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Table of Contents
1.Objective: .............................................................................................................................................. 3
2.Apparatus: ............................................................................................................................................. 3
3.Raw Materials and Chemicals Required: ................................................................................................ 3
4.Apparatus Description:........................................................................................................................... 4
4.1 Hot Air Oven: ................................................................................................................................. 4
4.2 Muffle Furnace: .............................................................................................................................. 4
5.FTIR Spectrometer (Fourier Transform Infrared Spectroscopy) .............................................................. 5
6.Novelty: ................................................................................................................................................. 5
7. Introduction: ......................................................................................................................................... 6
8. Background:.......................................................................................................................................... 7
9. Working Principle: ................................................................................................................................ 9
10. Working Procedure............................................................................................................................ 10
11. Applications ...................................................................................................................................... 14
12.Interpretation of Results ..................................................................................................................... 16
13.Suggestions / Recommendations ........................................................................................................ 16
14.Problems Encountered During Experiment ......................................................................................... 18
15.References: ........................................................................................................................................ 20
Books.................................................................................................................................................. 20
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Production of Activated Carbon from Banana Peels via Biochar Formation and
Chemical Activation for Dye Removal Applications
1.Objective:
1. To prepare biochar from banana peels through controlled pyrolysis under limited oxygen conditions.
2. To convert the prepared biochar into activated carbon using a suitable chemical activation agent.
3. To characterize the prepared activated carbon in terms of yield, surface properties, and adsorption
performance.
4. To assess the feasibility of banana peels as a low-cost, sustainable precursor for activated carbon production.
2.Apparatus:
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Analytical balance
Hot air oven
Muffle furnace
Porcelain crucibles with lids
Mortar and pestle (or grinder)
Beakers (100 mL, 250 mL, and 500 mL)
Measuring cylinders
Volumetric flask (1 L)
Glass stirring rods
Magnetic stirrer or mechanical shaker
Funnel
Filter papers
Wash bottle
pH meter (or pH paper)
Thermometer
Desiccator
Crucible tongs/crucible holder
Safety gloves
Safety goggles
3.Raw Materials and Chemicals Required:
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Banana peels (500 g)
Distilled water (5–6 L)
Potassium hydroxide (KOH) (100 g)
Rhodamine dye (1.5 g)
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4.Apparatus Description:
4.1 Hot Air Oven:
A hot air oven is an electrical heating device used for drying and moisture removal from samples prior to
pyrolysis. It operates by circulating heated air uniformly within its insulated chamber, ensuring consistent
temperature distribution across the sample.
Role in this experiment:
The banana peels are dried in the hot air oven prior to carbonization in order to eliminate moisture content, which
can otherwise interfere with uniform pyrolysis and reduce biochar quality.
Operating Range:
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Temperature range: 50°C to 0°C
Operating temperature used in this experiment: 110°C ± 2°C
Heating medium: Forced hot air circulation
4. 2. Muffle Furnace:
A muffle furnace is a high-temperature laboratory heating device in which the sample is placed inside a thermally
insulated refractory chamber (muffle), isolated from direct contact with the heating elements and combustion gases.
It provides precise high-temperature control and is widely used for pyrolysis, carbonization, and ash determination
in biomass-related studies. It enables an oxygen-limited or controlled atmosphere when crucibles with fitted lids
are used, which is essential for biochar production.
Role in this experiment:
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Step 1 - Pyrolysis/Carbonization: The dried banana peels are placed in a covered crucible inside the muffle
furnace to produce biochar under limited oxygen conditions. Biochar is a carbon-rich material produced by
heating biomass at temperatures of 400–700°C in a closed container in which oxygen is absent or depleted.
Step 2 - Activation: The prepared biochar is subjected to further thermal treatment in the muffle furnace at
elevated temperatures to develop its porous structure and convert it into activated carbon.
Operating Range:
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Maximum temperature capacity: up to 1200°C-1500°C (depending on model)
Pyrolysis temperature range used: 400°C -500°C
Activation temperature range used: 700°C-800°C
For ash content determination, the muffle furnace maintains steady temperatures generally around 450°C to
550°C for extended periods of often 3 hours to ensure complete combustion.
Heating rate: 5°C – 10°C per minute
Atmosphere: limited air supply (crucible with lid)
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5.FTIR Spectrometer (Fourier Transform Infrared Spectroscopy)
An FTIR spectrometer is an analytical instrument used to identify the chemical functional groups present in a
material by measuring how the sample absorbs infrared radiation at different wavelengths. The instrument passes
a broad-spectrum infrared beam through the sample and records the resulting absorption spectrum, which acts as a
molecular fingerprint of the material.
Role in this experiment:
FTIR is used to characterize both the biochar and the activated carbon by identifying functional groups such as O–
H, C=O, C–H, and C–O bonds. It allows comparison of the surface chemistry before and after activation, confirming
structural changes induced by the pyrolysis and activation process. FTIR is a rapid, non-destructive, and costeffective method for detecting chemical functional groups in a sample, rendering it ideal for biochar
characterization.
Operating Range:
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Spectra are acquired within the 400 – 4000 cm⁻¹ wavenumber range, with a resolution of 4 cm⁻¹, and data
points are collected at intervals of 1 cm⁻¹.
Key absorption regions relevant to this experiment:
Table 1 A table representing corresponding wavelength to a specific functional group
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Wavenumber (cm⁻¹)
Functional Group
3200 – 3500
2850 – 2950
1600 – 1700
1000 – 1300
700 – 900
O–H stretching (hydroxyl)
C–H stretching (alkyl)
C=O stretching (carbonyl)
C–O stretching (ether/alcohol)
Aromatic C–H bending
Sampling technique: ATR (Attenuated Total Reflectance) or KBr pellet method
Output: Transmittance (%) vs. Wavenumber (cm⁻¹) spectrum
6.Novelty:
Banana peels are an abundantly generated agricultural waste that is conventionally discarded without value
recovery. The significance of this experiment lies in the utilization of this low-cost biomass waste as a precursor
for the synthesis of activated carbon through a two-step process of pyrolysis and chemical activation. Unlike
commercially produced activated carbon derived from non-renewable sources such as coal or wood, this approach
offers a sustainable, cost-effective, and environmentally responsible alternative. The conversion process allows the
development of a porous carbon material with an enhanced surface area, making it potentially applicable in water
treatment, heavy metal removal, and dye adsorption. The novelty further extends to the optimization of
experimental parameters such as pyrolysis temperature and activation agent concentration, which directly influence
the structural and functional properties of the final product, thereby offering meaningful scope for scientific
investigation at the undergraduate level.
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7. Introduction:
The rapid growth of food processing industries and agricultural activities has led to a substantial increase in organic
waste generation worldwide. Among such wastes, banana peels represent a significant proportion of solid waste,
produced in large quantities by households, food vendors, and processing plants on a daily basis. When improperly
discarded, these peels decompose and contribute to foul odors, soil contamination, and the release of greenhouse
gases, posing considerable environmental and public health concerns. The need to manage such waste in a
sustainable and value-added manner has therefore become an important area of research in environmental
engineering.
Figure 1 Banana peels generated as agricultural and food waste.
One promising approach is the thermochemical conversion of lignocellulosic biomass waste into biochar and
subsequently into activated carbon. Banana peels are particularly well-suited as a precursor material due to their
high content of cellulose, hemicellulose, and lignin — organic compounds that yield a carbon-rich char upon
thermal decomposition. Through a two-stage process involving carbonization under limited oxygen conditions,
followed by chemical activation using potassium hydroxide (KOH), a highly porous activated carbon with a large
surface area can be obtained. This material exhibits strong adsorption properties, making it effective in capturing
pollutant molecules from aqueous solutions.
Figure 2 Banana peel to activated carbon conversion process
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Industrial dyes, particularly methylene blue, are among the most persistent and hazardous contaminants found in
wastewater from textile, pharmaceutical, and chemical manufacturing industries. Even at low concentrations, these
dyes can be toxic to aquatic organisms and reduce light penetration in water bodies, disrupting aquatic ecosystems.
Conventional water treatment methods often struggle to remove such compounds efficiently and cost-effectively.
Activated carbon adsorption has emerged as one of the most reliable techniques for dye removal, owing to its
versatility, high efficiency, and capacity for reuse.
This experiment aims to produce activated carbon from banana peel waste through biochar formation and KOH
chemical activation, and to evaluate its performance in removing methylene blue dye from a simulated wastewater
solution. The work represents a waste-to-value approach, transforming an abundant agricultural by-product into a
functional material with practical environmental applications
8. Background:
8.1 Biochar and Its Properties:
Biochar is a carbon-rich solid material formed through the pyrolysis of biomass - the thermal decomposition of
organic matter in the absence or limited presence of oxygen, typically at temperatures between 400–500°C. Unlike
complete combustion, pyrolysis preserves the carbon framework of the biomass, resulting in a stable, porous solid.
The properties of biochar depend on both the feedstock used and the conditions of pyrolysis, including temperature,
heating rate, and residence time. Biochar derived from lignocellulosic materials such as banana peels tends to
exhibit a moderately porous structure, basic surface chemistry, and good thermal stability. Beyond its role as an
intermediate in activated carbon production, biochar has independent applications in soil amendment, carbon
sequestration, and the removal of heavy metals from contaminated environments.
8.2 Chemical Activation and Activated Carbon:
Activated carbon is produced from biochar through an activation process that
significantly increases its surface area and porosity. In chemical activation, the biochar
is impregnated with a chemical activating agent - in this case, KOH - and subjected to
high temperatures (700–800°C). KOH acts by etching into the carbon matrix, generating
a network of micropores and mesopores during thermal treatment
The resulting activated carbon possesses a surface area that can reach several
hundred to over a thousand square meters per gram, far exceeding that of the
original biochar. The enhanced porosity provides a large number of adsorption
sites, enabling the material to effectively bind pollutant molecules. After
activation, the sample is Figure washed with dilute hydrochloric acid (HCl) and
distilled water to remove residual potassium compounds and restore a neutral
pH.
Figure3 Porous surface
morphology of activated carbon.
8.3 Adsorption of Methylene Blue:
Adsorption is a surface phenomenon in which molecules from a liquid or gas phase
adhere to the surface of a solid material, known as the adsorbent. Methylene blue is a
cationic dye widely used as a model adsorbate in activated carbon studies due to its
strong visible absorbance, ease of quantification by UV-Vis spectrophotometry,
and well-documented adsorption behavior.
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Figure 4 Methylene blue
contaminated wastewater
used for adsorption studies.
The interaction between methylene blue and activated carbon is primarily governed by electrostatic attraction, π–
π interactions between the aromatic rings of the dye and the graphitic carbon surface, and hydrogen bonding with
oxygen-containing functional groups. The efficiency of dye removal is typically assessed by measuring the
decrease in absorbance of the dye solution before and after contact with the adsorbent.
Figure 5 Adsorption of dye molecules onto activated carbon surface.
8.4 Characterization Techniques:
Understanding the properties of the prepared activated carbon requires appropriate characterization. Fourier
Transform Infrared Spectroscopy (FTIR) is used to identify surface functional groups, providing insight into the
chemical changes that occur during carbonization and activation. Scanning Electron Microscopy (SEM) offers
visual evidence of the surface morphology and pore development, allowing comparison of the material before and
after activation. X-Ray Diffraction (XRD) is employed to assess the degree of crystallinity or amorphous nature
of the carbon structure, confirming successful conversion of the biomass feedstock into a carbonaceous material.
Figure 6 FTIR spectrum, SEM micrograph, and XRD pattern of KOH-activated carbon produced from banana peel biochar.
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Together, these techniques provide a comprehensive picture of the physical and chemical characteristics of the
produced activated carbon.
9. Working Principle:
9.1 Drying of Banana Peels
The experiment begins with the drying of freshly collected banana peels in a hot air oven at 110°C. The purpose of
this step is to remove the moisture content present in the biomass, as excess moisture can interfere with subsequent
thermal treatment and reduce the efficiency of carbonization. Drying also prevents uneven heating, improves
process consistency, and ensures that the carbonization process primarily affects the organic constituents of the
banana peels rather than consuming energy for water evaporation.
9.2 Carbonization of Banana Peels
After drying, the banana peels are subjected to carbonization under limited oxygen conditions at elevated
temperatures. During carbonization, the major biomass components, including cellulose, hemicellulose, and lignin,
undergo thermal decomposition, releasing volatile substances such as water vapor, carbon dioxide, carbon
monoxide, and other organic compounds. This process leaves behind a carbon-rich solid material known as biochar.
Carbonization increases the fixed carbon content and develops an initial pore structure that serves as the foundation
for subsequent activation.
9.3 Chemical Activation
The biochar is then chemically activated using potassium hydroxide (KOH). The biochar is impregnated with a
KOH solution and heated at high temperatures, typically between 700–800°C. During activation, KOH reacts with
the carbon matrix, removing carbon atoms and generating a large number of micropores and mesopores throughout
the structure. This process significantly increases the surface area, pore volume, and adsorption capacity of the
material, producing highly porous activated carbon suitable for pollutant removal applications.
9.4 Washing and Purification
Following activation, the activated carbon is thoroughly washed with distilled water and dilute hydrochloric acid
to remove residual KOH, potassium salts, and ash formed during activation. Washing is continued until the pH of
the wash water becomes neutral. This purification step ensures that the pores remain accessible and prevents
interference from residual chemicals during adsorption studies.
9.5 Dye Adsorption Mechanism
The prepared activated carbon is used for the removal of rhodamine dye from aqueous solution through adsorption.
Owing to its highly porous structure and large surface area, the activated carbon provides numerous active sites
where dye molecules can attach. The dye molecules diffuse from the bulk solution into the pores and become
retained on the carbon surface through physical adsorption, pore filling, electrostatic attractions, and interactions
with surface functional groups. As adsorption proceeds, the concentration of dye in the solution decreases,
indicating successful pollutant removal.
9.6 FTIR Characterization
The activated carbon is characterized using Fourier Transform Infrared Spectroscopy (FTIR) to identify the
functional groups present on its surface. FTIR works on the principle that different chemical bonds absorb infrared
radiation at characteristic wavelengths. When infrared light passes through the sample, specific wavelengths are
absorbed by surface functional groups such as hydroxyl (–OH), carbonyl (C=O), carboxyl (–COOH), and ether (C–
O) groups. The resulting spectrum provides information about the chemical structure and surface chemistry of the
activated carbon. These functional groups play an important role in adsorption because they act as active sites that
facilitate interactions between the activated carbon and dye molecules.
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9.7 Overall Working Principle
Overall, the experiment is based on the conversion of banana peel waste into activated carbon through drying,
carbonization, and chemical activation, followed by the removal of dye contaminants from water through
adsorption. Drying removes moisture, carbonization converts biomass into biochar, and chemical activation
develops a highly porous structure with a large surface area. The resulting activated carbon adsorbs rhodamine dye
from water through various surface interactions. FTIR analysis is then used to confirm the presence of functional
groups responsible for adsorption, thereby evaluating the effectiveness of the prepared activated carbon as a
sustainable and low-cost adsorbent for wastewater treatment.
10. Working Procedure & Observations:
A. Preparation of Biochar
1. Collect fresh banana peels and wash thoroughly with distilled water to remove dirt and impurities.
2. Dry the washed banana peels in a hot air oven at 100–110°C for 24 hours.
3. Cut the dried peels into small pieces to ensure uniform heating.
Figure 7 Preparation of banana peel powder (washing, cutting, drying)
4. Grind the dried sample.
5. Place the dried banana peels in a covered crucible.
Figure 8 grinded dry banana peels
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6. Carbonize in a muffle furnace at 500°C for 3-4 hours under limited oxygen conditions.
Figure 9 At 400 C dried peels in muffle furnace for carbonization
7. Allow the sample to cool and collect the produced biochar.
Figure 10 Biochar from banana peels
B. Preparation of Activated Carbon
7. Crush the obtained biochar into a fine powder.
Figure 11 Fine powder of biochar
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8. Prepare a KOH solution by dissolving 100 g KOH in 200 mL distilled water.
9. Mix biochar and KOH solution in a 1:1 ratio.
10. Soak the mixture for 24 hours for chemical impregnation.
Figure 12 mixture of KOH and Biochar for further activation
11. Dry the impregnated sample at 105°C.
12. Thermally activate the sample in a furnace at 700–800°C for 1–2 hours
Figure 13 Dried impregnated sample
13. Crushed the activated carbon and stored it for further use.
Figure 14 Activated Carbon before crushing
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C. Confirmation test for activated carbon:
1.Rhodamin dye solution test:
To evaluate the mesoporous surface area and adsorption performance of the prepared banana peel activated
carbon (BPAC), a batch adsorption test was conducted using Rhodamine B (RhB) as a model pollutant. A
stock solution of RhB 5.35g/L was prepared. An exact mass of 1.5g of RhB was added to 280 mL of the dye
solution and agitated for 5 minutes at room temperature to ensure adsorption equilibrium. After becoming
a homogenous mixture 2.5 grams of crushed activated carbon sample was added in this solution. The
solution was stirred for 5 to 10 minutes and then allowed to settle. After that it was filtered to another beaker
and a pale pink liquid was obtained showing partial adsorption result. carbon is working, but it hit its
maximum adsorption equilibrium before all the dye could be removed.
Figure 14 picture shows stirring of 5.35g/L Rhodamin dye solution
Figure 155 picture shows addition of activated carbon in dye
in 280 ml of water
and allowing it to settle
Figure 16: Picture shows pale pink filtered solution of
dye-activated carbon
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2. FTIR (Fourier transform infrared spectroscopy):
A representative sample of the prepared banana peel biochar was collected, dried, and finely ground before
being analyzed using a Fourier Transform Infrared (FTIR) spectrometer over a wavenumber range of
approximately 4000–400 cm⁻¹. The obtained spectrum was used to identify the functional groups present
on the biochar surface by analyzing the characteristic absorption peaks and assigning them to their
corresponding chemical bonds, thereby evaluating the surface chemistry and adsorption potential of the
produced biochar.
Figure 17: FTIR spectrum of the prepared banana peel biochar showing the characteristic functional groups present on the biochar surface.
11. Applications
Activated carbon produced from banana peels has significant industrial importance due to its high surface area,
porous structure, low production cost, and environmentally friendly nature. The conversion of banana peel waste
into activated carbon not only helps in waste management but also creates a valuable product with numerous
industrial applications. As industries increasingly seek sustainable and cost-effective materials, banana peel-derived
activated carbon has gained considerable attention as an alternative to commercial activated carbon.
1. Wastewater Treatment Industry
One of the most important applications of activated carbon is in wastewater treatment. Activated carbon prepared
from banana peel scan effectively remove dyes, heavy metals, pesticides, pharmaceutical residues, and other toxic
pollutants from industrial effluents. Industries such as textile, leather, pharmaceutical, and chemical manufacturing
generate contaminated wastewater that requires treatment before discharge. The high adsorption capacity of
activated carbon makes it an excellent material for purifying wastewater and protecting aquatic ecosystems.
2. Drinking Water Purification
Activated carbon is widely used in municipal and industrial water treatment plants for the removal of organic
contaminants, unpleasant odors, colors, and harmful chemicals. Banana peel-based activated carbon can serve as a
low-cost alternative for water purification, especially in developing countries where access to clean drinking water
is a major challenge.
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3. Air Pollution Control
Many industries release harmful gases and volatile organic compounds (VOCs) into the atmosphere. Activated
carbon is commonly used in air filtration systems to adsorb toxic gases, smoke, odors, and industrial emissions.
Activated carbon derived from banana peels can be utilized in air purification units, gas masks, and industrial
exhaust treatment systems, helping industries comply with environmental regulations
4. Food and Beverage Industry
The food and beverage industry uses activated carbon for purification and decolorization processes. It is employed
in the refining of sugar, edible oils, fruit juices, and alcoholic beverages to remove unwanted color, taste, and
impurities. Banana peel-based activated carbon can potentially replace more expensive commercial adsorbents in
these applications, reducing operational costs.
5. Pharmaceutical Industry
Activated carbon plays a vital role in the pharmaceutical sector. It is used for purification of pharmaceutical
products, removal of impurities during manufacturing, and treatment of poisoning cases due to its excellent
adsorption properties. Sustainable activated carbon produced from agricultural waste can provide an economical
and environmentally friendly option for pharmaceutical applications.
6. Energy Storage Devices
Recent research has shown that activated carbon can be used as an electrode material in supercapacitors, batteries,
and fuel cells. Due to its porous structure and large surface area, banana peel-derived activated carbon can
contribute to the development of efficient and low-cost energy storage systems. This application is becoming
increasingly important with the growing demand for renewable energy technologies.
7. Gold Recovery and Metallurgical Industries
Activated carbon is extensively used in the mining industry for gold extraction and recovery processes. It adsorbs
gold-cyanide complexes from mining solutions, allowing efficient recovery of precious metals. Banana peel-based
activated carbon may serve as a sustainable alternative in metallurgical operations while reducing dependence on
commercially manufactured adsorbents.
8. Catalyst and Catalyst Support Material
In chemical industries, activated carbon is used as a catalyst or catalyst support due to its high surface area and
stability. It enhances reaction rates and improves process efficiency in various chemical manufacturing operations.
Activated carbon produced from banana peels has the potential to be utilized in catalytic applications, contributing
to greener industrial processes.
9. Environmental Sustainability and Circular Economy
The production of activated carbon from banana peels supports the concept of a circular economy by converting
agricultural waste into a valuable industrial product. This approach reduces waste disposal problems, minimizes
environmental pollution, and promotes sustainable resource utilization. Industries can benefit from both
environmental and economic advantages by adopting biomass-derived activated carbon
10. Cost-Effective Alternative to Commercial Activated Carbon
Commercial activated carbon is often expensive because it is produced from coal, wood, or other costly raw
materials. Banana peels are abundant agricultural wastes that are readily available at little or no cost. Therefore,
producing activated carbon from banana peels significantly reduces raw material expenses while maintaining
excellent adsorption performance. This makes it attractive for large-scale industrial applications.
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13.Interpretation of Results
Fourier Transform Infrared (FTIR) spectroscopy was employed to identify the surface functional groups present on
the prepared banana peel biochar and to evaluate the chemical changes that occurred during the carbonization
process. The FTIR spectrum provides information about the chemical bonds and functional groups present on the
adsorbent surface, which play a crucial role in its adsorption performance.
A broad absorption band was observed at approximately 3116 cm⁻¹, corresponding to the stretching vibrations of
hydroxyl (–OH) groups. These hydroxyl groups may originate from adsorbed moisture, phenolic compounds,
alcohols, and residual cellulose or lignin-derived structures that remain after carbonization. The presence of
hydroxyl groups is particularly significant because they increase the hydrophilic nature of the biochar and provide
active sites for the adsorption of dye molecules through hydrogen bonding and electrostatic interactions.
The peaks observed around 1440 cm⁻¹ and 1344 cm⁻¹ are attributed to C–H bending vibrations and O–H
deformation vibrations, respectively. These peaks indicate the presence of aliphatic carbon structures and oxygencontaining functional groups on the biochar surface. Such functional groups contribute to the chemical reactivity
of the adsorbent and enhance its ability to interact with contaminants present in aqueous solutions. The retention of
these oxygenated groups after carbonization suggests that the biochar possesses a chemically active surface capable
of participating in adsorption mechanisms.
A distinct peak near 876 cm⁻¹ corresponds to aromatic C–H out-of-plane bending vibrations, indicating the
formation of aromatic ring structures during the thermal decomposition of the banana peel biomass. The
development of aromatic carbon structures is a characteristic feature of successful carbonization and contributes to
the stability and porous nature of the resulting biochar. Aromatic structures also provide π-electron-rich regions
that can interact with organic pollutants, thereby improving adsorption efficiency.
Additional absorption bands observed at approximately 695 cm⁻¹, 584 cm⁻¹, and 528 cm⁻¹ may be associated with
deformation vibrations of aromatic compounds, inorganic mineral constituents, and metal-oxygen bonds
originating from naturally occurring minerals present in the banana peel. These peaks suggest that the biochar
contains trace inorganic components that remained after thermal treatment. Such mineral residues can contribute
to adsorption through ion-exchange mechanisms and surface complexation reactions.
Overall, the FTIR spectrum confirms the presence of various oxygen-containing and carbonaceous functional
groups, including hydroxyl, aliphatic, and aromatic functionalities. These groups are essential because they provide
chemically active adsorption sites and enhance the interaction between the biochar surface and pollutant molecules.
The presence of these functional groups, together with the aromatic carbon framework developed during
carbonization, indicates that the banana peel biomass was successfully converted into a functional biochar
adsorbent. Consequently, the prepared biochar possesses favourable surface chemistry for the removal of
contaminants, particularly dyes and other organic pollutants, from wastewater through adsorption processes.
14.Suggestions / Recommendations
Enhancing Carbonization Yield and Conversion Efficiency
a) To maximize the mass yield of activated carbon from the raw Musaceae (banana) peel biomass and ensure
complete pyrolytic conversion, the following process adjustments are recommended:
b) Pre-Carbonization Thermal Stabilization: Implementing a controlled, low-temperature devolatilization
phase 200-300C prior to high-temperature activation can prevent rapid volatile blow-out. This preserves the
structural carbon framework and increases final yield.
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c) Inert Atmosphere Purging: Future trials should replace static, limited-oxygen environments with a
continuous nitrogen N2) gas sweep inside the muffle furnace. This eliminates partial gasification and
unintended ash formation, ensuring a higher conversion of fixed carbon.
Optimization of Adsorbate Hydrodynamics and Contact Time
d) To overcome the temporal and boundary layer limitations observed during the preliminary batch testing:
e) Extended Kinetic Equilibrating: The contact period should be extended from 60 minutes to a minimum of
120 to 180minutes. This ensures that lower adsorbent dosages have adequate time to transition from a
transient mass transfer state to true thermodynamic steady-state equilibrium Ce.
f) Hydrodynamic Velocity Control: Agitation should be standardized using digital orbital shakers or
calibrated magnetic stirrers maintained strictly between 150 and 200 rpm. This specific range provides
sufficient energy to completely suspend the carbon particles (maximizing external surface wetting) without
creating high-shear vortices that fracture fragile carbon grains.
Calibration of Initial Dye Concentrations and System Volume
g) To establish highly accurate, reproducible adsorption profiles that avoid premature pore saturation:
h) Systematic Concentration Brackets: The initial dye concentration C0 should be evaluated across a broader,
systematically diluted range (e.g.,10, 25, 50, and 100 mg/L. This prevents the immediate saturation of active
sites and allows for the accurate plotting of Langmuir and Freundlich adsorption isotherms.
i) Volumetric Scaling: Increasing the total fluid volume per batch run (e.g., from 50 mL to250 mL ensures
that fluid samples extracted for UV-Vis analysis do not significantly alter the overall material balance of
the system.
Standardization of Mechanical Pulverization and Particle Sizing
j) To eliminate mass transfer discrepancies caused by hand-crushing the char:
k) Mechanical Milling and Classification: It is highly recommended to process the raw char using a
laboratory ball mill, followed by mechanical particle classification through ASTM standard wire cloth
sieves.
l) Diffusion Homogeneity: Restricting the adsorbent to a uniform mesh fraction (e.g.,150 micrometers ensure
a constant external surface-area-to-volume ratio. This eliminates anomalies in intraparticle pore diffusion
rates during kinetic modeling.
Isothermal and Instrumentation Calibration Upgrades
m) To mitigate systemic errors and ensure high data integrity:
n) Thermal Regulation: Adsorption flasks should be placed inside an isothermal water bath shaker to maintain
a constant operating temperature 25C. This isolates the exothermic or endothermic nature of the adsorption
mechanism from ambient laboratory temperature swings.
o) Mass Balance Verification: Analytical electronic balances must undergo certified calibration prior to
weighing trace carbon dosages. This minimizes the propagation of measurement errors when computing the
absolute adsorption capacity qe.
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15.Problems Encountered During Experiment
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Lack of Mechanical Crusher (Particle Size Inhomogeneity):
Due to the unavailability of a mechanical grinding mill or crusher, the carbonized banana peel char was
pulverized manually. This resulted in a non-uniform particle size distribution, which may have caused
variations in surface area and adsorption behavior, affecting the consistency of dye removal.
Analytical Balance Instability (Mass Measurement Uncertainty):
Minor fluctuations and calibration drift were observed in the analytical balance during the weighing of
adsorbent and dye samples. Although multiple measurements were taken and averaged, slight
uncertainties in mass determination may have introduced small errors in adsorption calculations.
Apparatus Constraints (Experimental Setup Discrepancies):
Variations in flask sealing and magnetic stirrer performance were encountered during the experiment.
These inconsistencies may have affected mixing efficiency and mass transfer rates, leading to minor
differences in the adsorption process.
Time Limitations:
Due to fixed laboratory working hours (9:00 a.m. to 4:00 p.m.), some experimental steps could not be
performed for their ideal durations. For example, the adsorption experiment ideally required 60 minutes
of stirring followed by 60 minutes of contact time for adsorption equilibrium. However, only 30–40
minutes could be allocated, which may have reduced the extent of dye adsorption and affected the final
results.
Human Handling Errors:
Manual handling during weighing, sample transfer, filtration, and solution preparation may have
introduced minor experimental inaccuracies, contributing to deviations in the observed adsorption
performance.
Incomplete Adsorption Equilibrium:
Because of the reduced contact time, the adsorbent may not have reached complete adsorption
equilibrium with the dye solution, potentially resulting in lower measured adsorption capacities than the
actual values.
Direct Addition of Activated Carbon (Poor Dispersion Effect):
Activated carbon was directly added into the rhodamine dye solution without pre-dispersing it in a
separate medium or pre-wetting step. This likely caused particle agglomeration and uneven distribution in
the solution, reducing the effective surface area available for adsorption and resulting in poorer
adsorption performance than expected. A better approach would have been to prepare a well-dispersed
carbon suspension before introducing it into the dye solution.
Insufficient Pre-Activation/Pre-Treatment of Adsorbent:
The activated carbon derived from banana peel biochar was not subjected to additional chemical
activation (e.g., acid/base treatment). This may have limited the development of functional groups and
pore structures, thereby reducing its adsorption capacity for rhodamine dye.
Non-Optimized pH Conditions of Dye Solution:
The pH of the rhodamine solution was not adjusted or optimized prior to adsorption. Since adsorption of
dyes on carbon surfaces is highly pH-dependent, especially for cationic dyes like rhodamine, suboptimal
pH conditions could have significantly affected adsorption efficiency.
Loss of Adsorbent During Filtration/Separation:
During the separation of activated carbon from the dye solution (via filtration), some fine carbon particles
may have passed through the filter paper or been lost during transfer. This would lead to underestimation
of actual adsorption capacity and introduce error in concentration calculation
18
17.Contributions:
Roll Number
Contributions
Percentage
2023-CH-11
 Assisted in experimental work (raw material handling to
FTIR analysis) Helped in understanding working
principle
 Recorded observations during experiment
 Contributed to interpretation of results
 Identified and discussed problems encountered during
experiment
16.67%
2023-CH-17
 Assisted in experimental work (raw material handling to
FTIR analysis)
 Supported data collection and observations
 Helped in result interpretation
 Contributed to troubleshooting during experiment
 Assisted in documentation of experimental findings
16.67%
2023-CH-15




Prepared introduction and theoretical background
Assisted in literature review and concept understanding
Provided support during experimental sessions
Helped in explaining basic principles of the experiment
16.67%
2023-CH-37




Developed introduction and theoretical background
Assisted in explaining core concepts and principles
Provided support during experimental work
Helped in understanding experimental methodology
16.67%
2023-CH-39




Prepared apparatus description section
Contributed to novelty and uniqueness of experiment
Assisted in identifying equipment components
Helped in understanding experimental setup
16.67%
2023-CH-47
 Handled report formatting and structuring
 Selected and finalized topic of experiment
 Contributed to applications and industrial relevance
section
 Organized content for final submission
16.67%
19
16.References:
Books
[1] M. A. Islam, M. J. Ahmed, W. A. Khanday, M. Asif, and B. H. Hameed, "Mesoporous activated carbon prepared
from NaOH activation of rattan (Lacosperma secundiflorum) hydrochar for methylene blue removal," Ecotoxicology
and Environmental Safety, vol. 138, pp. 279–285, 2017.
[2] T. Bohli, A. Ouederni, N. Fiol, and I. Villaescusa, "Evaluation of an activated carbon from olive stones used as an
adsorbent for heavy metal removal from aqueous phases," Comptes Rendus Chimie, vol. 18, no. 1, pp. 88–99, 2015.
[3] M. Olivares-Marín, C. Fernández-González, A. Macías-García, and V. Gómez-Serrano, "Preparation of activated
carbon from cherry stones by chemical activation with ZnCl₂," Applied Surface Science, vol. 252, no. 17, pp. 5967–
5971, 2006.
[4] J. Hayashi, T. Horikawa, I. Takeda, K. Muroyama, and F. N. Ani, "Preparing activated carbon from various
nutshells by chemical activation with K₂CO₃," Carbon, vol. 40, no. 13, pp. 2381–2386, 2002.
[5] A. Aworn, P. Thiravetyan, and W. Nakbanpote, "Preparation and characteristics of agricultural waste activated
carbon by physical activation having micro- and mesopores," Journal of Analytical and Applied Pyrolysis, vol. 82,
no. 2, pp. 279–285, 2008.
[6] M. Danish and T. Ahmad, "A review on utilization of wood biomass as a sustainable precursor for activated carbon
production and application," Renewable and Sustainable Energy Reviews, vol. 87, pp. 1–21, 2018.
[7] R. Azargohar and A. K. Dalai, "Steam and KOH activation of biochar: Experimental and modeling studies,"
Microporous and Mesoporous Materials, vol. 110, no. 2–3, pp. 413–421, 2008.
[8] A. G. Liew, A. Noor Aini, M. H. Zulkali, and A. Idris, "Banana peel as a low-cost adsorbent for removal of
methylene blue dye from aqueous solution," Bioresource Technology, vol. 98, no. 16, pp. 3017–3021, 2007.
[9] T. A. Saleh and V. K. Gupta, "Column with CNT/magnesium oxide composite for lead(II) removal from water,"
Environmental Science and Pollution Research, vol. 19, no. 4, pp. 1224–1228, 2012.
[10] V. K. Gupta and Suhas, "Application of low-cost adsorbents for dye removal — a review," Journal of
Environmental Management, vol. 90, no. 8, pp. 2313–2342, 2009.
[11] J. Lehmann and S. Joseph, Eds., Biochar for Environmental Management: Science, Technology and
Implementation, 2nd ed. London, U.K.: Routledge, 2015.
[12] K. Y. Foo and B. H. Hameed, "Preparation, characterization and evaluation of adsorptive properties of orange
peel based activated carbon via microwave induced K₂CO₃ activation," Bioresource Technology, vol. 104, pp. 679–
686, 2012.
20