Removal of divalent nickel from aqueous solutions by adsorption onto modified holly sawdust: equilibrium and kinetics

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

[Removal of acid blue 113 [AB113] dye from aqueous solution by adsorption onto activated red mud: a kinetic and equilibrium study]

Dyes are among the most important sources of environmental pollutants which are found in wastewater of different industries such as textile manufacturing industries and are harmful for human health and environment. The purpose of this study was to assess removal of AB 113 dye from aqueous solution by its adsorption onto activated red mud as a cheap absorbent. This study was a laboratory study. At first red mud was activated by adding 20 ml nitric acid for each 10 gr of red mud for 24 hours, and dried out in 150 [degree sign] C for 4 hours. Acquired equilibrium time was determined which was 60 min. The effect of pH, contact time and initial AB113 dye concentration, kinetic and isotherm models were studied at constant equilibrium time. Data were interpreted and analyzed by Excel software and regression coefficient. Increased pH and increased initial dye concentration led to decreased rate of dye removal. But dye removal increased by increasing contact time. The results showed that AB113 adsorption follows Longmuir isotherm [R[2] = 0.9943, q[e] = 0.172 mg/g] and pseudo second order models [R[2] = 0.9999, q[e] = 3.86 mg/g] to a greater degree. Considering the constant distribution coefficient, with increasing initial amount of red mud adsorbent surface became homogeneous. The results of this study showed that red mud can be used as a fast, effective and cheap adsorbent with high efficiency for the treatment of textile manufacturing wastewater