Preparation Of Chemically Modified Mixed Fruit Peels Waste Adsorbent For Removal Of Chromium (Vi) From Aqueous Solution

Abstract

Hexavalent chromium, (VI) from industrial effluent is a major water pollutant whose concentration needs to be reduced with in permissible limits. Therefore, in this study the modified mixed fruit peels (banana and orange peels) biomass with and without turmeric was investigated as an adsorbent for Cr(VI) removal from aqueous solutions. The adsorbents were prepared from banana, orange and turmeric after drying in an oven for 2hr at 80 oC and powdered to pass a micro sieve (250μm).The powdered fruit waste was mixed in equal proportion to yield mixed banana and orange (RBO) and mixed banana, orange, and turmeric(RBOT). A portion of this mixed powder was chemically modified by using H3PO4 to yield chemically modified mix of banana and orange (CMBO), and chemically modified mix of banana, orange and turmeric (CMBOT). Batch adsorption method was used to evaluate efficiency of adsorbent by varing the different parameters such as pH (1-5), adsorbent dose (0.2g – 2.5g), initial concentration of adsorbate (20mg/L - 80mg/L), and contact time (30min - 120 min) at room temperature.The concentration of Cr(VI) were measured using an ultraviolet-visible (UV-Vis) spectrophotometry using 1,5diphenylcarbazide at 540nm. Adsorbents were characterized using spectroscopic techniques including FT-IR and SEM-EDX to know the functional group of the adsorbents, pore properties and composition respectively. SEM Imaging indicated that the chemical modification increased the adsorption site of the adsorbents. The optimum parameters pH=2, adsorbent dose of 0.5 g , initial concentration of 60 (mg/L) and contact time of 60 min for CMBOT,RBO,RBOT and 60min of CMBO,were obtained. The maximum adsorption of CMBOT, CMBO, RBO and RBOT were found to be 5.99, 5.99, 5.79, 5.78 mg/g, respectively. The results showed maximum removal of Cr(VI) 99.83%, 99.75%, 96.5%, and 96.33% for CMBOT, CMBO, RBO, and RBOT, respectively. The experimental data were best fitted the Freundlich adsorption isotherm model (r2 = 0.960, 0.780, and 0.285) for CMBOT, RBOT, and RBO respectively while CMBO best fit to Langmuir (r2 =818). Moreover, the result showed pseudo second order fit experimental result and this reveals that the adsorption is physical. In general, the observed result confirmed Cr(VI) removal efficiency of fruit peels were enhanced by mixing fruit peel biomass and subsequent chemical modification , so that it can be used effectively and sustainably in waste water treatments technology. Moreover, the sludge of mixed fruit peel formed is biodegradable and environmentally friendly and therefore attractive in hexavalent chromium removal in water.