Kimia Air

Hidrosfer/Kimia Air - 1

2HCO3- + hv Fotosintesis {CH2O} +

O2(g) + CO3

2-

CO32- + H2O Asam-basa H CO3

- + OH-

Ca2- + CO32- pengendapan CaCO3

- (s) {CH2O} + SO4

2- + 2H+ mikroba

H2S + H2O + CO2(g)

O2 CO2

Cd2+

Red

uksi

-oks

idas

i

NH4+

NO3-

Lindi Penyerapan

LumpurAir

tanah

Dasar Kimia AirDasar Kimia Air


Suber Sepesi Kimia dalam Air AlamiOrigin Positive Ions Negative Ions

Contact of water with minerals, soils, and rocks

Ca+2, Fe+2 Mg+2, Mn+2 K+, Na+, Zn+2

HCO3 -, CO3 -2 Cl-, F-, NO3 - PO4 -3, OH -, SO4 H2BO3 -, H3SiO4

The atmosphere, in rain H+ HCO3 -, Cl-, SO4

Decomposition of organic matter in the environment

NH4 +, H+, Na+ Cl-, HCO3 -, OH -, NO2 -, NO3 -, HS-Organic radicals

Municipal, industrial, and agricultural sources and other human activity

Inorganic ions, including a variety of heavy metals

Inorganic ions, organic molecules, color


Parameter Kunci Kualitas Air untuk Berbagai Keperluan

Public water supply Industrial water supply Agricultural water supply

Aquatic life and wildlife

Recreation and aesthetics

Coliform bacteriaTurbidityColourTaste-odourTrace metalsDissolved solidsTrace organicsChloridesFluoridesSulphatesNitratesCyanidesRadioactivity

Processing (except foods)pHTurbidityColourHardnessAlkalinity/acidityDissolved solidSuspended solidsTrade metalsTrade organicsCoolingpHTemperatureSilicaAluminiumIronManganeseHardnessAlkalinity/aciditySulphatesDissolved solidsSuspended solidsSanitary (same as for public supply

Farmstead:(same as for public supply)Livestock: (similar to that for public supply) Irrigation:Dissolved solidsSpecific conductanceSodiumCalciumMagnesiumPotassiumBoronChloridesTrace metals

TemperatureDOpHAlkalinity/acidityDissolved solidsSalinityCarbon dioxideTurbidityColourSettleable materialsFloating materialTainting substancesToxic materialsNutrientsSubstances adversely affecting wildlife

RecreationColiformsTurbidityColourpHOdourFloating materialsSettleable materialsNutrientsTemperatureAestheticsTurbidityColourOdourFloating materialsSettleable materialsNutrientsTemperatureSubstancesadverselyaffecting wildlife


Temperatur

Measured with a thermometer Units are ◦C Range is <0 to ? (in Phoenix?) Important because:

Temperature influences the amount and diversity of aquatic life Helps us better understand other hydrology measurements like

Dissolved Oxygen (DO) pH Electrical Conductivity (EC)

Water temperature affects air temperature via evaporation & condensation Possible indication of:

mixing of nutrient-rich waters spawning


pH

pH is a measure of the acid content of water. Measured with a pH meter or pH paper Units are pH units – are a logarithmic scale of hydrogen ion

concentration Small change in pH can mean a big change in water quality


Transparensi (Turbidity)

Transparency is a measure of how clear the water is Units are length, usually cm Range is 0 to >100 cm Measured with either a secchi disc or a

transparency tube Important because:

suspended particles in water behave similarly to dust in theAtmosphere

an increase in suspended particles reduces the depth to whichlight can penetrate

this affects plants’ ability to photosynthesize sediments can come from both natural and human sources


Electrical Conductivity (EC)

We call the amount of mineral and salt impurities in the water the total dissolved solids (TDS)

We measure TDS and parts per million (ppm). This tells us how many units of impurities there are for one million units

of water by mass. We use an indirect measure to find the TDS of water. One way to

measure impurities is to see if it conducts electricity. We use an EC meter to measure electrical conductivity. Units are μS/cm (microSiemens per cm). This is the same as a micromho. Range is 0 to >2000 μS/cm We need to convert from μS/cm to TDS, and this requires a conversion

factor. This conversion factor varies from 0.54 to 0.96, but 0.67 is commonly used for an approximation

TDS (ppm) = Conductivity (μS/cm) x 0.67


Kesetimbangan muatan

Aqueous solutions must be electrically neutral. In other words, the sum of all negative charges must equal the sum of all positive charges.

One check on the quality of a water analysis is the charge-balance error, calculated as follows:

There is always some error in the measurement of cation and anion concentrations.

Thus, we cannot expect a charge-balance error of zero for any analysis. The C.B.E. may be positive or negative, depending on whether cations or

anions are more abundant. A reasonable limit for accepting an analysis as valid is ±5%.

100C.B.E.

aacc

aacc

zmzm

zmzm



Oksigen dalam airOksigen dalam airOksigen dalam airOksigen dalam air Fungsi

pernafasan ikan penguraian zat organik konsumsi alga pada malam hari

Reoksigenasi badan air Difusi dari atmosfer (O2 = 20,95%)

Pergerakan air: Aliran dan gelombang Angin

hasil fotosintesis alga

JuvenilesAdults

Stress

Mortality

Preferred


Dissolved Oxygen (DO)

DO is a measure of molecular oxygen (O2) dissolved in water The amount of dissolved oxygen the water will hold is called the

solubility of dissolved oxygen. Factors that affect solubility are: Water temp (Increase in temperature, decrease in DO) Atmospheric pressure (higher elev., lower pressure, DO decreases) Salinity (increase in salinity, DO decreases)

Units are mg/L or ppm Dissolved oxygen can range from 0-18 mg/L, but most natural

watersystems require 5-6 mg/L to support a diverse population Measured with a DO kit or a DO probe Important because:

amount of DO in water determines what can live there some organisms require higher oxygen levels than others DO is affected by what lives in the water


Karbon dioksida dalam airKarbon dioksida dalam airKarbon dioksida dalam airKarbon dioksida dalam air

Sumber: Udara (0.0350 % V) Penguraian zat organik Pelapukan Mineral Anorganik

Manfaat: fotosintesis pada alga Konsentrasi yang tinggi berpengaruh pada

pernafasan binatang air (25 ppm mematikan ikan) Kesetimbangan dengan udara-airCO2(g) CO2(aq) ............. KH

CO2(aq) HCO3- + H+ ......... Ka1

HCO3- CO3

2- + H+ . ........ Ka2

H2O OH- + H+ .............. KW

0KKK2HKKKH 2a1aHC1aHCW

3

22 COCO pp


Karbon dioksida dalam AirKarbon dioksida dalam AirKarbon dioksida dalam AirKarbon dioksida dalam Air

0

0,2

0,4

0,6

0,8

1

1,2

2 3 4 5 6 7 8 9 10 11 12 13 14 15

CO2HCO3CO3

pH

fraksi

CO

a a a

H

H K H K K2

2

2

1 1 2

HCO

a

a a a

K H

H K H K K3

1

2

1 1 2

211

221

3

aaa

aaCO

KKHKH

KK

Fraksi masing-masing spesi


Alkalinitas Alkalinitas Alkalinitas Alkalinitas Alkalinitas:

Kapasitas air untuk menetralkan asam Penting untuk:

pengolahan air mempelajari kimia dan biologi air

Alkalinitas dipengaruhi oleh: CO2, HCO3-, CO3

= dan OH- (utama) fosfat, silikat, asam organik, garam-garam asam

lemah, amonia Alkalinitas tidak sama dengan kebasaan

Alakalinitas:gambaran sumber karbon anorganikberperan dalam pertumbuhan ganggangukuran kesuburan airfaktor kapasitas

Kebasaan:tergantung pada kesetimbangan asam basaditunjukkan oleh pHfaktor intensitas


Alkalinitas Alkalinitas Alkalinitas Alkalinitas

Reaksi:(1) CO2 + H2O HCO3

- + H+ ..pka1= 6,36

(2) HCO3- + H2O CO3

= .......pka2 = 10,32

(3) H2O H+ +OH- .................pkw = 14

Alk. pp (pH=8.3)

Alk. total (pH= 4,3)

Pernyataan AlkalinitasCO3

2- + OH- HCO3- CO2

[Alk] = [HCO3- ] + 2[CO3

2-] +[OH- ]

[C] = [CO2] + [HCO3- ] + [CO3

2-]


Alkalinity

Related to pH but different Alkalinity is a measure of pH buffering capacity of

the water What happens to the pH of water if acid is added? The answer depends on:

How much buffering capacity (alkalinity) is in the water How much acid is added

Measured with an alkalinity test kit Expressed as amount of calcium carbonate

(CaCO3) in the water Units are ppm or mg/L (1 ppm = 1 mg/L)


Alkalinity – some examples

If water has a high alkalinity and acid is added, the alkalinity neutralizes the acid. Some of the alkalinity will be used up, so the alkalinity will go down. If more acid is added the alkalinity will continue to decrease. Eventually, when the alkalinity is low enough, adding acid will cause the pH to decrease.

When water has a high alkalinity we say it is well buffered. It resists a decrease in pH when acidic water such as rain or snowmelt enters it.

Alkalinity comes from dissolved rocks, particularly limestone and soils with CaCO3. It is added to the water naturally as water comes in contact with rocks and soil. Water dissolves the CaCO3,,carrying it to lakes and rivers.

If water has an alkalinity below about 100 mg/L as CaCO3, it is poorly buffered and pH sensitive. A big rainfall or snowmelt could add enough acid to lower the pH in a sensitive system. This could harm the organisms that live there, esp. at certain times of the year (fish or insect larvae hatching)


Nitrate (NO3-)

Nitrogen can have many chemical forms in water bodies: Molecular nitrogen (N2) as organic compounds (both dissolved and particulate) as numerous inorganic forms such as

ammonium (NH4+) Nitrite (NO2-) Nitrate (NO3-)

Nitrate (NO3-) is usually the most important inorganic form of nitrogen because it is an essential nutrient for the growth and reproduction of many algae and other aquatic plants

Nitrogen is a “limiting nutrient” because in low amounts, plants use up all the available nitrogen in the water and cannot grow or reproduce anymore. So it “limits” the amount of plants in the water


Nitrate (NO3-)

Nitrate (NO3-) is very difficult to measure directly, whereas nitrite (NO2 -) is easier to measure

Nitrate kits convert the nitrate (NO3-) in the water sample to nitrite (NO2-)

You will add a chemical to the water sample to accomplish this conversion, and then a second chemical is added that reacts with the nitrite (NO2-) to cause a color change

The measurement gives a combined concentration of nitrite (if resent) and nitrate (which was converted to nitrite (NO2-) )

Units are mg/L Most natural waters have nitrate levels under 1.0 mg/L

nitrate-nitrogen, but concentrations over 10 mg/L are found in some areas. This affects whether you use a low-range or high range test in the kit


Logam dalam AirLogam dalam AirLogam dalam AirLogam dalam Air

Logam dalam air terdapat sebagai ion dan akan mengalami reaksi membentuk spesi paling stabil yang tergantung pada sifat logam dan kondisinya

Reaksi yang terjadiHidrasi

Fe3+ + 6H2O Fe(H2O)63+

Asam-basaFe(H2O)6

3+ FeOH(H2O)53+ + H+

PengendapanFe(H2O)6

3+ Fe(OH)3(s) + 3H2O + H+

RedoksFe(H2O)6

2+ Fe(OH)2(s) + 3H2O + H+ + e


Logam dalam AirLogam dalam Air


Logam dalam AirLogam dalam Air


KesadahanKesadahanKesadahanKesadahan

Pengaruh: Sabun mengendap dan tidak berbusa Pengerakan pada ketel uap

Ukuran kesadahan: mg CaCO3/L:

air lunak ( 0-75 mg /L) air agak sadah (76 - 150 mg/L) air sadah (151-300 mg/L)

Penyebab kesadahan

Penyebab pasangan KeteranganCa2+ HCO3

- Kesadahan sementaramg2+ SO4

= Kesadahan tetapSr2+ Cl-

Fe2+ NO3-

Mn2+ SiO3-


KesadahanKesadahan

°GH °e °f ppm mmol/l

German degree 1°GH = 1 1,253 1,78 17,8 0,1783

English degree 1°e = 0,798 1 1,43 14,3 0,142

French degree 1°f = 0,560 0,702 1 10 0,1

CaCO3 (USA) 1 ppm = 0,056 0,07 0,1 1 0,01

mmol/l 1 mmol/l

= 5,6 7,02 10,00 100,0 1


Kesetimbangan Kalsium karbonat-karbondioksida

CaCO3 + CO2 + H2O Ca2- + H CO3

-

CO2

CO2

Lumpur

CaCO3

Ca2-

CO32-

2a

1asp

2

23`

K

KK

CO

COCaK

2




Cara menghilangkan kesadahan Penggunaan bikarbonat dan pemanasanCa2+ + 2 HCO3

- CaCO3(s) +CO2 (g)+ H2O

Soda KapurCa2+ + 2 HCO3

- +Ca(OH)2 2 CaCO3(s) + H2O

Soda AbuCa2+ + CO3

2- 2 CaCO3(s)

Ortofosfat5 Ca2+ +3 PO4

3- + H2O 2 Ca5OH(PO4)3(s)

Penukar ion Adsorben tanah liat, zeolit dsb. Penambahan pengkompleks khelat


Senyawa Kompleks dalam AirSenyawa Kompleks dalam AirSenyawa Kompleks dalam AirSenyawa Kompleks dalam Air Senyawa Kompleks

Ion logam : sebagai inti (pusat)Air alamiah: Mg2+, Ca2+, Fe2+, Fe3+, Cu2+, Zn2+, VO2+

Ligan: donor pasangan elektron bebas (basa Lewis) dapat bebentuk molekul, ion positif atau ion negatif. Gugus fungsi dapat berupa:

O-R CO

CO-

HR N:

HO-O P

O

O

R

Unidentat: membentuk satu ikatan koordinasi

Khelat : dapat membentuk lebih dari satu ikatan koordinasi


Senyawa Kompleks dalam AirSenyawa Kompleks dalam AirSenyawa Kompleks dalam AirSenyawa Kompleks dalam Air

SUMBER: ALAMIAH:Asam sitrat, Humus, Asam amino SINTETIK: Polifosfat, EDTA, NTA

PENGARUH LIGAN TERHADAP LOGAM: Menentukan bilangan oksidasi logam Memnentukan tosisitas logam Mempengaruhi logam terlarut

REAKSI ANTAR LIGAN: Redoks Hidrolisis Dekarboksilasi


Senyawa Kompleks dalam AirSenyawa Kompleks dalam AirSenyawa Kompleks dalam AirSenyawa Kompleks dalam Air Perhitungan spesi senyawa kompleks

Kestabilan senyawa kompleks tergantung pada konstanta pembentukannya: Konstanta pembentukan pertahap, Kn

Konstanta pembentukan total (overall), n

n=K1K2K3…Kn

Zn2+ + NH3 Zn(NH3)2+

3

2

23

1 NHZn

NHZnK

Zn(NH3)2+ + NH3 Zn(NH3)22+

3

23

2

232

NHNHZn

NHZnK

2= K2K1


Senyawa Kompleks dalam AirSenyawa Kompleks dalam AirSenyawa Kompleks dalam AirSenyawa Kompleks dalam Air Pelarutan Ion Logam oleh NTA

Pb(OH)2(s) + HT2- PbT- + OH- + H2O

w

fasp

K

KKK

HT

OHPbTK 3

2

2a

f3asp2

3

K

KKK

HT

HCOPbTK

PbCO3(s) + HT2- PbT- + HCO3-

Ksp = Hasil kali kelarutan

Ka3 = Konstanta kesetimbangan deprotonasi H3T tahap 3

Kw = Konstanta ionisasi air

K`a2 = Konstanta kesetimbangan deprotonasi H3CO3 tahap

2 Suatu limbah mengandung kalsium, timbal karbonat dan NTA, hitung nisbah PbT/CaT yang terlarut!


Polifosfat Sumber

Mineral fosfat Pertanian Pemukiman Industri Pengisi detergen

Kegunaan Pelunakan air Pengolahan air Pengisi detergen

Polifosfat sederhana adalah Asam pirofosfat (difosfat )Polifosfat merupakan pengkomplek yang baik untuk ion logam alkaliHidrolisis polifosfat menghasilkan asam fosfat (ortofosfat)

Senyawa Kompleks dalam AirSenyawa Kompleks dalam AirSenyawa Kompleks dalam AirSenyawa Kompleks dalam Air


Senyawa Kompleks dalam AirSenyawa Kompleks dalam AirSenyawa Kompleks dalam AirSenyawa Kompleks dalam Air Humus

Bahan kimia sisa penguraian tumbuhan, terdapat dalam tanah, gambut dan batubaraPengelompokkan

Humus

Endapan(Humin)

Larutan

Endapan asam humat

Larutan asam fulfat

+ basa kuat

+ asam kuat


KESETIMBANGAN REDOKSKESETIMBANGAN REDOKSKESETIMBANGAN REDOKSKESETIMBANGAN REDOKS

STUM DAN MORGAN

OXREDlognpnp

OXREDlog]elog[nKlog

eOXREDK

o

e

ne

Pada Kesetimbangan, 25 oC

Nerst : Log K = 16,92 Eo

Stum-Morgan: log K = npo

Hubungan peo dengan Eo

npo = 16,92 Eo

Redoks : Ox + ne Red

]Ox[]d[Relog

NFRT303,2EE

OPERSAMAAN NERST


KESETIMBANGAN REDOKSKESETIMBANGAN REDOKSKESETIMBANGAN REDOKSKESETIMBANGAN REDOKS

Batas p dalam airp tertinggi: Suasana air paling oksidatif Proton teroksidasi H+ + 1/4 O2+e 1/2 H2O Eo = 1,229

po = 16,92 Eo = 20,75

p= po +log[H+] [PO2]1/4

Bila PO2 = 1atm, [H+] = 1M : p= po = 20,75

Bila PO2 = 1atm, [H+] =? : P= 20,75 – pH

p terendah: Suasana air paling reduktif Proton tereduksi

H+ + e 1/2 H2 Eo = 0, po = 0Bila PH2 = 1atm, [H+] =?

P= - pH


pE-pH Diagrams

ALLOWED CONDITIONS

IN THE PRESENCE OF LIQUID WATER

AT 1 ATM TOTAL PRESSURE

20

15

10

5

0

-5

-102 3 4 5 6 7 8 9 10

pE

pH

FORBIDDEN ZONE

FORBIDDEN ZONE

H2O

O2

H2O

H2


The Stability of Water and the pe- and pH-conditions in Natural Environments


KESETIMBANGAN REDOKSKESETIMBANGAN REDOKS

-14

-12

-10

-8

-6

-4

-2

0

2

4

6

8

10

12

14

16

18

20

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Batas atas

A

B

C

D

E

Batas bawah

Fe3+

Fe2+

Fe(OH)3

Fe(OH)2

O2

H2

Diagram pe vs pH Sistem Besi dalam Air




pe-pH stability in the Fe-H2O-CO2 system

at 25oC andTIC = 10-2.5 mol/l



O2/H2O

C2HO


Kimia Air

Documents

water hidrosferkimia

public supply

ht2

hidrosferkimia

dissolved

co32

balance error

high alkalinity