Water treatment receives wide attention due to its close relationship with the environment and its protection from pollutants. This study investigates the effectiveness of applying chitosan/essential oil/nanoemulsion (NE) hydrogel beads in water treatment, which were produced by combining chitosan and various NEs containing different fractions of mixed surfactants of tween 80 and span 20, oils of either clove or peppermint, and distilled water. The physicochemical properties were determined using the scanning electron microscope (SEM), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR). SEM images exhibited that the clove beads presented sharp edges with parallel lines of networks and uniform pores (6.947 ± 1.45 μm, coefficient of variation (CV) = 20%), whereas peppermint beads displayed a spongy surface with spherical pores (11.203 ± 3.34 μm, CV = 29%). DSC analysis revealed that both clove and peppermint beads were thermally stable until 100 °C. The FTIR curve of the beads displayed new peaks confirming chemical interactions between the chitosan and the constituents of the NE. The adsorption capacity of the beads for the copper sulfate and bromophenol blue was more than 50% achieved within 1 h at 25 °C. In conclusion, chitosan–NE hydrogel beads have promising potential for use in water treatment.

  • Synthesis of chitosan/peppermint oil/nanoemulsion (NE) beads.

  • Synthesis of chitosan/clove oil/NE beads.

  • The new materials have great potential to adsorb copper sulfate from the wastewater.

  • The new materials have great potential to adsorb bromophenol blue from the wastewater.

  • The new materials are inexpensive and easy to manufacture for water treatment applications.

Water treatment is considered a key component of environmental sustainability because it reduces the waste that is released into the ecosystem as well as generates energy by producing biogases such as methane while empowering the water treatment complex (Crini & Lichtfouse 2019; Ahmed et al. 2024). The primary goal of water treatment ensure the continuation of life on the planet by providing clean water to various living organisms. Water treatment can also contribute to the production of fertilizers by using the resulting biomass that forms from the sludge phase of water treatment. Some other environmental sustainability aspects can be achieved through water treatment such as disease prevention, reusing and recovering water resources, ensuring long-term availability and accessibility of water resources, and preserving the quality and quantity of different freshwater resources (Saleh et al. 2022; Obiuto et al. 2024).

Water treatment involves a diverse range of techniques, with some methods requiring less energy, such as coagulation and sedimentation, while others demand more energy, like membrane processes that provide superior removal efficiencies (Cheremisinoff 2019; Silva 2023).

The formation of hydrogels for wastewater treatment has recently attracted the manufacturing industries due to their cost-effectiveness and ease of production (Etale et al. 2023; Hossain et al. 2024). Hydrogel is a novel kind of polymer material that has a three-dimensional network porous structure. It may be used to remove heavy metal ions, dyes, and auxiliaries from dye effluent by fully utilizing its high specific surface area, high porosity, and surface activity (functional groups). In the meantime, the hydrogel's strong water absorption helps to enhance its capacity to absorb dyes and heavy metal ions, making it an excellent adsorbent. Adding polymers (polyacrylate, alginate, chitosan sugar, and cellulose derivatives) to the hydrogel improved its adsorption ability and further improved the hydrogel's advanced treatment impact on heavy metal ions and dye wastewater (Chen et al. 2020). In addition, the hydrogel has significant benefits in water absorption and transportation due to its strong hydrophilicity and excellent pore structure. Hydrogels possess exceptional water absorption capabilities because they may contain a multitude of hydrophilic groups, including –OH, –COOH, –NH2, and –SO3H. Hydrogels are becoming a promising material in the collection of water resources with high water retention and excellent recyclability (Zhou et al. 2019, 2020; Akter et al. 2021).

Chitosan is a linear polysaccharide composed of randomly distributed β-(1 → 4)-linked D-glucosamine (the deacetylated unit) and N-acetyl-D-glucosamine (the acetylated unit). It 's like a molecular dance of sugar molecules. As an alkaline hydrolytic derivative of chitin, chitosan has amine, hydroxyl, and acetamido functional groups that provide it a higher solubility profile, reduced crystallinity, and chemical modification flexibility. The chemical modification of chitosan is intriguing because it preserves the organic structure of the material, imparts new or enhanced qualities, and does not alter its basic physicochemical and biological characteristics (Li et al. 2020; Aranaz et al. 2021; Wang & Zhuang 2022).

Nanoemulsions (NEs), double phasic dispersion, can be water-in-oil (W/O) or oil-in-water (O/W), both of which consist of two immiscible liquids stabilized together by the right surfactant. Typically, the mean droplet diameter obtained in NEs is less than 500 nm. Their appearance is hazy or transparent due to their small droplet size, which contrasts with the milky white color of a coarse emulsion, where the droplets are micron-sized and participate in multiple light scattering. While submicron and mini emulsions are occasionally used interchangeably with the term ‘nanoemulsion,’ the two terms should not be confused. Even though they both have a similar droplet size range, NEs and microemulsions differ greatly in terms of long-term thermodynamic stability and structural features (Alkhatib et al. 2012; Ozogul et al. 2022; Mushtaq et al. 2023).

Essential oils solubilized in NEs may add beneficial properties to the hydrogels (Barradas & de Holanda e Silva 2012; Herman et al. 2019). Clove oil is well-known for its antibacterial, analgesic, and anesthetic qualities in medicine. Its antibacterial and antifungal qualities make it effective against warts, parasites, scars, and acne. Peppermint oil has antioxidant and antimicrobial activities in addition to its unique flavor and aroma.

It may be feasible to create innovative NE hydrogel beads that exhibit characteristics including significant adsorption capacity, decreased sensitivity to pH variations, and thermal stability. These beads have the potential to offer both cost-effectiveness and efficiency, making them attractive to water treatment plant enterprises. Importantly, such beads have not been previously employed in water treatment applications. The aim of the present study was to synthesize hydrogel beads consisting of chitosan, tween 80, span 20, and natural oils (clove and peppermint). It also intended to characterize the synthesized hydrogel beads and quantify the hydrogel bead's adsorption capacity both physically and chemically.

Preparation of the hydrogel beads

The essential oils used for bead formation, clove oil, and peppermint oil were acquired from iHerb store (California, USA). The other chemicals, including chitosan, span 20, tween 80, sodium hydroxide, and methanol, were purchased from Merck (Darmstadt, Germany). First, the chitosan was prepared by dissolving 5 g of chitosan powder in 100 mL of 2.5% glacial acetic acid solution. To neutralize the prepared solution, 150 mL of 0.1 M sodium hydroxide was added followed by warming the solution at 40 °C to produce a jelly mixture. Second, the NEs were produced by blending different volume fractions of clove (C) or peppermint (P) oil, distilled water, and mixed surfactants of span 20 and tween 80 at a fixed ratio of 1:2, respectively, at 25 °C. The produced NEs consisting of fixed 15% (w/w) surfactant mixture comprising 5% span 20 and 10% tween 80 were signified according to the amount of oil (C or P) and water content as NECH or NEPH (75% oil and 10% water), NECL or NEPL (10% oil and 75% water), and NECE or NEPE (42.5% each of oil and water). Third, the prepared chitosan solution was slowly added to the desired NE in a 1:1 ratio in order to ensure proper and uniform dispersion of the chitosan within the NE, facilitating the subsequent interactions. Second, the bead formation solution was prepared by mixing 40 mL of distilled water, 50 mL of methanol, and 10 g of sodium hydroxide in a 250 mL glass beaker with continuous stirring until the solid sodium hydroxide dissolved. To expedite the bead formation process, the mixture was subjected to a controlled cooling process by placing it in the refrigerator (−5 °C). Finally, the produced chitosan–NE mixture was introduced into the cold bead formation solution using a dropper. It should be noted, however, that not all of the mixture had undergone bead formation. The steps of bead formation are shown in Figure 1.
Figure 1

Schematic presentation for the formation of the chitosan/essential oil/NE hydrogel beads.

Figure 1

Schematic presentation for the formation of the chitosan/essential oil/NE hydrogel beads.

Close modal

Testing the adsorption efficiency of the produced beads

After the synthesis of the hydrogel beads, a preliminary experimental evaluation was performed to evaluate their adsorption capacity. This evaluation involves preparing different concentrations of copper (II) sulfate (CuSO4) (0.02, 0.06, and 0.1 M). The aim of this step was to verify the effectiveness and efficiency of the hydrogel beads in purifying water for safe use. Prior to the addition of the beads, the initial absorbance of different concentrations of CuSO4 was recorded using ultraviolet–visible (UV-Vis) spectrophotometry (BioTek, Winooski, USA). After that, the desired beads were added to 5 mL of CuSO4 for two different periods of time (1 and 24 h). The adsorption efficiency was determined according to the following equation:
where is the adsorption capacity, is the final absorbance, and is the initial absorbance.

For further investigation of the adsorption capacity of the successful hydrogel beads, the temperature and time effects were determined. A 1.0 g of clove or peppermint beads was added to 0.1 M copper (II) sulfate or 10 ppm of bromophenol blue. Then, the adsorption capacity was measured at a certain period of time or temperature.

Formation of the chitosan/essential oils/NE beads

Different combinations of chitosan and NE were produced by mixing 1 mL of 20 mg/mL of chitosan solution (CH) and 1 mL of various essential oil NEs consisting of fixed percentages (15%) of mixed surfactants of span 20 and tween 80 at a ratio of 1:2, respectively, and several volume fractions of oil and water. Three NEs of each oil [clove (C) or peppermint (P)] were produced as follows: (1) NE with (75%) high (H) oil content relative to (10%) water (NECH or NEPH); (2) NE with equal (E) oil and water contents at (42.5%) for each (NECE or NEPE); and (3) NE with (10%) low (L) oil content relative to (75%) water (NECL or NEPL). During the process of manufacturing the beads by adding each combination of (NE–CH) to a cold solution containing 100 mL of the basic alcohol cold solution, not all NE and chitosan mixtures were suitable for forming the beads. The beads formation resulted from the mixing of the chitosan (CH) and the NEs with low (NEL), equal (NEE), or high (NEH) oil contents, relative to the water amount, are illustrated in Table 1.

Table 1

Nanoemulsion–chitosan (NE–CH) mixture that resulted in the formation of beads

Type of beadNEL–CHNEH–CHNEE–CH
Clove (C) beads Formed Formed Not formed 
Peppermint (P) beads Not formed Formed Formed 
Type of beadNEL–CHNEH–CHNEE–CH
Clove (C) beads Formed Formed Not formed 
Peppermint (P) beads Not formed Formed Formed 

Adsorption capacity of the produced beads

Concentration effect

The suitability of the hydrogel beads for water treatment application was tested by determining the relationship between the adsorption capacity of different hydrogel beads and the concentration of CuSO4 (Figure 2). The graph indicates that at the different concentrations, the adsorption capacities differ significantly among the hydrogel beads but there is a consistent trend observable across all concentrations. NECL–CH clove beads with low oil content in the NE and NEPE–CH peppermint beads with a comparable amount of oil and water have the highest value of adsorption capacity. Apparently, the amount of oil in the beads affects their formation as well as their adsorption capacity. Therefore, both NECL–CH (clove beads) and NEPE–CH (peppermint beads) will be used for further investigations.
Figure 2

The adsorption capacity of the hydrogel beads at different concentrations of CuSO4.

Figure 2

The adsorption capacity of the hydrogel beads at different concentrations of CuSO4.

Close modal

Temperature effect

The adsorption capacity of both clove and peppermint beads in copper (II) sulfate (0.1 M) and bromophenol blue (10 ppm) solutions at various temperatures (10, 20, 30, 40, and 50) °C are presented in Figure 3. In copper (II) sulfate solution, the adsorption capacity of peppermint beads was decreased as the temperature increased whereas the adsorption capacity of clove beads was slightly increased as the temperature increased (Figure 3(a)). In the bromophenol blue solution, the correlation between the temperature and the adsorption capacity of both clove and peppermint beads was polynomial (Figure 3(b)). It should be mentioned that the highest adsorption capacity of peppermint beads was approximately between 40 and 50 °C, but the adsorption capacity of clove beads was the least at 40 °C. Overall, the adsorption capacities of both clove and peppermint beads were affected by the temperature.
Figure 3

Temperature effect on the adsorption capacity of peppermint and clove oil beads in (a) CuSO4 solution (0.1 M) and (b) bromophenol blue (10 ppm).

Figure 3

Temperature effect on the adsorption capacity of peppermint and clove oil beads in (a) CuSO4 solution (0.1 M) and (b) bromophenol blue (10 ppm).

Close modal

Time effect

The temporal evolution of absorbance percentage for beads using copper (II) sulfate and bromophenol blue is displayed in Figure 4. In copper (II) sulfate, an increasing trend in the adsorption capacity of the beads was observed over time (Figure 4(a)). Initially, the adsorption capacity is gradually increased for both bead types. However, after approximately 3 h, it stabilizes, indicating minimal further change. The correlations of determination (R2) for both types were determined to be 0.86 for peppermint beads and 0.89 for clove beads, revealing a linear relationship between the absorbance capacity and time in both types. It is worth mentioning that the clove bead's adsorption capacity was faster than that of peppermint ones in the first hour, indicating the high rate of interaction between the salt and pore of the clove beads.
Figure 4

Time effect on the adsorption capacity percentage of peppermint and clove beads in (a) CuSO4 (0.1 M) and (b) bromophenol blue (10 ppm).

Figure 4

Time effect on the adsorption capacity percentage of peppermint and clove beads in (a) CuSO4 (0.1 M) and (b) bromophenol blue (10 ppm).

Close modal

A rise in the adsorption capacity over time for both bead types added to the bromophenol blue is depicted in Figure 4(b). Initially, there is a notable peak in the adsorption capacity during the first hour, attributed to the high absorbance percentage of stain from the water. Subsequently, the absorbance percentage gradually decreases as time progresses. Also, the values of R2 were determined to be 0.94 for peppermint beads and 0.93 for clove beads, confirming a linear relationship between the adsorption capacity and time in both types of beads. Interestingly, the adsorption capacity of the clove beads was considerably larger than that of peppermint ones at all times, implying that the structure of the clove beads' pores is more hydrophobic since they attracted the bromophenol blue and adsorbed it. Additionally, the presence of eugenol, the major constituent of clove oil that has a similar structure to the bromophenol, may potentiate the adsorption capacity of the clove beads.

Characterization of the selected hydrogel beads

Scanning electron microscopy for morphology visualization

The scanning electron microscope (SEM) allows us to analyze samples with a diameter of up to 200 mm and a height of 80 mm. The magnification of the device ranges from x to 300,000 x. Materials that can be used in SEM are organic and solid inorganic materials including metals and polymers (Zu et al. 2012). While preparing the beads for scanning, it was important to cover the beads with materials that could conduct electricity, which was a thin layer of gold in our study. This layer prevented the surface of the beads from accumulating electric charge and also increased the emission of secondary electrons to make the surface more suitable for analysis and imaging (Fourie 1982).

Several images of both clove and peppermint beads were taken at different dimensions to determine the morphological differences between the two beads. The external shape and dimensions of the clove and peppermint beads are displayed in Figure 5(a) and 5(b). Although the morphology of both beads is spherical, there are discrepancies among their networks and apparent surfaces (Figure 5(c) and 5(d)). Clove beads presented sharp edges with parallel lines of networks and uniform pores (6.947 ± 1.45 μm, CV = 20%) whereas peppermint beads displayed spongy surfaces with spherical pores (11.203 ± 3.34 μm, CV = 29%), as shown in Figure 5(e) and 5(f). The sharp edges and smaller pores of the clove beads indicate that their constituents were exposed to the pollutants resulting in their better and faster adsorption capacity relative to the folded peppermint beads.
Figure 5

SEM images of the external shape, pores, and surface of clove (a, c, and e, respectively) and peppermint (b, d, and f, respectively) beads.

Figure 5

SEM images of the external shape, pores, and surface of clove (a, c, and e, respectively) and peppermint (b, d, and f, respectively) beads.

Close modal

Differential scanning calorimetry for thermal stability determination

Differential scanning calorimetry (DSC) is a technique used for measuring the energy necessary to establish a nearly zero temperature difference between a substance and an inert reference material, as the two specimens are subjected to identical temperature regimes in an environment heated or cooled at a controlled rate (Ghanbari et al. 2023). It is used for measuring the thermal properties of various materials, such as glass transition, melting, crystallization, and chemical reactions. In addition, DSC instruments can also be used to determine the specific heat capacity and purity of samples. The DSC thermographs of the chitosan, clove NE, peppermint NE, clove beads, and peppermint beads are exhibited in Figure 6.
Figure 6

DSC thermographs of (a) chitosan, (b) clove NE, (c) peppermint NE, (d) clove beads, and (e) peppermint beads. The heat ranges from (0 to 300) °C with a heat rate of 10 °C/min. The temperatures of crystallization, evaporation, formation, melting, and glass transition are signified as Tc, Te, Tf, Tm, and Tg, respectively.

Figure 6

DSC thermographs of (a) chitosan, (b) clove NE, (c) peppermint NE, (d) clove beads, and (e) peppermint beads. The heat ranges from (0 to 300) °C with a heat rate of 10 °C/min. The temperatures of crystallization, evaporation, formation, melting, and glass transition are signified as Tc, Te, Tf, Tm, and Tg, respectively.

Close modal

Analyzing the DSC curves depends on the baseline that indicates the physical and chemical transitions of the sample. The region over the baseline shows exothermic behavior, which means the sample releases energy as it crystallizes or crosslinks. Conversely, the region below the baseline shows endothermic behavior, which means the sample absorbs energy as it melts from a solid state to a liquid state or evaporates from liquid to vapor. The chitosan solution has undergone evaporation at 110 °C followed by crystallization at 120 °C as revealed in Figure 6(a). By contrast, the average evaporation temperatures of both clove and peppermint NE were around 125 °C (Figure 6(b) and 6(c)). In fact, the nanosuspensions of peppermint NE were less stable as bond formation was constructed among them evidenced at the temperature of 65 °C. Both clove and peppermint beads were thermally stable until 100 °C as they endured glass transition, but their melting temperature differed, to 127 and 139 °C for clove and peppermint beads, respectively (Figure 6(d) and 6(e)). Although there were some differences in the determined temperatures at which the physical and chemical changes occur, the shape of the thermographs of the peppermint NE and peppermint beads were very similar and differed from the shape of the chitosan solution indicating that the NE effect was more dominant. By contrast, the shape of the thermographs of the clove beads differed from that of clove NE and chitosan solution, implying that distinct beads were produced with different chemical and physical properties.

FTIR for chemical structure characterization

Fourier transform infrared (FTIR) spectroscopy involves passing infrared (IR) light through a material. A portion of the IR light is transmitted while a part of it is absorbed by the sample. The resulting spectrum provides a molecular fingerprint of the sample by illustrating the molecule's absorption and transmission. Similar to how two fingerprints are never the same, no two different molecular structures can have the same infrared spectrum. This makes infrared spectroscopy applicable to various kinds of analysis. The spectrum is divided into two regions: the fingerprint region and the functional group region. The fingerprint region displays the distinct pattern for each compound and can be used to positively identify an unknown sample by comparing it to a known one. However, the functional group region is utilized to forecast a molecule's chemical structure and indicate whether or not it has common functional groups (Nandiyanto et al. 2019).

The study was conducted to assess how chitosan interacts with NE to create beads. The long-chain polymeric chitosan possesses free groups, including amino, alkyl, and hydroxyl, which may harbor radicals (Pati et al. 2020). The application of γ-irradiation facilitates crosslinking between these radicals, resulting in the formation of novel functional groups. Interestingly, both the NE and chitosan solution have similar FTIR spectra that differed from the clove and peppermint beads (Figure 7). Indeed, the spectral data indicate that the chitosan or tween 80/span 20 in NE readings – 3,292.68 cm−1 for the O–H bond, 1,636.38 cm−1 for the N–H or C = C bond, and 1,541.54 cm−1 for the C–C bond – align with the previously mentioned functional groups. As a new peak appeared on the FTIR curve, it was confirmed that chitosan and NE interact chemically. Because of the interactions between the four components, a new structure was revealed by the formation of the = C–H bend. Also, beads contain O–H stretch. Interestingly, both the NE and chitosan solution have similar FTIR spectra that differed from the clove and peppermint beads.
Figure 7

FTIR spectra of the chitosan, NE, and both clove (a) and peppermint (b) beads.

Figure 7

FTIR spectra of the chitosan, NE, and both clove (a) and peppermint (b) beads.

Close modal

In conclusion, water scarcity is a global challenge that impacts countries worldwide, especially emerging countries such as the Sultanate of Oman. The present study produced new hydrogel beads made from chitosan, tween 80, span 20, and essential oils (clove and peppermint) that exhibited desirable physicochemical properties and adsorption performance. Further investigations are recommended to comprehensively assess the scalability, treatment efficiency, and any potential environmental impacts of this innovative water treatment technology. In particular, the environmental compatibility, long-term stability, and regeneration potential of the beads need to be examined. It is also highly recommended to test the produced beads on a broader range of pollutants, which will enhance the applicability of the beads at a larger scale in real-world water treatment plants. Additionally, the mechanism of pollutant adsorption onto the bead surface should be further investigated to better understand the process.

This research did not receive any specific funding.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.

Ahmed
A. A.
,
Sayed
S.
,
Abdoulhalik
A.
,
Moutari
S.
&
Oyedele
L.
(
2024
)
Applications of machine learning to water resources management: a review of present status and future opportunities
,
Journal of Cleaner Production
,
441
(
6
),
140715
.
doi:10.1016/j.jclepro.2024.140715
.
Akter
M.
,
Bhattacharjee
M.
,
Dhar
A. K.
,
Rahman
F. B. A.
,
Haque
S.
,
Rashid
T. U.
&
Kabir
S. F.
(
2021
)
Cellulose-based hydrogels for wastewater treatment: a concise review
,
Gels
,
7
(
1
),
30
.
doi:10.3390/gels7010030
.
Alkhatib
M. H.
,
Albishi
H. M.
&
Mahassni
S. H.
(
2012
)
Impact of nanoparticles on cancer therapy
,
Tropical Journal of Pharmaceutical Research
,
11
(
6
),
1001
1011
.
doi:10.4314/tjpr.v11i6.18
.
Aranaz
I.
,
Alcántara
A. R.
,
Civera
M. C.
,
Arias
C.
,
Elorza
B.
,
Heras Caballero
A.
&
Acosta
N.
(
2021
)
Chitosan: an overview of its properties and applications
,
Polymers
,
13
(
19
),
3256
.
doi:10.3390/polym13193256
.
Barradas
T. N.
&
de Holanda e Silva
K. G.
(
2021
)
Nanoemulsions of essential oils to improve solubility, stability and permeability: a review
,
Environmental Chemistry Letters
,
19
(
2
),
1153
1171
.
doi:10.1007/s10311-020-01142-2
.
Chen
M.
,
Ni
Z.
,
Shen
Y.
,
Xiang
G.
&
Xu
L. C.
(
2020
)
Reinforced swelling and water-retention properties of super-absorbent hydrogel fabricated by a dual stretchable single network tactic
,
Colloids and Surfaces A: Physicochemical and Engineering Aspects
,
602
,
125133
.
doi:10.1016/j.colsurfa.2020.125133
.
Cheremisinoff
P. N.
(
2019
)
Handbook of Water and Wastewater Treatment Technology
.
New York, NY, USA: Routledge
.
Crini
G.
&
Lichtfouse
E.
(
2019
)
Advantages and disadvantages of techniques used for wastewater treatment
,
Environmental Chemistry Letters
,
17
,
145
155
.
doi:10.1007/s10311-018-0785-9
.
Etale
A.
,
Onyianta
A. J.
,
Turner
S. R.
&
Eichhorn
S. J.
(
2023
)
Cellulose: a review of water interactions, applications in composites, and water treatment
,
Chemical Reviews
,
123
(
5
),
2016
2048
.
doi:10.1021/acs.chemrev.2c00477
.
Fourie
J. T.
(
1982
)
Gold in electron microscopy
,
Gold Bulletin
,
15
(
1
),
2
6
.
Ghanbari
E.
,
Picken
S. J.
&
van Esch
J. H.
(
2023
)
Analysis of differential scanning calorimetry (DSC): determining the transition temperatures, and enthalpy and heat capacity changes in multicomponent systems by analytical model fitting
,
Journal of Thermal Analysis and Calorimetry
,
148
(
22
),
12393
12409
.
doi:10.1007/s10973-023-12356-1
.
Herman
R. A.
,
Ayepa
E.
,
Shittu
S.
,
Fometu
S. S.
&
Wang
J.
(
2019
)
Essential oils and their applications – a mini review
,
Advances in Nutrition and Food Science
,
4
(
4
),
1
3
.
Hossain
M. S.
,
Hossain
M. M.
,
Khatun
M. K.
&
Hossain
K. R.
(
2024
)
Hydrogel-based superadsorbents for efficient removal of heavy metals in industrial wastewater treatment and environmental conservation
,
Environmental Functional Materials
,
2
(
2
),
142
158
.
doi:10.1016/j.efmat.2024.01.001
.
Li
Q.
,
Dunn
E. T.
,
Grandmaison
E. W.
&
Goosen
M. F.
(
2020
)
Goosen, M. F. (ed.) Applications and properties of chitosan
. In:
Applications of Chitan and Chitosan
:
Boca Raton, FL, USA: CRC Press
, pp.
3
29
.
Mushtaq
A.
,
Wani
S. M.
,
Malik
A. R.
,
Gull
A.
,
Ramniwas
S.
,
Nayik
G. A.
,
Ercisli
S.
,
Marc
R. A.
,
Ullah
R.
&
Bari
A.
(
2023
)
Recent insights into nanoemulsions: their preparation, properties and applications
,
Food Chemistry: X
,
18
,
100684
.
doi:10.1016/j.fochx.2023.100684
.
Nandiyanto
A. B.
,
Oktiani
R.
&
Ragadhita
R.
(
2019
)
How to read and interpret FTIR spectroscope of organic material
,
Indonesian Journal of Science and Technology
,
4
(
1
),
97
118
.
doi:10.17509/ijost.v4i1.15806
.
Obiuto
N. C.
,
Ugwuanyi
E. D.
,
Ninduwezuor-Ehiobu
N.
,
Ani
E. C.
&
Olu-lawal
K. A.
(
2024
)
Advancing wastewater treatment technologies: the role of chemical engineering simulations in environmental sustainability
,
World Journal of Advanced Research and Reviews
,
21
(
3
),
019
-
031
.
doi:10.30574/ijsra.2024.11.1.0289
.
Ozogul
Y.
,
Karsli
G. T.
,
Durmuş
M.
,
Yazgan
H.
,
Oztop
H. M.
,
McClements
D. J.
&
Ozogul
F.
(
2022
)
Recent developments in industrial applications of nanoemulsions
,
Advances in Colloid and Interface Science
,
304
,
102685
.
doi:10.1016/j.cis.2022.102685
.
Pati
S.
,
Jena
P.
,
Shahimi
S.
,
Nelson
B. R.
,
Acharya
D.
,
Dash
B. P.
&
Chatterji
A.
(
2020
)
Characterization dataset for pre-and post-irradiated shrimp waste chitosan
,
Data in Brief
,
32
,
106081
.
doi:10.1016/j.dib.2020.106081
.
Saleh
T. A.
,
Mustaqeem
M.
&
Khaled
M.
(
2022
)
Water treatment technologies in removing heavy metal ions from wastewater: a review
,
Environmental Nanotechnology, Monitoring & Management
,
17
,
100617
.
doi:10.1016/j.enmm.2021.100617
.
Wang
J.
&
Zhuang
S.
(
2022
)
Chitosan-based materials: preparation, modification and application
,
Journal of Cleaner Production
,
355
,
131825
.
doi:10.1016/j.jclepro.2022.131825
.
Zhou
X.
,
Guo
Y.
,
Zhao
F.
&
Yu
G.
(
2019
)
Hydrogels as an emerging material platform for solar water purification
,
Accounts of Chemical Research
,
52
(
11
),
3244
3253
.
doi:10.1021/acs.accounts.9b00455
.
Zhou
X.
,
Guo
Y.
,
Zhao
F.
,
Shi
W.
&
Yu
G.
(
2020
)
Topology-controlled hydration of polymer network in hydrogels for solar-driven wastewater treatment
,
Advanced Materials
,
32
(
52
),
2007012
.
doi:10.1002/adma.202007012
.
Zu
Y.
,
Zhang
Y.
,
Zhao
X.
,
Shan
C.
,
Zu
S.
,
Wang
K.
,
Li
Y.
&
Ge
Y.
(
2012
)
Preparation and characterization of chitosan–polyvinyl alcohol blend hydrogels for the controlled release of nano-insulin
,
International Journal of Biological Macromolecules
,
50
(
1
),
82
87
.
doi:10.1016/j.ijbiomac.2011.10.006
.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying, adaptation and redistribution, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/).