Kimmuh.com

Kimya Mühendisliği

Sodyum Karbonat

Sodyum karbonat nedir, ne zaman bulundu,  sodyum karbonat nerelerde kullanılır..

XVIII. Yüzyılda en verimli iki sanayinin madencilik ve dokuma olduğunu hatırlatalım. Kimya, dokuma alanında, lavoisier’den önceki yıllarda da büyük rol oynamıştı. O kadar ki, bu yüzyılın sonlarına kadar kimya her şeyden önce kumaş boyama sanatıydı diyebiliriz. O dönemde şu boyayıcı maddeler kullanılmaktaydı:

Meksika’dan, Kanarya Adalarından ve Hindistan’dan ithal edilen kırmız böceği; Meksika ve Antiller’den bakam ağacı; Hindistan ve Uzak Doğu’dan çivit, Brezilya’dan brezil. Orta Doğu’dan mazı, vb. Bazen kumaş, boyayı kendiliğinden emerdi, bazen de boyadan önce kumaşı yağlardan arıtmak gerekiyordu. Kısacası, dokuma eskiden beri bilime dayanan bir teknik olmuştu.

Kumaşları yağlarından arıtmakta şapın ne gibi yararları olabileceğini ilk sezen, İngiliz Wtlliam Petty (1623-1687) olmuş ve: “Şap, kumaşla boya arasında bir bağdır,” demişti. Ama boyamada en yararlı çalışmaları yapanlar Fransızlar oldular. Fizikçi Cisternay Du Fay (1698-1739) boya ve şap oranını tam olarak tespit etti. Kimyagerler “Jean Hellot (1685-1766), Pierre-Joseph Macquer (1718-1784) ve İngiliz meslektaşları Bancroft (1744-1818)” yüzlerce yıllık tekrarların dışında bir teknik bulmaya çalıştılar. “Boya Sanatının öğeleri” adlı eserin yazarı olan büyük kimyacı Claude Berthollet (1748-1822), Lavoisier’nin görüşlerine dayanarak kimyaya, bilime dayanan bir yöntem kazandırmaya çalıştı.

[Devamini Okuyun...]

Feldispat-kuvars ayırımında hidroflorik asit kullanılmayan flotasyon yöntemlerinin karşılaştırılması

The comparision of non-hydrofluoric acid flotation methods used in feldspar
quartz separation
Derya KALYON, Özcan Y. GÜLSOY
Hacettepe Üniversitesi, Mühendislik Fakültesi, Maden Mühendisli¤i Bölümü, 06532 Beytepe, ANKARA

 

ABSTRACT
In this study, non-hydrofluoric acid flotation methods used in feldspar-quartz separation were compared with each
other and conventional HF/amine method. Although, there are many studies in the literature, only the most effec-
tive and the suitable methods for the laboratory facilities were selected for comparision. The methods are catego-
rized into three groups in the literature. These are anionic + cationic collector combinations, only cationic collector
and non-ionic collector group used. The selected methods were applied to an artificial feldspar-quartz mixture. In
order to compare the results, an alkaline index was developed and a selectivity parameter was calculated from the
alkaline index for each separation. The results showed that conventional HF/amine method is the most effective
and selective method. Duomeen TDO method was the second effective method on the feldspar-quartz separati-
on. Therefore, the flotation kinetics of feldspar were determined in both HF/amin and Duomeen TDO methods. The
tests results suggested that the flotation rate of the feldspar obtained in both methods was the same.
Key Words:

Anionic collector, cationic collector, feldspar, quartz, hydrofluoric acid, nonionic collector

[Devamini Okuyun...]

POLYMERS

Polymers are substances whose molecules have high molar masses and are composed of a large number of
repeating units. There are both naturally occurring and synthetic polymers. Among naturally occurring polymers are
proteins, starches, cellulose, and latex. Synthetic polymers are produced commercially on a very large scale and have
a wide range of properties and uses. The materials commonly called plastics are all synthetic polymers.
Polymers are formed by chemical reactions in which a large number of molecules called monomers are joined
sequentially, forming a chain. In many polymers, only one monomer is used. In others, two or three different
monomers may be combined. Polymers are classified by the characteristics of the reactions by which they are formed.
If all atoms in the monomers are incorporated into the polymer, the polymer is called an
addition polymer
. If some
of the atoms of the monomers are released into small molecules, such as water, the polymer is called a
condensation
polymer
. Most addition polymers are made from monomers containing a double bond between carbon atoms. Such
monomers are called olefins, and most commercial addition polymers are polyolefins. Condensation polymers are
made from monomers that have two different groups of atoms which can join together to form, for example, ester
or amide links. Polyesters are an important class of commercial polymers, as are polyamides (nylon).

Güneş Pili Uygulamaları İçin Benzotriazol İçeren Çok Amaçlı Malzemeler

A. Balan, L. Toppare
Kimya Bölümü, Orta Doğu Teknik Üniversitesi, 06531 Ankara, Türkiye
Konjuge polimerler gelişmiş işlenebilirlikleri nedeniyle büyük ölçekli uygulamalarda kullanılabilirler. Geliştirilmiş elektriksel ve fiziksel özellikleri ve artan sayıdaki mevcut işlenebilir malzemelerle konjuge polimerler hızla dikkat çekmiştir. Yeni yapısal tasarımlı bu polimerler bazı alanlara örneğin; Organik Işık Yayan Diyotlar (OLEDs), Organik Transistörler (OFETs), Organik Güneş Pilleri (OSCs), ve Elektrokromik Cihazlar (ECDs)’a yenilik getirmiştir.
Hızlı tepki süreleri, yüksek geçirgenlikleri, işlenebilirlikleri ve yapısal değişikliklerle bant aralığı ve renk ayarlanabilmesi nedeniyle konjuge polimerlerin optoelektronik cihazlarda aktif katman olarak kullanılması zaman içinde popüler olmuştur.
Birçok alana uygulanabilir olmalarından dolayı polimerlerin organik elektronik cihazlarda ucuz aktif katman olarak kullanılma potansiyelleri vardır. İletken polimerlerde bant aralığının ayarlanabilir olması malzemenin görünür bölgedeki soğurma ve emisyon dalga boylarında değişikliğe yol açar. Ayrıca polimer üzerindeki yapı değişiklikleri ile renkte çeşitlilik sağlanabilir. Çoklu renklere sahip polimerler görüntü cihazları ve akıllı camlar gibi çeşitli uygulama alanlarında kullanılabilir.
Son zamanlarda, grubumuz tarafından sentezlenen benzotriazol içerikli donör-akseptör tipi polimerler elektrokromik cihaz ve güneş pilleri gibi birçok alanda kullanılabilen çok amaçlı malzemelerdir. Elektrokromik cihazlarda aktif katman olarak kullanılabilen donör-akseptör tipi polimerlerin özel davranışları bizi alkillenmiş benzotriazol türevlerinin akseptör birimi olarak kullanımına yönlendirmiştir. Benzotriazol ve etilendioksitiyofen içeren bu tip polimerler polietilendioksityofene göre üstün özellikler gösterdiğinden dolayı elektrokromik cihazlarda kullanımları öngörülmüştür. Bu sonuç benzotriazol biriminin polietilendioksitiyofen homo polimerinin elektrokromik özelliklerinin iyileştirilmesi açısından çarpıcıdır. Bu durum tiyofen içeren polimerler içinse politiyofen homo polimerine göre çok yeni özellikler göstermesi bakımından sevindiricidir. Bu polimer, homo polimerlerde son derece nadir görülebilen hem p tipi hem n tipi yarı iletken özelliği göstermektedir. Bu polimerin optik kontrastı ve iki faz arasındaki geçiş süresi politiyofene göre geliştirilmiştir. Ek olarak bu polimer floresan olma özelliği ile ışık saçan diyotlarda kullanılabilecektir. Ayrıca polimer organik çözücülerde çözünebilir olduğundan ve görünür bölgede kuvvetli soğurma özelliği ile güneş pillerinde kullanılabilme kapasitesine sahiptir.

Benzotriazol Metodolojisinin Bazı Sentetik Uygulamaları

Anadolu Üniversitesi Fen Bilimleri Fakültesi Kimya Bölümü’nden Dr. Araş. Gör. İlhami Çelik “Benzotriazol Metodolojisinin Bazı Sentetik Uygulamaları” isimli doktora tezini Doç Dr. Nevin Kanışkan danışmanlığında yaptı. İkinci tez danışmanı Prof. Dr. Alan Roy Katritzky olan Çelik, Benziatrol Metodolojisinin uygulamasını Florida Üniversitesi’nde gerçekleştirdi. Metodolojinin laboratuar uygulamalarının 1,5 yıl sürdüğünü ifade eden Çelik, tezinde yeni bir yöntem uygulayabilmesinin bilim açısından önemini vurguladı.

Tez çalışmasıyla ilgili bilgi veren Çelik, “Benzotriazol maddesi kolay elde edilebilen ve ucuz olması yanında etanol, benzen, toluen, kloroform, eter ve DMF gibi çözücülerle kolaylıkla çözünmesinden dolayı, kimyasal reaksiyonlarda son zamanlarda yoğun olarak aktive edici grup olarak kullanılmaktadır” şeklinde konuştu. Bir yüzyılı aşkın bir süredir bilinmesine rağmen, Benzotriazol maddesinin, kimyasal ve fiziksel özellikleri açısından son yıllarda keşfedildiğini ifade eden Çelik, aktive edici bir madde olması açısından benzotriazol maddesinin önemini vurguladı.

Dr. Çelik, kimyasal reaksiyonları kolayca teşhis edilen, saflaştırma işlemleri sırasında kararlı olan, tekrar kullanılabilen ve atık olarak çevreye zarar vermeyen Benzotriazol maddesini, tezinde iki ayrı bölümde inceledi. İlk aşamada literatürde kullanılan bir yöntem ile N-(α-amidoalkil) benzotriazolleri elde edilen çalışmada yeni bir yöntem geliştirildi. Bu yöntemde, nitroalkanlar, esterler, aklinler ve β-keto esterler ile N-(α-amidoalkil) benzoatriazoller arasındaki reaksiyon sonucu tamamı yeni olan N-( β-nitroalkil)amitler, β-(N-asilamino)alkil ester ve N-asil proparjil aminler elde edildi. Çalışmasının bu kısmının SCI(Science Citation Index)’deki ARKIVOC dergisinde yayınlandığını ifade eden Çelik, yayının 2007 senesinde gerçekleştiğini belirtti. Çelik çalışmasının ikinci bölümünün de SCI’de Synthesis dergisinde 2007 yılında yayınlandığı ifade etti. Tezinin ikinci kısmı ile ilgili şunları dile getirdi: “Tezin ikinci bölümünde yine literatürde kullanılan bir yöntem ile N-( α-tiyoamidoalkil)benzotriazoller ara ürün olarak elde edildi. Dana sonra geliştirilen yeni bir yöntemle çeşitli 1,3-dikarbonil bileşikleri ve ketonlar ile N-( α-tiyoamidoalkil)benzotriazoller arasındaki reaksiyonlar sonucu tamamı yeni olan β-tiyoamido-1,3-dikarnobil, β-tiyoamidoketon bileşikleri sentezlenmiştir.”

Çalışmasının sonucunda, yeni bir sentez yöntemi geliştirdiklerini ve bu yöntem ile tamamı yeni olan maddelerin yüksek verim ile sentezlendiğini ifade eden Çelik, “Geliştirilen bu yeni yöntemle alifatik, aromatik ve heteroaromatik sübstitüe amit ve tiyoamit türevleri elde edildi” dedi.

anadolu.edu.tr

Water Clarification

Steps of clarification
Inorganic coagulants
Polyelectrolytes
Color Reduction
Conventional clarification equipment
In-line clarification
Suspended matter in raw water supplies is removed by various methods to provide a water suitable for domestic purposes and most industrial requirements. The suspended matter can consist of large solids, settable by gravity alone without any external aids, and nonsettleable material, often colloidal in nature. Removal is generally accomplished by coagulation, flocculation, and sedimentation. The combination of these three processes is referred to as conventional clarification.

Coagulation is the process of destabilization by charge neutralization. Once neutralized, particles no longer repel each other and can be brought together. Coagulation is necessary for the removal of the colloidal-sized suspended matter.

Flocculation is the process of bringing together the destabilized, or “coagulated,” particles to form a larger agglomeration, or “floc.”

Sedimentation refers to the physical removal from suspension, or settling,   that occurs once the particles have been coagulated and flocculated. Sedimentation   or subsidence alone, without prior coagulation, results in the removal of only   relatively coarse suspended solids.

Steps of Clarification

Finely divided particles suspended in surface water repel each other because most of the surfaces are negatively charged. The following steps in clarification are necessary for particle agglomeration:

  • Coagulation. Coagulation can be accomplished through the addition of inorganic salts of aluminum or iron. These inorganic salts neutralize the charge on the particles causing raw water turbidity, and also hydrolyze to form insoluble precipitates, which entrap particles. Coagulation can also be effected by the addition of water-soluble organic with numerous ionized sites for particle charge neutralization.
  • Flocculation. Flocculation, the agglomeration of destabilized particles into large particles, can be enhanced by the addition of high-molecular-weight, water-soluble organic polymers. These polymers increase floc size by charged site binding and by molecular bridging.

Therefore, coagulation involves neutralizing charged particles to destabilize   suspended solids. In most clarification processes, a flocculation step then   follows. Flocculation starts when neutralized or entrapped particles begin to   collide and fuse to form larger particles. This process can occur naturally   or can be enhanced by the addition of polymeric aids.

[Devamini Okuyun...]

Flocculant Polymers

1- DEFINITIONS

Tramfloc flocculants consist of various molecular weight anionic, nonionic and cationic . They are used to increase the efficiency of settling, clarification, filtration and centrifugation operations.

Flocculation means a process in which individual particles of a suspension form aggregates. In the water treatment industry, the terms coagulation and flocculation imply different mechanisms.

[Devamini Okuyun...]

ALUMINIUM POTASSIUM SULFATE – ALUMİNYUM POTASYUM SÜLFAT

ALUMINUM POTASSIUM SULFATE
PRODUCT IDENTIFICATION
CAS NO. 7784-24-9 (Decahydrate) 10043-67-1 (Anhydrous)

ALUMINUM POTASSIUM SULFATE

EINECS NO. 233-141-3
FORMULA AlK(SO4)12H2O
MOL WT. 474.37
H.S.CODE
TOXICITY
SYNONYMS Kalinite; Potash alum; Potassium alum dodecahydrate;
Alum; white alum; Aluminiumkaliumbis(sulfat) (German); Bis(sulfato) de aluminio y potasio (Spanish); Bis(sulfate) d’aluminium et de potassium (French); Sulfuric acid, aluminium potassium salt (2:1:1);
SMILES aluminium hydroxide with potassium sulfate in sulfuric acid
CLASSIFICATION
PHYSICAL AND CHEMICAL PROPERTIES
PHYSICAL STATE white crystals or powder
MELTING POINT 92 – 93 C
BOILING POINT 200 C (Decomposes)
SPECIFIC GRAVITY 1.757
SOLUBILITY IN WATER very soluble
pH 3 – 3.5 (10% solution)
VAPOR DENSITY 16.4
AUTOIGNITION
NFPA RATINGS Health: 1 Flammability: 0 Reactivity: 0
REFRACTIVE INDEX
FLASH POINT Not combustible
STABILITY Stable under ordinary conditions
GENERAL DESCRIPTION & APPLICATIONS
The term of alum refers to various isomorphous solid sulfates composed of trivalent metals and univalent metals, especially aluminum potassium sulfate, AlK(SO4)2·12H2O, a white, crystalline compound. Alums have the general formula M2SO4·MIII2(SO4)3·24H2O, where M is one of alkali metals (potassium, sodium, rubidium, caesium, silver. thallium or ammonium), and MIII denotes one of the trivalent cation (e.g., aluminum, chromium, iron, manganese, cobalt, or titanium). In aqueous solution, alums show all the chemical properties that their components show separately. These salts are used in water purification, leather tanning, coagulation agent for rubber latex, setting dyes (mordant), fireproofing textiles, modifying concrete, baking powder, preparation of lakes, clarifying of turbid liquids and as astringents.

  • Potassium aluminum sulfate (KAl(SO4)2·12H2O, CAS RN: 7784-24-9 (Dodecahydrate), 10043-67-1 (Anhydrous))
  • Sodium aluminum sulfate (NaAl(SO4)2·12H2O, CAS RN: 10102-71-3)
  • Ammonium aluminum sulfate (NH4Al(SO4)2·12H2O, CAS RN: 7784-25-0 (Anhydrous), 7784-26-1 (Dodecahydrate))
  • Chromium potassium sulfate (KCr(SO4)2·12H2O, CAS RN: 10141-00-1 (Anhydrous), 7788-99-0 (Dodecahydrate))
  • Aluminum fluorosulfate (FAl(SO4)2·12H2O, CAS RN: 73680-58-7)

Flocculants are used in water treatment. The addition of flocculants to raw water causes colloids and other suspended particles to stick together and form heavier particles (floc) which will be removed by the sedimentation or filterability. This flocculation (or called coagulation) process is to aid the removal of contaminants like fine solid pollutants or microscopic molecules which are difficult or impossible to be removed by filtration alone. Generally flocculants are multivalent cations such as aluminium, iron, calcium or magnesium. Many of the suspended water particles have a negative electrical charge which repels each other. Positively charged flocculants attract and stick to many of the suspended water particles. Many of s cations, under appropriate pH and other conditions, react with water to form insoluble hydroxides which join together to form larger settleable particles or physically traps small particles into the larger floc. There are organic flocculants also. The most common and powerful organic is which have the long-chain to trap small particles into the larger floc. One of the common coagulants is aluminum sulfate which ,under neutral or slightly-alkaline conditions, reacts with water to form gelatinous precipitate of aluminum hydroxide. () of the general formula AlnCl(3n-m)(OH)m is useful as this compound have a wide range of pH value according to the subscripts n and m. The actual pH correlates to the formula m/(3n). It provides a choice forthe exact pH value applications. The most common PAC for water purification is Al12Cl12(OH)24. The form of Al2Cl(OH)5 is used as adeodorant and an antiperspirant. Other modified PAC compouinds include polyaluminum hydroxidechloride silicate () and polyaluminum hydroxidechloride silicate sulfate (PASS). Members of flocculants include:

  • Alum
  • Aluminum sulfate
  • Calcium oxide
  • Iron chloride
  • Iron sulfate
  • Polyacrylamide
  • Polyaluminum chloride
  • Polyaluminum hydroxidechloride silicate sulfate
  • Polyaluminum hydroxidechloride silicate
  • Sodium aluminate
  • Sodium silicate

PAC is also used in reducing the need of pH adjustment and is often employed in the place where the pH of the receiving stream is higher than 7.5. PAC is also used in the pulp (or paper) industry as a size bonding agent, drainage work aid and surface trash scavenger.

POLYALUMINUM CHLORIDE – POLİALUMİNYUM KLORÜR

PRODUCT IDENTIFICATION
CAS NO. 1327-41-9 (Basic)

 

EINECS NO. 215-477-2 (Basic)
FORMULA Aln(OH)mCl3n-m
MOL WT.  
H.S.CODE 2827.32
TOXICITY  
SYNONYMS PolyAluminum chlorohydrate; ;
Polyaluminum hydroxychloride;
SMILES  
CLASSIFICATION  
PHYSICAL AND CHEMICAL PROPERTIES (SOLUTION)
PHYSICAL STATE clear to yellow liquid
MELTING POINT -12 C
BOILING POINT > 100 C
SPECIFIC GRAVITY 1.36 – 1.38
SOLUBILITY IN WATER Soluble
pH  
VAPOR DENSITY  
AUTOIGNITION  
NFPA RATINGS Health: 13; Flammability: 0; Reactivity: 0
REFRACTIVE INDEX  
FLASH POINT Not combustible
STABILITY Stable under ordinary conditions
GENERAL DESCRIPTION & APPLICATIONS
Flocculants are used in water treatment. The addition of flocculants to raw water causes colloids and other suspended particles to stick together and form heavier particles (floc) which will be removed by the sedimentation or filterability. This flocculation (or called coagulation) process is to aid the removal of contaminants like fine solid pollutants or microscopic molecules which are difficult or impossible to be removed by filtration alone. Generally flocculants are multivalent cations such as aluminium, iron, calcium or magnesium. Many of the suspended water particles have a negative electrical charge which repels each other. Positively charged flocculants attract and stick to many of the suspended water particles. Many of s cations, under appropriate pH and other conditions, react with water to form insoluble hydroxides which join together to form larger settleable particles or physically traps small particles into the larger floc. There are organic flocculants also. The most common and powerful organic is which have the long-chain to trap small particles into the larger floc. One of the common coagulants is aluminum sulfate which ,under neutral or slightly-alkaline conditions, reacts with water to form gelatinous precipitate of aluminum hydroxide. Polyaluminum chloride (PAC) of the general formula AlnCl(3n-m)(OH)m is useful as this compound have a wide range of pH value according to the subscripts n and m. The actual pH correlates to the formula m/(3n). It provides a choice forthe exact pH value applications. The most common PAC for water purification is Al12Cl12(OH)24. The form of Al2Cl(OH)5 is used as a deodorant and an antiperspirant. Other modified PAC compouinds include polyaluminum hydroxidechloride silicate () and polyaluminum hydroxidechloride silicate sulfate (PASS). Members of flocculants include:

  • Alum
  • Aluminum sulfate
  • Calcium oxide
  • Iron chloride
  • Iron sulfate
  • Polyacrylamide
  • Polyaluminum chloride
  • Polyaluminum hydroxidechloride silicate sulfate
  • Polyaluminum hydroxidechloride silicate
  • Sodium aluminate
  • Sodium silicate

PAC is also used in reducing the need of pH adjustment and is often employed in the place where the pH of the receiving stream is higher than 7.5. PAC is also used in the pulp (or paper) industry as a size bonding agent, drainage work aid and surface trash scavenger. The term of alum refers to various isomorphous solid sulfates composed of trivalent metals and univalent metals, especially aluminum potassium sulfate, AlK(SO4)2·12H2O, a white, crystalline compound. Alums have the general formula M2SO4·MIII2(SO4)3·24H2O, where M is one of alkali metals (potassium, sodium, rubidium, caesium, silver. thallium or ammonium), and MIII denotes one of the trivalent cation (e.g., aluminum, chromium, iron, manganese, cobalt, or titanium). In aqueous solution, alums show all the chemical properties that their components show separately. These salts are used in water purification, leather tanning, coagulation agent for rubber latex, setting dyes (mordant), fireproofing textiles, modifying concrete, baking powder, preparation of lakes, clarifying of turbid liquids and as astringents.

  • Potassium aluminum sulfate (KAl(SO4)2·12H2O, CAS RN: 7784-24-9 (Dodecahydrate), 10043-67-1 (Anhydrous))
  • Sodium aluminum sulfate (NaAl(SO4)2·12H2O, CAS RN: 10102-71-3)
  • Ammonium aluminum sulfate (NH4Al(SO4)2·12H2O, CAS RN: 7784-25-0 (Anhydrous), 7784-26-1 (Dodecahydrate))
  • Chromium potassium sulfate (KCr(SO4)2·12H2O, CAS RN: 10141-00-1 (Anhydrous), 7788-99-0 (Dodecahydrate))
  • Aluminum fluorosulfate (FAl(SO4)2·12H2O, CAS RN: 73680-58-7)

Coagulant Chemicals – Koagülantlar Çöktürücüler


chemicals come in two main types – primary coagulants and aids.  Primary coagulants neutralize the electrical charges of particles in the water which causes the particles to clump together.  aids add density to slow-settling flocs and add toughness to the flocs so that they will not break up during the mixing and settling processes.

Primary coagulants are always used in the coagulation/flocculation process.  Coagulant aids, in contrast, are not always required and are generally used to reduce flocculation time. 

Chemically, coagulant chemicals are either metallic salts (such as alum) or are man-made organic compounds made up of a long chain of smaller molecules.  can be either cationic (positively charged), anionic (negatively charged), or nonionic (neutrally charged.)  The table below shows many of the common coagulant chemicals and lists whether they are used as primary coagulants or as coagulant aids.

Chemical Name
Chemical Formula
Primary Coagulant
Coagulant Aid
Aluminum sulfate (Alum)
Al2(SO4)3 · 14 H2O
X

Ferrous sulfate
FeSO4 · 7 H2O
X

Ferric sulfate
Fe2(SO4)3 · 9 H2O
X

Ferric
FeCl3 · 6 H2O
X

Cationic polymer
Various
X
X
Calcium hydroxide (Lime)
Ca(OH)2
X*
X
Calcium oxide (Quicklime)
CaO
X*
X
Sodium aluminate
Na2Al2O4
X*
X
Bentonite
Clay

X
Calcium carbonate
CaCO3

X
Sodium silicate
Na2SiO3

X
Anionic polymer
Various

X
Nonionic polymer
Various

X

*Used as a primary coagulant only in water softening processes.

 


Alum

There are a variety of primary coagulants which can be used in a water treatment plant.  One of the earliest, and still the most extensively used, is aluminum sulfate, also known as alum.  Alum can be bought in liquid form with a concentration of 8.3%, or in dry form with a concentration of 17%.

When alum is added to water, it reacts with the water and results in positively charged ions.  The ions can have charges as high as +4, but are typically bivalent (with a charge of +2.)  The bivalent ion resulting from alum makes this a very effective primary coagulant.  Bivalent ions are 30 to 60 times more effective in neutralizing particles’ charges than are monovalent ions (with +1 charge.)

Coagulant Aids

Nearly all coagulant aids are very expensive, so care must be taken to use the proper amount of these chemicals.  In many cases, coagulant aids are not required during the normal operation of the treatment plant, but are used during emergency treatment of water which has not been adequately treated in the flocculation and sedimentation basin.  A couple of coagulant aids will be considered below.

Lime is a coagulant aid used to increase the alkalinity of the water.  The increase in alkalinity results in an increase in ions (electrically charged particles) in the water, some of which are positively charged.  These positively charged particles attract the colloidal particles in the water, forming floc.

Bentonite is a type of clay used as a weighting agent in water high in color and low in turbidity and mineral content.  This type of water usually would not form floc large enough to settle out of the water.  The bentonite joins with the small floc, making the floc heavier and thus making it settle more quickly.

Sayfa 1 / 3012345...102030...Son »