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In this study, the removal of heavy metals Pb(II), Cr(III), Zn(II) and Co(II) in wastewater with activated carbon (KB-A) obtained by boric acid impregnation to poplar sawdust (K-S) grown in the Van region was investigated. The parameters affecting adsorption were examined and optimum values were determined. For this purpose, the effects of different parameters such as solution pH, KB-A dosage, contact time and metal concentration were studied for their effects on the removal of heavy metals. As a result of the adsorption process, It was observed that the adsorption of all metals decreased with increasing temperature. The adsorption process was found to follow the Langmuir and Freundlich models. The maximum adsorption capacity values were determined as 30.89 mg g-1 for Cr(III), 30.49 mg g-1 for Pb(II), 30.30 mg g-1 for Zn(II) and 27.70 mg g-1 for Co(II). According to the thermodynamic parameter results, the adsorption process was spontaneous, and the reaction followed a pseudo-second-order kinetic model. The KB-A adsorption ability showed a trend ordered from large to small as Cr(III)˃ Pb(II) ˃Zn(II) ˃ Co(II). [ABSTRACT FROM AUTHOR]

In recent years, the removal of heavy metals from water by using low-cost agricultural waste activities were accelerated. Removal of dissolved Cr(VI) and Cu(II) heavy metals in water by olive pomace which olive oil industry waste was investigated. The parameters that affect the heavy metal adsorption such as pH (2-6), contact time (2-120 min.), and initial heavy metal concentrations (5-100 mg/L) were studied in batch experiments at a temperature of 20oC, 0.5 g adsorbent dose and, particle size of between 0.5 and 2.0 mm. The maximum removal efficiencies were obtained 98.8% and 93.2% for Cr(VI) and Cu(II), respectively by using activated olive pomace (AP), at a pH 4, contact time of 15 min. and initial heavy metal concentration of 5 mg/L. The maximum adsorption capacity was determined 0.988 and 0.932 mg/g onto AP for Cr(VI) and Cu(II), respectively. Following this preliminary study, the same optimum conditions were applied to the battery industry wastewater and high removal efficiency was obtained. Moreover, kinetic and isotherm studies were carried out by applying pseudo second order kinetic and Langmuir isotherm model, observing good agreement between theoretical and experimental results at the optimum operation conditions. Various active functional groups were identified by FTIR analysis and SEM images showed that the AP has a porous structure. The study results show that AP has proven its suitability for use in various fields as a low-cost adsorbent in adsorption. [ABSTRACT FROM AUTHOR]

In the present study a new, cheaper, more abundantly available natural adsorbent is purposed to gain as an alternative to activated carbon, commonly used in heavy metal refining. When the walnut tree shavings (Juglans regia L.) used as adsorbent on chromium (VI) adsorption; contact time, pH, adsorbent concentration, initial metal concentration and temperature parameters were tested for the suitability of adsorption isotherms. It was observed that adsorption reached to equilibrium in first 120 min, where the best performance is obtained at 40°C and at pH 2, with the 10g/L adsorbent concentration. When the suitability of those obtained values with the isotherms is examined, it is observed that the R² value gets closer to 1 in Langmuir isotherm. Q0 value that shows single layered adsorption capacity, obtained by using Langmuir isotherm, is found as 7.46 mg/g at 40°C. As the result of this research, it can be thought that the walnut tree shavings (Juglans regia L.) may be used as an alternative adsorbent instead of active carbon. [ABSTRACT FROM AUTHOR]

In this study, it was investigated batch adsorption of Reactive Blue 221 which is a textile dye with pumice stone. pH, shaking time, shaking rate, adsorbent particle size and amount were selected as constant parameters but solution temperatures and dye concentrations were selected as variables. Adsorption capacities were determined as 36.60 mg/g ve 47.90 mg/g ve 54.20 mg/g for pumice stone at 293 K, 318 K and 333 K temperatures respectively, in the 7.0 pH, 0.59 mm particle size, 2.00 g adsorbent amount and approximately 1.5 hours shaking time for 8x10-4 M dye concentration. Adsorption data were good agreement with Langmuir isotherm and adsorption was an endothermic and spontaneous process in the results of thermodynamic parameters. The kinetic data of the sorption showed that the pseudo second- order equation was the more appropriate and it was not only obtained an economic process with using of environmentally friendly, easily finded and low cost adsorbent and but also high color removal was obtained in dye. [ABSTRACT FROM AUTHOR]

In this study, the adsorption of humic acid by activated carbon was investigated. The adsorption experiments were carried out as a function of contact time, initial concentration and temperature. The adsorption kinetic results were interpreted by the Lagergren first-order equation and the adsorption rate constants were calculated. Adsorption isotherms were modeled with the help of both Langmuir and Freundlich isotherms. The constants of both isotherms were also calculated. According to the Giles classification, adsorption was found to be H type. Thermodynamic parameters were also calculated. The positive value of enthalpy change in the range of the studied temperature indicated the endothermic nature of the adsorption process. Negative values of free energy change indicated the spontaneity of the adsorption process. In addition, column experiments were carried out using aqueous solutions of humic acid at the initial concentrations of 30, 35, and 50 mg. dm-3. The removal efficiency for column studies were changed from 43% to 50% for the concentration from 50 mg.dm-3 down to 30 mg.dm-3. [ABSTRACT FROM AUTHOR]