Department of Chemistry, COMSATS Institute of Information Technology, Abbottabad 22060, PakistanInterdisciplinary Research Centre in Biomedical Materials, COMSATS Institute of Information Technology, Lahore 54000, PakistanDepartment of Environmental Sciences, COMSATS Institute of Information Technology, Abbottabad 22060, PakistanSchool of Chemical and Material Engineering, National University of Science and Technology, H-12, Islamabad 44000, Pakistan
r t i c l e i n f o
rticle history:eceived 31 July 2012eceived in revised form 15 October 2012ccepted 3 December 2012vailable online 3 January 2013
a b s t r a c t
The present study investigates the use of different wastes such as blue Pine wood shavings, walnutshell and chick pea testa in arsenic removal from aqueous solutions. Various conditions that affect theadsorption such as pH, biosorbent dose, contact time, temperature and concentration of adsorbate wereinvestigated. Blue Pine wood shavings showed a tremendous potential as a remediation material for theremoval of arsenic from water samples (surface and ground water). Walnut shell pieces also showed
eywords:rsenic remediationlue Pinealnut shell
iosorption
good biosorption (88%); however, the chick pea testa was not much effective. Experimental data weremodeled by Langmuir and Freundlich isotherms. It was observed that arsenic biosorption conformed toboth Langmuir and Freundlich isotherms. The Blue Pine biomass could be used as a low-cost biosorbentfor arsenic removal from water samples.
Arsenic is considered to be a very toxic element due to itsdverse effects on human health. In nature it is present in the earthrust and also in the human body. In earth crust arsenic is 20thost profuse element while in human beings its number is 12th
Mandal, 2002). Arsenic gathers together by natural weatheringeactions, biological activity, geochemical reactions, volcanic emis-ions and other anthropogenic activities. Soil erosion and leachingontribute to 612 × 108 and 2380 × 108 g/year of arsenic, respec-ively, in dissolved and suspended forms in the oceans (Mackenziend Petorson, 1979). Most environmental arsenic problems are theesult of mobilization under natural conditions. However, miningctivities, combustion of fossil fuels, use of arsenic pesticides, herbi-ides, crop desiccants, wastewater discharge from mining/industry
nd use of arsenic additives to livestock feed create additionalmpacts. Arsenic and its derivatives are being used for many yearsnd still they are in use like in electronics, material sciences andn medicines (Mudhoo et al., 2011). Long-term exposure to arsenic
ncreases health risks like skin conjunctivitis, vascular, reproduc-ive, neurological effects, internal cancers and diabetes (Baidyat al., 2006; Ghosh et al., 2007; Mukherjee et al., 2003; Tseng,004). Arsenic has been determined to be a class A human carcino-en by the US EPA, the Department of Health and Human Services,nd the WHO from evidence substantiated from global studies (USnvironmental Protection Agency, 1997).
In aqueous systems, arsenic exhibits anionic behavior. In aer-bic waters, arsenic acid predominates only at extremely low pH<2); within a pH range of 2–11, it is replaced by H2AsO4
− andAsO4
2−. Arsenious acid (H3AsO3) appears at low pH and underildly reduced conditions, but it is replaced by H2AsO3
− as the pHncreases. HAsO2
3− appears when pH exceeds 12. At low pH, in theresence of sulfide, HAsS2 can be formed; arsine, arsine derivatives,nd arsenic metal can occur under extremely reducing conditionsMudhoo et al., 2011; Kumaresan, 2001).
The WHO provisional guideline of 0.01 mg L−1Arsenic has beendopted by many countries as the standard for drinking water.owever, many countries including Pakistan have retained the ear-
ier WHO guideline of 0.05 mg L−1Arsenicas the national standard
r as provisional target (PEPA, 2007).
Arsenic contamination is considered to be a universal issue dueo its toxicity and wide spread availability in water sources. Pres-nce of Arsenic in ground water is observed in many Asian countries
ike Bangladesh, India, Nepal, Myanmar and Pakistan (Mudhoot al., 2011; Malik et al., 2009; Baig et al., 2010; Khan, 2011). Arseniconcentration was found to be high in surface and groundwatern Pakistan mainly in two provinces i.e., Punjab and Sindh. Wateresources having arsenic contamination level of over 50 ppb are in
percentage of 3% and 16%, respectively, in Punjab and Sindh while0% and 36% of water resources of Punjab and Sindh are contami-ated with arsenic above the WHO permissible limit of 10 ppb (Baigt al., 2010; Ahmad et al., 2004). Deaths of more than 40 peopleere reported in Hyderabad, Pakistan in 2004 due to contamina-
ion of municipal treated water with lake water containing highevel of arsenic and other toxic metals (Arain et al., 2008).
Arsenic retention and mobility in surface water and ground-ater are of great concern because of their toxic effects in
he environment. Current remediation technologies are expen-ive. Thus, any lowering of the standard will put increasedconomic pressure on rural communities with high levels ofrsenic in their drinking water. Several treatment technolo-ies have been adopted to remove arsenic from drinking waternder both laboratory and field conditions. The major mode ofemoving arsenic from water is by physico-chemical treatment.echnologies for the removal of arsenic from drinking waternclude adsorption, membrane and point-of-use methods such asoagulation/precipitation/adsorption/filtration etc. Out of these,dsorption is evolving as a front line of defense. The adsorptionethod is appealing for its easy handling, minimal sludge produc-
ion and its regeneration capability. Several adsorptive media haveeen reported to remove arsenic from drinking water. Selectivedsorption utilizing biological materials, mineral oxides, activatedarbons, or polymer resins have added increasing excitement.umber of reviews published in recent years demonstrate the mer-
ts and demerits of these adsorption methods (Lievremont and Lett,009; Mohan, 2007; Rahaman and Islam, 2008; Zahra, 2010).
The removal of arsenic from our environmental waters, espe-ially, wastewater is now shifting from the use of conventionaldsorbents to the use of biosorbents (Igwe, 2006). The different lowost biomaterials include animal biopolymer, plant biomass, chitinnd chitosan, algae, fungi and bacteria; however, few studies haveetermined the possibility of using native biomaterials (withouthemical modification) in removing arsenic from aqueous solu-ions. Recently, the use of native biomass (powdered) taken fromtem of a thorny Acacia nilotica was reported to remove arsenicrom surface waters (Baig et al., 2010). Earlier, other biomasseserived from fish scales, coconut fiber, dried roots of water hyacinthlant, seed powder of Moringa oleifera, Momordica charantia, pow-ered eggshell, human hair, rice husk, rice polish; without chemicalreatment have been reported (Ranjan and Hasan, 2009; Oke anddewusi, 2008; Nurul-Amin et al., 2006; Rahaman and Islam, 2008;asiuddin and Islam, 2002; Kumari et al., 2006; Pandey et al., 2009;
l-Rmalli et al., 2005). However, there is still a strong challengen developing economical and commonly available biosorbents forrsenic removal.
Pinus wallichiana is a Pine native to the Himalaya, Karakoramnd Hindu Kush mountains, from eastern Afghanistan east acrossorthern Pakistan and India to Yunnanin southwest China. Theree grows in mountain valleys in temperate climate with dryinters and wet summers, at altitudes of 1800–4300 m, and is a
ree from 30 to 50 m in height. It is also known as ‘Blue Pine’ ands ‘Himalayan White Pine’. The leaves (needles) are in fasciclesbundles) of five and are 12–18 cm long. They are noted for beingexible along their length, and often droop gracefully. It is also a
opular tree for planting in parks and large gardens, grown for itsttractive foliage and large, decorative cones. It is also valued forts relatively high resistance to air pollution, tolerating it betterhan some other conifers (Wikipedia, 2011 (accessed 29.06.11)).
Ltwp
gineering 51 (2013) 88– 94 89
he wood of this tree is commonly used for making furniture andsed for other house hold purposes.
Biomass of Pine has been reported for the removal of heavyetals like Cr4+ using pine needles powder, Cd2+ using ground
ine cone and pine saw dust, and pinus bark powder for theemoval of crystal violet dye (Amjad et al., 2007; Izanloo, 2005;adjmohammadi and Biparva, 2011; Ahmad, 2009).
Very little studies have been conducted on the biosorption ofrunk shavings of Blue Pine (P. wallichiana). The present studynvolved the use of blue pine shavings, walnut shells (Juglans regia)nd chickpeas testa (Cicer arietinum, Indian variety) to investi-ate their potential arsenic removal from drinking water. Variousarameters such as the contact time for biosorption, biosorbentose, pH, adsorbate concentration and temperature were investi-ated to obtain the most optimum conditions.
. Materials and methods
.1. Reagents and solutions
Plastic ware was used throughout the experiment to avoid metalontaminations. The plastic ware was cleaned in hydrochloric acid20%, v/v) followed by nitric acid (20%, v/v) (Merck, Darmstadt,ermany) and thoroughly rinsed with high purity water. Lab-wareas thoroughly rinsed with ultra-pure water (0.067 �S cm−1, Pure-
ab Option, Elga, UK). All the reagents and the standards were ofnalytical grade unless otherwise stated and prepared in ultra-highurity (UHP) water.
Arsenic stock solution of 1000 �g mL−1 was prepared fromtomic absorption standard (Perkins Elmer, USA), other standardsere made by serial dilution of the stock in UHP water. 0.5 M
olutions of HCl, HNO3, and NaOH were prepared in UHP wateror pH adjustment. For interferences studies, stock cations solu-ions of 1000 �g mL−1 were used from atomic absorption standardsPerkins Elmer, USA). Stock anion solutions of 1000 �g mL−1 wererepared in UHP water from their respective sodium salts.
.2. Biosorbent collection and media preparation
Three different biomaterials which were cheap and easily avail-ble i.e. indigenous native biomasses of walnut shells, chick peaesta and chopped shavings of Blue Pine tree were used in theresent study. The biomass of Blue Pine was collected in the form ofaste material from furniture manufacturing outlets. It was further
round to reduce its size using pestle and mortar before subject-ng it to washing with distilled water to remove dust, color andther impurities. After washing, it was dried in oven at 105 ◦C for
h. Walnut shells and chick pea testa were obtained from localarket. After collection both of them were ground to reduce the
ize using pestle and mortar. After grinding the biomasses, bothere subjected to washing and drying by the same method as men-
ioned above. The obtained dried biomasses were then stored inesiccators till further use.
.3. Water sample collection
Water samples were collected from various origins like lakeater, underground water, and river irrigation water in HDPE
high density polyethylene) bottles pre-cleaned with HNO3 andCl and thoroughly washed with UHP water. The Lake water sam-les were collected from Manchar Lake Sindh Province, Pakistan.
ake water samples were collected in clean bottles at a depth ofwo meters below surface by using a peristaltic pump equippedith acid washed Teflon tubing. Samples were filtered througholypropylene capsule filter (0.2 �m) and stored un-acidified at
9 ical Engineering 51 (2013) 88– 94
rlwawwPs
2
WigaaWs
fta2cc
2
E(tot2eabaaWmt
%
o
3
3
wsutrA1sbB
Table 1Comparison of various biosorbents for arsenic removal using optimum conditions.
Parameters Blue Pine Walnut shell Chick pea testa
Arsenic removal efficiency (%) 97 88 35
crac
3
taflbspsPasrb4
3
btoIicmdoiodmr
3
a2cnaiTrta
0 A.N.S. Saqib et al. / Ecolog
oom temperature in the dark. Ground water samples were col-ected using hand pumps with the depth of 80–100 feet, situated
ithin the vicinity of Lake (within 2 km) which is used for drinkingnd domestic purposes. Other samples were collected from surfaceaters near coalmines from Quetta (Balochistan, Pakistan). Riverater samples were collected from Harnou River near Abbottabad,
akistan, the water of which is contaminated by the coalminesituated nearby.
.4. Instrumentation and characterization of biomass
Wagtech Arsenic Testing Kit (WagtechArsenator® WAG-E10500) was used for the determination of arsenic concentration
n the standards and water samples according to the manufacturersiven procedure. The lower detection limit of the kit is 1.0 �g L−1
rsenic. The kit was calibrated daily by running the blank andrsenic standard solutions to ensure the accuracy of the results.agtech pH meter was used intensively for pH determination of
amples throughout the study.Scanning Electron Microscope JEOL model JSM 6510 was used
or the surface studies of adsorbent materials. Scanning Elec-ron Micrographs of the adsorbent material with and withoutrsenic loaded samples at different magnifications i.e., 50×, 500×,500×, 5000×, 15,000×, 100,000× were used to study the surfaceharacteristics of the adsorbent material after selected optimumondition for biosorption.
.5. Biosorption procedure
Effects of different parameters were investigated batch wise inrlenmeyer flasks using different amounts of biosorbent material1–50 g) with varying amounts of adsorbate (25–500 �g L−1) main-ained at 20 ◦C. Different pH ranges (2–13) were adjusted using HClr NaOH, 0.5 M each. Flasks were shaken in water bath with elec-rical shaker at 60 cycles per min for period of time ranging from.0 to 60 min. The time required to reach sorption equilibrium wasstimated by analyzing the adsorbate (standard solution of arsenic)t regular interval of time. After giving sufficient period of time, theiomass was removed by filtration, washed with UHP water twice,nd the resulting solution was analyzed. The arsenic concentrationt all intervals of time was determined by commercially availableagtech kit. All experiments were conducted in triplicate and theean value was used in all calculations. The percent adsorption of
he biosorbent was calculated by using the following formula:
Sorption = Ci − Ce
Ci× 100
where Ci and Ce are the initial and equilibrium concentrationsf arsenic expressed in �g L−1.
. Results and discussion
.1. Selection of the best media
Three different inexpensive and easily available biomaterialsere used in the present study. Indigenous biomasses of walnut
hells, chick pea testa and chopped shavings of Blue Pine tree weresed. They were compared in terms of removal of arsenic (% sorp-ion), contact time and pH range. The data in Table 1 shows theesults of which the best results were obtained by using Blue Pine.ll of these studies were performed with arsenic concentration of
00 �g L−1 while using 20 �g L−1 dose of biosorbent at 20 ◦C. Theorption efficiency of walnut shells is comparable with that of thelue pine; however chick pea testa did not show better results.lue pine was selected as the best media due to superior results
siga
pH 10 10–11 8Contact time (min) 20 40 35
ompared to walnut shell which gave some problems like colorelease in water even after washing several times with UHP water,lso when it was packed in the column it caused blockage in theolumn after some time.
.2. Effect of contact time on arsenic biosorption
The time required to reach the equilibrium for arsenic biosorp-ion on the biomass was investigated by using 200 �g L−1ofdsorbate concentration (arsenic test solution) in glass stopperedasks using 20 g L−1and 40 g L−1of adsorbent biomass (Blue pineiomass and Walnut biomass) respectively at pH 8.0 (20 ◦C). Fig. 1ahows that by increasing the time from 2.0 to 20 min in case of Blueine and 2.0 to 40 min in case of Walnut, there is a sharp increase inorption efficiency and it becomes the maximum at 20 min for Blueine and 40 min for Walnut. Further increase up to 60 min does notffect the equilibrium of arsenic adsorption on the biomass. Thehort equilibrium time shows the adsorption with rapid rate ofeaction and presence of a large number of sorption sites on theiomass. Therefore, further studies were carried out using 20 and0 min contact time for Blue pine and Walnut respectively.
.3. Effect of biosorbent dosage on arsenic biosorption
To determine the effect of biosorbent dosage on the percentiosorption (i.e. uptake of arsenic) the studies were conducted inhe range of 1.0–50 g L−1using optimum equilibrium contact timef 20 min at pH 8.0 (20 ◦C) with arsenic concentration of 200 �g L−1.n case of Blue Pine, percent removal of arsenic increased byncreasing biosorbent dose up to 20 g L−1 with 90% sorption effi-iency, while 40 g L−1 of Walnut was found to be optimum withore than 80% sorption efficiency. Further increase in biosorbent
osage up to 50 g L−1 caused no effect on the percent removalf arsenic (Fig. 1b). The removal of arsenic was enhanced withncreasing biosorbent material dosage, which is obvious becausef increase in the number of active sites as the biosorbent materialosage increased. On this basis 20 g L−1 and 40 g L−1of biosorbentaterials were found as the optimum for Blue Pine and Walnut
espectively.
.4. Effect of pH on arsenic biosorption
The effect of pH in the range of 2–13 (20 ◦C) on the removal ofrsenic using biosorbent dosage of 20 and 40 g L−1, equilibrated for0 and 40 min respectively for Blue Pine and Walnut and arseniconcentration of 200 �g L−1 was studied. It was found that pH doesot have a marked effect on the arsenic biosorption. The percent-ge adsorption of arsenic was found to increase with an increasen pH up to 11 and then it decreased with a further increase of pH.he optimum pH for the removal of arsenic was found to be 10 (97%emoval with Blue Pine and 88% removal with Walnut); however,he sorption efficiency remained higher than 70% for both Blue Pinend Walnut when the pH was greater than 5 till 11, after which it
howed decreasing sorption efficiency of biosorbent (Fig. 1c). Thisndicated that the effect of pH on the sorption of arsenic was in aood working range of water at house hold level. The WHO accept-ble pH range of the potable water is 6.5–8.5, which can be used
ig. 1. (a) Effect of contact time on the biosorption of arsenic. (b) Effect of Biosorbeffect of adsorbate concentration on the biosorption. (e) Effect of temperature on th
ithout pH adjustment. Keeping in view the normal pH range ofotable water, pH 8.5 was selected for further studies.
.5. Effect of adsorbate concentration on biosorption
The effect of arsenic concentration on biosorbent material wasnvestigated while using optimum amount of biosorbent material
ith contact time of 20 and 40 min for Blue Pine and Walnut, at pH of 8.5 (20 ◦C) in the concentration range of 10–500 �g L−1.he result showed that arsenic removal efficiency was high atower concentrations up to 100 �g L−1with removal efficiencies of4% and 88% (maximum), for Blue Pine and Walnut, respectively.owever the removal efficiency was higher than 83% up to theoncentration of 200 �g L−1 for both sorbents. Further increase inrsenic concentration resulted in lower sorption up to 500 �g L−1
n the range of 60–85% (Fig. 1d). For further studies arsenic concen-ration of 100 �g L−1 was chosen as an optimum concentration.
.6. Effect of temperature on arsenic biosorption
The effect of temperature on the efficiency of arsenic removalas studied in the range of 10–50 ◦C. The optimum temperature
pcds
age on the biosorption of arsenic. (c) Effect of pH on the biosorption of arsenic. (d)orption of arsenic.
ange for the adsorbent to remove arsenic from water samplesas found in the range of 15–25 ◦C. The maximum removal was
ecorded at a temperature of 20 ◦C (Fig. 1e). Further increase orecrease in temperature resulted in lower sorption efficiency forrsenic removal by biomass of both Blue Pine and Walnut.
.7. SEM of biosorbent
Using the optimized conditions for the biosorption of arsenic,he loaded biomass was filtered, washed and dried at 105 ◦Cor 30 min and cooled to room temperature. A blank biomassunloaded) was also subject to the same conditions and both theoaded and unloaded biomass was subjected to SEM to check thehanges on the surface of the biomass before and after loadingy the adsorbate molecules. The micrographs were taken at dif-erent resolutions from 500 to 35,000×. The Figs. 2a and 3a showhe unloaded biomass of Blue Pine and Walnut respectively, hav-ng very rough surface with large number of pores, which possibly
rovides the sites for biosorption of arsenic physically or chemi-ally. Fig. 2b and b shows that the pores are somewhat coveredue to the biosorption of arsenic aggregates and form layers whichettle on the rough surfaces. Figs. 2c and 3c have been taken on
swoaa8tmtbrought under the permissible limit set by WHO of 10 �g L−1.
Table 2Arsenic removal efficiency of the proposed biosorbent in uncontaminated freshwater samples.
Samples Arsenic addedbefore biosorption(�g L−1)
Arsenic found afterbiosorption(�g L−1)
Arsenicremovalefficiency (%)
RSDa (%)
1. 50 2.5 95 1.5100 7.7 92 2.5150 12.8 91.5 2.1
2. 50 3.5 93 2.9100 10 90 3.2150 9.5 94 2.1
ig. 2. SEM of biomass of Blue Pine, (a) unloaded (b) loaded and (c) high resolutionEM of a single pore shown in (a).
igher resolution of 15,000× by focusing on the available pores.his high resolution micrograph shows a large number of irregularutgrowths showing high surface area providing more space forccommodation of arsenic.
.8. Interference study
The interference of common foreign ions present in water atnvironmentally acceptable concentrations was investigated bynalyzing solutions containing 100 �g L−1 arsenic. The tolerableoreign species were taken as a relative error not greater than ±10%o the sorption efficiency of arsenic in the absence of these ions.o interference was found when 500-fold higher concentration ofa+, K+, Ca2+, Mg2+, CO3
2−, SO42−, Cl−, NO3
−, PO43−, Zn2+, 50-fold
e2+and Fe3+ were present with arsenic.
.9. Biosorbent applications in arsenic removal
To assess the applicability of the biosorbent, natural wateramples were collected. All of the samples showed arsenic con-entration less than 1.0 �g L−1. Standard addition in the range00–200 �g L−1 of arsenic was added in these water samples andiosorption was determined under the aforementioned optimumonditions. The results (Table 2) indicate that the arsenic removal
fficiency of the proposed biosorbent under natural conditions isell suited for potable water applications. The applicability of the
iosorbent was further extended using potable water samples sup-lemented with arsenic collected from various sources. Table 3
ig. 3. SEM of biomass of Walnut, (a) unloaded (b) loaded and (c) high resolutionEM of a single pore shown in (a).
ummarizes all the physico-chemical parameters of contaminatedater samples supplemented with arsenic and removal efficiency
f the proposed biosorbent. The data clearly demonstrates that thersenic supplemented lake water was found to be the highest inrsenic (79 �g L−1) which was successfully decreased to a level of.5 �g L−1using the biosorbent. Most of the other samples were inhe range of 9.5 ± 0.5 to 21 ± 2 �g As3+ L−1 which are within the per-
issible limits of arsenic guidelines of Pakistan (50 �g L−1). Afterreatment with the biosorbent (Blue Pine), most of samples can be
Adsorption isotherms give a quantitative relationship betweenhe solute concentration in the solution and the amount of solutedsorbed per unit mass of the adsorbent surface at equilibrium con-itions. Langmuir, Freundlich, Dubinin–Radushkevich (D–R) arehe commonly used isotherms. Selection of the type of isothermepends upon number of factors such as environment, nature ofdsorbent and adsorbate, their concentrations and types, and othernvironmental factors like pH and ionic strength. In the presenttudy, two of the isotherms, Langmuir and Freundlich, were appliedo the experimental data to check its credibility.
The basic assumption of the Langmuir Isotherm is that a singleolute binds to a specific homogenous site on the surface of thedsorbent and that the adsorbent active sites have the same affinityor the adsorbate. The following straight line equation can be usedor plotting Langmuir isotherm.
1q
= 1qmKads
(1C
)+ 1
qm
Where, q is the sorbed concentration (mass of adsorbate/massf adsorbent), qm the maximum capacity of adsorbent for thedsorbate (mass of adsorbate/mass of adsorbent), C the initial
y = 18.367x + 0.2941R² = 0.99
0.00
0.20
0.40
0.60
0.80
1.00
1.20
1.40
0.00 0.01 0.02 0.03 0.04 0.05 0.06
1/q
1/C
y = 0.575x - 0.815R² = 0.973
-0.20
-0.10
0.00
0.10
0.20
0.30
0.40
0.50
1.00 1.20 1.40 1.60 1.80 2.00
log
q
log C
ig. 4. (a) Langmuir plot of the experimental data (Blue Pine). (b) Freundlich plotf experimental data (Blue Pine).
wot
Fe
1250 ± 50 21 ± 2 ND670 ± 12 16 ± 1 ND
4012 ± 36 79 ± 6 8.5 ± 1.2
oncentration of adsorbate in solution (mass per unit volume) Kadshe adsorbate affinity for adsorbent.
The experiment was carried out with different biosorbentosages and the effect of biosorbent dosage on arsenic abatementrom water samples was noted. A plot of 1/q against 1/C produced
straight line with an intercept of 1/qm and A slope of 1/qm.KadsFigs. 4a and 5a). The r2 value of 0.99 and 0.98 clearly shows thathe adsorption of arsenic by the biosorbents follow the Langmuirsotherm model.
The Freundlich adsorption isotherm is the most widely usedathematical model in aqueous systems. Freundlich proposed the
ollowing expression for the adsorption from solutions, on the basisf absorption studies:
= KC(1/n)
On the basis of this assumption there are different active sitesn the adsorbent surface that have different affinities for differentdsorbate; the Freundlich Isotherm can be derived from the Lang-uir isotherm model. Where K is the measure of the capacity of
ith a change in adsorption density in the above equation. A valuef n = 1 means that all the active sites on the adsorbent surface havehe same affinity for the adsorbate and results in a linear isotherm.
y = 66.74x + 0.253R² = 0.988
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
0.00 0.02 0.04 0.06 0.08 0.10
1/q
1/C
y = 0.880x - 1.703R² = 0.982
-0.80
-0.70
-0.60
-0.50
-0.40
-0.30
-0.20
-0.10
0.00
1.00 1.20 1.40 1.60 1.80 2.00
log
q
log C
ig. 5. (a) Langmuir plot of the experimental data (Walnut). (b) Freundlich plot ofxperimental data (Walnut).
9 ical En
Taf
l
s(I
acmmtl
4
eomsfsala(i
R
A
A
A
A
A
B
B
G
H
I
I
K
K
K
L
M
M
M
M
M
M
N
O
P
PR
R
T
U
W
4 A.N.S. Saqib et al. / Ecolog
he n value of greater than 1 shows the decrease in affinity fordsorbate with an increase of adsorption density. The linearizedorm of the equation can be used to plot the Freundlich isotherm:
og q = log K + 1n
log C
A plot of log q against log C produced a straight line with alope of 1/n and an intercept of log k. Values of r2 > 0.97 and 0.98Figs. 4b and 5b) indicate that the data fits to the Freundlichsotherm.
In the present study, the amounts of different biomasses weredded to a specific volume of arsenic containing solutions of knownoncentration and the removal of arsenic was calculated by deter-ining the remaining amount of arsenic after the adsorbent wasade to stand in the solution up to already known equilibrium
ime. The same data was used for Langmuir isotherm and Freund-ich Isotherm.
. Conclusion
The biomass of the indigenous Blue Pine tree (P. wallichiana)stablished a good arsenic biosorption (arsenic removal efficiencyf >90%), substantiating its potential for the drinking water treat-ent process. The Walnut biomass is also very efficient in arsenic
orption but its column choking characteristic renders it unfitor use. The proposed Blue Pine biomass is appropriate and isuitable for homemade approaches to arsenic removal in localreas, because of their simplicity and easy operation and hand-ing. Arsenic concentration also influenced the abatement processnd found to be effective for a wide range of concentrationsi.e. >200 �g L−1). P. wallichiana biomass followed both Langmuirsotherm (r2 = 0.99) and Freundlich isotherm (r2 = 0.97).
eferences
hmad, R., 2009. Studies on adsorption of crystal violet dye from aqueous solutiononto coniferous pinus bark powder (CPBP). J. Hazard. Mater. 171, 767–773.
hmad, T., Kahlown, M.A., Tahir, A., Rashid, H., 2004. Arsenic an emerging issues:experiences from Pakistan. In: 30th WEDC International Conference, Lao PDR,Vientiane.
l-Rmalli, S.W., Harrington, C.F., Ayub, M., Haris, P.I., 2005. A biomaterial basedapproach for arsenic removal from water. J. Environ. Monit. 7, 279–282.
mjad, F., Hazany, S.M., Chaudhary, M.M., Irfan, N., 2007. Removal of Cd(II) fromaqueous solution using blue pine sawdust: equilibrium, kinetics and thermody-namic studies. Main Group Metal Chem. 30, 345–362.
rain, M.B., Kazi, T.G., Jamali, M.K., Afridi, H.I., Jalbani, N., Shah, A., 2008. Total dis-solved and bioavailable elements in water and sediment samples and theiraccumulation in Oreochromis mossambicus of polluted Manchar Lake. Chemo-sphere 70, 1845–1856.
aidya, K., Raj, A., Mondal, L., Bhaduri, G., Todani, A., 2006. Persistent conjunctivitis
associated with drinking arsenic-contaminated water. J. Ocul. Pharmacol. Ther.22, 208–211.
aig, J.A., Kazi, T.G., Shah, A.Q., Kandhro, G.A., Afridi, H.I., Khan, S., Kolachi, N.F., 2010.Biosorption studies on powder of stem of Acacia nilotica: removal of arsenic fromsurface water. J. Hazard. Mater. 178, 941–948.
W
Z
gineering 51 (2013) 88– 94
hosh, P., Banerjee, M., Chaudhuri, S.D., Chowdhury, R., Das, J.K., Mukherjee, A.,Sarkar, A.K., Mondal, L., Baidya, K., Sau, T.J., Banerjee, A., Basu, A., Chaudhuri,K., Ray, K., Giri, A.K., 2007. Comparison of health effects between individ-uals with and without skin lesions in the population exposed to arsenicthrough drinking water in West Bengal, India. J. Exp. Sci. Environ. Epidemol. 7,215–223.
adjmohammadi, M.R., Shakeri, M., Biparva, P., 2011. Removal of Cr (VI) from aque-ous solution using Pine needles powder as a biosorbent. J. Appl. Sci. Environ.Sanitation 6, 1–13.
gwe, J.C., Abia, A.A., 2006. A bioseparation process for removing heavy metals fromwaste water using biosorbents. Afr. J. Biotechnol. 5, 1167–1179.
zanloo, H., Nasseri, S., 2005. Cadmium removal from aqueous solutions by groundPine cone. Iranian J. Env. Health Sci. Eng. 2, 33–42.
han, M.A., Ho, Y.S., 2011. Arsenic in drinking water: a review on toxicologi-cal effects, mechanism of accumulation and remediation. Asian J. Chem. 23,1889–1901.
umaresan, M., Riyazuddin, P., 2001. Overview of speciation chemistry of arsenic.Curr. Sci. 80, 837–846.
umari, P., Sharma, P., Srivastava, S., Srivastava, M.M., 2006. Biosorption studies onshelled Moringa oleifera Lamarck seed powder: removal and recovery of arsenicfrom aqueous system. Int. J. Miner. Process. 78, 131–139.
ievremont, D., Bertin, P.N., Lett, M.C., 2009. Arsenic in contaminated waters: biogeo-chemical cycle, microbial metabolism and biotreatment processes. Biochimie91, 1229–1237.
ackenzie, E.T., Lantzy, R.J., Petorson, V., 1979. Global trace metals cycles and pre-dictions. J. Int. Assoc. Math. Geol. 6, 99–142.
alik, A.H., Khan, Z.M., Mahmood, Q., Nasreen, S., Bhatti, Z.A., 2009. Perspectives oflow cost arsenic remediation of drinking water in Pakistan and other countries.J. Hazard. Mater. 168, 1–12.
andal, B.K., Suzuki, K.T., 2002. Arsenic round the world: a review. Talanta 58,201–235.
ohan, D., Pittman, C.U., 2007. Arsenic removal from water/wastewater usingadsorbents—a critical review. J. Hazard. Mater. 142, 1–53.
udhoo, A., Sharma, S.K., Garg, V.K., Tseng, C., 2011. Arsenic: an overview of appli-cations, health, and environmental concerns and removal processes. Crit. Rev.Environ. Sci. Technol. 41, 435–519.
ukherjee, S.C., Rahman, M.M., Chowdhury, U.T., Sengupta, M.K., Lodh, D., Chanda,C.R., Saha, K.C., Chakraborti, D., 2003. Neuropathy in arsenic toxicity fromgroundwater arsenic contamination in West Bengal, India. J. Environ. Sci. HealthPart A 38, 165–183.
urul-Amin, M., Kaneco, S., Kitagawa, T., Begum, A., Katsumata, H., Suzuki, Ohta,T.K., 2006. Removal of arsenic in aqueous solutions by adsorption onto wasterice husk. Ind. Eng. Chem. Res. 45, 8105–8110.
ke, I.A., Olarinoye, N.O., Adewusi, S.R.A., 2008. Adsorption kinetics for arsenicremoval from aqueous solutions by untreated powdered eggshell. Adsorption14, 73–83.
andey, P.K., Choubey, S., Verma, Y., Pandey, M., Chandrashekhar, K., 2009.Biosorptive removal of arsenic from drinking water. Biores. Technol. 100,634–637.
EPA, 2007. http://www.environment.gov.pk/act-rules/DWQStd-MAY2007.pdfahaman, M.S., Basu, A., Islam, M.R., 2008. The removal of As(III) and As(V) from
aqueous solutions by waste materials. Biores. Technol. 99, 2815–2823.anjan, D., Talat, M., Hasan, S.H., 2009. Biosorption of arsenic from aqueous solution
using agricultural residue ‘rice polish’. J. Hazard. Mater. 166, 1050–1059.seng, C.H., 2004. The potential biological mechanisms of arsenic-induced diabetes
