alkylation processes are exothermic and are fundamentally similar to refining industry polymerization processes but they differ in that only part of the charging stock need be unsaturated. As a result, the alkylate product contains no olefins and has a higher octane rating. These methods are based on the reactivity of the tertiary carbon of the iso-butane with olefins, such as propylene, butylenes, and amylenes. The product alkylate is a mixture of saturated, stable isoparaffins distilling in the gasoline range, which becomes a most desirable component of many high-octane gasolines.

Alkylation is accomplished by using either of two catalysts: (1) hydrogen fluoride and (2) sulfuric acid. In the alkylation process using liquid hydrogen fluoride (Fig. 1), the acid can be used repeatedly, and there is virtually no acid-disposal problem. The acid/hydrocarbon ratio in the con- tactor is 2:1 and temperature ranges from 15 to 350 C can be maintained since no refrigeration is necessary. The anhydrous hydrofluoric acid is regenerated by distillation with sufficient pressure to maintain the reactants in the liquid phase.

In many cases, steel is suitable for the construction of alkylating equipment, even in the presence of the strong acid catalysts, as their corrosive effect is greatly lessened by the formation of esters as catalytic intermediate products.

In the petroleum industry, the sulfuric acid and hydrogen fluoride employed as alkylation catalysts must be substantially anhydrous to be effective, and steel equipment is satisfactory. Where conditions are not anhydrous, leadlined, monellined, or enamel-lined equipment is satisfactory. In a few cases, copper or tinned copper is still used, for example, in the manufacture of pharmaceutical and photographic products to lessen contamination with metals.

Distillation is usually the most convenient procedure for product recovery, even in those instances in which the boiling points are rather close together. Frequently such a distillation will furnish a finished material of quality sufficient to meet the demands of the market. If not, other means of purification may be necessary, such as crystallization or separation by means of solvents. The choice of a proper solvent will, in many instances, lead to the crystallization of the alkylated product and to its convenient recovery.

The converse reactions dealkylation and hydrodealkylation are prac- ticed extensively to convert available feedstocks into other more desirable (marketable), products. Two such processes are: (1) the conversion of toluene or xylene, or the higher-molecular weight alkyl aromatic compounds, to benzene in the presence of hydrogen and a suitable presence of a dealkylation catalyst and (2) the conversion of toluene in the presence of hydrogen and a fixed bed catalyst to benzene plus mixed xylenes.

Types of deaerators

There are many different horizontal and vertical deaerators available from a number of manufacturers, and the actual construction details will vary from one manufacturer to another. Figures 1 and 2 are representative schematic diagrams that depict each of the two major types of deaerators.

Tray-type deaerator

The typical horizontal tray-type deaerator in Figure 1 has a vertical domed deaeration section mounted above a horizontal boiler feedwater storage vessel. Boiler feedwater enters the vertical dearation section above the perforated trays and flows downward through the perforations. Low-pressure dearation steam enters below the perforated trays and flows upward through the perforations. Some designs use various types of packing material, rather than perforated trays, to provide good contact and mixing between the steam and the boiler feed water.

The steam strips the dissolved gas from the boiler feedwater and exits via the vent at the top of the domed section. Some designs may include a vent condenser to trap and recover any water entrained in the vented gas. The vent line usually includes a valve and just enough steam is allowed to escape with the vented gases to provide a small and visible telltale plume of steam.

The deaerated water flows down into the horizontal storage vessel from where it is pumped to the steam generating boiler system. Low-pressure heating steam, which enters the horizontal vessel through a sparger pipe in the bottom of the vessel, is provided to keep the stored boiler feedwater warm. External insulation of the vessel is typically provided to minimize heat loss.

Spray-type deaerator

As shown in Figure 2, the typical spray-type deaerator is a horizontal vessel which has a preheating section (E) and a deaeration section (F). The two sections are separated by a baffle(C). Low-pressure steam enters the vessel through a sparger in the bottom of the vessel.

The boiler feedwater is sprayed into section (E) where it is preheated by the rising steam from the sparger. The purpose of the feedwater spray nozzle (A) and the preheat section is to heat the boiler feedwater to its saturation temperature to facilitate stripping out the dissolved gases in the following deaeration section.

The preheated feedwater then flows into the dearation section (F), where it is deaerated by the steam rising from the sparger system. The gases stripped out of the water exit via the vent at the top of the vessel. Again, some designs may include a vent condenser to trap and recover any water entrained in the vented gas. Also again, the vent line usually includes a valve and just enough steam is allowed to escape with the vented gases to provide a small and visible telltale plume of steam

The deaerated boiler feedwater is pumped from the bottom of the vessel to the steam generating boiler system.

Aluminum sulfate

Aluminum sulfate [Al2(SO4)3, alum, filter alum, papermaker’s alum] is manufactured from aluminum oxide (Al2O3, alumina, bauxite). A mixture of the crude ore and sulfuric acid is heated at 105 to 110 degree C for 15 to 20 hours.

Al2O3.2H2O + 3H2SO4 → Al2(SO4)3 + 5H2O

Filtration of the aqueous solution is followed by evaporation of the water to give the product, which is processed into a white powder. Alum has two prime uses. It is bought by the pulp and paper industry for coagulating and coating pulp fibers into a hard paper surface by reacting with small amounts of sodium carboxylates (soap) present. Aluminum salts of carboxylic acids are very gelatinous. In water purification it serves as a coagulant, pH conditioner, and phosphate and bacteria remover. It reacts with alkali to give an aluminum hydroxide floc that drags down such impurities in the water. For this reason it also helps the taste of water.

6RCO2–Na+ + Al2(SO4)3 → 2(RCO2–)3Al3+ + 3Na2SO4
Al2(SO4)3 + 6NaOH → 2Al(OH)3 + 3Na2SO4

Pharmaceutically, aluminum sulfate is employed in dilute solution as a mild astringent and antiseptic for the skin. The most important single application of aluminum sulfate is in clarifying water; sodium aluminate, which is basic, is sometimes used with aluminum sulfate, which is acid, to produce the aluminum hydroxide. Aluminum sulfate is also used in sizing of paper, as a mordant in the dye industry, chemical manufacturing, concrete modification, soaps, greases, fire extinguishing solutions, tanning, cellulosic insulation, and in some baking powders.

Aluminum chloride

Aluminum chloride (AlCl3) is a white solid when pure that sublimes on heating and, in the presence of moisture, decomposes with the evolution of hydrogen chloride. Anhydrous aluminum chloride is manufactured primarily by the reaction of chlorine vapor on molten aluminum.

2Al + 3Cl2 → 2AlCl3

In the process, chlorine is fed in below the surface of the aluminum, and the product sublimes and is collected by condensing. These air-cooled condensers are thin-walled, vertical steel cylinders with conical bottoms. Aluminum chloride crystals form on the condenser walls and are periodically removed, crushed, screened, and packaged in steel containers. Aluminum chloride is used in the petroleum industries and various aspects of organic chemistry technology. For example, aluminum chloride is a catalyst in the alkylation of paraffins and aromatic hydrocarbons by olefins and also in the formation of complex ketones, aldehydes, and carboxylic acid derivatives.

Aluminum

Aluminum (melting point: 660 C, boiling point: 2494o C) is the most abundant metal in the world and makes up 7 to 10% by weight of the earth’s crust. Aluminum is manufactured by the electrolytic reduction of pure alumina(Al2O3) in a bath of fused cryolite (Na3AlF6). It is not possible to reduce alumina with carbon because aluminum carbide (A14C3) is formed and a back-reaction between aluminum vapor and carbon dioxide in the condenser quickly reforms the original aluminum oxide again. The electrolytic cells are large containers (usually steel), and each is a cathode compartment lined with either a mixture of pitch and anthracite coal or coke baked in place by the passage of electric current or prebaked cathode blocks cemented together. Two types of cells are used in the Hall-Heroult process: those with multiple prebaked anodes (Fig. 1), and those with a self-baking, or Soderberg, anode. In both types of cell, the anodes are suspended from above and are connected to a movable anode bus so that their vertical position can be adjusted. The prebaked anode blocks are manufactured from a mixture of low-ash calcined petroleum coke and pitch or tar formed in hydraulic presses, and baked at up to C.

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