Sorption of Aspirin from Aqueous Solutions using Rice Husk as Low Cost Sorbent

Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 1, Pages: 1-5

J. Environ. Treat. Tech.

ISSN: 2309-1185

Journal web link: http://www.jett.dormaj.com

Sorption of Aspirin from Aqueous Solutions

using Rice Husk as Low Cost Sorbent

Abdoulaye Demba N’diaye * and Mohamed Sid’Ahmed Kankou ²

¹Laboratoire de Chimie, Service de Toxicologie et de Contrôle Qualité, Institut National de Recherches en Santé Publique, BP

95, Nouakchott, Mauritanie

Unité de Recherche Eaux Pollution et Environnement, Département de Chimie, Faculté des Sciences et Techniques, Université

de Nouakchott Al-Aasriya, BP 880, Nouakchott, Mauritanie

Received: 31/08/2019

Accepted: 12/11/2019

Published: 30/02/2020

Abstract

The Rice Husk (RH) was used as low cost sorbent for the removal of aspirin by sorption from aqueous solution. The RH was

characterized by using the point of zero charge (pHpzc), Boehm titration and Fourier transform infrared spectroscopy (FTIR).

Batch sorption experiments are intended to identify the adsorption isotherms of aspirin on the RH. The experimental data were

fitted to the Langmuir and Freundlich isotherms. The Sum of the Squares of the Errors (SSE) and the correlation coefficient R

between the calculated and the experimental data by nonlinear regressive analysis were used. The Langmuir model better

described the isotherm data with the maximum Langmuir monolayer adsorption capacity was 47.03 mg g at pH 2. As a

conclusion, RH could be one of the low cost and environmentally friendly sorbent.

Keywords: Aspirin, Rice Husk, low cost sorbent, isotherms

waste materials from forest industries have been used

successfully as alternative to high cost commercial

activated carbon [12].

Therefore, in this study, a local agricultural, cheap,

ecofriendly, abundant and solid waste material Rice Husk

Introduction

Aspirin or Acetylsalicylic acid is a non-steroidal anti-

inflammatory drug used to treat pain, fever and

inflammation [1] and prevention of first myocardial

infarction, cardiovascular diseases, cancer and treatment of

human immuno-deficiency virus infection [2].As a result,

aspirin is also one of the most commonly detected

pharmaceutical compounds in the environment [3-5].

Several methods to treat pharmaceutical pollutants have

been reported, such as via electrochemical advanced

oxidation processes [6], photocatalysis [7], membrane

filtration [8] and adsorption process [9; 10]. However the

adsorption is seen as the most promising removal method

because of its versatility in removing different pollutant and

also its efficiency. In adsorption processes the cost of

commercial activated carbons may be limiting, creating

necessity to develop new materials with lower investment.

An alternative is the utilization of agricultural residues

directly as sorbents or as precursors to activated carbon

synthesis, since these materials are inexpensive, or even

free, available in large quantities and renewable [11]. Low-

cost sorbents including raw agricultural solid wastes and

(

RH) selected for the removal of aspirin from aqueous

solution. The point of zero charge (pHpzc), Boehm

titration, Fourier and transform infrared spectroscopy

(

FTIR) analyses were performed. The equilibrium data

were described by the Langmuir and Freundlich isotherm

models with using the nonlinear method.

Material and methods

.1 Aspirin solutions

All the solutions are prepared using pure aspirin and

distilled water. The stock solution is prepared by adding

00 mg of the active ingredient to 500 mL of distilled

water. Other concentrations are prepared by dilutions of the

stock solution and used to develop the standard curves. The

physico-chemical properties of aspirin are given in table 1.

Table 1: Physico- chemical properties of aspirin

Chemical name

Molecular formula

Molecular weight (g mol )

Water solubility (g L )

pKa

Acetylsalicylic Acid

C H 0

9 8 4

180.16

3.3 (20 °C)

3.5 (25 °C)

1.18

Corresponding author: Abdoulaye Demba N’diaye,

Laboratoire de Chimie, Service de Toxicologie et de

Contrôle Qualité, Institut National de Recherches en Santé

Publique, BP 695, Nouakchott, Mauritanie. E-mail :

abdouldemba@yahoo.fr.

-1

Log Kow

Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 1, Pages: 1-5

.2 Preparation and characterization of RH

The agricultural wastes, RH, are collected from the

number of identical sites. The Freundlich model is

commonly used to describe the adsorption characteristics

for a heterogeneous surface [17]. The Langmuir and

Freundlich models can be expressed as (2) and (3),

respectively:

south of Mauritania. RH was crushed, sieved, thoroughly

rinsed with distilled water and then dried at 105 °C for 2 h

until reaching a constant weight. Finally, the RH was

powdered, sieved (< 100 µm) and stored in desiccator

before use (figure 1).

q K C

(2)

q_e

 K C

L e

/ n

q  K C

(3)

where q

and k

are Langmuir constants related to

adsorption capacity and affinity of the binding sites,

respectively. k and n are Freundlich constants representing

adsorption capacity and the energy of adsorption

effectiveness, respectively.

The factor of separation of Langmuir, R , which is an

essential factor characteristic of this isotherm is calculated

by using the relation (4):

Figure 1: RH before and after grounding

The point of zero charge (pHpzc) of the RH was carried

out [13] and the surface area was obtained using Sears

method [14]. The surface acidic and basic functional groups

of the RH were determined by the acid-base titration

method proposed by Boehm [15]. The samples of RH were

analyzed by the Fourier transform infrared spectroscopy

1 k C )

(4)

R 

(

L 0

where C

and q

is the higher initial concentration of aspirin, while

is the Langmuir constant and the maximum

(

FTIR) to determine the surface functional groups. The

wavenumber scanning is in the range of 650–4,000 cm .

-1

adsorption capacity respectively. The parameters indicate

the shape of the isotherm as follows: R values indicate the

type of isotherm. When R = 1 adsorption is linear; when 0

< R < 1, it is favourable, when R = 0, it is irreversible,

.3 Adsorption isotherms

The sorption isotherms at ambient temperature (25 °C)

are obtained by mixing (70 rpm), for 180 minutes, 0.5 g of

sorbent with 50 mL of aspirin solutions with different

while to be unfavorable, while when R > 1, it is

unfavorable.

The correlation coefficient R²and the Sum of the

Squares of the Errors (SSE) analysis is used to fit

experimental data with isotherm using the Excel Solver

determined by following equations (5) and (6),

respectively:

concentrations varying from 10 to 100 mg L . The pH of

the solutions was adjusted using a pH-meter to constant

values by drop-wise addition of 0.1 M HCl or 0.1 M NaOH

solutions. At the end of each experiment the agitated

solution mixture was micofiltered using micro filter and the

residual concentration of aspirin was determined by High

Performance Liquid Chromatography (HPLC). Mixture of

acetonitrile-water (25:75 v/v) adjusted to pH 2.5 with

phosphoric acid was used as a mobile phase at a flow rate









q -q

exp mod

(5)

R =100 1-



q -q

exp

avr



-1

of 2 ml min [16] at a selected wave length of 222 nm.

The adsorbed quantity at equilibrium (q ) is calculated

according to the following equation (1):



mod

SSE=



q  q

exp

(6)

-1

where qexp (mg g ) is equilibrium capacity from the

experimental data, qavr is equilibrium average capacity from

the experimental data and qmod is equilibrium from model.

C C_eV

 

(

q 

So that R ≤ 100 – the closer the value is to 100, the more

where:

perfect is the fit.

-1

q : quantity of aspirin per g of RH (mg g ),

-1

: initial solution concentration of aspirin (mg L ),

3 Results and discussion

-1

: equilibrium solution concentration of aspirin (mg L ),

3.1 Characterization of RH

m: the RH weight (g),

V: Volume of the solution (L).

The physical and chemical characteristics of RH

sorbent are described in table 2. The quantification of the

RH sorbent by Boehm titration reveals that the sorbent has

also the greatest content of acidic surface than the basic

surface groups. The predominance of acidic surface is

confirmed by pHpzc value of 5.8. The retention area for RH,

without any thermal and /or chemical process, is found to

Adsorption isotherm gives an idea about the feasibility

of a sorbate–sorbent system. In this work Langmuir and

Freundlich models were tested for describing the

experimental results. The Langmuir isotherm is valid for

monolayer adsorption onto a surface containing a finite

Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 1, Pages: 1-5

−1

be 5.6 m g . To determine the surface functional groups

of RH, its FTIR spectrum is obtained as shown in Figure 2.

O–H stretching of the hydroxyl of the alcohols groups and

The values of R are compared, Langmuir isotherm are

shown to have slightly higher than Freundlich isotherm.

The lowest SSE value further confirmed the suitability of

Langmuir model in describing the equilibrium data,

suggesting the existence of monolayer adsorption of aspirin

onto RH. Furthmore, it can be seen from table 3 that all

-1

bonded hydroxyl groups of cellulose: 2925 cm .

Table 2: Physical characteristics of the RH

Parameters

values of K

confirms that the adsorption of aspirin onto RH. It is

interesting to note that the value of K < 0.1 is a sign of low

L L

, R and 1/n are in between zero and one. This

Value

pHpzc

5.8

-1

Total surface acidity (meq g ) 0.600

Total surface basicity (meq g ) 0.155

Specific surface (m g )

Particle size (µm)

-1

surface energy, which indicates stronger bonding between

aspirin and RH sorbent.

−1

5.6

< 100

The peak at 2854.3 cm⁻¹was assigned to C–H

asymmetrical stretching of methyl groups on the surface of

2,5

-1

RH adsorbent. Peak at 1743.9 cm (C =O stretching of

-1

Experimental data

Langmuir

COOH). The peak lying in the region of 1036.6 cm shows

the presence of Si-O-Si linkages. The analysis of the FTIR

spectrum showed the presence of carboxyl and hydroxyl,

these functional groups may be the major sorption sites for

aspirin removal.

Freundlich

Ce (mg L^-¹

)

Figure 4: Langmuir and Freundlich non linear for RH at pH 7

Experimental data

Langmuir

Freundlich

Ce (mg L^-¹

)

Figure 5: Langmuir and Freundlich non linear for RH at pH 12

Figure 2: FTIR Spectrum of RH

Table 3: Isotherm parameters with nonlinear methods

.2 Adsorption isotherms

The adsorption isotherm gives an idea of the

Models

47.03

0.0011

0.90

33.36 17.30

0.00150.0038

0.87 0.72

equilibrium behavior of an aspirin–RH system. Figures 3, 4

and 5 shows the experimental equilibrium data and the

predicted theorical isotherms for the sorption of aspirin

onto RH at pH 2, 7 and 12, respectively. The values of

isotherm parameters that are studied in this work are shown

in Table 3.

Langmuir

SSE

R (%)

0.0055

99.51

0.81

0.00180.0119

99.97 99.81

0.87 0.72

1/n

0.108

0.104

98.24

0.077 0.154

0.02420.1189

99.52 98.01

Freundlich

SSE

R (%)

The best pH for the adsorption of aspirin is pH 2 which

is the initial pH of aspirin without addition of NaOH. A

decrease in adsorption was observed with an increase in

Experimental data

Langmuit

-1

pH. The adsorption capacity decrease from 47.03 mg g at

Freundlich

-1

pH 2, to 33.36 and 17.30 mg g at pH 7 and 12. The same

finding was reported from previous study where the

adsorption of aspirin favours a more acidic solution [9; 10].

The pHPZC is an important parameter for biosorbent to

characterize the sensitivity to the pH and their surface

charges. The pHpzc value is a key factor in the electrostatic

Ce (mg L^-¹

)

Figure 3: Langmuir and Freundlich non linear for RH at pH 2

Journal of Environmental Treatment Techniques

2020, Volume 8, Issue 1, Pages: 1-5

interactions between sorbate and sorbent. The pHPZC of RH

was found to be 5.8. This means that at pH more than 5.8,

the RH sorbent surface will be negatively charged. Aspirin

is a weak acid (pKa = 3.5) and undergoes partial

deprotonation in water to produce negatively charge ions

[2] Ritu N., Asheesh S., Dinesh B. Aspirin: an overview of

randomized controlled trials. Int J Res Pharm Sci, 2012; 2:53–

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environmental water samples by using silica supported Fe3O4

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(

figure 6). By increasing the pH of aspirin solution, the

surface of RH and aspirin will be negatively charged

resulting in electrostatic repulsion which hindered the

adsorption [1; 18].

[4] Tewari S., Jindal R., Kho Y. L., Eo S., Choi, K. Major

pharmaceutical residues in wastewater treatment plants and

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5] Gumbi B. P., Moodley B., Birungi G., Ndungu P. G. Detection

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Chemosphere, 2017, 168, 1042–1050.

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6] Feng L., Van Hullebusch E. D, Rodrigo M.A , Esposito G.,

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Figure 6: Protonated (a) and unprotonated (b) aspirin structure [19]

electrochemical advanced oxidation processes.

A review.

Chem Eng J., 2013; 228: 944–64.

Moreover, the interactions between sorbate-sorbent are

strongly influenced by medium pH. Which explain RH

adsorption drop from 47.03 mg g at pH 2 to 17.30 mg g

[

7] Dalrymple OK, Yeh D.H., Trotz M.A. Removing

pharmaceuticals and endocrine-disrupting compounds from

wastewater by photocatalysis. J Chem Technol Biotechnol

2007; 82: 121–34

[8] Yoon Y., Westerhoff P., Snyder S.A, Wert E.C, Yoon J.

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9] Mukoko T., Mupa M., Guyo U., Dziike F. Preparation of Rice

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Mukoko et al., J Environ Anal Toxicol. 2015, S7

[10] Wong S., Lee Y., Ngadi N., Inuwa I. M., Mohamed, N. B.

Synthesis of activated carbon from spent tea leaves for aspirin

removal. Chinese Journal of Chemical Engineering, 2018, 26

-1

at pH 12. The same finding was reported by Moreno-

Castilla (2004) [20]. Best adsorption capacity obtained for

-1

RH occurred at pH 2 corresponding to 47.03 mg g .This

value is inferior than that reported by Hoppen et al. (2018)

[

21] for aspirin onto activated carbon of babassu coconut

[

-1

mesocarp with 72.441 mg g at pH 2. Value attained for

RH is lower than that obtained by Ferreira et al. (2015) [22]

for paracetamol adsorption with 64.75 mg g and 58.91 mg

-1

at pH 2 onto activated carbons of dende and babassu

coconut mesocarp, respectively. Similarly, the capacity of

aspirin adsorption onto RH is lower than that obtained by

Portinho et al. (2017) [23] for caffeine adsorption with

(5), 1003–1011.

-1

[11] Yahya M.A., Al-Qodah Z., Ngah C.W.Z. Agricultural bio-

waste materials as potential sustainable precursors used for

activated carbon production: a review. Renew. Sustain. Energy

Rev.2015, 46, 218e235.

[12] Ali I., Asim M., Khan T.A, Low cost adsorbents for the

removal of organic 617 pollutants from wastewater, J.

Environ. Manage. 2012, 113, 170–183,

13] Roudani A., Mamouni R., Saffaj N., Laknifli A., Gharby S.

Faouzi A.. Removal of carbofuran pesticide from aqueous

solution by adsorption onto animal bone meal as new low cost

adsorbent. Chemical and Process Engineering Research,

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8.633 mg g at pH 2 onto Grape Stalk. Like other

pharmaceuticals, for to improve the retention capacity of

aspirin, the setting up of activation processes (thermal and /

or chemical) of the RH is necessary.

Conclusions

The aim of this study was to investigate the adsorption

[

capacity of aspirin onto RH. The RH was characterized by

using pHpzc, Boehm titration and FTIR. The isotherm data

of aspirin retention give a good ﬁt with Langmuir model

and shows

monolayer adsorption. The maximum

[14] Yadav S., Tyagi D. K., Yadav O. P. Equilibrium and kinetic

studies on adsorption of aniline blue from aqueous solution

onto rice husk carbon. International Journal of Chemistry

Research, 2011, 2 (3), 59–64.

adsorption capacity obtained for the RH is 47.03 mg g at

pH 2. The present study showed that the powdered RH is a

promising sorbent for the removal of aspirin from aqueous

solution, since the raw material RH was easily available in

large quantity and the treatment method of biomaterial

seemed to be economical.

[

15] Evangelin D.C, Naren S.V., Dharmendirakumar

F., Comparison of the surface features of the three

chemically modified silk cotton hull activated carbons. Orient.

J. Chem.2012, 28 (4), 1761–1768.

[

16] Franeta J. T., Agbaba D., Eric S., Pavkov S., Aleksic, M.,

Vladimirov, S. HPLC assay of acetylsalicylic acid,

paracetamol, caffeine and phenobarbital in tablets. IL

Farmaco, 2002, 57 (9), 709–713.

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