Journal of Environmental Protection, 2011, 2, 1240-1244
doi:10.4236/jep.2011.29142 Published Online November 2011 (
Copyright © 2011 SciRes. JEP
Lead Remediation of Contaminated Water by
Charcoal, LA Red Clay, Spinach, and Mustard
Lovell Agwaramgbo*, Eucharia Agwaramgbo, Chanel Mercadel, Shelby Edwards, Eric Buckles
Chemistry Department, Dillard University, New Orleans, USA.
Email: *
Received August 29th, 2011; revised October 3rd, 2011; accepted November 4th, 2011.
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
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
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
2.2. Preparation of 750 PPM of Lead Nitrate
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).
Copyright © 2011 SciRes. JEP
Lead Remediation of Contaminated Water by Charcoal, LA Red Clay, Spinach, and Mustard Green
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
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-
opyright © 2011 SciRes. JEP
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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