THE EFFECT OF CONTACT TIME, ADSORBENT DOSE,INITIALION CONCENTRATION AND PH ON THE ADSORPTION CAPACITY OF EDTA
ABSTRACT
  The effect of contact time, initial ion concentration, adsorbent dose and ph on 5he adsorption capacity of EDTA modified groundnut shell, rice husks, cassava peels and maize cobs for chronium (iii) ion was carried out using batch adsorption procedure wind atomic adsorption spectrophometer. Result of analysis I dictate that they was a general increase in cr (iii) adsorption with increase in contact time, initial ion concentration, adsorption dose and ph with all the modified adsorption. Results of analysis also show that rice husks exhibited excellent binding characteristics followed by groundnut shells, maize cobs and cassava peels in that order. The few discrepancies encountered in cr (iii) adsorption by cassava peels with repect to adsorption dose and ph show that adsorption of metal ions could also be influenced by the nature of adsorption.
CHAPTER ONE
INTRODUCTION
1.1. BACKGROUND INFORMATION
Heavy metal pollution occurs in many industrial waste waters such as those produce by metals plating facilities mining operation, battery manufacturing processes, the production of plant and pigment and the glass production industries. This waste water commonly contains chromium, cadmium, mercy, sernic and leads etc. These heavy metals are not biodegradable and their presence in streams and lakes leads to bioaccumulation in living organisms causing health problem animals, plants and human beings (Adejoh, et al 2015).
 Heavy metals are naturally componente of th earth crust, they cannot be degraded or destroyed, to a small extent they enter our bodies via food, drinking water and air. Examples of heavy metals include mercury (Hg), cadnium (cd) arsemic (As), chronium (Cr) thailium (Ti) and lead (pb) (akponsh, 2017). As trace elements, some heavy metals (e.g copper, selenium,  zinc) are essentials to maintain the metabolism of the human body. However at higher concentration the can lead to poisoning. Heavy metal poisoning could result for instance from drinking a contaminated water. (E.g lead pipe contaminated water). (David, 2018).
Heavy metals are dangerous because they tend to bioaccumulation and enter a water supply by industrial and consumer waste or even from acidic rain breaking down soils and releasing heavy metals into streams, lake, rivers and ground water. (Ouemeh et al 2013).
    Excessive human intake of chromium leads to severe muscular irritation and corrosion, wide spread capillary damage, hepatic and renal damage and central nervous system irritation followed by depression (faramarzi, 2018). Some metals are also known as carcinogen therefore some heavy metals are also known as carcinogen therefore the removal of excessive heavy metals ion from waste water is essential to protect human and environment heath. As a result, the removal of toxic heavy metals ions from sewage and from industrial effluent have been widely studied in recent years (Diarra, 2014). Several technologies are presently being utilized for the removal of these metals from industrial waste in order to present their release into the environment. Conventional technologies used include, chemical precipitation, coagulation, electronic chemical reduction, solvent extraction and electrolysis (Igwe, 2016). These method of treatment surfer several limitations based on their technical and economical viability and they do not posses removal efficiency which are sufficient for meeting the ever increasing environment requirement being sought by regulatory bodies. Also, the possibility of secondary pollutions is a subject of concern when utilizing these converntional techniques (Dizadji et all, 2016).
    Adsorption technology especially those carried out in the biosorption model, using non-living biomass have been shown to be promisinmg alternative technology for waste water treatment. major advantages includes the minimal cost associated with obtaining and preparing a possible environmental nuisance into a material of economics importance (Igwe, 2016).
    There is an exponential increase in the growth rate of the worlds population which calls for an aggressive approach towards food production to feed the already high human population to amehorate inadequate food supply and consequent malnutrition (Feramarzi et al; 2018). In Nigeria, large quantities of tubers are produced and they form an important energy source for human and livestock feeding the peels of these tubers are really available at cheap costs in many parts of the country because they are thought to have limited or no human food value (Diarra et al 2014). The use of biomass as adsorbent for heavy metal remediation has been demonstrated by several researcher (okoro and Abii, Zoll, Owgmah et all; 2013 and Eniola, 2012 etc).
This renewed intrest in research into the use of Agricultural by-product as adsorptions is informed by inherent disadvantage in the use of conventional method for heavy metal remediation. Grains constitute of high percentage of edible crops produced in Nigeria. The higher volume of these grains when processed and consumed result in the production of large quantities of by-product which are discarded indiscriminately thereby constituting environmental hazards. The utilization of these wastes in adsorption process will not only be of great scientist value but will also help in environmental sanitation. Maize cobs, Rice husk, cassava peels and groundnut shells are abundant agricultural naiste products with millions of tons generated annually polluting the environment in Nigeria.
    Agricultural by-products are less expensive, easily available, the do not produce chemical and biological sludge, simple to use and environmental friendly (hossain et al; 2017). The adsorption capacities od agricultural by-product have been shown to be dependent concentration and other physicochemical properties. (adejoh et al 2015).
Heavy metals cannot be destroyed through biological degradation, as in the case with most organic pollutions therefore, it is important to take protective measure against excessive exposures (Igwe, 2016).
1.2    PROBLEM STATEMENT AND JUSTIFICATION
Heavy metals are classes of pollutions often toxic and dangerous, widely preset in industrial and household waste water. Electroplating and metal finishing operation. Electronic circuit production, steel and aluminum processes. Industries produce large quantity of waste water containing metals. The production, processing and consumption of agricultural products is often accompanied with production of by-products which are considered to be of low or no  nutritional or economic value. These products are often discarded in the environment thereby constituting environmental pollution. It thereby becomes unperative for these waste materials to the properly disposed of the use of these waste in bioremediation of heavy metals from waste waters will therefore serue a dual purpose of ensuring clean water and environmental sanitation.
AIM
The aim of the project therefore is to determine the impact of EDTA modification on the adsorption of chronum by some agricultural waste as a function of pH, adsorption does, contect time, initial ion concentration and particle size.