Sequestration of trivalent arsenic from aqueous solution by using banana peels (Musa paradisiaca L.) modified in calcium alginate beads
International Journal for Research in Applied Science and Engineering Technology
Banana peels (Musa paradisiaca L.) was modified into calcium alginate beads via entrapment, were used as biosorbent for the removal of arsenic (III) in aqueous solution. The extent of arsenic (III) removal capacity was tested by the material by varying the solution parameters such as effect of pH, biosorbent dose concentration, initial arsenic (III) concentration, contact time, temperature and agitation rate. Desorption efficiency of banana peels modified into calcium alginate beads was highest
... e beads was highest for sulphuric acid followed by hydrochloric acid and nitric acid. The biosorption process followed pseudo-second-order kinetics and biosorption data were best fitted to linearly transformed Langmuir isotherm with correlation coefficient of R 2 = 0.9951. Maximum biosorption capacity calculated from Langmuir isotherm was found to be 52.083 mg g -1 . The thermodynamic study confirmed that reaction of biosorption of arsenic (III) was spontaneous, endothermic and increasing randomness of the solid solution interfaces. The results indicating that calcium alginate beads have better biosorption properties than other naturallyoccurring materials like algae, flower wastes and minerals like zeolite and bentonite. This study demonstrated that alginate beads are good candidates for a fast and efficient removal of arsenic (III) from aqueous solution. Keywords: Arsenic (III), banana peels (Musa paradisiaca L.), calcium alginate beads, adsorption isotherm, adsorption kinetics, thermodynamic study. I. INTRODUCTION One of the most challenging environmental problems today is the removal of heavy metals and other toxic contaminants from industrial wastewater. Many aquatic environments face metal concentrations that exceed water quality limits designed to protect the environment, animals, and humans  . Metals hazardous to humans include lead, cadmium, mercury, arsenic, copper, zinc, and chromium. Arsenic is carcinogenic metal. Cadmium can cause bone and kidney damage. Copper and lead can cause brain and bone damage . Arsenic (As) is a component of many industrial raw materials, products and wastes. Elevated levels of arsenic in drinking water have been implicated in human diseases and mortality  . Chronic exposure to arsenic causes neurological and haematological toxicity  . Arsenic impacts the major organs and is a potential carcinogen    . The most common arsenic species observed in the environment are the trivalent form arsenite As (III) and pentavalent form arsenate As (V) in which As (III) is more toxic than As (V)  . Because arsenic readily changes valence state and reacts to form species with varying toxicity and mobility, effective treatment of arsenic can be challenging. Removal of arsenic (III) contaminated water has thus become a major environmental issue. Several approaches for metal-treatment wastewater have been described including chemical and surface chemistry processes. Sensitive operating conditions, low efficiency, and production of secondary sludge demanding additional expensive disposal are inherent limitations in the application of these methods    . These short comings, together with the need for more economical and efficient technique for removal of metal from wastewater, have focused interest towards other techniques. One such option is biosorption that is based binding ability of certain types of biomass with metals even from very dilute aqueous solution  . The adsorption technique can operate over wide range of pH and temperature exhibiting high efficiency, economic feasibility along with less chemical and biological sludge, therefore find niche in potential metal treatment technologies  . The Powdered form provides some difficulties associated with separation of biomass after biosorption, mass loss after regeneration and small particle size which make it difficult to use in column applications. Therefore, modification of raw biomass can improve the sorption capacity. The modification can be achieved by physical processes, chemical processes, and chemical entrapment of the biomass to form membranes, beads, pellets or granular biosorbents  .