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COMPARATIVE BIOSORPTION STUDY OF ARSENIC AND CADMIUM FROM AQUEOUS SOLUTION USING COCONUT SHELL AND GROUNDNUT SHELL
ABSTRACTS
Comparative biosorption of heavy metals (Cd, and As) in batch system using agro-mass obtained from groundnut shell and coconut shell was carried out. The heavy metal adsorption was found to be dependent on the initial pH, contact time, initial concentration of heavy metal and agro-mass dose. Activated carbon from coconut shell and groundnut shell using phosphoric acid (H3PO4) as activating agents by means of a two step activation process was characterised. The result of the analysis indicate the percentage of dry matter, moisture contents, Ash contents, bulk density and surface area of the samples were shown as 97.78%, 2.22%, 1.85%, 0.58g/cm3 and 179.30m2 while 98.93%, 1.07%, 1.46%, 0.20g/cm3 and 289.10m2 for coconut shell and groundnut shell respectively. The groundnut shell sample gave different results on analysis to that of coconut shell sample. The percentage removal efficiency of Cd2+ and As3+ before and after with the activated carbon of the samples and the amount Cd2+ and As3+ adsorbed at different contact time range was determined using the Atomic Adsorption Spectrophotometer (AAS) “ICE 3000 AA02134104v130”. Langmuir and Freundlinch model were used to study the adsorption isotherms. Langmuir was found to be better fit for adsorption of Cd2+ and As3+ ions with good correlation coefficient (0.936) and (0.958) for coconut shell than for groundnut shell (0.084) and (0.906) respectively. These results reveal that activated carbon made from groundnut shell with good characteristic are better than activated carbon made from coconut shell for the adsorption of heavy metal ions from aqueous solution.
CHAPTER ONE
INTRODUCTION
1.1. BACKGROUND OF THE STUDY
The natural environment is constantly contaminated by various pollutants coming from domestic, industrial and agricultural sectors, which in turn showed a considerable change. Poisonous metals are widespread hazardous and affect the environment with a negative impact on the ecosystem, causing life threaten diseases to both animals and humans. Among heavy metals, Arsenic, Mercury, Cadmium, Chromium, e.t.c. (Cd, As, Hg, Cd, As, Cr, As) are cited (Salem et al. 2012) which must be removed before discharge to the aquatic environment. Unlike organic pollutants, heavy metals are refractory and cannot be degraded and accumulate in living organisms (Ali and Ateeg 2015).The elimination of heavy metals has been the theme of several works using different techniques like adsorption (Abolhasani and Behbahani 2015); ion electrodialysis (Esalah et al. 2000), coagulation/flocculation (Yue et al. 2009), sedimentation (Gupta et al. 2001), ionexchange (Dabrowski et al. 2004; Kang et al. 2008), biological operations (Rashid et al. 2014), nano filtration (Hafiane et al. 2000), solid-phase extraction (Khezami and Capart 2005), (Behbahani et al. 2014) and electro kinetic remediation (Sawada et al. 2004).
However, all these techniques suffer from high costs of capitals and operations as well as the elimination of metallic sludge (Malairajan 2011). On the other hand, the adsorption has become advantageous for removing poisonous metals because of its environmentally friendly characteristic, efficiency and low cost. In this regard, many agricultural wastes were used as adsorbents for both inorganic and organic pollutants (Copat et al. 2012; Izquierdoetal.2014; Samiey and Ashoori 2012; Vilar et al.2008).
In this respect, coconut shell and groundnut shell will be utilize to see their efficacy in adsorbing heavy metals from solution because of their specific characteristics that motivate their utilization for the elimination of various pollutants, including metals. The present study is devoted specifically to the adsorption of heavy metals. (As and Cd) onto coconut shell and groundnut shell. The optimization of the operating conditions (initial pH value, contact time, metal concentration and adsorbent dose) in batch system allow an elimination a good percentage of the metals. The Langmuir and Freundlich, adsorption isotherm were applied to the experimental data to get information on the interaction metals/coconut shell and groundnut shell. (Ashoori 2012).
Adsorption is a surface phenomenon with common mechanism for organic and inorganic pollutants removal. When a solution containing absorbable solute comes into contact with a solid with a highly porous surface structure, liquid-solid intermolecular forces of attraction cause some of the solute molecules from the solution to be concentrated or deposited at the solid surface. The solute retained (on the solid surface) in adsorption processes is called adsorbate, whereas, the solid on which it is retained is called as an adsorbent. This surface accumulation of adsorbate on adsorbent is called adsorption. This creation of an adsorbed phase having acomposition different from that of the bulk fluid phase forms the basis of separation by adsorption technology. (Vilar et al. 2008).
The adsorption technique has become more popular in recent years for wastewater treatment owing to its efficiency in the removal of pollutants too stable for biological methods. Metals adsorption is a result of six mechanisms (adsorption, chemical precipitation, ultrafiltration, nanofiltration, electrodialysis and ionexchange) and is influenced by many factors such as metal/adsorbent interaction, adsorbent’s surface area, particle size, temperature, pH and contact time. The main advantage of adsorption recently became the use of low-cost materials, which reduces the procedure cost. However, following the economic boom in the l970s-where the procedure cost was not such a big problem (or had not been taken into account) the economic crisis of the 2000s arose and led researchers to turn their interest to other fields with lower procedure costs. Therefore, different materials were tested as possible wastewater adsorbents. The selection for the most appropriate adsorbent would be based on some major characteristic properties such as:
i. The low-cost along with the satisfactory adsorption properties (capacity, reuse, industrial-scale use etc.) and
ii. The environmentally-friendly nature of each adsorbent. It is fundamental to use only materials which either have the lowest impact on environmental balance or are absolutely environmentally friendly (from abundant natural sources, biodegradable, non toxic etc.). (Salem et al.2012)
Recent studies on adsorption have drawn the attention to waste materials produced by large-scale industrial processes. Such materials are the by-products of industrial materials produced from natural resources such as peat, wood, barley, brown rice, hay, peanut shell, almond shell, coconut shell, groundnut shell, biomass, soybean, cotton seed meal, bark, sugar beet pulp, leaves, green algae, wood chips, fertilizer, com silk, and dried aquatic plants, as well as plant wastes and other industrial products. All of these materials have been the subject of numerous studies due to their ability to remove trace metals from water. Most of the researches that used adsorbents for organic compounds are based on batch kinetic and batch equilibrium studies. (Abdessalem et al. 2001).The objective of this research is to study and compare the adsorptive capacities of activated carbon from coconut shell and groundnut shell for the removal of Cd and As from aqueous solution.
1.2. STATEMENT OF PROBLEM
Arsenic and Cadmium causes toxicity in living cells by following ionic mechanism and that of oxidative stress. These heavy metals have proven to be a major threat and it has several health risks associated with it. Its ability to accumulate in the human body and food chain, exhibiting a health effect (chronic nature) is of immense concern hence the continual search for more effective adsorbent for its removal from effluents and water waste.
1.3 SCOPE AND LIMITATION OF THE STUDY
This research focuses on the use of agricultural waste in the removal of heavy metals particularly Arsenic and Cadmium, utilizing coconut shell and groundnut shell as adsorbent for removal of Arsenic ion and Cadmium ion from aqueous solution. This study will also investigate the influence of uptake of Arsenic ion and Cadmium ion b coconut shell and groundnut shell at different contact times and concentration of the adsorbent
1.4. SIGNIFICANCE OF THE STUDY
Several biomasses are considerable for application in adsorption knowing their different adsorption capacity. Therefore, this study will not only reduce the rate of importation of adsorbent, but would also encourage and promote the use of local raw material as competitive alternatives, also reduce high sludge generating treatment which is prone to environment contamination.
1.5 AIM OF THE STUDY
- To compare the biosorption study of arsenic and cadmium from aqueous solution using coconut shell and groundnut shell
1.6. OBJECTIVE OF THE STUDY
• To identify useful information for the utilization of native agricultural byproduct for the removal of heavy metals (As and Cd).
• To compare the adsorption capacity of coconut shell and groundnut shell.
• To illustrate the adsorption by application of isotherm and kinetic model.
• To explore optimum experimental conditions for the removal of Cd and As ions from aqueous solution.
SOLD BY: Enems Project| ATTRIBUTES: Title, Abstract, Chapter 1-5 and Appendices|FORMAT: Microsoft Word| PRICE: N2000| BUY NOW |DELIVERY TIME: Within 24hrs
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