[Comparison of efficiency of photochemical and sonochemical processes combined with hydrogen peroxide in removal of direct blue 71 [DB71] from aqueous solution: a kinetic study]

One of the important sources of environmental pollution existing in different industrial wastewater, including loom wastewater are dyes which are harmful for human health and environment. The purpose of this study was to investigate the efficiency of photochemical and sonochemical processes combined with hydrogen peroxide in removal of DB71 from aqueous solution. This study was experimental - laboratory study. At first, a reactor was designed and made. Then, optimum pH was determined which was 7 for photochemical and 3 for sonochemical process in constant condition. The effects of initial concentration of hydrogen peroxide, DB71 and contact time were studied at the constant optimum pH. Then data were interpreted and analyzed by use of Excel software and regression coefficient. The results of this study showed that with increased initial concentration of DB71, its removal decreased. But removal efficiency of DB71 increased by increasing contact time and initial concentration of hydrogen peroxide. In addition, kinetic parameters were obtained by application of first-order [Langmuir-Hinshelwood] equations. The results showed that UV/ H[2] O[2] and US/ H[2]O[2] processes can be effective in the removal of DB71 from aqueous solutions. Considering dye removal efficiency and availability, photochemical process combined with hydrogen peroxide can be recommended as a fast effective method for removal of dyes from aqueous solutions

[Cadmium adsorption by a bacterial biofilm supported on clinoptilolite from aqueous solution]

Heavy metals pollution represents a serious problem for human health and for life in general and bacterial biofilms are able to adsorb heavy metals from dilute aqueous solutions and accumulate them within their cell structure. The aim of this study was to investigate the ability of Escherichia coli biofilm [an effective agent for metal adsorption] supported on clinoptilolite for the removal of cadmium from aqueous solutions. Adsorption experiments were carried out in a laboratoryscale batch model with clinoptilolite alone and clinoptilolite covered by a bacterial biofilm. The effects of initial heavy metal concentrations, pH, and agitation time on the removal efficiency were studied. Finally, experimental results were analyzed using isotherm equations. The results of this study revealed that cadmium adsorption to clinoptilolite was lower than that of clinoptilolite covered by biofilm and adsorption of the cadmium was influenced by several parameters such as initial concentration of cadmium, biosorption time and solution pH. The uptake values for clinoptilolite and for clinoptilolite covered by biofilm were 6.8 mg/g and 9.6 mg/g respectively in the batch model, for initial cadmium concentrations of 25 and 100 mg/L. It was also observed that as the initial cadmium concentration increased, the uptake increased, but the removal rate decreased. Maximum adsorption efficiency was achieved at pH value of 6. The biosorption equilibrium for cadmium was best described by the Freundlich and Longmuir models. It is concluded that the presence of biofilm increased the uptake efficiency of clinoptilolite and the biofilm tested in our study seems very promising for the removal of cadmium from aqueous solution

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 cyanide from aquatic solution by using of iron and copper powder: equilibrium and kinetic study

Industrial wastewater included the cyanide is one of the important sources of environmental pollution which founded in Industrial wastewater which are harmful for human health and environment. Therefore, the purpose of this research that was fundamental designed is investigation of Removal of cyanide from aquatic solution by using of iron and copper powder in experimental scale. At first, pilot was designed. Then, acquired pH optimum equal to 2,7 for copper and iron by variation pH= [2,4,6,8,12] and constant other parameters. The effect of initial cyanide concentration [40,60,80 mg/1], initial iron and copper dosage [0.08-1 g/100CC] and contact time [15-12 min] studied at the constant of optimum pH. The result showed removal efficiency Increased from 46.6% to 90.56% and 31% to 93.78% for copper and iron by increasing of contact time from 15 to 120 minute in constant conditions, respectively. Also result showed Removal efficiency decreased and increased by increasing initial cyanide concentration and initial iron and copper dosage. The results showed equilibrium data were explained acceptably by Langmuir isotherms and kinetic parameters were obtained by application of Langmuir and Hinshelwood equation. The results showed that removal of cyanide can be quick and effective done by iron and copper in experimental scale

Removal of reactive black 5 [RB5] dye from aquatic solution by using of adsorption onto synthesized sodium alginate magnetic beads

Industrial wastewater included the dyes one of the important sources of environmental pollution, that founded in loom wastewater which are harmful for human health and environment. Therefore, the purpose of this research was investigated removal of RB5 dye from aquatic solution by using of adsorption onto synthesized magnetic sodium alginate beads. At first, synthesized magnetic sodium alginate beads. Then, acquired beads optimum dosage equal to 18 g/l00CC, with constant other parameters. The effect of pH contact time and initial RB5 dye concentration was studied at the constant of beads [18 g/l00CC]. Results showed that removal efficiency was decreased by increasing of initial RB5 dye concentration. Also the results showed the removal efficiency was increased by increasing of adsorbent dose and contact time. The results showed data were explained acceptably by Langmuir isotherms and pseudo-second-order kinetics models respectively. The results showed that removal of RB5 dye from aqueous solution by using of magnetic sodium alginate beads can be done cheaper and effective