USINGJOB’SMETHODTODETERMINETHESTOICHIOMETRICRATIOOFAMETAL-AMINOPOLYCARBOXYLATECOMPLEXINANON-AQUEOUSMEDIUM

NsombiJ.RobertsDepartmentofChemistry,SouthernUniversityandA&MCollege

BatonRouge,LA

INTRODUCTIONFirst world countries are plagued with high density industrialized areas that produce largeamounts of pollutants on a daily basis. This is not to be confused with the general term forunwanted remains and byproducts or waste that these corporations expel. A pollutant isdescribed as a waste material that pollutes or contaminates the environment. Pollution iscategorized into several different groups: air, thermal, soil, radioactive, and water. Waterpollution occurs when pollutants spread from a source to the environment, leaving naturalresources such as water systems fouled by human existence. Contaminated water sourcescan contain various dense, potentially toxic metals or heavy metals that are a danger to thehuman condition. The heavy metals of major health concern are cadmium, mercury, leadand arsenic. Other heavy metals that are less toxic are manganese, chromium, cobalt,nickel, copper, zinc, selenium, silver, antimony and thallium. These heavy metals can onlybe removed through transformation from one oxidation state or organic complex toanother. As of 2016, the major environmental issue at hand in the United States is thedrinking water contamination crisis in Flint, Michigan. The city of Flint is currently in afederal state of emergency which allows the federal government to take the forefront onhandling the issue at hand. The drinking water for the city of Flint was switched from thesame source used by the city of Detroit to the Flint River, a previous back up source. Thecity originally did not use the Flint River as a primary source because the overall cost for thetreatment of that water was more expensive than water from Lake Huron, Detroit’s currentwater source.. The water from the Flint River was contaminated by lead that leached intothe water system from outdated pipes. Leaching is described as the process of removing asoluble mineral or chemical from a solid source with a liquid either naturally or throughforced means. The improper treatment of the water and the ineffective methods used toremove the leached lead posed a serious health risk to the citizens of Flint. Lead is thesecond most hazardous metal according to the Priority List of the US EnvironmentalProtection Agency. News stations across the country displayed the unnatural discolorationof water in the homes of dozens of Flint residents. Many children were found having highlyelevated levels of lead in their blood stream which translates to lead poisoning. Leadpoisoning can lead to “deficits in intellectual functioning, academic performance, problemsolving skills, motor skills, memory and executive functioning are consistently observed inlead-exposed children, in addition to an increased likelihood of experiencing ADHD andhaving conduct problems in childhood, and decreased brain volume in adulthood.” Greenchemistry is “the utilization of a set of principles that reduces or eliminates the use orgeneration of hazardous substances in the design, manufacture, and applications ofchemical products.” It is upon this foundation that purification systems were born. Waterpurification methods are costly to the average citizen forced by their social economic statusto live in these nearly uninhabitable areas. The current green chemistry methods in place,while less costly and efficient, employ an aminopolycarboxylic acid that is a suspectedcarcinogenic to humans.. The increasing world population has led to a rapid increase inpollution. The increasing cost of pollutant removal has led the world to turn to producingnewer methods. There is a need for a sequestering agent that has effectiveness in removingheavy metals from solutions, has minimum health effect, and is cost efficient. Pollutants inwater systems and soils negatively affect the lifecycles of plants and animals, ultimatelyaffecting human life. Metal removal from aqueous and non-aqueous solutions through theuse of an aminopolycarboxylic acid can be a cheaper and more efficient purificationprocess. The purpose of this study is to develop a green chemistry method for removingpollutants fromaqueous or non-aqueous solvents.

ABSTRACTThe increasing world population has led to a rapid increase inpollution. The increasing cost of pollutant removal has led theworld to turn to producing newer, cheaper, and safer methods.There is a need for a sequestering agent that has effectiveness inremoving heavy metals from solutions, has minimum healtheffect, and is cost efficient. This study sets to utilize anaminopolycarboxylic acid to develop a method that is effective inremoving pollutants from aqueous and non-aqueous mediums.The titrimetric methods of analysis were used to develop amethod that is cheap and safe for removing pollutants such astoxic metals from non-aqueous and aqueous mediums. Thephysiochemical properties of the aminopolycarboxylic acidobserved were used to develop a method that is cheap and safefor removing pollutants such as toxic metals from non-aqueoussolutions. 3, 3’, 3”-Nitrilotripropionic acid (NTP) was synthesizedfrom acrylic acid and β-Alanine using Michael Addition andcoordinated to a metal complex in a non-aqueous solution. Themethod of continuous variation was used to find thestoichiometric ratio of the metal complex.

SpecificAim1:Synthesisof3,3’,3”–Nitrilotriproionic acidfromβ-Alanineandacrylicacid.

SpecificAim2:Coordinationofsynthesized3,3’,3”–Nitrilotriproionic acidtoCupricchlorideinanon-aqueousmediumusingtheJob’sMethod

Results ConclusionFrom the solubility test and melting point test, it can be concluded that NTP wassuccessfully made. The process of forming NTP from b-alanine and acrylic acid wasfaster than previous methods and produced a substantial yield. The conclusion that thetime-consuming process is due to the third step of reaction has been disproven. Due tothe first leg of NTP already being attached, it can be concluded that the formation ofthe primary amine compound, the first step, is the rate limiting step. It has also beenconcluded that NTP fully deprotonates in basic mediums, making it the optimalenvironment for coordination to metal ion. This confirms the pH dependency of NTPcoordination. Future studies of NTP coordination should be conducted in basicmediums or with a salt form of NTP to allow maximum potential for coordination. TheNTP ligand successfully coordinated to Copper, as observed by the distinct colorchanges with varying metal to ligand ratios. A single new peak emerged at 726.7 nm ata metal to ligand ratio of 1:9, giving a starting point for future studies for finding the tothe stoichiometric ratio. Other methods such as the mole-ratio and slope-ratio methodsshould be examined to find an exact ratio.

AcknowledgmentsDr. Scott A. WickerSouthern University Chemistry DepartmentZeta Phi Beta Sorority, Inc.Dolores Margaret Richard Spikes Honors College

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MichaelAdditionSynthesisofNTP

TitrationofNTPinNaOH

VolumeNTP(L)

molesofNTP

VolumeCopper(II)Chloride(L)

molesofCopper(II)ion

TotalMolesMoleFraction

ofLigand

MoleFractionof

Metal

MoleRatioofLigandtoMetal

0 0.0000E+00 0.005 1.0265E-05 1.0265E-05 0 1 0/10.0005 1.0265E-06 0.0045 9.2385E-06 1.0265E-05 0.1 0.9 1/90.001 2.0530E-06 0.004 8.2120E-06 1.0265E-05 0.2 0.8 1/40.0015 3.0795E-06 0.0035 7.1855E-06 1.0265E-05 0.3 0.7 3/70.002 4.1060E-06 0.003 6.1590E-06 1.0265E-05 0.4 0.6 2/30.0025 5.1325E-06 0.0025 5.1325E-06 1.0265E-05 0.5 0.5 1/10.003 6.1590E-06 0.002 4.1060E-06 1.0265E-05 0.6 0.4 3/20.0035 7.1855E-06 0.0015 3.0795E-06 1.0265E-05 0.7 0.3 7/30.004 8.2120E-06 0.001 2.0530E-06 1.0265E-05 0.8 0.2 4/10.0045 9.2385E-06 0.0005 1.0265E-06 1.0265E-05 0.9 0.1 9/10.005 1.0265E-05 0 0.0000E+00 1.0265E-05 1 0 1/0

MolarityofNTP(M)

MolarityofCopper(II)Chloride(M)

TotalVolume(mL)

0.002053 0.002053 5

PhaseDiagramforNTPwithCopper(II)ChlorideinDMSO

Varyingratios(M:L)of2mMCopper(II)chlorideand2mMNTPinDMSO.Fromlefttoright:1:0,9:1,8:2,7:3,6:4,5:5,4:6,3:7,2:8,1:9,0:1.

Varyingratios(M:L)of0.05MCopper(II)chlorideand0.05MNTPinDMSO.Fromlefttoright:1:0,9:1,8:2,7:3,6:4,5:5,4:6,3:7,2:8,1:9,0:1.

0

0.1

0.2

0.3

0.4

0.5

0.6

380 480 580 680 780 880

Absorban

ce

Wavelength(nm)

ContinuousVariationof0.002MCuCl_2and0.002MNTPinDMSO

1:0

9:1

8:2

7:3

6:4

5:5

4:6

3:7

2:8

1:9

0:1

Metal toLigandRatio

Peak=391.6nm

Copper(II)chlorideinwaterandCopper(II)chlorideinDMSO

Enhancedspectrumof2mMNTPand2mMCopper(II)ChlorideinDMSOat(fromtoplefttorighttobottomlefttoright)metaltoligandratiosof4:6,3:7,2:8,and1:9

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

380 480 580 680 780 880

Absorba

nce

Wavelength(nm)

Absorbanceof1:90.05MCuCl_2and0.05MNTPinDMSO

Peak=726.7nm