جستجوی مقالات مرتبط با کلیدواژه « biosorbent » در نشریات گروه « شیمی »

Brown seaweed is a biosorbent for textile dyes from industrial effluent, but the presence of pigments and particle size restricts its adsorption capabilities and kinetics. Here, we fabricated seaweed Sargassum wightii as carbonated ash (SWCA) for cationic (methylene blue (MB), crystal violet (CV), safranin (SAF)) and anionic dyes (congo red (CR)). Biosorbent SWCA contains hydroxyl, primary amines, carboxyl, OH, C-O, C≡C-H, C=C, C-C≡C, C-N, N-H, and other functional groups. The pyrolysis process transformed the several types of oxygen in the seaweed waste into carbon-oxygen single bonds, which functioned as a bonding chain. The X-ray diffraction (XRD) spectra of SWCA diffractograms show that the structure is crystalline. As the calcite peak grows stronger, the Ca (OH)Cl peaks become weaker. The scanning electron microscope (SEM) image showed that organic carbonization caused SWCA pores. Strong energy dispersion x-ray (EDX) signals for C, O, Na, S, Cl, K, and Ca indicate SWCA has been carbonized. This investigation showed that when the concentration of SWCA was increased from 0.5 to 2 g/L, the quantity of MB, CV, SAF, and CR adsorbed dyes decreased significantly.

Spherical alginate-based hydrogels have been applied for environmental pollutants removal from aqueous solutions. In this study, zinc alginate beads were prepared using an ionotropic gelation process. The wet hydrogels prepared in various operational conditions were studied to remove eosin-B dye. The effect of operational variables such as pH, initial concentration of eosin-B, contact time, dose of synthesized hydrogel beads, and environmental temperature on the eosin-B removal process was evaluated. The maximum dye removal efficiency was obtained by zinc alginate biosorbent at pH = 3, contact time of 40 min, and 35 mg of biosorbent dose. The maximum adsorption capacity of zinc alginate beads for eosin-B uptake was 53.48 mg/g of biosorbent. The mechanism, kinetics, isotherms, and thermodynamic studies of eosin-B sorption by zinc alginate hydrogels were investigated. Based on the results, the biosorption process follows pseudo-second-order kinetics. The experimental data of the biosorption process are matched with the Langmuir isotherm model, suggesting that monolayer adsorption plays a vital role in the analyte biosorption. According to the thermodynamic studies, the parameters ∆H° (+4679.12 J.mol-1), ∆G° (from -173.45 to -499.13 J.mol-1), and ΔS° (+16.284 J.mol-1.K-1) confirmed the endothermic, spontaneity and randomness of the biosorption process, respectively. This study shows that zinc alginate can be a suitable biosorbent for removing eosin-B from aqueous solutions.

Todays, activated carbon derived from biomass sources has wide applications. In this study, activated carbon of tea waste has been considered for adsorption of phenylephrine hydrochloride drug from aqueous solution via batch adsorption process. The adsorption tests were carried out under several conditions such as equilibrium time, pH, adsorbent dose, and temperature. FESEM, TEM, and EDX techniques applied for characterization of activated carbon of tea waste before and after adsorption. The equilibrium results fitted to Langmuir and Freundlich isotherm models and it has been described as well via Freundlich model with best multilayer adsorption efficiency. According to analyses and experimental data, activated carbon of tea waste as a low cost, economically feasible and abundantly available adsorbent has great potential to high removal efficiency for phenylephrine hydrochloride drug.

In this research, wheat bran and waste coffee without any chemical treatment are used as low-cost biosorbents for the removal of zinc ions from an aqueous solution. Parameters such as contact time, adsorbent dose, initial concentration, and pH were studied. To describe adsorption equilibrium, Langmuir and Freundlich isotherms were used. Experimental results confirm that the adsorption of zinc ions on waste coffee fits well with the Langmuir isotherm while Freundlich isotherm is a better fit for wheat bran. The maximum capacity of zinc ions adsorbed, with the Langmuir model for wheat bran is a bit higher (qmax= 9.01 mg/g) than waste coffee (qmax= 6.41 mg/g). The thermodynamic parameters, enthalpy (ΔHo), entropy (ΔSo), and Gibbs free energy (ΔGo), provide that the adsorption process is exothermic, spontaneous, and favorable for both used biosorbents. The structure of both biosorbents was analyzed by the pH of the point zero charge (pHPZC) and FT-IR spectra.

The objective of this study is to characterize the Biosorbent (Atriplex Halimus leaves) and its application in the removal by adsorption of anionic and cationic dyes known for their toxicity such as Bemacid Blue (BB), Bemacid Red (BR), and Methylene Blue (MB) contained in water. The Atriplex Halimus was characterized by Boehm's method, FT-IR, XPS, SEM, pH Zero Charge Point (pHZPC), iodine value, and Methylene Blue value. The tests carried out in this experiment showed that the Biosorbent can remove Bemacid Blue (BB), Bemacid Red (BR), and Methylene Blue (MB). The effect of several parameters such as pH of the solution, biomass dose, contact time, initial concentration of dye used, and the temperature was studied in a batch system. The adsorbate-adsorbent equilibrium times are reached after 60 min for MB and 90 min for BB and BR. The adsorption is maximal for an adsorbent dose of 8 g/L for the three dyes. The best retentions were observed at pH 11, 6.45, and 5.12 for MB, BB, and BR respectively. The maximum adsorption capacities are 289.8, 29.7, and 32.9 mg/g for Methylene Blue (MB), Bemacid Blue (BB), and Bemacid Red (BR) respectively. Modeling of the experimental data showed that the Langmuir and pseudo-second-order models describe, respectively, the adsorption isotherms and the kinetics in a satisfactory way. The study of the thermodynamic aspects showed that the adsorption of the three dyes by the leaf biomass of Atriplex Halimus is a favorable, exothermic, and spontaneous phenomenon.

The work is a feasible study about the performance of woody skin and outer soft shell of Hazelnut for the removal of lead ions from water. The Hazelnut woody skin and soft outer shell are crushed by an innovative ball mill to prepare micro and nano powders. TEM images show that the produced nano powder includes uniform nanoparticles with 8-10 nm average diameters. The produced nanoparticles were used as a suitable and effective biosorbent to remove lead ions from water. Experimental data shows that the adsorption of lead ions on the surface of hazelnut skin nanoparticles is acceptably fitted to Langmuir isotherm model. Based on the Langmuir isotherm, a maximum adsorption capacity of 91 mg g-1 is achieved for adsorption of lead ions on the surface of hazelnut skin nanoparticles. The obtained results showed that the best removal of lead ions can be done under conditions includes 50 ml initial solution, pH=4, 120 mg L-1 initial concentration of lead ions per 70 mg biosorbent for contact time of 20 minutes at room temperature. The adsorbed ions are easily eluted by 1.5 ml 0.7 M HNO3 solution. Under the optimal conditions, preconcentration factor of 200, %RSD of less than 5% with detection limit of 100 ppb are obtained. The effects of some interfering ions such as Fe2+, Cu2+, Mg2+, Zn2+, Mn2+ and Ni2+  on the removal efficiency of lead ions were studied. The presented method is successfully applied for removal and determination of lead ions from real samples.

Chlorella vulgaris green microalgae live cells show great potential for removal of pollutant. In this study, the potential of the Chlorella vulgaris microalga as an inexpensive biosorbent was investigated for the removal of formaldehyde (FA). The experimental conditions including pH, contact time, and temperature on the removal of FA were considered and optimized. The sorption thermodynamics and kinetics of FA on biosorbent were studied using linear and nonlinear regressions. Chlorella vulgaris as biosorbent was able to remove 98% of FA within 22 minutes at the pH of 6.0. The sorption isotherm fitted well to the Langmuir isotherm and the sorption kinetics followed the pseudo-second-order model. Based on the Langmuir model, the maximum capacity of the monolayer sorption of Chlorella vulgaris for FA was found to be 180 mg g-1. The rapid and relatively high capacity of natural and untreated Chlorella vulgaris is the main advantage of this biosorbent for wastewater treatment.

Nickel (Ni) as a heavy metal due to its toxicity should be removed from wastewater and aquatic environments  using  efficient  technology.  The  aim  of this  study  was  to  remove  Ni  from  an aqueous  solution  using  palm  leaf  ash  produced  in  a  furnace.  To  do  so,  kinetic  and thermodynamic experiments were conducted on the adsorption process. Moreover, the effect of time, pH, adsorbent and initial concentration of Ni was studied on Ni adsorption. The results of the experiment indicated that the Ni adsorption process followed the Freundlich isotherm model. The study  of kinetic data  also displayed the  removal of  Ni ions  from  the  pseudo-second-order kinetics.  The  results  showed  that  the  percentage  removal  of  Ni  (II)  and  maximum  adsorption capacity  of  an  adsorbent  for  Ni  (II)  ions  were 94.67%  and 40.81  mgg-1,  respectively. Furthermore, the enthalpy of the adsorption process (ΔH) was 62706.8 j.mol-1.

Two locally available, cost-effective, renewable biosorbents including the untreated straw of Smyrniopsis Aucheri and untreated leaf of Acer Negundo  were used for the removal of Methylene Blue dye. The influence of initial dye concentration on the dye removal was investigated. Isotherm and kinetics of the biosorption process were studied. The optimum pH was found to be 6 and 5 for Smyrniopsis Aucheri and Acer Negundo, respectively. The optimum biosorbent dosage was found to be 0.3 g for Smyrniopsis Aucheri and 0.5 g for Acer Negundo. The removal of Methylene Blue by Smyrniopsis Aucheri and Acer Negundo  occurred during 10 and 15 min, respectively. The quick biosorption using reasonably small amount of such natural and untreated materials is a big advantages of this work for wastewater treatment applications in an environmental friendly way. The Langmuir adsorption isotherm model, was found to be the best applicable one to fit the experimental data. The pseudo-second and pseudo-first order kinetic models were applied well to describe the kinetics of Smyrniopsis Aucheri and Acer Negundo biosorption, respectively.

In this research, the batch removal of toxic hexavalent chromium ions from wastewater and aqueous solution using dried (BD) Sargassum sp. (brown marine algae) and Activated Carbon (AC) prepared from it was examined. Biomass, pH and the initial concentration of Cr(VI), adsorption models and kinetic studies were investigated. The experiment was performed in a batch system and the effect of solution pH, initial concentration and contact time on biosorption by both biomasses were investigated and compared. When we used AC and BD as biosorbents, optima conditions were established at pH=2.0, Cr6+ concentration at 3.69 mg/g BD and 6.877 mg/g AC and equilibrium time of 120 min. The adsorption was in the range of 83.55% and 91.98%, respectively. The experimental adsorption data were fitted to the Langmuir adsorption model. The chromium (VI) uptake by the biosorbents was best described by a pseudo second-order rate model.