ABSTRACT
Present study deals with the preparation of activated charcoal from Rice Husk dust. Rice husk dust was collected from the home which was collected from mill and grinded into small pores by Baltra company grinder. It was then modified by using conc.H2SO4, The surface are between the raw dust, chemically modified charcoal and commercially available charcoal was compared. The data of these charcoal were analyzed by Langmuir adsorption isotherm. The surface area of raw dust, chemically modified charcoal and commercially available charcoal was found to be 243.1 049 m²/g, 247.06m²/g and 503.4Im/g respectively. The surface area of commercially available charcoal was found to be greater than raw dust and chemically modified charcoal. This results that commercially available charcoal has greater adsorption than chemically modified and raw dust.
CHAPTER 1
INTRODUCTION
Adsorption is defined as the shift in a substance's concentration at the interface relative to its
1.1 General Introduction
neighboring phases. Adsorption depends on the types of phases in contact such as liquid-gas, liquid-liquid, solid-liquid and solid-gas. It depends on the interaction like van der Waal's force, electrostatic forces or chemical bond between the adsorbate and adsorbent (Dąbrowski, 2001).
Adsorption is the process by which particles adhere to a surface as a result of chemical
interactions, hydrogen bonds, or van der Waals forces, among other forces. This phenomenon is frequently applied in many fields, such as catalysis and water purification. Adsorption play an important role in every living being. It is widely used in industrial fields such as activated charcoal, synthetic resin, water filtration etc. Adsorption is present in natural, physical, biological and chemical system.
The term "adsorbent" and "adsorbate" terms are often used in adsorption.
Adsorbent
Adsorbent is a substance whose surface adsorbs adsorbate during the adsorption process. For instance, skin, silica gel, activated charcoal, etc. Usually, it's a porous substance with a large surface area, including metals like Ni, Cu, and Pt 69, silica gel, or activated charcoal. The surface on which the adsorption process takes place is supplied by the adsorbent. Adsorbents are significant because of the numerous industrial, environmental, and medical applications in which they are used. Since the adsorbent bears the majority of the procedure's expense, they are crucial to the effectiveness of the adsorption process. By leveraging the special qualities of bio-sorbents including chitosan, industrial waste, and agricultural waste, adsorbents are utilized to extract dissolved contaminants from water and other liquids. Additionally, they are important for the purification and separation of gases like oxygen and nitrogen during air separation procedures. Adsorbents also help particles and chemicals flow across TLC plates more effectively during chromatography. Adsorption is a technique used in wastewater treatment that helps industrial wastewater be cleaned up of a variety of pollutants.
Adsorbate
Adsorbate is a substance which gets adsorbed during the process of adsorption. For example, gas molecule, dust, sugar solution etc. The function adsorbate in the adsorption process, a vital phenomenon in surface chemistry, is what gives rise to the substance's significance in chemistry. Adsorbate is a material that adsorbs on a surface is essential in the formation of a film on the adsorbent's surface. Additionally, the capacity of adsorbate to transfer chargers to the surface during adsorption has important ramifications for a number of different chemical reactions and process.
Figure 1: Adsorption process
There are two categories of adsorption: physical adsorption and chemical adsorption.
1.1.1 Physical Adsorption:
When an adsorbate is held on the surface of adsorbent by a weak Vanderwaal's force of attraction then it is called as physical adsorption. The heat of adsorption in this case is low. The adsorbed gas molecule can be easily desorbed by increasing temperature so it is
reversible process.
1.1.2 Chemical Adsorption:
When adsorbate is held on the surface of adsorbent by a strong force then it is called as chemical adsorption. The heat of adsorption is higher as compared to physical adsorption. The adsorbed gas molecule cannot be desorbed with increase in temperature so it is an irreversible process, chemical increase with increase in temperature. ("Adsorption,"2022]
Figure 2: Physical and Chemical adsorption
Activated Charcoal
Activated charcoal is found in many water supplies which is a broad-spectrum agent that efficiently eliminates dangerous materials like pesticides, herbicides, heavy metal ions, chlorinated hydrocarbons, phenol etc. AC is a non-graphitic, micro-crystalline from of carbon which has undergone processing to increase its porosity. It possesses a large surface area, high porosity and high degree of surface reactivity. The primary physical characteristics of AC is that it enables the physical adsorption such as gases, vapors and dissolved compounds from liquids which is really its enormous specific surface area ranges from (500 to 2000m/g) beverages. Due to its tiny pores, the AC has a huge inner surface area which is the base for its exceptional adsorption capabilities. For many harmful chemicals (organic, inorganic, microbial, and biological), they are efficient adsorbents in the water and wastewater treatment processes (Mohammad-Khah & Ansari, 2009).
AC is known to be one of the most traditional and commonly utilized adsorbents to remove both organic and inorganic contaminants from the water and wastewater. AC is mainly applied in adsorption process for pore structure and surface chemistry of porous carbons. The pore structure and surface functional groups of activated carbon are mainly influenced by activation process and type of precursor utilized. Activated carbon is a well-developed interior pore structure in the term of carbon-based materials. A carbonaceous rich materials including wood, coal, lignite and coconut shell are used to make AC. The versatility of AC is noticeable in its wide range of functional groups present on its surface, large porosity, well-developed internal pore structure. These properties make AC an ideal material for a variety of applications, primarily in the environmental field (Bhatnagar et al., 2013).
History of Charcoal
Approximately 1500 B.C., the Egyptians recorded the first medical application of charcoal, mostly for the purpose of addressing offensive odors from open wounds. Information about the carbonaceous adsorbent properties of charcoal and ash can be found in other ancient writings. The use of charcoal for water treatment dates back to 400 B.C., according to archeological discoveries. Seafarers, in particular, were known to char the inside of water barrels to preserve and cleanse the water for extended ocean trips. Since then, healers have utilized activated charcoal to enhance intestinal health and absorb toxins.
New developments in the antiseptic, water purification, sugar bleaching, and odor elimination fields were achieved with the usage of charcoal between the 16th and 19th centuries AD. With the advent of the first World War, granular activated charcoal was utilized in gas masks, solvent recovery, and air purification. Commercial production of powdered activated charcoal began in the 20th century. While there are many forms of activated carbon available today, granular activated charcoal (GAC) and powdered activated charcoal (PAC) are the two most often used varieties on the market. Its high porosity is primarily responsible for activated charcoal's unique qualities. Because of its many tiny pores, the material has an incredibly wide surface area; 500-1500 square meters can be covered by one gram of it. The material's great adsorption capability is a result of its huge surface area. As a result, the surface area will rise with a bigger number of pores, increasing the element's adsorption capability. Surface area increases are contingent upon the kind of biomass and activation method used to create activated charcoal. More focus is currently being placed on this feature of activated charcoal as it is now known that the adsorptive characteristics are significantly influenced by the surface chemistry of the carbon (Okoli, 2021).
Figure 3: Activated Charcoal
The contamination of water by toxic heavy metals through the discharge of industrial wastewater is a worldwide environmental problem. Many chemical methods such as chemical precipitation, electro-floatation, ion exchange and reverse osmosis have been used for the removal of heavy metals. However, adsorption is most suitable to solve these problems. Activated carbon from cheap and readily available sources such as coal, coke, peat, wood, rice husk may be successfully employed for the removal of cadmium and other toxic heavy metals from aqueous solution. Other adsorbents such as petiolar felt-sheath of palm have also been used for the adsorption of heavy metals. Wood charcoal and heat-treated sulphurized activated carbon have been used for the removal of cadmium from acidic wastewater. Fifteen coniferous barks were used for removal of heavy metals, as well as red mud, fly ashes (Apak et al., 1998) and sunflower stalks (Ajmal et al., 2003).
Rice husk has tremendous potential as a remediation material for the removal of arsenic from groundwater. The present work investigates the possibility of the use of rice husk adsorption technology without any pretreatment in the removal of arsenic from aqueous media. Various conditions that affect the adsorption/desorption of arsenic are investigated. Adsorption column methods show the complete removal of both As(III) and As(V) under the following conditions: initial As concentration, 100 µg/L; rice husk amount, 6 g; average particle size, 780 and 510 um; treatment flow rate, 6,7 and 1.7 mL/min; and pH, 6.5 and 6.0, respectively. The desorption efficiencies with 1 M of KOH after the treatment of groundwater were in the range of 71-96%. The present study might provide new avenues to achieve the arsenic concentrations required for drinking water recommended by Bangladesh and the World Health Organizatión (Amin etal., 2006).
Surface Area
The total area of a three-dimensional object's or material's outermost layer is known as surface area. It shows how much of the surface is open to the environment. It is a crucial parameter in science terminology for processes such as adsorption, in which the accessible surface affects how well materials interact with one another (Wikipedia, 2024).
An essential component of adsorption processes is surface area. The process of molecules from a fluid adhering to a solid surface is called adsorption. The surface area of the adsorbent material has a major impact on the process's scope and effectiveness. Adsorbate molecules can attach to multiple locations on a surface area. In general, this improves the adsorbent's ability to draw in and retain molecules from the surrounding fluid.
1.2 Adsorption isotherm
Adsorption isotherms are curves or plots created by graphing the extent of adsorption against pressure at a fixed temperature. At constant temperature a certain relation obtained between the amount of gas adsorbed and pressure. Five types of isotherm are found in adsorption phenomena.
Type I adsorption isotherm: This isotherm shows that as pressure rises, the amount of adsorption increases until it reaches the saturation stage, at which point it stops. Type II adsorption isotherm: It is produced when the bilayer forms only subsequent to the monolayer's complete formation, the trilayer following the bilayer's completion, and so forth. Types III adsorption isotherm: It results from simultaneous monolayer, bilayer, and trilayer production. hence there is an almost exponential increase in the extent of adsorption.
Types IV and Type V adsorption isotherm: These kinds of adsorption isotherms can only be produced when adsorption occurs within capillaries and pores.
Many scientists have introduced several types of isotherm which are describe below:
i) Freundlich Adsorption isotherm
ii) Langmuir Adsorption isotherm
iii) BET Theory
1.2.1 Freundlich Adsorption isotherm
In 1909, German scientist Freundlich provided an empirical relationship between the amount of gas adsorbed by a unit mass of solid adsorbent and pressure at a particular temperature. It is expressed using the following equation-
y=Kp l/n-------------------- eq(i)
Where K= constant for a gas at particular pressure (n) = 1,2,3,4.......
The mass of the gas adsorbed per gram of the adsorbent is plotted against pressure in the form of a curve to show the relationship. Here, at a fixed pressure, physical adsorption decreases with increase in temperature. The curves reach saturation at high pressure. Now, if you take the log of the above
logy = log k + 1/n log p______eq(ii) (1/n 0 to 1)
1.2.2 Langmuir Adsorption isotherm
Langmuir Adsorption Isotherm refers to equilibrium between the adsorbent and adsorbate system. The isotherm is based on the following assumptions:
1. Adsorption is always monolayer.
2. Adsorption is reversible process, forward process is adsorption and backward is desorption. At equilibrium, these two process are equal.
3. Heat of adsorption is constant and uniform across all sites.
The equation for Langmuir adsorption is as follows:
Ce/Qe.-1/kbAs,+Ce/As_________eq(iii)
C Concentration of adsorbate solution (mg/L)
Q-Adsorption capacity of the sample (mg/g)
As Saturated adsorptive capacity (mg/g)
determined from the intercept and slope of linear plot of logQ, vs logC
1.2.3 BET Theory
Brunnauer-Emmett-Teller (BET) theory describes the physical adsorption for gas molecules on the solid surface. The assumption of BET adsorption isotherm are listed below:
. Many layers are formed on the surface of solid gases molecules.
. The principle of Langmuir theory can be applied to each layer.
. A dynamic equilibrium exists between successive layers and the rate of vaporization from a particular layer is equal to the rate of condensation of proceeding layer ("BET Theory,"2022).
1.3 Statement of the problem
Figure 4: Rice Husk Dust
In today's generation due to the human, agricultural and industrial activities water have become polluted with various toxic heavy metals like Chromium, Arsenic, Zinc, Lead, Cadmium, Mercury etc which has created a major problem for living being. These are some heavy metals which can cause serious health problem in living beings.
Hence, water treatment has become necessary to remove these heavy metals. There are various process for the treatment of contaminated water for example filtration, ion exchange, electrodialysis and coagulation. However, adsorption is the most economically feasible process which can remove the heavy metals completely in low cost. Adsorption is mainly used for the management of aqueous solution and one example is the utilization of rice husk
which is inexpensive in terms of cost and it is waste biomaterial. Wastes are also utilized for the water treatment and also helps economically in developing countries.
1.4 Objectives of Research
1.4.1 General Objectives of the Research work
The goal of this research is to measure and compare the surface area of rice husk dust and commercially available charcoal.
1.4.2 Specific Objectives of Research work
i) To find easily available bio-adsorbent.
ii) To prepare the raw bio-adsorbent.
iii) To prepare the chemically modified bio-adsorbent.
iv) To find out the surface area of commercial bio-adsorbent.
2. LITERATURE REVIEW
CHAPTER 2
Malik. (2003) investigated that, acid dyes have been removed from aqueous solutions using activated carbons, which are made from inexpensive rice husk. Acid Yellow 36, an acid dye, has been employed as the adsorbate. The adsorption of acid dye has been demonstrated to be most advantageous at a pH of 3. The Freundlich and Langmuir equations could provide a good description of the isothermal data. Adsorption kinetic characteristics were measured, including the intraparticle diffusion rate constant and the Langergren pseudo-first-order constant. The intraparticle diffusion of the dye molecule within the particle has been found to be the rate limiting factor for the current adsorption process. It was discovered that rice husk carbon (RHC) had an adsorption capacity of 86.9 mg per g of the adsorbent. According to the investigation's findings, rice husk, a cheap material, may be used to make activated carbon, and this carbon has a enough adsorption ability to remove Acid Yellow 36 from its aqueous solution. Contact time, adsorbent dosage, and pH all have a significant impact on adsorption.
Ahmad et al. (2011) studied that in an effort to remove reactive dye, specifically Remazol Brilliant Blue, from aqueous media, substitute adsorbents such as sawdust and rice husk have been tried in place of charcoal. Remazol brilliant blue has been tested for its adsorption onto rice husk, sawdust, and charcoal at varying temperatures, adsorbent dosages, and pH values. The outcomes of these studies are compared. The adsorption data was matched to the Langmuir and Freundlich isotherms, and the appropriate adsorption parameters were computed for each. To determine the amount adsorbed at equilibrium (Qe), pseudo first and second order kinetic models were applied. It was discovered that there was a good match between the experimental and computed values of Q. for the pseudo-second order equation. Compared to charcoal (0.074 mg g/sup -1/) and sawdust (0.114 mg g/sup -1/), rice husk (0.699 mg g/sup -1/) has a higher monolayer capacity (Vm). In comparison to charcoal and sawdust, rice husk is found to be a superior adsorbent for the removal of Remazol brilliant blue.
Feng et al. (2004) investigated to employ the rice husk ash, an agricultural waste, as an adsorbent for the removal of lead and mercury from water. Research is conducted based on the parameters of pH, particle size, ionic strength, and contact periods. Lead and mercury ions can be effectively adsorbed using rice husk ash as an adsorbent. The mechanism for lead and mercury ion adsorption by rice husk ash can be expressed using the Bangham equation. Compared to mercury ions, its adsorption capacity and rate for lead ions are significantly higher and faster. The amount of lead and mercury ions absorbed on rice husk ash increases with finer rice husk ash particle size, higher pH, and lower potassium nitrate solution concentration. It is discovered that rice husk ash is a byproduct of agriculture, works well as an adsorbent for removing lead and mercury ions from aqueous solutions.
Jaman et al. (2009) investigated the use of rice husk as a low-cost adsorbent for the removal of copper from wastewater. To improve the sorption qualities, alkali was applied to the rice husk In addition, the effects of temperature, pH, stirring rates, weight of the biosorbent, and metal ion concentration were assessed.
Adsorption isotherm models were used to match the data. According to the experiment's findings, processed rice husk may remove between 90 and 98 percent of the copper. In batch studies, the distribution of copper between the liquid and solid phases was described using the Langmuir adsorption isotherm, Freundlich isotherm, and Tempkin isotherm models. It was found that the Langmuir isotherm more accurately captured the adsorption phenomena.
Ye et al. (2012) examined the ability of modified rice husk to extract Cu(II) from water. The modified rice husk's adsorption properties for Cu(II) removal from aqueous solutions were assessed by batch tests. We looked at the kinetics, desorbability, pH influence, adsorption isotherms, and thermodynamic factors. The findings indicate that at a temperature of 25 °C, with an initial concentration of 400 mg/L and a pH of 7.0, the modified rice husk's maximum adsorption capacity
Yi et al. (2017) determined that the ideal pH level and dosage for the adsorption of Cr(VI) were quickly in 80 minutes and nearly reached adsorption equilibrium in 100 minutes. Lastly, the 1-4 and 8.0 g L-1, respectively. Additionally, the adsorption process on Cr(VI) increased adsorption of Cr(VI) increased as temperature increased. Moreover, the equilibrium process was examined using the Freundlich and Langmuir models. It was discovered that for the adsorption of Cr(VI) on modified litchi peel and Litchi peel, the Langmuir model offered superior correlation. LP has a maximum adsorption of just 7.05 mg g-1 at 303 K, whereas modified litchi peel has a maximum adsorption of 9.55 mg g-1 at 303 k. Pseudo-second-order model may more accurately represent the kinetics of Cr(VI) adsorption on modified litchi peel
Yusuff. (2019) investigated that using modified carbon derived from the seed shell of Leucaena leucocephala, hexavalent chromium was eradicated. Reaction surface methodology was used to optimize the variables that influence the adsorption process. An analysis of variance revealed that 95.63% of the adsorption was achieved at 26.2°C, with the hexavalent content, pH of the 4.22 solution, and 0.57g of adsorbent provided. Best fit to the experimental data were the pseudo second order kinetic model and the equilibrium adsorption isotherm.
Enniya et al. (2018) worked on the elimination of Hexavalent chromium from aqueous solution using activated carbon made from apple peels (ACAP). The pH (2-7), adsorbent dosage (0.025-0.15 g/50 mL), starting Cr(VI) concentration (10-50 mg/L), and temperature (10-40°C) were the adsorption parameters that were investigated. With a Cr(VI) concentration of 50mg/L, pH of 2, adsorbent dose of 0.05 g/50 mL, contact period of 4hr, and temperature of 28°C, the maximum Cr(VI) adsorption of 36.01 mg/g was obtained. Better than conventional activated carbon, this ACAP provided a Cr(VI) adsorption capacity. The pseudo-second order model for kinetics was followed by the experimental results, which suited the Freundlich isotherm (R2 = 0.99) quite well.
Nur-E-Alam et al. (2018) studied on tea leaves which are readily available and inexpensive, they can be treated and used as a good adsorbent to remove chromium (Cr) from wastewater from tanneries. These leaves are abandoned as waste material from tea shops to hotels. A pH of 10 and an adsorbent dosage of 14 g/L were found to be the optimal conditions for the greatest removal of Cr, according to experimental results. The first effluent concentration determines the duration of contact. The lengths of contact for Samples S1 and S3 were 60 and 150 minutes, respectively. After reaching equilibrium for a sample with the same concentration, the percentage of elimination increased over time. The findings of the experiment were supported by the 0.915 and 0.935 Langmuir and Freundlich adsorption isotherms, respectively. It was discovered that Cr had a maximum adsorption capability of 10.64 mg/g on tea trash. According to this study, tea waste is an inexpensive, widely accessible, environmentally benign, and effective bio adsorbent for removing Cr from wastewater.
Moreno-Piraján & Giraldo. (2012) reported that to remove the heavy metal ions (Cr, Cd, and Co) from aqueous solutions, activated carbon made from orange peels was created. For the concentration levels under investigation, it was observed that adsorption occurred for the four metals in 15 to 25 minutes. pH has a significant impact on the adsorption process in our experimental setup, especially on the adsorption capacity. The adsorption capability of the beavy metals under study is significantly influenced by pH. For all ions under investigation, a pH of 5.0 has been chosen as the ideal value for adsorption. The amounts adsorbed per gram of ACOP at equilibrium (Qe) for Cd2+, Cr3+, and Co2+ are 28.67 mg/g-1, 30.11 mg/g-1, and 45.44 mg/g-1 respectively, indicating that ACOP has a comparatively high adsorption capacity for these heavy metals. An isotherm of type I describes this adsorption, and the Langmuir isotherm provides complete verification. It was discovered that a pseudo-second-order rate equation described the kinetics of the cobalt, cadmium, and chromium adsorption on the ACOP. One advantage of this approach that its low cost makes it suitable for use in underdeveloped nations.
Larous et al. (2005) investigated the copper adsorption using sawdust that is produced locally as a byproduct of wood usage. Batch wise operation was used to conduct the copper retention investigation, and important physico-chemical factors like temperature, agitation speed, beginning concentration, contacting time, liquid to solid ratio, and ionic strength were taken into account. The equilibrium adsorption capacity of sawdust for copper has been obtained by using linear Freundlich and Langmuir isotherms. The results tend to explain the retention mechanism as an ion exchange process for binding the divalent metal ions to the sawdust.
Jha & Maharaja. (2022) focuses on using banana peels to prepare activated carbons. In c air, nitrogen gas, and a combination of nitrogen gas and water steam generated to 60-70°C, the banana peels were open subjected to pyrolysis at 700 °C for one hour. Using XRD, FTIR, and
methylene blue adsorption techniques, the raw and activated carbons from banana peels were identified. As (III) ions from an aqueous solution were adsorbed using the N2+H2O-BP. The adsorption procedure was conducted using a range of starting metal ion concentration, contact period, and pH (4 to 10) as different factors. The Langmuir and Freundlich isotherms were used to calculate adsorption isotherm.
CHAPTER 3
3. MATERIALS AND METHOD
3.1 Preparation of Reagent
3.1.1 Preparation of Sodium hydroxide (NaOH)
A solution of NaOH was created by dissolving 4g of solid NaOH IN 1000ml of volumetric flask and diluted it with distilled water up to the mark of flask.
3.1.2 Preparation of Oxalic acid (0.1N approx.)
To prepare the oxalic acid of 0.1N, 3.15g of oxalic acid crystal was added to 500ml of volumetric flask and then diluted it with distilled water till the mark on the flask.0.1N oxalic acid was used for the standarization of NaOH solution and found to be 0.0952N.
3.1.3 Preparation of 0.2N acetic acid
To prepare acetic acid of 0.2N, 5.8ml of acetic from the bottle was taken in 500ml of volumetric flask and then diluted it by adding distilled water till the mark.
3.2 Preparation of adsorbent
3.2.1 Preparation of raw adsorbent
At first, rice husk dust was collected from the home which was collected from mill and it was sieved and then grinded to get it into the powder form
3.2.2 Chemically modified adsorbent
First of all, 50 grams of rice husk dust was weighed and was kept it into the beaker. The powder was then mixed with concentrated H2SO4 and left for 24 hours to allow for condensation cross linkage reaction occur. In the result, black residue was seen, which was then washed with water and filtered it until the pH 7 obtained. The residue was then dried in an oven for 12 hours at 80°C. The obtained dried powder was then grinded in mortar and pestle to obtained fine powder.It was grinded until fine powder was obtained because more fine powder more the surface area.
3.3 Experimental Process
Figure 5: Charcoal
The prepared charcoal was weighed 1gm each in 5 bottles and kept in specific reagent bottles. After that water and acetic acid was added making the total volume 50ml each and given thesame for each bottle as B1, B2, B3, B4 and Bs.
Bottle (B1) contains 1 gm charcoal+10ml acetic acid and 40 ml water.
Bottle (B2) contains 1gm of charcoal+20ml acetic acid and 30 ml water.
Bottle (Bs) contains 1gm of charcoal+30ml acetic acid and 20ml water.
Bottle (B4) contains 1gm of charcoal+40ml acetic acid and 10ml water.
Bottle(Bs) contains 1gm of charcoal+50ml of acetic acid.
These bottles were tighten with lid and kept in shaker for 1 hour to shake in speed of about 440sc/min. After that the mixture was taken out and allowed it to settle down for about 30 minutes. The settle down mixture were then titrated. 5 bottles were titrated by pipetting out 5ml from the reagent bottles and added dropwise phenolphthalein as an indicator, then it was titrated out with NaOH.
Figure 6: settle down adsorbent
Figure 7: Flask Shaker
The similar process above mentioned were carried out for commercially available charcoal, nice husk dust and self-made chemically modified charcoal.
CHAPTER 4
Surface area of different adsorbent were determined with the help of Langmuir adsorption
4. RESULTS AND DISCUSSION
4.1 Surface area of raw adsorbent derived from rice husk dust
Table 1: Determination of C/X for raw rice husk dust
DISCUSSION
From the above data, it can conclude that commercially available charcoal has greater surface area than the chemically modified charcoal and raw dust. Raw dust has less surface area but after chemically modified, the surface area of raw dust has also increased. So, it can conclude that commercial charcoal adsorbs better than the raw rice husk dust and chemically modified charcoal.
CHAPTER 5
5. CONCLUSION AND RECOMMENDATIONS
5.1 Conclusions
Rice husk dust can be used as bio adsorbent from my modification or it with conc.H₂SO. The charcoal thus obtained from our evaluation turns out to be less effective. Under the adsorption study of thus prepared charcoal and commercially available charcoal following conclusions were drawn:
. The charcoal was successfully prepared from rice husk dust.
.The adsorbent thus obtained was used for the adsorption of heavy metals like zinc, mercury, lead, arsenic etc. Adsorption behavior shows the process here is dependent on pH, concentration and dose of adsorption. Thus, the obtained data are used to calculate the adsorption isotherm as well.
.From the data calculation, it shows that commercially available charcoal has more surface area than the chemically modified charcoal and raw dust. But it does not mean it can't be used as adsorbent, it can be used as adsorbent where it required in lessb amount.
5.2 Limitation of work
.Due to the lack of time, adsorption of arsenic from the water was not studied.
.Due to limitation of time, kinetic of adsorption was not studied.
•Studied only about of monolayer adsorption due to the limitation of time.
5.3 Recommendations for Further Study
•This research work only involved the rice husk dust for the adsorption but different bio-adsorbent can be used for the adsorption such as saw dust, tea dust, peanut shell dust, sugarcane bagasse dust.
• Heavy metals can also be removed by above mentioned bio-adsorbent.
.Didn't work on arsenic adsorption from water due to the limitation of time but upcoming student can work on this topic.
.Characterization of adsorbent can be done by using different techniques such as XPS, FTIR, XRD and TEM.
.Titration was done to detect the surface area of liquid phase but BET Theory can be used for better result.
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