Nadya Nursidah Pratiwi Subroto et al. Indo. J. Chem. Res., 10(1), 53-57, 2022 

 

DOI: 10.30598//ijcr.  53   
 

Lead Ion Removal in Water Using Low Methoxy Pectin-Guar Gum Beads Hybrid Adsorbent 

 
Nadya Nursidah Pratiwi Subroto, Fadhil Muhammad Tarmidzi*, Ina Wati1, Velia Mulya Armans 

Chemical Engineering Department, Faculty of Industrial and Process Technology, Institut Teknologi Kalimantan, Jalan 

Soekarno Hatta KM 15, Balikpapan, Indonesia 
*Corresponding Author: fadhil.tarmidzi@lecturer.itk.ac.id 

 
Received: February 2022 

Received in revised: March 2022 

Accepted: May 2022 

Available online: 

Abstract 

A high level of lead in the sediment will cause contamination of aquatic biota. Lead 

pollutants in water may be treated by an easy and common adsorption process. A 

combination of both environmentally friendly and renewable materials, low methoxy 

pectin (LMP), and guar gum as adsorbents can reduce the need of activated carbon 

which requires high temperatures in its synthesis process. LMP was prepared from 

high methoxy pectin using a demethylation process under alkaline conditions. LMP 

and guar gum are diluted in 1 M calcium chloride as a crosslinking agent. The degree 

of esterification was carried out to determine the demethylation process. Adsorption 

of lead was carried out with a lead concentration of 165 ppm in acidic conditions for 

24 hours. Lead concentration was measured using AAS. Results show that the optimal 

pH for demethylation was 12. The ratio of 1:2 pectin-guar gum produces the strong 

beads related to more O-H bonds in guar gum that can be developed. pectin-guar gum 

beads can adsorb 63% of lead at pH  6 due to the development of hydro-complex metal 

ions under more basic conditions. 

Keywords: Lead, Beads adsorbent, Low methoxy pectin, Guar gum  

 

 

INTRODUCTION 

Pulp and paper are the biggest contributors of lead 

pollutants in water. A lead pollutant can be found in 

black liquor, especially in aerosol synthesize, along 

with a non-volatile sulfur compounds (Kevlich, 

Shofner, & Nair, 2017). The presence of non-

biodegradable lead in waters causes damage to aquatic 

ecosystems so that waters that meet quality standards 

are not obtained that are safe for the environment 

(Tanheitafino, Zaharah, & Destiarti, 2016). Lead also 

has a bad influence on human health, both children and 

adults which can cause cancer, hypertension, coronary 

heart disease, and other. Lead levels in water also cause 

damage to mammalian organs (Male et al., 2017). 

Therefore, special attention is needed in the form of 

treatment of the waste to be discharged into the waters. 

There are various methods to reduce metal levels 

in wastewater, including chemical precipitation 

filtration, ion exchange, adsorption, and membrane 

systems (Darjito, Purwonugroho, & Ningsih, 2014). 

The adsorption process is popular because of several 

advantages, including relatively high efficiency, does 

not have a bad impact on the environment, and is 

effective (Bijang, Tanasale, Kelrey, Mansur, & Azis, 

2021). In addition, Adsorption has a simple process, 

can work with low concentrations, and can be recycled. 

Adsorption is a separation process that can be used for 

the removal of low concentration pollutants from large 

volumes of process, wastewater, and solution water. 

There are 3 types of adsorption systems, namely gas-

liquid, liquid-liquid, solid-liquid, and solid gas 

(Nwodika & Onukwuli, 2017). 

Pectin can be used as an adsorbent to absorb heavy 

metals where pectin content can be obtained, one of 

which is orange peel waste. Pectin is a polymer derived 

from D-galacturonic acid which can be found in plant 

cell walls linked by 1,4 glycosidic bonds and is 

commonly found in the middle lamellae of the wall 

(Latupeirissa, Fransina, Tanasale, & Batawi, 2019) 

(Rahayu, Harisma, Syamsuddin, Sofyana, & Mulyati, 

2021). Pectin has the ability to form a good gel with 

the level of esterification of galacturonic acid residues 

as a parameter of the effect of solubility and gelling on 

pectin (Liu, Fishman, & Hicks, 2007). Pectin contains 

a carboxylate group which causes pectin to be used to 

absorb metals. The carboxylate group reacts with 

heavy metal ions to form complex compounds that can 

be excreted through feces and are insoluble in water. 

The reactivity of pectin on heavy metal ions depends 

on the value of the degree of esterification. As an 

adsorbent, the type of pectin used is pectin with many 

carboxyl groups (Tahir, Safitri, & Suhaenah, 2019). 

Based on the degree of esterification, pectin is 

divided into two from the methoxy group. Low 

Methoxy Pectin (LMP) has less than 50% while High 

Methoxy Pectin (HMP) has more than 50% (Santos et 



Nadya Nursidah Pratiwi Subroto et al. Indo. J. Chem. Res., 10(1), 53-57, 2022 

 

DOI: 10.30598//ijcr.  54   
 

al., 2020). HMP can be found in fruit peels and it needs 

modification through a demethylation step to convert 

to LMP. One of the modifications has been done by 

using the alkaline demethylation method to convert 

pectin into Low Methoxyl Pectin (Yapo & Koffi, 2014) 

(Sarandi, Alhusna, & Pandia, 2015). 

This study focus on the synthesis of hybrid bead 

adsorption using LMP and guar gum. Guar-gum is a 

natural hydrocolloid as an interpenetrating agent that 

helps improve the mechanical strength of the gel 

formed (Sugita, Sjahriza, & Lestari, 2015). The 

addition of guar-gum is expected to increase the 

resistance of the beads so that they are not easily 

destroyed during the adsorption process. 

METHODOLOGY 

Materials and Instrumentals 

This study was using HMP from citrus peel, guar, 

and gum as the main precursors. The demethylation 

process was done by using isopropanol alcohol, NaOH, 

and ethanol 96% from Merck. CaCl2 was also added as 

a crosslinker in beads synthesis. The adsorption 

process was done by using HCl 37% and Pb(NO3)2 

from Merck. Lead concentration in water was 

measured using Atomic Adsorption 

Spectrophotometer (AAS) in the Center for 

Standardization and Industrial Services, Samarinda.  

 

Methods 

The demethylation process was adapted and 

modified from Sarandi et al., (2015). The process 

begins with dissolved pectin in IPA with the 

concentration of 1.5% w/v. The base condition was 

adjusted and varied by using 3M NaOH solution to 

achieve a pH level of 10-12. The solution was 

incubated at 55 oC for 6 hours. Next, the solution was 

cooled to room temperature and then 3N HCl solution 

was added until the pH became 3. LMP was 

precipitated by adding ethanol 96% at 18 oC for 2 

hours. The solid was filtered and washed with ethanol 

and dried using the oven at 50 oC. The degree of 

esterification was analyzed by dissolving 0.2 grams of 

LMP with distilled water and a phenolphthalein (PP) 

indicator was added.  

The sample was titrated with 1 N NaOH and the 

titration results were recorded as initial conditions 

where the initial conditions indicated the number of 

carboxyl groups of beads. Then, 10 mL of 1 N NaOH 

solution was added to the sample and shaken 

vigorously until polygalacturonic acid was neutral and 

left for 2 hours at room temperature to de-esterify 

pectin. 

 

Figure 1. LMP from the demethylation process 

Then, 1 N HCl solution was added to the sample 

to neutralize the NaOH and shaken until the pink color 

in the sample disappeared. Then 3 drops of PP 

indicator were added and titrated with 1 N NaOH. Then 

the titration results were recorded as final conditions. 

To calculate the degree of esterification of pectin that 

has undergone a demethylation process, the following 

Equation 1 can be used. 

 

 𝐷𝐸 =
𝐹𝑖𝑛𝑎𝑙  𝑡𝑖𝑡𝑟𝑎𝑡𝑖𝑜𝑛

𝐼𝑛𝑖𝑡𝑖𝑎𝑙+ 𝐹𝑖𝑛𝑎𝑙 𝑡𝑖𝑡𝑟𝑎𝑡𝑖𝑜𝑛
× 100%

       

(1) 

 

Synthesize hybrid bead adsorbent was adapted 

from (Jakóbik-Kolon, Milewski, Karoń, & Bok-

Badura, 2016). Pectin and guar gum mixed with water 

with a ratio of LMP: guar gum are 1:0, 2:1, 1:1, and 

1:2. The sample was stirred at 70°C for 4 hours and 

cooled to room temperature. Then the solution was 

dropped into a cold 1 M CaCl2 solution to form beads. 

Beads were allowed to stand for 24 hours in a cold 1 M 

CaCl2 solution at 12 
oC for 24 hours. The chloride ions 

in the beads are removed by washing them with 

distilled water. Finally, the beads were filtered and 

dried at       35 °C for 24 hours. 

To durability test of the beads was performed by 

adding 0.3 grams beads to 300 mL distilled water The 

stirring was done at 1000 rpm for 24 hours. The beads 

were observed to determine the beads resistance to 

shear stress. The adsorption step was carried out by 

making a solution of Pb(NO3)2 with a concentration of 

165 ppm. HCl solution was added to vary its condition 

at pH level of 3-6. Adsorption of lead was done by 

adding 1% of beads into 300 mL of lead solution and 

stirring for 24 hours (Jakóbik-Kolon et al., 2016). Lead 

concentration in water was analyzed using AAS. 

 



Nadya Nursidah Pratiwi Subroto et al. Indo. J. Chem. Res., 10(1), 53-57, 2022 

 

DOI: 10.30598//ijcr.  55   
 

 
Figure 2. LMP - Guar Gum Hybrid Beads Pectin 

RESULTS AND DISCUSSION 

Effect of pH on LMP Degree of Esterification  

The process used to decrease the degree of 

esterification is base demethylation caused by the 

reaction rate factor which when compared with all 

available methods, base demethylation is relatively 

faster (El-Nawawi & Heikal, 1995), the reaction that 

occurs in the process is irreversible, and the need for 

high temperatures in the process (Einhorn-Stoll et al., 

2020). HMP from citrus peel was used for this process 

have a degree of esterification (DE) of 63%. After the 

demethylation process is carried out, then an analysis 

of the DE is carried out which has a function so that the 

number of carboxyl groups esterified by methyl to the 

total galacturonic acid in a number of pectin samples is 

known. The titration method was used to test the 

degree of esterification of pectin. From the pectin 

esterification degree test that has been carried out, the 

results are as shown in Figure 3. 

Among all the variations in pH values that have 

been tested, pH 12 has the lowest esterification degree 

value which is in accordance with previous research 

conducted by (Kesuma, Widarta, & Permana, 2018). 

Lowering pH during the process that will bring the 

methoxy content higher by promoting the esterification 

of the carboxyl group. Higher pH means that there is 

more hydroxyl ion, which represents more ester groups 

will be demethylated to carboxylic acids and replace 

the ester groups in galacturonic acid in the pectin chain. 

The ratio of the number of galacturonic acid groups 

esterified by methyl to the total galacturonic acid in a 

number of pectin samples is called the degree of 

esterification. The number of demethylated ester 

groups from the galacturonic acid group of pectin 

affects the value of the esterification degree because 

the more galacturonic acid groups in the demethylated 

pectin chain, the smaller the value of the degree of 

esterification of pectin will be. This pectin can be 

referred to as LMP. Therefore, pH 12 is the optimal 

condition for demethylating under alkaline conditions 

because it produces the lowest esterification degree 

value is 20%. 

 
 

 

 

 

 

 

 

 

 

 

Figure 3. Effect of pH toward Degree of Esterification 

Beads Resistance from Shear Stress 

To increase the resistance of the beads from shear 

stress during the adsorption process, LMP was mixed 

with guar gum to develop a strong bead (Figure 4). 

because the molecular weight of pectin is greater than 

guar gum, when pectin is mixed with guar gum, the 

amount of guar gum must be 40% more so that it can 

be completely mixed (Satyamaiah, Prasad, 

Chandrasekhar, Suhasini, & Suryanaraya, 2014). 

Figure 5 shows that the beads with a ratio of 1:2 

(D) have the best shear stress resistance ability at 1000 

rpm for 24 hours. With a ratio of 1:2 (D) the amount of 

guar gum used has met the requirements so that pectin 

and guar gum can be mixed perfectly so that the beads 

formed have better resistance characteristics in stirring. 

 

Effect of pH to Lead Adsorption using Hybrid 

Beads Adsorbent 

The initial lead concentration in the water was 

165 ppm. The adsorption was carried out for 24 hours 

in acidic conditions by varying from pH level of 3-6 

(Figure 6). It is shown that the value of pH is inversely 

proportional to the value of the concentration of the 

lead solution that is removed through the adsorption 

process. The higher the pH variable, the lower the 

concentration of the Pb solution that has been 

adsorbed. The efficiency of the adsorption of beads is 

directly proportional to the pH value, where the greater 

the pH value, the greater the adsorption efficiency 

(Yantyana, Amalia, & Fitriyani, 2018). 

15

20

25

30

35

9 10 11 12

D
e
g
re

e
 o

f 
E

st
e
ri

fi
c
a
ti

o
n
 

(%
)

pH



Nadya Nursidah Pratiwi Subroto et al. Indo. J. Chem. Res., 10(1), 53-57, 2022 

 

DOI: 10.30598//ijcr.  56   
 

 
Figure 4. Hybrid Beads Adsorbent after Shear Stress 

Test 

 

 

 

 

 

 

 

 

 

 

 

Figure 5. Shear Stress Resistance of Beads at 1000 

rpm with Ratio LMP: Guar Gum A. 1:0, B. 2:1, C. 

1:1. And D. 1:2. 

 

 

 

 

 

 

 

 

 

 

 

 

Figure 6. Final Lead Concentration at Various pH 

from Initial Lead Concentration 165 ppm 

Based on Figure 7, it is known that the percentage 

of decrease in lead concentration was highest at pH 6, 

which was 63%. This is because the active site on the 

adsorbent can absorb more lead metal ions because the 

number of H+ ions has decreased at this condition. 

Otherwise, a low pH value will result in low absorption 

of metal ions because the surface of the adsorbent is 

surrounded by H+ ions, and the surface of the adsorbent 

will be positively charged which will cause the 

adsorbent's repulsion with metal ions (Yantyana et al., 

2018). The metal ions of hydro-complexes do not 

dissociate in solution and have a large size making it 

difficult to bind to the active groups present in the 

beads. Therefore, it can be concluded that pH 6 is the 

optimal condition for adsorption. 

 

 

 

 

 

 

 

 

 

 

 

 
 

Figure 7. Percentage of Lead Removal in Water after 

24 Hours of Adsorption 

CONCLUSION 

This study shows that the demethylation process 

can be done in base conditions with the optimum DE 

10% was achieved at pH 12 because more ester groups 

will be demethylated to carboxylic acids and replace 

the ester groups in galacturonic acid in the pectin chain. 

Hybrid beads adsorbent from LMP and guar gum have 

successfully developed. The ratio of 1:2 pectin-guar 

gum produces the best characteristics with stirring 

resistance at 1000 rpm for 24 hours. The bond that 

occurs between LMP and guar gum increases the 

mechanical strength and increases the resistance of the 

beads to temperature and solvent. As well as pectin-

guar gum beads can adsorb Pb metal well. The largest 

Pb adsorption capacity was obtained when the Pb 

solution was at pH 6 which was the optimal condition 

for adsorption. This happens because at pH 6 the 

carboxyl group is not protonated and metal ions do not 

become hydro-complex ions. Under these conditions, 

the pectin-guar gum beads can adsorb as much as 

104.08 mg/L of Pb or the concentration of the Pb 

solution decreased by 63%. The metal ions of hydro-

complexes do not dissociate in solution and have a 

large size making it difficult to bind to the active 

groups present in the beads. Therefore, it can be 

concluded that pH 6 is the optimal condition for 

adsorption. 

 

 

 

0

200

400

600

800

1000

1200

1400

1600

A B C D

T
im

e
 (

M
in

u
te

s)

Sampel

0

200

400

600

800

1000

1200

1400

1600

A B C D

T
im

e
 (

M
in

u
te

s)

Sampel

0%

10%

20%

30%

40%

50%

60%

70%

3 4 5 6
L

e
a
d
 A

d
so

rb
e
d
 (

%
)

pH



Nadya Nursidah Pratiwi Subroto et al. Indo. J. Chem. Res., 10(1), 53-57, 2022 

 

DOI: 10.30598//ijcr.  57   
 

REFERENCES 

Bijang, C. M., Tanasale, M. F. J. D. P., Kelrey, A. G., 

Mansur, I. U., & Azis, T. (2021). Preparation of 

Natural Ouw Clay-Chitosan Composite and Its 

Application as Lead and Cadmium Metal 

Adsorbent. Indonesian Journal of Chemical 

Research, 9(1), 15–20.  

Darjito, D., Purwonugroho, D., & Ningsih, R. (2014). 

The Adsorption of Cr ( VI ) Ions Using Chitosan-

Alumina Adsorbent. Journal of Pure and Applied 

Chemistry Research, 3(June), 53–61. 

Einhorn-Stoll, U., Kastner, H., Fatouros, A., Krähmer, 

A., Kroh, L. W., & Drusch, S. (2020). Thermal 

Degradation of Citrus Pectin in Low-Moisture 

Environment–Investigation of Backbone 

Depolymerisation. Food Hydrocolloids, 107, 

104–115.  

El-Nawawi, S. A., & Heikal, Y. A. (1995). Production 

of a Low Ester Pectin by De–Esterification of 

High Ester Citrus Pectin. Carbohydrate Polymers, 

27, 191–195. 

Jakóbik-Kolon, A., Milewski, A. K., Karoń, K., & 

Bok-Badura, J. (2016). New, Hybrid Pectin-

Based Biosorbents. Separation Science and 

Technology (Philadelphia), 51(15–16), 2604–

2611.  

Kesuma, N. K. Y., Widarta, I. W. R., & Permana, I. D. 

G. M. (2018). Effect of Acid Type and Ph 

Solution on Characteristics Of Pectin From 

Lemon Peel (citrus limon). Jurnal Ilmu Dan 

Teknologi Pangan (ITEPA), 7(4), 192.  

Kevlich, N. S., Shofner, M. L., & Nair, S. (2017). 

Membranes for Kraft Black Liquor Concentration 

and Chemical Recovery: Current Progress, 

Challenges, and Opportunities. Separation 

Science and Technology, 52(6), 1070–1094.  

Latupeirissa, J., Fransina, E. G., Tanasale, M. F. J. D. 

P., & Batawi, C. Y. (2019). Extraction And 

Characterization of Pectin from The Oranges Peel 

of Kisar (Citrus sp.). J. Chem. Res, 7(1), 61–68. 

Liu, L. S., Fishman, M. L., & Hicks, K. B. (2007). 

Pectin in Controlled Drug Delivery-A Review. 

Cellulose, 14(1), 15–24.  

Male, Y. T., Malle, D., Bijang, C. M., Fransina, E. G., 

Seumahu, C. A., Dolaitery, L. M., Gaspersz, N. 

(2017). Analysis of Cadmium (Cd) and Lead (Pb) 

metal content in sediments in Inner Ambon Bay. 

Indonesian Journal of Chemical Research, 5(1), 

22–31.  

 

 

 

 

 

Nwodika, C., & Onukwuli, O. D. (2017). Adsorption 

Study of Kinetics And Equilibrium of Basic Dye 

on Kola Nut Pod Carbon. Gazi University Journal 

of Science, 30(4), 86–102. 

Rahayu, W. P., Harisma, I. W., Syamsuddin, Y., 

Sofyana, S., & Mulyati, S. (2021). Extraction Of 

Pectin from Orange Peel and Banana Peel as 

Biosorbent in Heavy Metal Fe Adsorption. Jurnal 

Serambi Engineering, 6(2), 1899–1907.  

Santos, E. E., Amaro, R. C., Bustamante, C. C. C., 

Guerra, M. H. A., Soares, L. C., & Froes, R. E. S. 

(2020). Extraction of Pectin From Agroindustrial 

Residue with an Ecofriendly Solvent: Use of 

FTIR And Chemometrics To Differentiate Pectins 

According to Degree of Methyl Esterification. 

Food Hydrocolloids, 107, 105921.  

Sarandi, R. R., Alhusna, Y., & Pandia, S. (2015). 

Production of Pectin From Yellow Passion Fruit 

(Passiflora edulis). Jurnal Teknik Kimia, 4(4), 

71–76. 

Satyamaiah, G., Prasad, M., Chandrasekhar, M., 

Suhasini, D.M., Suryanaraya, C., Subha, 

M.C.S. and Chowdoji Rao, K. 2014. 

Miscibility Studies on Guargum/Pectin 

Blends. Indian Journal of Advances in 

Chemical Science, 2(2): 116-123. 
Sugita, P., Sjahriza, A., & Lestari, S. (2015). Synthesis 

and Optimization of Chitosan-Guar Gum Gel, 

Jurnal Natur Indonesia, 9(1), 32–36. 

Tahir, M., Safitri, I., & Suhaenah, A. (2019). Analysis 

of Pamelo Citrus Albedo Pectin as Adsorbent for 

Heavy Metals Lead (Pb), Cadmium (Cd) and 

Copper (Cu). Jurnal Farmasi Galenika, 5(2), 

158–165.  

Tanheitafino, S., Zaharah, T., & Destiarti, L. (2016). 

Chitosan Modification with Kaolin and Its 

Application as Lead(II) Adsorbent, Jurnal JKK, 

5(2), 33–42. 

Yantyana, I., Amalia, V., & Fitriyani, R. (2018). 

Lead(II) Metal Ion Adsorption Using Ca-Alginate 

Microcapsules. Al-Kimiya, 5(1), 17–26.  

Yapo, B. M., & Koffi, K. L. (2014). Extraction and 

Characterization of Highly Gelling Low Methoxy 

Pectin from Cashew Apple Pomace. Foods, 3(1), 

1–12.