Introduction
Background of the Study
Currently, there is a rapid increase in contaminants in the environment. However, one of the major global concerns is the concentration of heavy metals due to human activities. Since the biosphere is a closed system, these heavy metals remain on earth and continuously increase as the human population grows. The acute and chronic effects of these heavy metals, especially lead, have been a worldwide concern.
Lead is a toxic metal that can have harmful effects on human health and the environment. It can enter water sources through various means such as industrial waste, mining activities, and the use of lead pipes. This contamination can be detrimental to aquatic life and pose a risk to human consumption.
In April 2000, Metro Manila phased out the use of leaded gasoline due to the implementation of Clean Air Act of 1999 and environmental concerns raised by former president Fidel V. Ramos. This movement was a significant step towards reducing lead pollution in the area.
To remove metals like lead from water sources, conventional methods such as chemical precipitation, lime coagulation, ion exchange, reverse osmosis and solvent extraction are commonly used.
Although methods for removing heavy metals from wastewater exist, they are often cost-prohibitive and have inadequate efficiency at low metal concentrations, especially in the range of 1 to 100 mg/L. Additionally, some of these methods generate toxic sludge that is difficult to dispose of and adds a burden to the techno-economic feasibility of treatment procedures. Therefore, researchers are searching for new technologies involving the removal of toxic metals from wastewater. One such technology is biosorption, which utilizes the metal-binding capacities of various biological materials.
Biosorption is the process by which biological materials accumulate heavy metals from wastewater through metabolically mediated or physico-chemical pathways of uptake. It provides an attractive alternative to physico-chemical methods for removing heavy metal ions. The major advantages of biosorption over conventional treatment methods include low cost, high efficiency in removing metals from dilute solutions, minimal production of chemical and/or biological sludge, no additional nutrient requirements, and the ability to regenerate biosorbent and recover metals.
In this present study, Musa sapientum L. peels are investigated as a potential low-cost de-leading agent due to their abundance and environmentally friendly nature. The peels are widely available and represent an unused resource.
The significance of the study is to generate a low-cost de-leading agent that can benefit readers by raising awareness about the prevalence and increasing concern for heavy metal contamination in Philippine waters.
Researchers aim to develop an inexpensive and effective biosorbent that is easily available in large quantities in the Philippines. This will be economically feasible for treating lead-contaminated water. Policy makers can use this information to create policies regarding wastewater treatment in factories and for those involved in the treatment of public water, such as MAYNILAD.
Statement of the Problem
Conventional methods of removing lead from the environment are said to be cost-prohibitive and generate toxic sludge. In this study, the researchers sought answers to the following problems:
- Can the peels of Musa sapientum (L.) (Fam. Musaceae) reduce the level of lead ions in contaminated water?
- What is the optimum pH of the solution for banana peels to exhibit maximum biosorption capacity?
- What is the effect of contact time on the biosorption capacity of banana peels?
- What is the effect of initial metal concentration of lead in solution on the amount adsorbed by banana peels?
Objectives of the Study:
General Objective:
The general objective of this study is to determine the potential biosorbent capacity of the peels of Musa sapientum (L.) (Fam. Musaceae).
Specific Objectives:
The specific objectives of this study are:
- Determine if banana peels can reduce the level of lead ions in contaminated water.
- Determine the optimum pH at which banana peels exhibit maximum biosorption capacity.
- Determine the optimum contact time and its effect on the biosorption capacity of banana peels.
- Determine the effect of initial lead concentration on the amount of lead adsorbed by banana peels.
Hypothesis:
- Ho 1: The fruit peels of Musa sapientum (L.) (Fam. Musaceae) can reduce the level of lead ions in contaminated water.
- Ha 1: The fruit peels of Musa sapientum (L.) (Fam. Musaceae) cannot reduce the level of lead ions in contaminated water.
- Ho 2: The maximum removal of lead ions by banana peel occurs at pH 3.
- Ha 2: The maximum removal of lead ions by banana peel does not occur at pH 3.
- Ho 3: There is no direct relationship between contact time and biosorption capacity of banana peels, up to a certain extent. Biosorption kinetics do not follow a pseudo-second-order model.
- Ha3 : There is a direct relationship between contact time and biosorption capacity of banana peels, up to a certain extent. Biosorption kinetics follow a pseudo-second-order model.
- Ho4 : There is no direct relationship between the initial concentration of chromium in the solution and the amount adsorbed by banana peels, as described best by Langmuir’s isotherm model.
- Ha4 : There is a direct relationship between initial concentrationof chromium in solution and amount adsorbed by banana peels, as described bestby Langmuir’s isotherm model.
The study evaluates the biosorbent effect of Musa sapientum L. (Banana peel) for Lead-contaminated water solution. The specific research was conducted at EAC School of Pharmacy 7th floor E7-laboratory room, and the use of instruments such as Flame Atomic Absorption Spectrophotometer was performed in De La Salle University-Taft, Manila. Samples were collected from a street vendor along U.N. Avenue. The study focused solely on Lead-contaminated water solution and did not investigate the lead content of banana peels per se.
Review of Related Literature
Lead in the Environment
Lead is a gray, soft, and malleable metal that naturally exists as a mixture of three isotopes. It is one of the most significant heavy metal contaminants and poses a severe threat to children’s environmental health, according to the WHO. Exposure to even low levels of lead may impair childhood cognitive function and cause abnormal infant behavior. In the rural Philippines, 21% of 2861 children had elevated levels of lead in their whole blood.
Lead is classified as a possible human carcinogen by the International Agency for Research on Cancer. It is also listed as one of the priority contaminants by the United States Environmental Protection Agency. Therefore, it is crucial to remove lead from wastewater before releasing it, due to its detrimental health effects on humans.
Biosorption as a Solution
Biosorption is a potential cost-effective alternative for removing heavy metals from water through adsorption. Most studies related to biosorption have focused on several fungal strains and various species of marine algae.
Biosorption is a physical-chemical adsorption process where metal ions attach to the surface of biomass. This process involves the ability of biological materials to accumulate heavy metals from wastewater through metabolically mediated or physico-chemical pathways. Biosorption has several advantages over conventional treatment methods, including low cost, high efficiency in removing metals from dilute solutions, minimal production of chemical and/or biological sludge, no additional nutrient requirements, and the possibility of regenerating the biosorbent and recovering metals.
Potential Uses of Bananas
Peel of the banana (Musa sp.) is an abundant and low-cost agricultural waste residue that is easily available in large quantities. Achak et al. [2009] investigated the efficiency of banana peel as a biosorbent for removing phenolic compounds from olive mill wastewater. Thirumavalavan et al. [2010] and Li et al. [2007] demonstrated that solid fruit peel residue can be converted into an effective adsorbent for metal ion adsorption and compared its activity with activated carbon.
Lemon peel, orange peel, and banana peel can be used as adsorbents to remove various metal ions such as Cu(II), Ni(II), Zn(II), Pb(II), and Cd(II). The peels of Musa sapientum were analyzed for minerals, nutritional, and anti-nutritional contents. Mineral content analysis showed the presence of potassium, calcium, sodium, iron, manganese, bromide, rubidium, strontium,zirconium,and niobium. Additionally,
protein,
crude lipid,
carbohydrate,
and crude fiber were also found.
If properly exploited and processed,Musa sapientum peels could be a high-quality and inexpensive source of carbohydrates and minerals for livestock.
The peels of Musa sapientum, which are usually ignored and treated as waste, could be repurposed for proper utilization. Morphologically, Musa sapientum is commonly known as a banana plant and belongs to the family Musaceae. It is the largest herbaceous flowering plant with an upright stem that grows from a corm to a height of 6 to 7.6 meters. The leaves are spirally arranged and can reach up to 2.7 meters in length and 60 cm in width. They are fragile and easily torn by wind, giving them their familiar frond-like appearance.
Each pseudostem produces a single bunch of bananas. After fruiting, the pseudostem dies, and offshoots usually develop from the base of the plant. The banana heart is a single inflorescence produced by each pseudostem and contains many bracts between rows of flowers. Banana fruits develop from the heart in a hanging cluster made up of tiers (hands), with up to 20 fruits per tier. According to a study conducted by Anhwange et al., the concentration of potassium is highest (78.10mg/g).
The concentration of calcium, sodium, iron, and manganese were 19.0 mg/100g, 24.30 mg/100g, 0.61 mg/100g and 76.20 mg/100g respectively.
The appreciable high content of potassium signifies that if the peel is taken, it will help in the regulation of body fluids and maintaining normal blood pressure.
Materials and Methods
Modify the procedures in Chapter 3. I have already changed the objectives and hypotheses.
Collection of Plant Material
Banana peels (Musa sapientum L) will be collected from the local market as biomass. The biomass will be dried in the sun for fifteen days, after which the buds will be removed and further dried in the sun for another fifteen days.
This biomass will be washed with tap water to remove any dust or foreign particles attached to it and then thoroughly rinsed with distilled water. The washed biomass will be dried at 50°C and ground into a powder using a mortar and pestle. The ground biomass will then be washed again with distilled water until the color of the washing water is clear. The powdered biomass will be dried in an oven at 50°C until it reaches a constant weight. Finally, the biosorbent will be ground into powder once again and screened using an 80-mesh sieve to achieve an approximate size of 1.5-2 millimeters.
Reagent Preparation
A stock solution of lead (1000mg/L) will be prepared by dissolving the desired quantity of hydrated lead acetate [Pb(CH3COO)2·3H2O] in distilled water. Other concentrations can be obtained by properly diluting the stock solution. All chemicals used will be of analytical reagent grade.
Determination of Biosorption Capacity
Biosorption studies will be carried out through a batch process. The biomass will be added to conical flasks that contain a known amount of metal solution with the desired concentration. To ensure equilibrium is reached, the mixture will be agitated for three hours using the Burell Wrist Action Shaker model 75.
The pH of the solutions will be adjusted by adding 0.1N NaOH or 0.1N HNO3. The biomass will then be removed by filtration using a vacuum filter with a pore size of 45 micrometers. The filtrates will be analyzed for residual lead concentration by atomic adsorption spectrophotometry using a Perkin-Elmer model with an air-acetylene flame. All experiments will be performed in triplicate, and mean values will be presented with a maximum deviation of 5% in all cases. Blank samples will also be run under similar experimental conditions but in the absence of the biosorbent.
Determination of the Optimum pH of the Solution:
Batch experiments will be conducted by contacting 0.1 g of banana peel with 100 mL of lead acetate solution having a concentration of 50 mg/L. The mixture will be placed in conical flasks and subjected to agitation using a shaker for three hours at room temperature (28°C). The pH values of the solution will range from pH 1 to pH 6.
Kinetics of Adsorption
Kinetic studies will be conducted in a conical flask with constant agitation. 0.1 g of banana peels will be added to 100 mL of lead acetate solution, which has a concentration of 50 mg/L, at room temperature (28°C).
Samples will be taken at predetermined time intervals of 0, 5, 10, 15, 20, 25, 30, 60, 90, 120,150 and180 minutes. The samples will be collected using a transfer pipet with a volume of25 mL and filtered immediately through vacuum filtration. To maintain the pH value at4 throughout the experiment either0.1N NaOH or0.1N HNO3will be added.
Adsorption Isotherm
A constant mass of 0.1 g of banana peel material will be added to conical flasks containing 100 mL of metal solution. The concentrations of lead acetate were varied in the range of 25-100 mg/L. A contact time of 3 hours will be allotted with constant agitation at room temperature (28°C).
A pH value of 3, 4, or 5 will be maintained throughout the experiment by adding either 0.1N NaOH or 0.1N HNO3. The amount of metal ion that the banana peel will absorb per gram of biomass will be calculated using the expression adapted from equation (3): qe=(V(Ci–Ce))/m. The efficiency of banana peel biosorption will be determined using the equation from reference [6]: %E=((Ci–Ce)/Ci) x 100, where qe represents equilibrium lead ion capacity in milligrams per gram (mg/g), E represents biosorption efficiency, V represents suspension volume in liters (L), m represents mass of banana material in grams (g), Ce is lead ion concentration at equilibrium in milligrams per liter (mg/L), and Ci is initial lead ion concentration also measured in milligrams per liter.
The root mean squared error (RMSE) will be calculated to determine the model fit. To calculate the RMSE, we will sum up the squared difference between the experimental metal uptake (q) and the corresponding model predictions for uptake (qm). This sum will then be divided by the number of data points (p) for each dataset to calculate the mean square error. Finally, we obtain RMSE by taking the square root of that term. The RMSE represents an average deviation between predicted and actual metal ion uptake. We will adapt an equation for RMSE from our sources.
