Lead Remediation of Contaminated Water by Charcoal, LA Red Clay, Spinach, and Mustard Green

doi:10.4236/jep.2011.29142

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Journal of Environmental Protection, 2011, 2, 1240-1244

doi:10.4236/jep.2011.29142 Published Online November 2011 (http://www.scirp.org/journal/jep)

Lead Remediation of Contaminated Water by

Charcoal, LA Red Clay, Spinach, and Mustard

Green

Lovell Agwaramgbo*, Eucharia Agwaramgbo, Chanel Mercadel, Shelby Edwards, Eric Buckles

Chemistry Department, Dillard University, New Orleans, USA.

Email: *[email protected]

Received August 29th, 2011; revised October 3rd, 2011; accepted November 4th, 2011.

ABSTRACT

Lead is a toxic and naturally occurring substance with documented neurotoxin, toxic, and long-lasting adverse health

effects globally. Lead exposure can cause impaired physical and mental development in children. Exposure to high lead

levels affects the intestinal tract, kidneys, joints and reproductive system in adults. This study evaluates the removal of

1500 PPM of lead from contaminated aqueous solution using Celite, Louisiana Red Clay, Charcoal, and supernatants

from aqueous extracts of Mustard Green (Brassica juncea), and Spinach (Spinacea oleracea). After shaking triplicate

reaction mixtures for each substrate for 22 hours at room temperature, lead removal by the five substrates were ana-

lyzed by EPA Method 6010, using Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES). Results sug-

gest that the order of lead removal is Spinach (98%) > Charcoal (96%) > LA Red Clay (88%) > Mustard Green (87%)

> Celite (4%). The study concludes that liquid substrates such as the supernatants from pureed spinach and mustard

green can effectively remove lead from contaminated water.

Keywords: Remediation, Heavy Met a l , Lead, Water Contamination, Spinach, Contaminated Water

1. Introduction

Water and soil lead contamination poses serious human

health risks with global dimensions [1-3]. Lead does not

undergo degradation or decomposition. Thus, its long

persistence in the environment exacerbates its threat to

human health. It is estimated to persist in the soil for

5000 years [4]. Historical lead pollution results from a

variety of human activities such as past practices of lead-

related industrial processes, smelting, chipping of old

lead paint, disturbance of old paint during renovation,

combustion of coal [5-8], mining activities [9], use of

lead based paints and automotive exhaust fumes [10-12],

manufacture and use of agricultural fertilizers, insecti-

cides, and pesticides [13].

Disasters such as hurricane Katrina exacerbate the re-

distribution of lead in the environment [14,15 ]. Ingestion

of lead contaminated soil, water, and food and inh alation

of lead dust [11,12] are important and serious routes of

lead exposure and entry into the human body. Various

adverse health effects of high lead exposure have been

reported in children; particularly, impaired mental deve-

lopment, reduced cognitive ability, learning difficulties,

and low IQ [11,12,16-19], low quantitative skills [20],

and neurotoxicity [21]. Lead exposure to adults has

health consequences such as cognitive dysfunction from

early childhood exposure [22], diabetes, damage to the

male and female reproductive systems, and renal disease

[23].

Recent studies suggest that neurological damage from

early childhood exposure to lead contributes to delin-

quent and criminal behaviors [24,25].

Each of the existing technologies for lead remediation

(capping, subsurface barriers, in-situ/ex-situ solidifica-

tion/stabilization, and chemical and biological treatment)

has its own inherent drawbacks or limitatio ns in terms of

cost, long term effectiveness, general acceptance, appli-

cability at higher lead concentration, type of contami-

nants, and reduction in toxicity, mobility, and volume

[26]. Phytoremediation, a vegetative environmentally fri-

endly and nascent green technology is proving to be very

cost effective and a safe method to remediate a variety of

pollutants. However, it also has its own limitations [27]:

1) limitation of root zone depth 2) phytotoxicity at high

contaminant levels and 3) rate of contaminant uptake by

Lead Remediation of Contaminated Water by Charcoal, LA Red Clay, Spinach, and Mustard Green1241

plant.

Although new methods for removing lead from water

are beginning to emerge, yet many of them have their

shortcomings [28-31], they either introduce chemical to

the water or affect the pH or salinity of the water. There-

fore, this project examines phytoremediation option that

does not use live-plant but uses supernatant extract of

spinach and mustard green.

2. Materials & Methods

2.1. Preparation of Lead Nitrate Solution 1500

Parts per Million (PPM)

Using an analytical balance, 1.5 g of lead Nitrate from

Fisher Scientific (L6200) was dissolved in enough deio-

nized water (added incrementally) to give 1000 ml of so-

lution. Then a stirring bar was dropped in to the volumet-

ric flask and the mixture was stirred until all the lead was

completely dissolved. The flask was wrapped with alu-

minum foil to avoid much exposure to light while the

solution con tinued to stir at room temperature until it was

used.

2.2. Preparation of 750 PPM of Lead Nitrate

Solution

To 25 ml of the 1500 PPM lead nitrate solution prepared

above was added 25 ml of deionized water. Th is will re-

present a control fo r the dilution that will occur when 25

ml of spinach and mustard green supernatants are added

to 25 ml of the 1500 PPM lead solution, respectively.

The resulting solution was vortex ed using a Genie 2 vor-

tex and stirred t o m i x.

2.3. Preparation of Spinach Supernatant

Fresh spinach (100 grams) bought from a local market

was washed with deionized water and patted dry with

kimwipes. The 100 g of spinach was pureed in a regular

kitchen blender using 200 ml of de-ionized water. The

puree was filtered using a white handkerchief bought

from a local Wal-Mart store. The filtrate was put into

four-50 ml centrifuge tubes and centrifuged at 3000 rpm

for 10 minutes using a Thermo Centra CL2 bench-t op cen-

trifuge. Using a pipette, three-25 ml portions of the re-

sulting supernatant was carefully transferred into three-

50 ml centrifuge tubes, respectively. The tubes were capped,

labeled, and put in the refrigerator for later use within

one hour.

2.4. Preparation of Mustard Green Supernatant

Following the procedure used for the Spinach, the Mus-

tard Green was pureed, filtered and centrifuged. The re-

sulting supernatant was transferred into three-50 ml cen-

trifuge tubes in 25 ml portions, respectively. The tubes

were capped, labeled, and put in the refrigerator for later

use within one hour.

2.5. Preparation for Charcoal, LA Red Clay, &

Celite Reaction with Lead Solution

2.5.1. Prepara ti on for Charcoal Reaction

Three 50-ml centrifuge tubes were charged with 4 g of

charcoal (activated carbon, Norit, RO 0.8 pellets) pur-

chased from Aldrich Chemical Company, cat # 329428).

The centrifuge tubes were capped and labeled.

2.5.2. Preparation for LA Red Clay Reaction

Three 50 ml centrifuge tubes were charged with 4 g of

Louisiana Red Clay soil (composed of 10.6% sand,

36.5% silt, and 52.9% clay), respectively. The centrifug e

tubes were capped and labeled.

2.5.3. Preparati on for Celi te Reaction

Three 50-ml centrifuge tubes were charged with 4 g of

activated charcoal (bought from Aldrich Chemical). The

centrifuge tubes were capped and labeled.

3. Reaction of the Supernatants, Celite, LA

Red Clay, and Charcoal

3.1. Reaction of Lead Solution with Spinach and

Mustard Green Supernatants

Into each centrifuge tube containing 25 ml of the spinach

and mustard green supernatants was added 25 ml of the

lead nitrate solution (1500 PPM) prep ar ed ab ov e . Th e s ix

tubes and their contents were vortexed, tightly secured

on the rack of a heavy duty Eberbach 6000 shaker, and

agitated for 22 hours at room temperature.

3.2. Reaction of Lead Solution with Celite,

Charcoal, and Louisiana Red Clay

Forty milliliters (40 ml) of lead solution (1500 PPM) was

added to each of the triplicate centrifuge tubes for the

three solid substrates (Charcoal, Louisian a Red Clay, and

Celite). The tubes and their contents were vortexed,

tightly secured on a rack of a heavy duty Eberbach 600 0

shaker, and agitated for 22 hours at room temperature.

4. Sample Preparation and Analysis

4.1. Sample Preparation

After 22 hrs, the shaker was stopped and the tubes were

centrifuged at 3000 rpm for ten minutes. The resulting

clear supernatant in each tube was transferred into an-

other labeled clean centrifuge tube. All the labeled cen-

trifuge tubes with their liquid contents were sent to

PACE Analytical Services, Inc for lead analysis using

EPA method 6010. Note that PACE Analytical Services,

Inc is a commercial environmental laboratory that is ac-

credited in accordance to the National Environmental

Laboratory Accreditation Conference (NELAC).

Lead Remediation of Contaminated Water by Charcoal, LA Red Clay, Spinach, and Mustard Green

1242

4.2. Sample Analysis for Lead after Reaction

After the reaction period, the lead concentration (in PPM)

in the liquid from each reaction tube was analyzed using

EPA Method 6010 (Inductively Coupled Plasma-Atomic

Emission Spectrometry (ICP-AES)).

5. Results

Table 1 shows the amount of lead in PPM remaining in

each reaction tube after 22 hrs: Control (1503); Celite

(1446); LA Red Clay (185); Mustard Green (98); Char-

coal (68); and Spinach (13). Table 1 also sh ows the ave-

rage percent of lead removed by each substrate: Celite

(4%), Mustard green (87%), LA Red Clay (88%), Char-

coal (96%), and Spinach (98%). Figure 1 illustrates the

varying ability of various substrates to remove lead from

aqueous lead solution in their reactions after twenty two

hours at room temperature.

6. Discussions

Figure 1 represents the data on the concentration of lead

remaining after the contaminated water was treated with

each substrate (see Table 1) relative to the control solu-

tion. In contrast, Figure 2 compares the percent of lead

removed from the contaminated water by each substrate.

The results showed that all the substrates except celite

removed more than 80% of lead from the aqueous lead

solution as clearly shown in Table 1 and Figure 1). The

data further showed the varying abilities of the five sub-

strates to remove lead from contaminated aqueous lead

solution.

Thus, the order of lead removal is Spinach (98%) >

Charcoal (96%) > LA red clay (88%) > mustard green

(87%) >>> Celite (4%) as shown in Figure 2. The per-

cent of lead removed by the spinach and mustard green

supernatants is based on the initial lead concentration

assumed to be 752 PPM. This assumption is based on a

two fold dilution that potentially occurred when 25 ml of

the 1,503 PPM of the aqueous lead solution were mixed

with 25 ml of the spinach or mustard green liquid super-

natants. Although we set out to prepare 1,500 PPM of

lead stock solution; however, the average ICP result of

the control after 22 hrs was 1503 PPM. Thus, using the

dilution equation (M1V1 = M2V2), where M1 = Initial

lead concentration; V1 = Initial volume of lead solution,

V2 = final volume reaction mixture, and M2, the initial

lead concentration when 25 ml of mustard green or spin-

ach each reaction mixture after 22 hrs for spinach was

added to 25 ml of aqueous lead solution is calculated to

be 751.5 (752) PPM .

It is important to note that a close look at Figure 1,

shows that mustard green removed more lead that LA red

clay but has a lower calculated percent led removal than

Table 1. Lead left in Reaction Mixtures.

Substrates [Pb] remaining after

22 hrs in PPM % Lead removal after 22 hrs

by various substrates

Control 1503 0

Celite 1446 4

LA Red Clay185 88

Charcoal 68 96

Mustaed Green98 87

Spinach 13 98

Figure 1. Lead Removal by Substrates Compared to Con trol.

Figure 2. Percent Lead Re move d by Substrates.

the value for LA red clay. This is because of the value

for the initial lead concentration is taken to be 752 PPM

due to dilution effect of the supernatants on lead concen-

tration in the reaction mixture. If the initial lead concen-

tration in the spinach and mustard green reactions is

taken to be 1502 PPM, then the percent lead removal by

Spinach will be 99% while that for mustard green will be

93.5%. For the percent lead removal in reactions of the

solid substrates (celite, Louisiana red clay, and charco al),

the initial lead concentration was based on 1503 PPM

7. Conclusions

Activated charcoal, Louisiana Red Clay, Mustard Green

(Brassica juncea), and extracts of Spinach (Spinacea ol-

Lead Remediation of Contaminated Water by Charcoal, LA Red Clay, Spinach, and Mustard Green1243

eracea) are found to be efficient in lead removal from

contaminated water. Celite did not remove any signifi-

cant amount of lead from the contaminated water. Al-

though phytoremed iation of lead has been reported in the

literature with live plants, however, the use of the water

extracts of plants for such remediation has not been re-

ported. Taking into account the presented results, the fo-

llowing conclusions are postulated: 1) the research pre-

sented here has demonstrated that it may be possible to

develop extract-based remediation technology for heavy

metals. 2) Although there could be some adsorptive lead

removal occurring in the case of clay and activated char-

coal reactions, it could not account for all the lead re-

moval considering that celite did not remove significant

amount of lead. Thus, the chemical properties of the

solid charcoal and red clay may play a critical role in

their lead removal ability. 3) Since very limited adsorp-

tive lead removal is expected to occur in the spinach and

mustard green extract-reactions, enzymatic or chemical

reactions may be involved in their lead removal.

8. Acknowledgements

We thank Dr. John Wilson, Atiereya Adley, Adriana

Hawkins, Danyelle Wilson, Gulf Coast Fund for Com-

munity Renewal and Ecological Health, and Peoples

Environmental Center.

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