Abstract
Lead is considered as a general protoplasmic poison which is cumulative and slow acting. It is used in different industrial processes. Its contamination in water may cause serious environmental problems. So removal of lead from environment is very necessary. For its removal the most suitable and cheapest process is biosorption. It is a process of passive metal binding by biomass. The biosorbent used in this study is teleosts biomass (fish scales) collected from local market. The purpose of this study is to search the effect of acid treatment on biosorbent and to optimize conditions for the uptake capacity of biosorbent. The optimal conditions for the Pb2+biosorption capacity of teleosts biomass (fish scales as waste of white meat) was investigated. For this purposes, the biomass was subjected to chemical treatments with mono, di and tri-protic acids such as hydrochloric acid, sulphuric acid and phosphoric acid. Among the treatment methods used, the highest Pb2+uptake was obtained with hydrochloric acid treatment of biomass. The effect of pH, biomass granular size, biomass concentration and initial Pb2+ion concentration was studied. The highest Pb2+removal (65.39%) was obtained at pH 4.0 for 50 mg L−1initial lead ion concentration with biomass granular size 80 micron and concentration of 0.05 g. The uptake was 75.70 mg g−1. The equilibrium data were analyzed using the Langmuir and Freundlich adsorption isotherm. The characteristic parameters for each isotherm were determined. Both the isotherms provided the best correlation for Pb2+on to the biomass. These results showed that teleosts biomass (fish scales) is a potential biomass to remove Pb2+ions from synthetic solutions so also with lead contaminated water. These values can be compared with those observed for other biosorbents and it is considerably higher than the value obtained with the majority of the biosorbent.
Highlights
Contamination of aquatic bodies by various pollutants such as pesticides, poly-aromatic hydrocarbons, heavy metals, etc., have caused imbalance in the natural functioning of ecosystem
Uptake capacity and percent removal of lead by the biosorbent treated with different acids were screened separately
This is attributed to the binding of H+ ions to the biomass after acid treatment may be responsible for the reduction in adsorption of heavy metal
Summary
Contamination of aquatic bodies by various pollutants (synthetic and organic) such as pesticides, poly-aromatic hydrocarbons, heavy metals, etc., have caused imbalance in the natural functioning of ecosystem. Heavy metals enter the water supply by industrial and consumer wastes or even from acid rain breaking down soil and rocks and releasing heavy metals into streams, lakes and ground water[1] Among these heavy metals lead is toxic element, which has conservative and cumulative characteristics[2] and can severely affect brain, kidneys, reproductive systems, and cardiovascular system. Conventional methods for removing dissolves heavy metal ions from wastewater include chemical precipitation, chemical oxidation and reduction, ion exchange, filtration, electrochemical treatment and evaporative recovery These techniques have significant disadvantages including incomplete metal removal, the need for expensive equipment and monitoring systems, high reagent or energy requirements or generation of toxic sludge or other waste products that require disposal[4]. The biosorption process involves a solid phase (sorbent or biosorbent; biological material) and a liquid phase (solvent, normally water) containing dissolved species to be sorbed (sorbate, metal ions) due to higher affinity of biosorbent for the sorbate species, the later is attracted and bound there by different mechanisms[6]
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