







































P. Dias & BM. Siddique /Future Sustainability                                                                              May 2025| Volume 03 | Issue 02 | Pages 
26-34 

26 

 

 

 

Article 

Developing porous copper/aluminium-chitosan 

biosorbent hydrogel beads for the removal of 

phosphate from wastewater 
Panchali Dias, Md Bazlul Mobin Siddique* 

Faculty of Chemical Engineering and Science, Swinburne University of Technology, Sarawak, Malaysia 

               A R T I C L E   I N F O 
 

Article history: 
Received 30 January 2025  
Received in revised form 
06 March 2025 
Accepted 18 March 2025 
 
Keywords:  
Chitosan-based hydrogel, Phosphate removal, 
Hydrophilic beads, eco-friendly water treatment 
 
*Corresponding author 
Email address: 
msiddique@swinburne.edu.my 
 
 
 
DOI: 10.55670/fpll.fusus.3.2.4 
 

A B S T R A C T 
 

Excess phosphorus is one of the principal causes of eutrophication, which 

causes severe ecological imbalance and harm to human health. In this study, 

several chitosan (CS)/copper and aluminum (CNT, ACH) hydrogel beads were 

created and tested for phosphorus removal. Further Microcrystalline cellulose 

and Cellulose Nano Fiber were also used to create stable CS/CNT - ACH hydrogel 

beads. The optimized CNT/CS settings with 0.2 mg CNT demonstrated 

outstanding removal efficacy. It effectively removed phosphate from an 

aqueous solution with a pH range of 4.5-5.5 using a completely mixed batch of 

0.01M sodium dihydrogen phosphate, with 80% phosphate absorption 

achieved after 48 hours of contact time. The measured maximum adsorption 

capacity at pH 5.5 solution was 11.39 mg per 0.0206g of the beads (10 beads). 

The FTIR study revealed that all three varieties of synthesized beads have a 

healthy microstructure. Furthermore, the findings of the kinetic study indicated 

a low absorption rate at 15ºC and a moderate absorption rate at 45ºC. The 

adsorbent efficiently removed phosphate during 12 hours of contact time, 

according to a batch adsorption study, using 20 beads weighing 0.0412g. 

Electrostatic attraction and ion exchange can both be responsible for phosphate 

absorption. Furthermore, 10 of the 21 control MCC and CNF beads could 

remove more than 60% phosphate after 48 hours of contact time with identical 

solute distributions. This adsorbent might be deployed to effectively treat 

phosphorus-contaminated water to prevent eutrophication. 

 

1. Introduction 

Regardless of the fact that water covers 71% of the 

earth's crust, we humans manage to endanger the natural 

equilibrium of water bodies across the world by releasing 

wastewater. For a multitude of reasons, the Earth's limited 

supply of fresh water, which accounts for around 2.5% of total 

water content, must be safeguarded. According to the UN, 

approximately 80% of wastewater created by all urban 

housing projects, big-scale production chains, and even small-

scale manufacturing enterprises, among other things, is 

released into natural water bodies untreated. This research 

focuses on the chemical component phosphate, which 

becomes contaminated in natural water bodies by 

wastewater discharge due to its widespread use in everyday 

goods. To design a long-term sustainable engineering solution 

for removing this chemical from a regulated wastewater 

sample. Phosphorous is a nonmetal element having a valency 

of 5+. When fluorapatite, often known as phosphate rock, is 

exposed to acid, it creates phosphoric acid. Orthophosphate, 

polyphosphates, and organically bound phosphates are the 

three types of phosphates. The natural phosphate cycle is 

critical for animal and plant health, and its imbalance arises 

when it is released in bulk quantities after human ingestion. 

All of these kinds are extra phosphate deposits that disrupt 

the normal chemical equilibrium. Phosphorous contributes 

significantly to water pollution, with negative impacts 

ranging from eutrophication, ocean acidification, and algae 

overgrowth to suffocating of some aquatic animal species, 

shortening their life span. Organically bound phosphates are 

primarily discharged in conjunction with waste solids or 

organic waste [1]. Phosphorous has a noteworthy impact on 

human health degradation, ranging from dehydration and 

Future Sustainability 

Open Access Journal 

https://doi.org/10.55670/fpll.fusus.3.2.4 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

May 2025| Volume 03 | Issue 02 | Pages 26-34 

Journal homepage: https://fupubco.com/fusus 

 
ISSN 2995-0473 

mailto:msiddique@swinburne.edu.my
https://doi.org/10.55670/fpll.fusus.3.2.4
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P. Dias & BM. Siddique /Future Sustainability                                                                              May 2025| Volume 03 | Issue 02 | Pages 26-34 

27 

 

diarrhoea to renal disease and endothelial dysfunction [2]. 

The significance of creating technology for chemical removal 

from effluent wastewater has long been explored and 

acknowledged. There have been several ways based on its 

scientific foundation. Physical removal methods such as 

adsorption and magnetic field use, chemical removal methods 

such as precipitation with lime or aluminium chromate, 

biological removal methods such as biomass adsorption and 

reagent use, physical-chemical removal methods, and even 

chemical-biological removal methods have all been studied 

and put into practice. This study focuses on the physio-

chemical removal approach, specifically the inclusion of 

Hydrogel in anion removal. Over the last few decades, 

researchers have created various hypotheses, proposed 

numerous chemical compositions, and even succeeded in 

many situations with phosphate removal using the physio-

chemical removal approach. The first limitation of present 

techniques appears with phosphate removal utilizing metal-

impregnated hydrogels. Phosphate anion has a valency of 3, 

and there haven't been many viable methods for eliminating 

it at a high percentage. The second limitation is that the effects 

of additive variations on phosphate absorption are not clearly 

examined. The majority of investigations use one kind of bead 

and one set type of additive (metal or non-metal). This makes 

guessing the absorption levels of a few distinct types of beads 

prepared for a substantial sort of anion elimination difficult. 

Hydrogel beads prepared in this study are simple structures 

of the biopolymer 'Chitosan' integrated with cationic ions 

such as Copper and Aluminium, which can conceive a gel 

bead-like structure after several experimental steps, with a 

hollow sponge-like middle sector with hydrophilic abilities 

due to its surface having water permeable qualities. Existing 

approaches do not generate significant outcomes when 

adding hydrogel beads in phosphate removal. The research 

gap is addressed by attempting to synthesize and characterize 

various types of hydrogel bead structures incorporating 

copper and aluminium, on their absorbance and ability to 

absorb targeted anions in a controlled experimentation 

series, with the hope of also monitoring the beads' response 

to stimuli changes. 

2. Literature review 

2.1 Phosphate in water 

Water is the 'universal solvent' due to its ability to 

dissolve more substances than any other liquid on earth. 

Phosphates occur in many ways, leading to adverse effects on 

mankind as well as flora and fauna. Depending on its 

contamination action, they can be listed into three different 

methods of contamination. 'Point source' pollution through 

phosphates is the way that they end up in natural water 

bodies in bulk loads without any objection, decay time, or 

treatment. Oil refinery effluents, wastewater from process 

industries such as dye and acid manufacture, chemical 

dumping by big-scale laboratories and supply networks, and 

medical waste from any institution of medicine are the finest 

examples. Phosphate contamination is caused by the late 

addition of phosphate-rich effluents to water bodies that do 

not originate from a single source or site. Excess fertilizer or 

weedicides used in agriculture, mine explosions that 

contaminate ground waterways, and landslides or volcanoes 

that are natural risks with a large release of phosphates that 

wash away to water over time are instances of pollution. 

Transboundary pollution is described as contamination that 

begins in one country but travels to another country's water 

sources. Oil spillage on ocean or river water, chemical 

deposits (medicine/cosmetics) from accidents on 

ships/boats traveling by water, and chemical manufacturing 

fumes carried away by winds or rain are the greatest 

examples. As previously established, all of these pollution 

strategies have negative effects on plant and animal species 

irrespective of water ecosystems. Phosphorus is a limiting 

nutrient needed for all plant development, including aquatic 

plants and algae. Excess concentrations can induce algal 

blooms, especially in rivers and lakes. A lake with a 

concentration of less than 0.010 mg/L is considered 

oligotrophic, whereas one with a concentration between 

0.010 and 0.020 mg/L is considered mesotrophy, and 

concentrations greater than 0.020 mg/L are classified as 

eutrophic [3]. The acceptable phosphate levels in Malaysia 

are 0.1 mg/L and 0.2 mg/L, according to the National Water 

Quality Standards, Malaysia. These two concentrations are 

divided into two water classes, and samples with 0.1 mg/L 

phosphorous content fall into water CLASS IIA/IIB. The 

samples with a phosphorus value of 0.2 mg/l fall into the 

water CLASS III. To be clear, CLASS IIA/IIB water is 

appropriate for water supply after simple treatment, for 

delicate aquatic species, and for recreational body contact. 

After considerable treatment, CLASS III water is appropriate 

for water supply, common species of fish, and cattle drinking. 

2.2 Existing methods of phosphate removal 

2.2.1 Ion exchange 

This method is applied in small-scale industries, 

municipal drinking water treatment units, and even in-home 

water softeners. Ion exchange requires passing the water 

through a specialized ion exchange resin in a closed vessel. 

The surface of the resin involves active sites, which help 

remove the constituent of interest in exchange for other 

feasible, less effective ions. Once all the active sites of the resin 

are used, the resin must be restored or regenerated, and since 

the used resin is a strong anion resin, NaCl can be used for 

restoration purposes. An example of this application is if a 

water flow with 5 mg/L phosphate ions is introduced to the 

ion exchanger, the treated water would contain less than 2 

mg/L of phosphate in the system [4]. 

2.2.2 Magnetic field method 

Here, phosphates are bound to a reagent in the 

insoluble compound. Once the magnetic field is activated with 

magnetic material addition to the water system, it isolates the 

phosphate-containing sediment.  

2.2.3 Electric coagulation method 

Here, electrodes are used to isolate the phosphates 

inside the water system. Electrodes of 2 types can be used, 

iron-aluminium or steel. This method ensures an easier 

extraction of phosphates too.  

2.2.4 Chemical removal methods 

A) Adding aluminium chromate to wastewater in the 

presence of an alkali generates the following reactions, 

Al2(CrO4)3 + 6HCO3
−  →  2Al(OH)3 + 3CrO4

2− +  6CO2  (1) 



P. Dias & BM. Siddique /Future Sustainability                                                                              May 2025| Volume 03 | Issue 02 | Pages 26-34 

28 

 

Al2(CrO4)3. 14H2O +  2PO4
3−  →  2AlPO4 ↓ +3CrO4

2− + 14H2O  (2)  

These reactions will fight for the aluminium ions dispersed 

after the addition of aluminium chromate. The aluminium 

hydroxide flakes attract the aluminium phosphate particles 

and colloid particles of solid impurities.  

B) Adding 3 valent iron salts as a coagulant 

FCl3 + PO4
3−  →  FePO4 + 3Cl−                              (3) 

In here the ferric phosphate particles sediment. Any excess of 

ferric ions will produce iron hydroxide. Iron hydroxide will 

attract ferric phosphate particles and other particles and 

sediment itself.  

C) Adding calcium hydroxide as a coagulant  

Ca(OH)2 + HCO3
−  →  CaCO2  ↓  + H2O + OH−                     (4) 

5𝐶𝑎 + 4𝑂𝐻− + 3𝐻𝑃𝑂4  →  𝐶𝑎5𝑂𝐻(𝑃𝑂4) ↓  +3𝐻2𝑂                (5) 

In here lime readily reacts with any bicarbonate ions in the 

water complex. In addition, it also reacts with phosphates. 

The orthophosphates are precipitated with the help of 

calcium ions and produce oxyapatite. When the pH value of 

the water body increases, the solubility of calcium oxyapatite 

decreases, and the removal of phosphate increases (pH > 9.5 

is the ideal). 

Biological methods are said to give the best removal 

percentage of phosphorous from water complexes. There are 

different approaches with different efficiencies in the matter, 

varying the effective removal percentages from 20% - 50%. 

This percentage can be enhanced up to 95% with the current 

technological maturity. Such biological treatment approaches 

are Phostrip, А/О (Anaerobic–Oxic), and EASC (Extended 

Anaerobic Sludge Contact process). However, there are 

several biological – chemical applications as well [5]. They all 

pose higher quality compared to chemical treatment and 

biological treatment separately. They each differ from each 

other by reagent source and reagent composition. 

2.2.5 Hydrogel beads 

Hydrogel beads are cross-linked polymers that have 

hydrophilic traits, and once immersed in aqueous solutions, 

they swell by attracting water inside the 3D structure. The 

component must account for at least 10% of the total weight 

of the material to be called a hydrogel [6]. Many alternative 

theories have been developed over the years to assist in 

predicting the structural result of hydrogels, which gives us 

the gel's elasticity value, porosity, and pore size of the 

hydrogel network. All these theories consider enthalpy, 

entropy, and other thermodynamic factors in order to 

establish the structure and pore sizes of hydrogels, and 

computer modeling methods may then be utilized to 

accurately create the hydrogel intended. Hydrogels are 

classified as those made from natural polymers, those made 

from synthetic polymers, and those made by modifying 

natural polymers with synthetic linkers (semi-synthetic 

hydrogels) [7]. As a result, hydrogels can undergo structural 

transformations in response to a stimulus, which can be 

chemical or physical. Chemically prepared gels rely on 

covalent bonding to introduce the integrity required to form 

a gel structure [8].  

The gels can be cationic, anionic, or neutral depending on 

the ionic charges on the bonded groups. By stacking various 

hydrogel layers that each react to a particular stimulus, 

shape-changing hydrogels may be constructed [9]. Hydrogels 

may also be classed as homopolymer or copolymer based on 

the different polymerization processes such as suspension, 

block, solution, and emulsion. Homopolymers have just one 

kind of monomer in their structure, and depending on the 

nature of the monomer and the polymerization process 

employed, they may have a cross-linked structure. 

Copolymeric hydrogels are made up of two types of 

monomers, at least one of which is hydrophilic. An 

interpenetrating network (IPN) can be formed by joining two 

polymers, provided that one of them is already present in the 

solution [6, 10]. Hydrogel is found in three different types: 

resins, films, and nanocomposites, and in an attempt to 

improve its adsorptive properties, many other chemicals can 

be integrated into the network. According to the literature 

survey, it is visible that hydrogels have a high potential to 

succeed with their applicability in wastewater treatment for 

intended anion removal [11]. The morphology of hydrogel 

beads suggests that their size can vary from 20nm – 5mm 

with porous, rough outer surfaces [12]. Their swelling ratio is 

mainly dependent on the pH of the solution and retention 

time. Biopolymers such as polysaccharides and polypeptides 

have garnered a serious welcome in the hydrogel bead 

production industry. 

2.2.6 Biopolymers  

There are various biopolymers incorporated in 

biodegradable research work nowadays. Within an organism, 

these various polymers are made up of numerous individual 

monomers or units. They are often sourced from plants and 

animals, making them both biodegradable and easily reusable 

for different purposes. Incorporating this feature of 

biodegradability came into use after the era of sustainable 

engineering started. Hence researchers have thrived in 

finding engineering solutions incorporating biodegradable 

materials. Attempting the use of biopolymers in adsorptive 

studies came into light around the early 2010s. Since its 

application has improved vastly in fields such as tissue 

engineering. Hydrogels are employed in a variety of 

industries due to their unique architectures and compatibility 

with various operating conditions. Hydrogels are 

distinguished from other biomaterials by their flexibility, and 

their versatility is unparalleled since their applications vary 

from industrial to biological. Drug delivery, dye, and heavy 

metal removal, scaffolds in tissue engineering, and even 

contact lenses are some of the major uses of hydrogels [6, 10]. 

Biopolymers, as previously discussed, are critical in the 

development of useful and novel hydrogels with improved 

biocompatibility [13]. Sugar-based polysaccharide 

biopolymers and protein-based polypeptides have both been 

used extensively in the development of novel biodegradable 

and biocompatible hydrogel materials. Polysaccharides 

utilized in the creation of hydrogels include chitosan, 

cellulose, alginate, and glycosaminoglycans. Polypeptides 

may contain collagen, gelatine, and other proteins [14]. 

 



P. Dias & BM. Siddique /Future Sustainability                                                                              May 2025| Volume 03 | Issue 02 | Pages 26-34 

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2.2.7 Hydrogel bead application in wastewater 

treatment 

There is a considerable number of works done in the 

area of hydrogel beads incorporated in wastewater 

treatment. However, there were some articles which 

provided an insight for the research. A study on phosphate 

removal from a complex water environment study 

incorporated Zr-bentonite hydrogels [15]. Testing on anion 

selectivity was further carried out by introducing other 

multivalent anion salts. Another study discusses the 

application of polyacrylic-based hydrogel beads for heavy 

metal removal [16]. These acrylic-based polymer hydrogel 

beads have garnered attention due to their applicability in 

pollutant adsorption and heavy metal extractions. This 

research further elaborates on the different approaches that 

can be taken into consideration when synthesizing acrylic 

hydrogels. An in-depth analysis of the thermodynamic factor 

affecting the hydrogel beads is also explained. Researchers 

attempted the removal of boron using modified chitosan 

hydrogel beads [17]. This was done using a synthesis of 

manganese chitosan hydrogel beads. This research was done 

in an attempt to clear freshwater samples entering irrigation 

systems. Results show a potential in commercial application 

for improving water quality. 

2.2.8 Materials of application  

Chitosan (CS), Copper nitrate trihydrate (CNT), 

Aluminium chloride hexahydrate (ACH), Microcrystalline 

cellulose (MCC), and Cellulose Nanofiber were used in this 

study to synthesize hydrogel beads (CNF). They are chosen 

after careful examination of the selected pollutant - 

'Phosphate' in water, its affinity to the metallic ions inside the 

hydrogel beads, the ability of the biopolymer to absorb and 

desorb water without hesitation, the adaptability of the 

biopolymer and enhancers, and the required strength of the 

hydrogel beads. Furthermore, extensive research and 

theories advanced by other researchers' work on hydrogel 

beads, such as [8,15,16] and many others, aided in finalizing 

the proper salts of application for each metal and the 

methodology of application of each additive and enhancer to 

the hydrogel prior to bead preparation.  

Chitosan: Chitosan is a polysaccharide with high 

antibacterial properties that is biocompatible, biodegradable, 

and non-toxic. Chitosan, hence, has many uses, including 

those in medicine, agriculture, food preservation, nutritional 

supplementation, cosmetics, and wastewater treatment. A 

polysaccharide generated from chitin is chitosan. 

Copper: Copper is a reddish-brown metal with a cubic 

crystalline structure. It is malleable, ductile, and an extremely 

good conductor of both electricity and thermal energy. It has 

a low chemical reactivity and falls under the category of 

transition metals in the periodic table. The molecular weight 

of copper is 63.55 g and has a density of about 8.9 gcm-1. The 

most common ionic form is when the atom releases 2 

electrons in the hope of ionic bond formation. Therefore, the 

most abundant cation type is the Cu2+ ion.  In this research 

this ion type is used as the metal dispersed in the hydrogel 

beads. Why use copper is due to its high affinity to form an 

attraction with negatively charged phosphate ions. This has 

promoted the amount of phosphate removed from the water 

sample drastically. The copper nitrate trihydrate of 2+ copper 

was the best choice since it showed very good results during 

experimentation. 

Aluminium: Although it makes up 8.1% of the Earth's crust, 

aluminum is rarely encountered in nature alone. It is typically 

present in minerals like cryolite and bauxite. These are 

aluminum silicate minerals. The Hall-Héroult technique is 

used to remove the majority of aluminum used in commerce. 

Given that aluminum is not a particularly strong metal on its 

own, it is frequently utilized as an alloy. Copper, manganese, 

magnesium, and silicon alloys are light but robust. They play 

a crucial role in the development of hydrogel and is often used 

in drug delivery and dye removal applications of hydrogel. 

The introduction aluminum can enhance the hydrogel’s water 

affinity percentage by high numbers. One of the reasons it is 

utilized as a crosslinker in the experimentation for some 

types of beads. 

Microcrystalline cellulose: Cellulose (C6H10O5) n is one of 

the most widely distributed organic polymers in nature. It is 

a crucial structural component of oomycetes, many kinds of 

algae, and green plants' main cell walls. The polysaccharide is 

composed of a linear chain of (1-4) linked d-glucose units 

numbering from several hundred to several thousand. 

Utilizing various processes, including oxidation, 

etherification, and esterification, which transform generated 

celluloses into derivatives of cellulose, many techniques of 

cellulose extraction have been developed [18].  

Cellulose nanofiber: Emerging nanomaterials called 

naturally generated cellulose nanofibrils (CNFs) have high 

strength, large surface area, and variable surface chemistry, 

enabling regulated interactions with the biological, 

nanoparticle, small molecule, and polymer materials. While 

the hydrophilicity of the nanocellulose interface has made it 

challenging to use CNFs as reinforcing agents in conventional 

plastics, it has been a significant advantage in the 

development of reinforced or structured hydrogel composites 

(or, when dried, aerogels) that exhibit mechanical 

reinforcement as well as a variety of other desirable 

properties [19]. The banana pseudo Cellulose nanofiber 

(CNF) used in this research was obtained by a master’s 

student at Swinburne University of Technology Sarawak. 

3. Methodology 

The fabrication procedure was conducted in 4 separate 

parts, which include the preparation of Control CS – CNT/ACH 

beads, the preparation of MCC CS – CNT/ACH beads, the 

preparation of CNF CS – CNT/ACH beads, and lastly, the 

conditioning of the film. The testing procedures include FTIR 

analysis, Absorbance performance, Temperature sensitivity, 

and Batch adsorption study. All the beakers, flasks, crucibles, 

and petri dishes were washed with distilled water and dried 

in an oven for 1 hour at 60ºC prior to use.  

3.1 Fabrication of hydrogel beads 

Preparation of control CS – CNT/ACH beads: 9g of CS were 

dissolved in 450 ml of 2% (v/v) acetic acid solution to create 

a chitosan solution of 2% (w/v). Following complete CS 

dissolution, the solution was separated into 9 samples of 

50ml given in Table 1. The beads were synthesized into 9 

different types by using the below additive amounts.  
 

 



P. Dias & BM. Siddique /Future Sustainability                                                                              May 2025| Volume 03 | Issue 02 | Pages 26-34 

30 

 

Table 1. Distribution of additives for Types A – I 

 

Homogenous distribution was achieved by continuous 

stirring at 300rpm for 24 hrs of each hydrogel mixture. 18g of 

SH is dissolved in 900ml of DI water to create a 2% (w/v) SH 

solution and divided into 9 samples of 100ml SH solution. The 

hydrogel mixtures were added dropwise into each of the SH 

samples using a micro dropper to form the hydrogel beads. 

The prepared beads were left at continuous stirring at 

300rpm for 24 hrs inside the SH solutions to ensure cross-

linking.  

Preparation of MCC CS – CNT/ACH beads: The same steps 

for the hydrogel mixture preparation are carried out for 

Types A – F as control hydrogel beads. Then, prior to leaving 

for continuous stirring, 0.2 g of MCC is added. Steps are 

repeated from then onwards.  

Preparation of CNF CS – CNT/ACH beads: The CNF pulp is 

prepared by soaking 0.3g of CNF in 30ml of DI water and 

letting to soak for 2 hrs. Using the sonicator machine, 

preparation of CNF pulp is done, the settings used are   40% - 

50% amplitude (gradually increase), elapsed time 8 mins 20 

secs, Pulse 5/10 and total energy used is 8184Joules. The 

same steps for the hydrogel mixture preparation are carried 

out for Types A – F as control hydrogel beads. Then, prior to 

leaving for continuous stirring 5 ml of CNF pulp is added. 

Steps are repeated from then onwards.  

Conditioning of hydrogel beads: The 21 types of hydrogel 

beads synthesized were washed with DI water till pH 6.5 – 7.5 

is reached (tabulated in Table 2). The washed beads must be 

dried in an oven at 60 for 4 hrs. After drying, the beads are 

stored in a desiccator to avoid contact with air.  
 

Table 2. Twenty-one types of synthesized hydrogel beads 

 

 

3.2 Testing procedure  

Fourier transform infrared analysis: The chemical 

alterations and bonding of the different types of composite 

films were analyzed using FTIR spectra. The equipment used 

to conduct the FTIR was a Perkin-Elmer Spectrum 400 FTIR 

spectrophotometer. 

Absorbance performance: The absorptive studies were 

carried out on the percentage weight of water of the soaked 

beads and the percentage of phosphate removal using 

titration. A solution of 0.01M SDP is prepared by adding 1.56g 

of SDP in 1000 ml of DI water. Sixty-three samples of 15ml, 

each 0.01M SDP, are distributed, and 10 beads of each of the 

21 types of beads are suspended into 3 solutions per type. For 

water absorbance testing the dry weight before soaking and 

wet weight after soaking of the hydrogel beads are obtained. 

For the phosphate removal efficiency testing, the 21 types, 

each out of the 63, are kept for 12 hrs, 24 hrs, and 48 hrs, 

respectively. Using a 0.1M SH solution the samples of SDP are 

titrated in the presence of phenolphthalein and pH meter for 

accuracy. The experiment is repeated for 3 rounds to reduce 

the error percentage.  

Temperature sensitivity: Once the absorbance and 

phosphate removal efficiencies are calculated, the best type of 

beads can be identified. A selective experimentation is done 

to observe the absorbance performance of the beads under 

temperatures lesser than room temperature and higher than 

room temperature. The same steps as absorbance testing are 

carried out for Type A control beads to prepare 9 samples of 

15ml 0.01M SDP and 10 beads each. Three samples are left in 

the refrigerator set at 15 for 24hrs, 3 samples at room 

temperature for 24 hrs, and 3 samples sealed inside the oven 

at 45 for 24 hrs. The same steps of titration are followed at the 

end of 24 hrs using 0.1M SH.  

Batch adsorption study: Using the same selection Type, A 

control, selective experimentation is done to observe the 

absorbance performance of the beads as a pack of 10 beads, 

15 beads, and 20 beads for comparison of the absorbance 

fluctuations with the varying of no: of beads. The same steps 

as absorbance testing are carried out for Type A control beads 

to prepare 9 samples of 15ml 0.01M SDP and let 10 beads each 

of 3 samples for 24 hrs, 15 beads each of 3 samples for 24 hrs, 

and 20 beads 3 samples for 24 hrs. The same steps of titration 

are followed at the end of 24 hrs using 0.1M SH.  

4. Results and discussion 

4.1 Fourier transform infrared analysis 

According to the FTIR results, Figures 1, Figure 2, and Figure 

3 display the FTIR spectra of the produced chitosan 

composite beads packed with Copper (II) particles and the Al 

(III). The amide (C=O) stretch, the C-N stretch, the bending 

owing to N-H stretching, and the absorptions due to C-H 

stretching at around 3000 cm-1 and the C-H bending at around 

1300 cm1 are the characteristic peaks for chitosan. The C-O 

skeletal stretch typical of polysaccharides can be seen at 1100 

cm-1, and C-O antisymmetric stretching can be seen at 1000 

cm-1. Copper and Aluminium exhibit absorption bands at 700 

cm.  

 

Figure 1. FTIR plot of MCC hydrogel beads 



P. Dias & BM. Siddique /Future Sustainability                                                                              May 2025| Volume 03 | Issue 02 | Pages 26-34 

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Figure 2. FTIR plot for CNF hydrogel beads 

 

Absorbance performance 

According to the graph, it is visible that the percentage 

weight of water absorbed is highest in Type F CNF beads. This 

type consists of CNF and Aluminium as additives in the 

hydrogel mixture. Also, the lowest water absorbed is by Type 

A control beads. This type consists of only copper as an 

additive. These results suggest that the water absorbance 

when only copper is integrated is very low compared to the 

other samples with high water affinity moving from Types C 

to F. Types C to F are consisted of aluminium, and types C, D, 

E are consisting of both copper and aluminium. Also, it is 

noticeable that water affinity slightly increases with the 

addition of MCC into the beads. However, the affinity reduces 

when CNF is tallied with copper suggesting strong bonds 

between copper and CNF as a structure more than hollow 

spaces with lower bonding percentage.  

 

 

Figure 3. FTIR plot of control hydrogel beads 

 

Types H and Type I show a high affinity towards water 

due to their high concentration of chitosan compared to Type 

H with the usual chitosan concentration. In testing the 

percentage removal of phosphate, calculations were done 

using a simple titration of acid base. The first set of results 

was tested after 12 hours, and 5 types of beads had a 

percentage removal higher than 50% already. Then, after 24 

hours, the results showed that 13 samples had a removal 

percentage of 50% and above, but already 7 samples showed 

more than 60% removal efficiency. At the end of 48 hours, 10 

samples recorded a removal efficiency of above 60%.  This 

result shows as shown in Figure 4, the experiment was indeed 

a success in recording more than 10 bead types with the 

effective removal of phosphate from controlled wastewater 

samples.  Discussing further, the bead type A had the best-

recorded removal percentage since the beginning of testing. 

It had a 66.67% removal percentage after 12 hours, a 73% 

removal percentage after 48 hours, and successful removal of 

80% phosphate at the end of 48 hours (Figures 5, Figure 6, 

and Figure 7).  This can be due to the fact that it has the least 

amount of copper and no other additives blended, ensuring a 

strong hydrogel network.  The fewer the additives, the better 

the percentage removal across each bead type from A to I. 

4.2 Temperature sensitivity 

As the Type A control beads showed the best results in the 

general titrations, it was used to test the effects of the bead 

when external stimuli changed. Temperature fluctuations 

were chosen for the matter. The same type of bead was 

distributed into 9 samples and were placed at three different 

temperatures. The samples at room temperature showed the 

highest phosphate removal at the end of 48 hours.  
 

 

 

 

 



P. Dias & BM. Siddique /Future Sustainability                                                                              May 2025| Volume 03 | Issue 02 | Pages 26-34 

32 

 

 
 

Figure 4. Plot of percentage weight of water per bead type 

 

 

 

 
 

Figure 5. The plot of percentage removal of phosphate after 12 hrs 

  

 

 

 
Table 3. Percentage removal of Phosphate at different temperatures  

 

 

 

Figure 6. The plot of percentage removal of phosphate after 24 hrs 

  
 

 

Figure 7. The plot of percentage removal of phosphate after 48 hrs 

 

 

 



P. Dias & BM. Siddique /Future Sustainability                                                                              May 2025| Volume 03 | Issue 02 | Pages 26-34 

33 

 

The sample set at a lower temperature did not show any 

progress toward phosphate removal since the percentage 

was very poor, somewhere around 6.7%. The samples set at a 

higher temperature still was able to absorb some amount of 

phosphate. Compared to that of the samples at room 

temperature, it was less. However, the removal of 66.67% 

shows good numbers. This shows that the beads lose their 

anion removal efficiency, which is very noticeable at lower 

temperatures (Table 3). Anyhow, a slight increment would 

not affect the case of anion removal as much as low 

temperatures. This could be due to the gel's tendency to 

harden at lower temperatures, limiting the amount of water 

absorbed. Further resulting in lesser adsorption of 

phosphate. However, the best temperature for anion removal 

is room temperature.  

4.3 Batch adsorption study 

Similar to section 4.3, the batch adsorption study utilized 

the same type of bead, Type A control, for the study of the 

effect of the beads per sample. The results showed good 

progress when compared to one another. When the no of 

beads increased the absorption, the cap was reached at 12 

hours. When using 10 beads, the sample was only able to 

recover 66.67% of the total phosphates in the solution. 

However, as expected, when the number of beads was 

increased by 5, the absorption percentage was increased to 

73% (Table 4). As per expectation, the sample with 20 beads 

was titrated with just 0.3 ml of titrant. This means that it 

reached the absorption cap of 80% over the time period of 12 

hours.  

Table 4. Percentage removal of Phosphate for batch adsorption 

studies 

 

 

5. Conclusions 

This experimental research was a success, considering 
the fact that 10 bead types had a phosphate removal 
percentage higher than 60%. From the FTIR results, the 
favorable bonding of Chitosan to Copper and Chitosan to 
Aluminum was observed. Also, with the introduction of 
cellulose matter, the rigidness of the beads increased 
considerably. However, the enhancers did not show any 
progress towards the affinity of phosphate anion surpassing 
the control set of beads. The best bead type at the end of the 
experiment was identified to be Type A control, which 
successfully eliminated 80% of the phosphate in all samples. 
The same bead was then tested for temperature sensitivity 
and batch adsorption studies where at room temperature, the 
beads still showed an 80% removal rate, at 45 Celsius, it had 

lowered its affinity by almost 13%, dropping the percentage 
of phosphate removal up to 60.67% at 15 Celsius the beads 
did not show any affinity towards the phosphate anions 
resulting the percentage of removal to be as low as 6.67. In 
the batch adsorption studies, the same type of bead showed 
that the maximum adsorption capacity was 80%, where 10 
beads in 12 hours resulted in 66.67% absorbance, 15 beads in 
12 hours resulted in 73% absorbance, and 20 beads in 12 
hours resulted in 80% absorbance. 

Ethical issue 
The authors are aware of and comply with best practices in 
publication ethics, specifically with regard to authorship 
(avoidance of guest authorship), dual submission, 
manipulation of figures, competing interests, and compliance 
with policies on research ethics. The authors adhere to 
publication requirements that the submitted work is original 
and has not been published elsewhere. 

Data availability statement 
The manuscript contains all the data. However, more data will 

be available upon request from the authors. 

Conflict of interest 

The authors declare no potential conflict of interest. 

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