ue

n Hs

Cladophora spp.

as toarchudyd Cdlicettebiosusio

2011 Elsevier Ltd. All rights reserved.

wastews. Heavanim

entionsive an et al

al., 2007; Tuzen and Sari, 2010).Algae are primary producers in ecological systems, widely dis-

tributed around the world, and closely connected with human life.In this study, we chose Spirogyra and Cladophora spp. as biosorp-tion materials due to their similar habitat distribution and closetaxonomic grouping. Both are benthic lamentous macroalgaebelonging to Division Chlorophyta. These species are naturallyabundant throughout the world (Simons and van Beem, 1990;

concentrations. Since more than one type of heavy metal is oftenpresent in wastewater, such as the simultaneous presence of Pb(II)and Cu(II) in the lead chemical fertilizer and the battery manufac-turing industries. Conditions of biosorption material of differentdivalent cation combinations can more accurately represent actualenvironmental problems. For this reason, we explored the effectsof the simultaneous presence of Pb(II) and Cu(II) on their respec-tive adsorption, using batch experiments to study kinetics andadsorption equilibrium. To understand desorption efciency, wealso performed continuous adsorptiondesorption experimentson Spirogyra and Cladophora spp. algae powder for Pb(II) and Cu(II).

Corresponding author. Tel./fax: +886 6 2055011.

Bioresource Technology 102 (2011) 52975304

Contents lists availab

T

elsE-mail address: spchang@mail.ksu.edu.tw (S.-P. Chang).activated carbon is the most efcient classical way but the costof its production is prohibitive and it cannot be regenerated andrecycled (Farooq et al., 2010). Adverse effects of heavy metals onthe environment and their accretion through the food chain havelead to research in the development of efcient, low cost tech-niques for wastewater treatment (Ahluwalia and Goyal, 2007;Juwarkar et al., 2010; Pan et al., 2009; Sahan et al., 2010; Singhet al., 2007), with methods using algae biomass receiving a greatdeal of attention (Andrade et al., 2005; Bishnoi et al., 2007; Guptaet al., 2006; Murphy et al., 2007; Mehta and Gaur, 2005; Singh et

The aim of this research is to develop a low cost adsorbent forwastewater treatment. The prime objective of this study is tosearch for suitable freshwater lamentous algae that have highheavy metal ion removal capability. This study evaluates the bio-sorption capacity of green algae, Spirogyra, and Cladophora spp.,for Pb(II) and Cu(II) from aqueous solutions. We performed adsorp-tion experiments using the aforementioned types of biosorptionmaterials on Pb(II) and Cu(II), two important hazardous heavymetals. Through these adsorption experiments, we tested theparameters of contact time, initial pH, and initial Pb(II) and Cu(II)Biosorption

1. Introduction

Industrial activity often createsmetals that ows into natural waterposes a potential health hazard to(Volesky and Holan, 1995). Convremoval from wastewater are expenfor metals in low concentrations (Pa0960-8524/$ - see front matter 2011 Elsevier Ltd. Adoi:10.1016/j.biortech.2010.12.103ater containing heavyy metal contaminationals and humans alikeal methods of metalnd not always effective., 2009). Adsorption by

Whitton, 1970) and ease of harvesting. In recent years, many stud-ies have applied both living and dead specimens of these two mac-roalgae to nutrient removal (DeBusk et al., 2004), biomonitoring(Oertel, 1993), tannery and textile wastewater treatment (Khalaf,2008; Mohan et al., 2002; zer et al., 2006; Onyancha et al.,2008), and pharmaceutical ingredients (Mihranyan et al., 2004).Obviously, these two genera of algae have high developmentalpotential as biomaterials.Cu(II)Spirogyra spp. experiments discovered that both types of biomass were excellent biosorbents with potential for further

development.The biosorption of heavy metals from aqand Cladophora lamentous macroalgae

Yi-Chao Lee, Shui-Ping Chang Department of Environmental Engineering, Kun Shan University, Yung-Kang City, Taina

a r t i c l e i n f o

Article history:Received 30 July 2010Received in revised form 23 December 2010Accepted 27 December 2010Available online 1 January 2011

Keywords:Pb(II)

a b s t r a c t

The aim of this research wtive of this study was to seremoval capability. This stalgae species, Spirogyra anof the Langmuir and Freunof biosorbents showed a bions by these two types ofmore signicant than diff

Bioresource

journal homepage: www.ll rights reserved.ous solution by Spirogyra

ien 71003, Taiwan, ROC

develop a low cost adsorbent for wastewater treatment. The prime objec-for suitable freshwater lamentous algae that have a high heavy metal ionevaluated the biosorption capacity from aqueous solutions of the green

ladophora, for lead (Pb(II)) and copper (Cu(II)). In comparing the analysish isotherm models, the adsorption of Pb(II) and Cu(II) by these two typesr t with the Langmuir isotherm model. In the adsorption of heavy metalorbents, chemical and physical adsorption of particle surfaces was perhapsn and adsorption between particles. Continuous adsorptiondesorption

le at ScienceDirect

echnology

evier .com/locate /bior tech

of 1.0 g L in 50 mL of solution. Samples were taken after

Tec5, 10, 15, 20, 30, 40, 50, and 60 min.

2.3.3. Effect of initial metal ions concentrationEffects of initial metal ion concentration on the biosorption of

Pb(II) and Cu(II) from 50 to 300 mg L1 were studied.

2.3.4. Effect of biosorbents doseDifferent amounts of biomass doses ranging from 0.1 to

10.0 g L1 for 50 mL of Pb(II) and Cu(II) solutions in a 250 mL Erlen-Many studies have reported that Spirogyra and Cladophora spp.have a very high capacity for binding with metals due to the pres-ence of polysaccharides, proteins, or lipids on the surface of cellwalls. These contain functional groups such as aminos, hydroxyls,carboxyls, and sulfates, which can act as binding sites for metals(Alimohamadi et al., 2005; Deng et al., 2007; Gupta and Rastogi,2008; Tuzen and Sari, 2010). This study also uses Fourier transforminfrared (FT-IR) spectroscopy to identify the main functionalgroups involved in the interaction between algae and metals.

2. Methods

2.1. Preparation of the test algae and chemicals

Fresh algae biomass was collected upstream of the Tseng-WenReservoir, Taiwan. Before use, it was washed with distilled waterto remove dirt and kept on lter paper to reduce water content.The biomass was then sun-dried for 4 days, followed by oven dry-ing at 70 C for 24 h, and ground in a gate stone pistol mortar. Thebiomass was then sieved to select particles between 150 and 250mesh size for use.

Stocks of 1000 mg L1 metal solutions were prepared usingPb(NO3)2, and Cu(NO3)23H2O (analytical grade) in deionized water.Nitrate was chosen as the counter ion because of its low tendencyto form metal complexes. The solutions were then diluted to thedesired concentrations and analyzed.

2.2. Optical microscopes examination and Fourier transform infrared(FT-IR) spectroscopy analysis

Researchers examined the algae with optical microscopes. Freshsamples for optical microscopy were suspended in distilled wateron standard microscope slides with cover slips. Optical microscopywas performed on an Olympus BX-51T transmission microscopewith a monochromatic lter. Fourier transform infrared (FT-IR)spectroscopy (Spectrum GX) was used to detect vibration fre-quency changes in dried Cladophora spp. biomass before and afterPb(II) and Cu(II) biosorption. Spectra within the range of 4000400 cm1 were collected.

2.3. Batch experiments for single-ion solution

2.3.1. Effect of pHThe experiment was conducted for biosorption at a concentra-

tion of 100 mg L1 of Cu(II) ions and 1.0 g L1 of biosorbent dosein a 50 mL metal solution for 60 min with varying pH from 3 to7. Solution pH value was adjusted using 1 M HCl or 1 M NaOH.

2.3.2. Effect of contact timeThe pH of the test solution was adjusted to 5 0.2, with a

constant metal concentration of 100 mg L1 and a biomass dose1

5298 Y.-C. Lee, S.-P. Chang / Bioresourcemeyer ask were used, while maintaining a pH of 5.0, a tempera-ture of 25 C and concentrations of the Pb(II) and Cu(II) ions at100 mg L1.2.4. Sorption of Pb(II) and Cu(II) from binary metal solution

The sorptions of Pb(II) and Cu(II) were also determined from abinary solution containing different concentrations (0, 100, and200 mg L1) of both metals. Biomass concentration and otherexperimental conditions were similar to those described earlier.

2.5. Analysis of experimental data

2.5.1. Analysis of Pb(II) and Cu(II)Amounts of Pb(II) and Cu(II) adsorbed by the biomass were

calculated using the following equation:

q C0 Ce V=W 1where q is the amount of Pb(II) or Cu(II) adsorbed by biomass(mgg1), C0 is the initial concentration of Pb(II) or Cu(II) ions(mg L1), Ce is the concentration of Pb(II) or Cu(II) at equilibrium(mg L1), V is the volume of the metal solution (L), and W is themass of adsorbent (g). All experiments were conducted at roomtemperature (25 C).

2.5.2. Biosorption isothermAdsorption data for a wide range of adsorbate concentrations

are best conveniently described by various adsorption isotherms,such as the Langmuir and Freundlich isotherms.

The Langmuir model can be described as:

qe QmaxbCe=1 bCe 2The logarithmic form of the equation is:

1=qe 1=Qmax 1=CebQmax 3where qe is the amount of metal ions sorbed (mgg1) and Ce is theequilibrium concentration (mg L1). Qmax represents maximumadsorption and b is the afnity between biosorbent and biosor-bate.The Freundlich isotherm is given as:

qe KC1=ne 4The logarithmic form of the equation is given as:

log qe logK 1=n logCe 5where K and 1/n are isotherm constants, respectively.

2.6. Successive adsorptiondesorption cycle studies

Pb(II) and Cu(II) ions sorbed onto Spirogyra and Cladophora spp.biomass was separately desorbed using 10 mL of 0.5 M HCl.

Pb(II) and Cu(II) solution contents were determined by Atomicabsorption spectrometry (AAS). To use the biomass for subsequentexperiments, the biomass was sequentially washed with an excessof 0.5 M HCl solution and distilled water.

3. Results and discussion

3.1. Comparison of biosorbents characteristics

Spirogyra and Cladophora spp. are benthic freshwater green al-gae widely distributed throughout the world. We selected thesetwo algae genera as adsorption materials and used optical micro-scopes to observe fresh samples, these two genera of algae couldbe easily differentiated by their characteristics. The plant bodiesof Cladophora spp. showed branches. The Spirogyra spp. did notshow any branching. Spirogyra chloroplast bands a spiral belt. On

hnology 102 (2011) 52975304the plant bodies of Cladophora spp., we could observe a largeamount of epiphytic algae, mainly Bacillariophyta, and small epi-phytic algae such as Chlorophyta, Cyanophyta, and Euglenophyta.

Conversely, on the plant bodies of Spirogyra spp., less species andamounts of epiphytic algae were observed. Various algae havingdifferent extracellular polymeric substances (Tien et al., 2002)caused the differences between epiphytic algae on Cladophoraspp. and Spirogyra spp. When comparing the tested portion ofCladophora FT-IR functional groups, we discovered that the mainlyfunctional groups were present in proteins and polysaccharides,and that the wave number of the portion that experienced changeafter adsorption occurred mainly in the carboxylic group. Onyan-cha et al. (2008) proposed the primary functional groups ofSpirogyra were hydroxyls, amines, alkyl, and carboxylic group. Acomparison of optical microscope observations and FT-IR testresults for the aforementioned types of adsorbents are shown inTable 1. After adsorbing Pb(II) and Cu(II), the FT-IR analysis showedthat amines, carboxylic, C@O and CO could combine intensivelywith metal ions.

3.2. Adsorption comparison for single heavy metal ions

equilibrium phase, with no signicant increase in the removal rate.Mohan et al. (2002) described similar results. It observed that twobiomaterials performed for various durations in different phases,due to different adsorbed heavy metals. For the adsorption of Pb(II)and Cu(II) single heavy metals, we discovered that the adsorptioncapacity of Spirogyra algae was signicantly higher than that ofCladophora algae. In comparing the characteristics of biomass,FT-IR testing showed that functional groups were similar. How-ever, plant bodies of Cladophora spp. often have large amounts ofepiphytic algae, thus causing differences in adsorption volume.Furthermore, differences in adsorption volume may be due to dif-ferences in proteins, lipids, or the composition of other carbohy-drates affecting the number of adsorption sites. The differencesmay be due to the epiphytic algae on Cladophora spp., which affectsthe quality of algae powder production.

3.2.2. Effects of pH on metal ion adsorptionNumerous studies show that pH is an important factor affecting

adsorption of heavy metals by biosorbents (Fourest and Roux,

l

m. a

boxnsof t

ers,

Y.-C. Lee, S.-P. Chang / Bioresource Technology 102 (2011) 52975304 52993.2.1. Effects of contact timeIdeal biosorption materials are able to rapidly adsorb high con-

centrations of heavy metals from waste emissions and use chemi-cal agents to desorb heavy metals from biosorption material (Singhet al., 2007). For these reasons, the results of Spirogyra and Clado-phora spp. adsorption on Pb(II) and Cu(II) used the relationship be-tween heavy metal adsorption and contact time as a function, asshown in Fig. 1a.

During the rst 30 min, adsorption rate of both materials wasextremely high, comprising approximately 95% of the total adsorp-tion. Then, the rate began to drop toward a steady state, with insig-nicant levels of adsorption. The two adsorption materials reachedsteady state for the same type of metal ion simultaneously, butachieved steady state at different times for different metal ions.As observed in the adsorption curve, the rapid adsorption of leadin the rst twenty minutes, and the rapid adsorption of copper inthe rst thirty minutes, may be due to physical adsorption or ionadsorption on the surface of the algae powder. Slower adsorptionthat followed may have involved other mechanisms, such as com-plexation, micro-precipitation, and binding site saturation. Thisstudy observed three phases of Spirogyra and Cladophora spp.adsorption materials in the contact time adsorption curve: the ini-tial phase, with rapid adsorption of heavy metal ions; the secondphase, with gradual slowing of the adsorption rate; and the

Table 1Comparison of characteristics between Spirogyra spp. and Cladophora spp.

Characteristics Cladophora spp.

Branches YesLength of cell 20100 lmWidth of cell 1540 lmLength of plant 10200 cmNucleate MultinucleateCell wall Low pectate containChloroplast Not belt distributionEpiphytic algae AbundanceFT-IR analysis for functional

groupsWave number(cm1)

Band assignment

3351 OH hydrogen bonded alcoho

2896 Alkyl chains (CH3 and CH2 systretch)

1658 C@O aldehydes, ketones, car1429 CO bend from carboxylate io1336 Amide II (CN), COO groups

acids1163 and 1059 CO stretches. Alcohols, ethacid, esters

FT-IR analysis of Spirogyra spp. from Onyancha et al. (2008).1992; Lia et al., 2006). Thus, higher pH value may affect the num-ber of negatively charged sites, which is highly dependent on thedissociation of functional groups. In addition, H+ competes withPb(II) and Cu(II) for the same adsorption position (Gupta andRastogi, 2008; Gupta et al., 2006).

The results of the pH value effects of Cladophora and Spirogyraalgae powder on heavy metal adsorption are shown in Fig. 1b.

When pH value was below 5, the amount of heavy metal ionsthat Spirogyra and Cladophora algae powder were able to absorb in-creased with increases in the pH value. In optimal pH and FT-IRtesting for metal ion adsorption, these two types of algae powderincluded carboxylic groups capable of playing a predominant rolein the adsorption of Pb(II) and Cu(II) (Singh et al., 2007). WhenpH was 5, the two types of algae powder reached their maximumadsorption volume. The capacity of Spirogyra to adsorb Pb(II) andCu(II) was 87.2 mgg1 and 38.2 mgg1, respectively. The capacityof Cladophora to adsorb Pb(II) and Cu(II) was 45.4 mgg1and13.7 mgg1, respectively. However, when pH exceeded 5, thecapacity to absorb Pb(II) and Cu(II) decreased for both biosorbents.This may have been due to the precipitation of copper hydroxidesand lead hydroxides (Gupta et al., 2006).

The formation of the precipitation of copper hydroxides andlead hydroxides was related to Ksp, and the optimal pH valuewas inuenced by the concentration of Cu2+ and Pb2+; therefore,

Spirogyra spp.

No20200 lm2035 lm530 cmMononucleateHigh pectate containBelt distributionFewWave number(cm1)*

Band assignment

3622 OH monomeric alcohols, phenols, NHamine stretches

nd asym. 3341 OH hydrogen bonded alcohol

ylic acid 2925 CH alkane stretches2360 CC triple bond (alkynes)

he fatty 1656 C@O aldehydes, ketones, carboxylic acid

carboxylic 1038 CO stretches. Alcohols, ethers, carboxylic

acid, esters

Tecorpt

ion(

mg/

g dr

y w

eigh

t)20

40

60

80

100

5300 Y.-C. Lee, S.-P. Chang / Bioresourcethe pH value of optimal adsorption of biomass could be a variable,with the decrease of concentration of Cu2+ and Pb2+. The pH valueof optimal operation was between the pH value of the isoelectricpoint and the pH value of forming hydrate sediments. Fig. 2 showsthe result of Zeta potential of adsorption of Cladophora spp. powderin solutions without heavy metal ions, 100 mg L1 Cu2+, and100 mg L1 Pb2+ at different pH values. The isoelectric point insolutions without heavy metal ions was at a pH value of 4.6. Theisoelectric points after adsorbing 100 mg L1 Cu2+ and 100 mg L1

Pb2+ were respectively at pH values of 4.9, and 5.1. We could inferthat the optimal pH value of adsorption of heavy metals by bioma-

Ti0 10 20 30A

ds 0

pH2 3 4 5

Adso

rptio

n(m

g/g

dry

wei

ght)

0

20

40

60

80

100

C0(mg/L0 50 100 150

Adso

rptio

n(m

g/g

dry

wei

ght)

0

20

40

60

80

100

M(g/L0 2 4 6

Adso

rptio

n(m

g/g

dry

wei

ght)

0

20

40

60

80

100

Fig. 1. (a) Changes in the Spirogyra and Cladophora spp. algae powder removal solutiondifferent pH values, Spirogyra and Cladophora spp. powder removes Pb(II) or Cu(II) heavySpirogyra and Cladophora spp. adsorption under various concentrations of heavy metal sheavy metal solutions, with heavy metal concentrations of 100 mg L1 and pH value of(a)

Spirogyra spp.-Cu(II)Cladophora spp.-Cu(II)Spirogyra spp.-Pb(II)Cladophora spp.-Pb(II)

hnology 102 (2011) 52975304terials with adsorption capability might uctuate at a pH valuewithin a small range. Lower isoelectric point, the available siteson surface of the biomass are protonated, hence sorption of cationsis more difcult (Naja et al., 2005). Therefore, determining the pHvalue of the optimal operating condition through estimatingisoelectric point is a favorable method.

3.2.3. Effect of initial concentration of metal ionsThe effects of Spirogyra and Cladophora algae on initial concen-

trations of Pb(II) and Cu(II) are shown in Fig. 1c. In this experiment,we compared the adsorption capacity of Spirogyra and Cladophora

me(min)40 50 60 70

(b)

6 7 8

Spirogyra spp.-Cu(II)Cladophora spp.-Cu(II)Spirogyra spp.-Pb(II)Cladophora spp.-Pb(II)

(c)

)200 250 300 350

Spirogyra spp.-Cu(II)Cladophora spp.-Cu(II)Spirogyra spp.-Pb(II)Cladophora spp.-Pb(II)

(d)

)8 10 12

Spirogyra spp.-Cu(II)Cladophora spp.-Cu(II)Spirogyra spp.-Pb(II)Cladophora spp.-Pb(II)

Pb(II) or Cu(II) reaction time. The pH value of the solution was set as 5.0. (b) Withmetal solutions from water. The dosage of algae powder was 1.0 g L1. (c) Results ofolution, with a pH value of 5.0. (d) Effects of various algae dosages on adsorption of5.0.

pH

2 3 4 5 6 7 8Ze

ta P

oten

tial [

mV]

-10

-5

0

5

10

algae powder))

ra sp

Y.-C. Lee, S.-P. Chang / Bioresource Technology 102 (2011) 52975304 5301algae powders. The results indicated that the Spirogyra algae poweradsorption of Pb(II) and Cu(II) was greater than that of the Clado-phora algae power. When Pb(II) and Cu(II) concentrations were100 mg L1, both adsorption materials reached their highest de-gree of adsorption capacity for metal ions, thereby providing max-imum removal rates for the two types of heavy metals present inthe solution. Since subsequent increases in adsorption capacitywere extremely low, the removal rate for metal ions signicantlydecreased. This may be due to the saturation of available sites onalgal cell surfaces preventing further adsorption of metal ions(Volesky, 2003). Based on the results of this experiment, we usedmetal ion concentrations of 100 mg L1, in subsequent experi-ments on adsorption.

3.2.4. Effect of algal dosageThe results of this experiment on adsorption for these two bio-

sorbents under different dosages on Pb(II) and Cu(II) are as shownin Fig. 1d. For these tests, we used metal ion concentrations of100 mg L1.

As seen in Fig. 1d, metal adsorption volume was inversely pro-

-15

algae powder+Cu(IIalgae powder+Pb(II

Fig. 2. Zeta Potential of Cladophoportional to the algae dosages, while the removal rate was propor-tional to the algae dosages. When the biosorbent was increased,absorption of metal ions also increased. Low dosages of biosorbentwith high concentrations of heavy metals resulted in the highestadsorption capacity.

(a)

1/Ce

0.00 0.01 0.02 0.03 0.04 0.05 0.06

1/q e

0.00

0.02

0.04

0.06

0.08

0.10

0.12 Spirogyra spp.-Cu(II)Spirogyra spp.-Pb(II)Cladophora spp.-Cu(II)Cladophora spp.-Pb(II)Regression line

Fig. 3. Langmuir (a) and Freundlich (b) adsorption isotherms for Pb(3.3. Comparison of adsorption isotherms

Fig. 3 shows the adsorption results of Spirogyra and Cladophoraalgae powder at 25 C for Pb(II) and Cu(II), respectively, as well asthe plots of 1/qe and 1/Ce, based on the Langmuir model (Eq. (2))described previously and the Freundlich isotherms (Eq. (4)). Theplots of log qe versus log Ce, are shown in Fig. 3. The constants ob-tained from Langmuir and Freundlich isotherms had very high cor-relation coefcients (R2) (Table 2). Comparisons betweencorrelation coefcients, with the adsorption correlation values forSpirogyra and Cladophora, t the Langmuir model better than theFreundlich model. These values indicated a strong positivecorrelation.

For the tting results of Langmuir isotherms (see Table 2), themaximum Qmax and minimum b value of the Langmuir constantswere 90.91and 0.024, respectively, for Spirogyra Pb(II) adsorption.In comparing the b value of the two biosorbents, each demon-strated differing adsorption results for different metal ions. Qmaxrepresents the maximum biosorption capacity of the biosorbent,while the b value indicates the afnity of a biosorbent towards

p. algae powder at different pH.an adsorbate.For the tting results of the Freundlich model (see Table 2),

higher K values, and n values are 9.22 mgg1 and 2.44, respectively,in the adsorption results for Spirogyra algae to Pb(II). A high K valueindicated a high adsorption volume. A high 1/n value (n > 1)

(b)

log Ce

1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6

log

q e

0.8

1.0

1.2

1.4

1.6

1.8

2.0

II) and Cu(II) using Spirogyra and Cladophora spp. algae powder.

indicated high adsorption strength. Table 2 shows a comparison ofcorrelation coefcients for various biosorbents in the adsorption ofPb(II) and Cu(II) (6.299.67). The results indicated that Spirogyra isa better biosorbent material than Cladophora.

In comparing the adsorption test results of Pb(II) and Cu(II) forboth types of adsorption materials, the adsorption of Pb(II) had alower b value, indicating that both types of biosorbents had a high-er afnity for Pb(II).

3.4. Comparison of Pb(II) and Cu(II) binary metal solution adsorption

Studying adsorption balance relationships in a systemized man-ner is extremely important in multi-metal systems. Adsorption isaffected by operational conditions, such as biomass surface charac-teristics and pH, as well as competition among various cations foractive biosorbent sites, and/or the cation screening effect, whichmay interfere with biosorption capacity of the metals of interest

type of multi-metal ion solution showed similar characteristics ofinhibition in related studies (Singh et al., 2007; Yan et al., 2010).

These two types of adsorbents displayed stronger adsorptioninhibition towards binary metal system Pb(II) compared to Cu(II).This indicated a higher afnity of these adsorbents towards Pb(II).The afnity of metal ions for the binding sites seem to be related toelectronegativity, ionic radii, state of the surface and steric cong-uration, etc.

3.5. Comparison of desorption efciency

Numerous studies reported that HCl is very effective for desorb-ing heavy metals from biosorbents (Singh et al., 2007; Tuzen andSari, 2010). We used 0.5 M HCl on Pb(II) and Cu(II) for Spirogyraand Cladophora algae powders to test the adsorptiondesorptionefciency. We discovered that 0.5 M HCl was highly effective, withup to an 85% recovery rate for both Spirogyra and Cladophora algae

Table 2Langmuir and Freundlich constants for Pb(II) and Cu(II) with Spirogyra and Cladophora biomass.

Algae Heavy metal ions Langmuir constants Freundlich constants

b Qmax R2 n KF R

2

Spirogyra spp. Cu(II) 0.040 38.61 0.995 4.15 9.67 0.958Pb(II) 0.024 90.91 0.991 2.44 9.22 0.981

Cladophora spp. Cu(II) 0.061 14.71 0.993 6.91 6.29 0.937Pb(II) 0.025 46.51 0.996 3.03 6.63 0.980

mg/

orp 40 Pb(II)-200

5302 Y.-C. Lee, S.-P. Chang / Bioresource Technology 102 (2011) 52975304C0 (

0 50 100 150

Ads

0

20

(b)50(Luna et al., 2010; Vilar et al., 2008).The biosorption results of Pb(II) or Cu(II) by Spirogyra and Clado-

phora spp. from binary metal solutions containing various concen-trations of Pb(II) and Cu(II) are shown in Fig. 4. Results clearly showthat the adsorption of the two algae tested mutually inhibit oneanother. Compared with single metal ion solution adsorption, this

(a)

tion

(mg/

g)

60

80

100C0(mg/L

0 50 100 150

Adso

rptio

n (m

g/g)

0

10

20

30

40

Fig. 4. (a) Spirogyra spp. and (b) Cladophora spp. from binary metalL)

200 250 300 350powders. Furthermore, these two types of biomass continued tomaintain high stability even after ve continuous adsorptiondesorption processes. The results are shown in Fig. 5.

In every cycle, Cladophora Pb(II) and Cu(II) recovery rates weremore than 88.0% and 82.6%, respectively, while those for SpirogyraPb(II) and Cu(II) were more than 92.5% and 85.1%, respectively. As

Cu(II)-0 Cu(II)-100 Cu(II)-200 Pb(II)-0 Pb(II)-100 )

200 250 300 350

Cu(II)-0 Cu(II)-100 Cu(II)-200 Pb(II)-0 Pb(II)-100 Pb(II)-200

solutions containing various concentrations of Pb(II) and Cu(II).

ber

Am 40

e Tec20Cycle num1 2 3

0

20

(b)

ount

(%)

60

80

100(a)

Amou

nt (%

)40

60

80

100

Y.-C. Lee, S.-P. Chang / Bioresourcdiscovered in studies of this type of adsorptiondesorption cycle,both Cladophora and Spirogyra were good biosorbents.

4. Conclusions

This study discovered that the adsorption effects of Spirogyraspp. for Pb(II) and Cu(II) are superior to those of Cladophora spp.FT-IR analysis indicated that the functional groups of these twogenera of algae are similar, but varied in their adsorption ef-ciency. This may be due to the differences in protein, lipid, or othercarbohydrate content of the two genera of algae. Furthermore,whether large amounts of epiphytic algae on Cladophora plantbodies affect subsequent algae powder manufacturing and adsorp-tion results warrants further study. Continuing adsorptiondesorp-tion experiments have discovered that both types of biomass areexcellent biosorbents with potential for further development.

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Fig. 5. Adsorptiondesorption efcie4 5

Spirogyra spp.-adsorption Spirogyra spp.-desorptionCladophora spp.-adsorptionCladophora spp.-desorption

Spirogyra spp.-adsorptionSpirogyra spp.-desorptionCladophora spp.-adsorptionCladophora spp.-desorption

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5304 Y.-C. Lee, S.-P. Chang / Bioresource Technology 102 (2011) 52975304

The biosorption of heavy metals from aqueous solution by Spirogyra and Cladophora filamentous macroalgaeIntroductionMethodsPreparation of the test algae and chemicalsOptical microscopes examination and Fourier transform infrared (FT-IR) spectroscopy analysisBatch experiments for single-ion solutionEffect of pHEffect of contact timeEffect of initial metal ions concentrationEffect of biosorbents dose

Sorption of Pb(II) and Cu(II) from binary metal solutionAnalysis of experimental dataAnalysis of Pb(II) and Cu(II)Biosorption isotherm

Successive adsorptiondesorption cycle studies

Results and discussionComparison of biosorbents characteristicsAdsorption comparison for single heavy metal ionsEffects of contact timeEffects of pH on metal ion adsorptionEffect of initial concentration of metal ionsEffect of algal dosage

Comparison of adsorption isothermsComparison of Pb(II) and Cu(II) binary metal solution adsorptionComparison of desorption efficiency

ConclusionsReferences