Tuesday, 28 February 2017

An Evaluation Of Adsorption Potential of Groundnut Shell Powder on Nickel ions in Aqueous Solution of Nickel Ammonium Sulphate


1.0   Introduction
1.1   Background of the study
Groundnut shell is a carbonaceous, fibrous solid waste which encounters disposal problem and is generally used for its fuel value,It  can also serve as as filter medium in removing heavy metal ions from solution of their ions. The removal of these heavy metal ions can be achieved through using resins containing functional groups such as amino, iminoacetate and amidoxime, which has the chelating ability towards metal ion.

The idea of using various agricultural products for adsorption has investigated the efficiency of number of different organic waste materials as adsorbents for heavy metals. Such adsorbents including coconut shell, peanut shell, rice husk and groundnut shell have been considered for the adsorption on heavy metal ions in solution.

These AWBs may be different parts of plant, such as bark, stem, leaves, root, flower, fruit biomass, husk, hull, skin, shell, bran and stone.AWBs mainly compose of cellulose, hemicellulose and lignin which have a high content of hydroxyl groups. Consequently, they have good abilities to attach heavy metals .

Besides, AWBs contain a variety ofother functional groups,such as acetamido, carboxyl, phenolic, structural polysaccharides,amido, amino, sulphydryl carboxyl groups, alcohols and ester.These functional groups substitute hydrogen 
ions for metal ionsin solution ordonation of an electron pair to form complexes withthe metal ions in solutions. Due to 
abundant binding groups, AWBs could be an enormous potential source of adsorbent  materials for decontaminating heavy metals from wastewater.

Nowadays, there are several methods attainable for the removal of heavy metal ion such as membrane process, chemical precipitation, reverse osmosis and ion exchange [1]. Among these techniques, adsorption of metal ions using chelating resins is preferred due to their lower cost, high adsorption capacities, durability and high efficiency, especially metal ions with moderate and low concentrations [2]. 

These heavy metals effluents affect the quality of life by causing serious ailment due to fact that they are not biologically degradable [1], when their concentration in the body exceeds a certain value. The accumulation could be by consuming contaminated  fruit and vegetables or heavy metal contaminated water from which the source of contamination are the industrial effluents which contaminate the soil, and plant takes up the metal ion ,and it is transferred to animals when the feed on the plants. 

Contamination water bodies results mostly from industrial effluent from tanneries .battery Company and metallurgical companies. Several biological materials have attracted many researchers and scientists as they offer both cheap and effective removal of heavy metals from waste water.

Therefore it is urgent to study and explore all possible sources of agro based inexpensive adsorbents for their feasibility in the removal of heavy metals. The objective of this work was to study inexpensive adsorbents like various agricultural wastes such as sugarcane bagasse, rice husk, oil palm shell, coconut shell, and coconut husk in eliminating heavy metals from waste water and their utilization possibilities

1.2   Factors Affecting the Adsorption Process
The biosorption process of heavy metals from wastewatermight be influenced by several physical andchemical factors, such as pH, temperature, initial heavy metal concentration, 
a.      Temperature
As the temperature increases, the adsorption capacity is found to decrease and vice versa. It is an exothermic process overall.

b.  pH
As pH increases from 7.0 to 7.5, the retention capacity of the adsorbing surface increased significantly, whereas in lower pH the adsorption process was affected.
c.  Pressure
With increase in pressure, adsorption increases up to a certain extent till saturation level is reached but after that no more adsorption takes place no matter how high the pressure is.
d. Adsorbent Activation
To provide higher number of vacant sites on surface of adsorbent, this can be done by breaking solid crystal in small pieces, heating charcoal at high temperature, breaking lump of solid into powder, or other methods suitable for particular adsorbent.

e. Surface Area of Adsorbent
As adsorption is a surface phenomenon it increases with increase in surface area. Thus for any big molecule with a higher surface area, the adsorption efficiency will increase. 

1.3 Problem Statement
Heavy metals are continuously released into the aquatic environment from natural processes like volcanic activity and weathering of rocks. Industrial processes have also released substantial amount  of heavy metals. The presence of heavy metals in the environment is of major concern because of their extreme toxicity and tendency for bioaccumulation in the food chain even in relatively low concentrations [1], [2]. 

They are highly toxic as ions or in compound forms; they are soluble in water and may be readily absorbed into living organisms. Nickel (II) containing wastewaters are common as it is used in a number of industries including electroplating, batteries manufacturing, mining, metal finishing and forging. Higher concentrations of nickel cause cancer of lungs, nose and bone. 

Dermatitis (Ni itch) is the most frequent effect of exposure to Ni, such as coins and jewellery. Industrial effluent containing nickel plays an important role in polluting water bodies. Additional potential sources of nickel bearing waste include ceramics, nuclear power plants, cryogenic containers, pollution abatement equipment. Nickel is a potent carcinogen.

The contact of nickel with skin results in painful disease, nickel itch, which is followed by sudden death. Acute poisoning of nickel causes chest pain, tightness of the chest, shortness of breath etc. The toxic nature of nickel to fish, lentil plants, crops and algae was also reported.

The higher concentration of Ni (II) in ingested water may cause severe damage to lungs, kidneys, gastrointestinal distress, e.g., nausea, vomiting, diarrhoea, pulmonary fibrosis, renal edema, and skin dermatitis [3].

 A number of methods are available for the removal of metal ions from aqueous solutions. These are ion exchange, solvent extraction, reverse osmosis, electro dialysis, precipitation, flocculation and membrane separation processes [4]-[8]. However, these techniques have certain disadvantages, such as high capital and operational costs or the treatment and disposal of the residual metal sludge. 

Adsorption compared with other methods appears to be an attractive process due to its efficiency and the ease with which it can be applied in the treatment of heavy metal containing wastewater [9]. In recent years, a number of adsorptive materials, such as aquatic plants [10], agricultural by-products [11], industry by-product [4], sawdust [12], clay [13], zeolite [14], and microorganisms [15] were used in heavy metal removal from wastewaters. 

Agricultural waste materials being economic and eco-friendly due to their unique chemical composition, availability in abundance, renewability, low cost and more efficiency seem to be a viable option for heavy metal remediation. Present investigation is devoted on the utilization of ground nut shell powder in the removal of nickel ions from synthetic aqueous waste water. This material is available everywhere in northern Nigeria.

1.4 Aims and Objectives
The aim of the research is to evaluate the adsorption potential of groundnut shell powder on nickel ions in aqueous solution of nickel ammonium sulphate, due to it ‘s low cost a availability.The objectives of this work is to :
a.   Clean and prepare the ground nut shell in a form that will favours it usage.
Check the effect of PH, time and adsorbent dosage on the extend of adsorption.



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