RESUMO
The removal of divalent nickel from aqueous solutions on modified holly sawdust was studied at varying contact times, pH, initial divalent nickel concentrations and adsorbent dose. Results showed the removal efficiency by increasing of pH increased and decreased with initial nickel divalent concentration. By increasing pH from 2 to 12 [equilibrium time= 240 min, adsorbent dose= 0.6g/100 mL, divalent nickel concentrations= 60 mg/L], the removal efficiency increased from 17.47% to 81.76%. Also removal efficiency was decreased from 98% to 19.3% by increasing of initial divalent nickel concentrations from 20 mg/l to 100 mg/L. Also the results showed the removal efficiency was increased by increasing of adsorbent dose and contact time. By increasing of adsorbent dose from 0.2 g/100CC to 1 g/100CC, the removal efficiency increased from 32.78% to 99.98%. The removal efficiency increased from 34.7% to 83.67% by increasing of contact time from 5 min to 240 min. Experimental equilibrium and kinetics data were fitted by Langmuir and Freundlich isotherms and pseudo-first-order and pseudo-second-order kinetics models, respectively. The results show that the equilibrium data follow Langmuir isotherm and the kinetic data follow pseudo-second-order model. The obtained maximum adsorption capacity was 22.47 mg/g at a pH 7. The results show that the modified holly sawdust can be used for the treatment of aqueous solutions containing nickel as a low cost adsorbent
Assuntos
Adsorção , Cinética , Resíduos Industriais , PoeiraRESUMO
Determination of Fluoride in drinking water has received increasing interest, duo to its beneifical and detrimental effects on health. The aim of this research is investigation of Effect of activated alumina in fluoride concentration reduction in drinking water. Expriment in batch system and with change effective parameters such as pH[5, 7,9], equilibration time [30, 60, 90, 120 minute], initial fluoride concentration[1.4, 2, 2.4 mg/1] and activated Alumina dosage [0.1,0.2,0.3 gr/1] was investigated. Also found data of this research were fited with Langmuir and Freundlich models, kinetic data with pseudo- first order, pseudo- second order and modifited pseudo-first order models. The results showed that with increasing of pH of solution, removal efficiency was decreased and optimum pH was found to be in the range of 5 to 7. Also removal efficiency of fluoride was increased with increasing of adsorbent dosage and decreasing of initial concentration of fluoride. Adsorption isotherm data show that the fluoride sorption followed the Langmuir model [r[2]=0.98]. Kinetics of sorption of fluoride onto Activated alumina was well described by pseudo- second order model. The concentration of Activated Alumina had significant effect on the reduction of fluoride ions concentration in water. The higher fluoride removals were observed for batch experiments at pH=5 because no free fluoride ion is present in the solutions, and it could be casued by electrostatic interactions between the surface of alumina and the dominant fluoride species in solution The kinetic model can adequately describe the removal behaviors of fluoride ion by alumina adsorption in the batch system