Introduction: Some of the heavy metals such as cadmium (Cd) and lead (Pb) are toxic and represent hazardous pollutants due to their persistence in the environment. These metals have adverse effects on human health, which include growth retardation, cancer, damage to the nervous and heart system. Heavy metals can cause malfunctioning of the cellular processes via the displacement of essential metals from their respective sites. Mainly heavy metals discharge into the environment from industrial and urban sewage. There are different methods to reduce water pollution and the removal of heavy metals from water that one of them is sorption by using organic and inorganic adsorbents such as sepiolite. The low cost of sepiolite along with the high specific surface area, chemical and mechanical stability, and layered structure have made these clay minerals as excellent adsorbent materials for the removal of heavy metals from wastewaters. This study aims to investigate the sorption of Cd and Pb by sepiolite as an inorganic absorbent and optimize process variables (initial concentration, pH and ionic strength) using Response surface Methodology (RSM) and Box– Behnken design (BBD). Materials and Methods: Response surface Methodology (RSM) is a statistical method that uses quantitative data from appropriate experiments to determine regression model equations and operating conditions. RSM is a collection of mathematical and statistical techniques for modeling and analysis of problems in which a response of interest is influenced by several variables. A standard RSM design called Box-Behnken Design (BBD) was applied in this work to study the variables for sorption of Cd and Pb by sepiolite from aqueous solution using a batch process. BBD for three variables (initial Cd and Pb concentrations, pH and ionic strength), each with two levels (the minimum and maximum), was used as an experimental design model. Sepiolite sample used in this study was taken from a mine in Fariman region, northeastern Iran. In the experimental design model, initial concentration (0-200 mg L-1), pH (3-6) and ionic strength (0. 01-0. 06 mol L-1) were taken as input variables. Design-Expert program was used for regression and graphical analysis of the data obtained. The optimum values of the selected variables were obtained by solving the regression equation and by analyzing the response surface contour plots. The variability independent variables were explained by the multiple coefficients of determination, R2 and the model equation was used to predict the optimum value and subsequently to elucidate the interaction between the factors within the specified range. Results: The results showed that the sorption of Cd and Pb intensified by increasing initial concentration and pH but ionic strength had an inverse effect. The sorption of Pb and Cd ions onto the sepiolite minerals were lowest at pH =3 and IS=0. 06 but increased with an increase in pH and initial concentration of the solution. High value for R2 (0. 99) and adjusted R2 (0. 99) showed that the removal of Cd and Pb can be described by the response surface method. One-way ANOVA showed (p< 0. 0001) that the quadratic model is the best model for determining the interaction variables. According to optimization results, the sorption of Cd and Pb are maximized when pH: 6, concentration: 200 mg. L-1 and ionic strength: 0. 02 mol. L-1. The predicted adsorption at these settings for Pb and Cd are 44. 4 and 34. 28 mg. g-1, respectively. It was found that the initial concentration is the most effective parameter in the sorption of Cd and Pb by sepiolite. Sepiolite adsorbed more lead ions than cadmium ions from aqueous solution. Conclusion: Response surface methodology using BBD, proved a very effective and time-saving model for studying the influence of process parameters (pH, initial concentration and ionic strength) on response factor (sorb). This model significantly reduces the number of experiments and hence facilitating the optimum conditions. The experimental values and the predicted values are in perfect match with an R2 value of 0. 99. The high correlation coefficient between the model and experimental data (R2=0. 99) showed that the model was able to predict the removal of Cd and Pb from aqueous solution by using sepiolite. The model revealed that concentration, metal type and pH were the most effective parameters on the response yield (adsorption by sepiolite), respectively. According to the results, sepiolite showed a greater efficiency for sorption of Cd and Pb from aqueous solution, also usage of sepiolite as an inorganic absorbent due to its low cost and abundance can be economically justified.

Chromium VI is a frequent pollutant of industrial liquid effluents. It is a substance classified as a carcinogen group I. In this study, a Cr VI sorption mechanism was developed by using nanocellulose spheroids (hydrogel) obtained from ivory nut. Cr VI was detected in water by a colorimetric method, using 1, 5-diphenylcarbazide at λ 540 nm. Then, the sorption capacity of nanocellulose spheroids was tested by varying the solution's pH and temperatures. The outcome of the experiment shows that the most efficient pollutant’s adsorption conditions are occur at pH 4 and 25 °C. Removal percentages of Cr VI reached 91.29% (+/-1.36) and 95.33% (+/- 0.86). Additionally, the sorption kinetics showed that the adsorption reaction on the material reaches its equilibrium 20 to 30 minutes after the reaction starts. Finally, an analysis of adsorption isotherms showed a high adjustment with the Langmuir and Freundlinch isotherms. In this frame, this work’s results show that nanocellulose beads are an interesting alternative to efficiently reduce Cr VI from industrial and drinking water.

The efficiency and performance of supported melamine/ copper complexes, S/ [CuCl2 (Mel) 2].2MeOH, as a new adsorbent, for the adsorptive removal of Indigo Carmine (IC) from aqueous solutions, has been evaluated with respect to several experimental conditions including contact time, initial IC concentration, temperature and adsorbent dosage. The maximum removal percentage (approximately 84%) was observed when used 0.05 g/L of S/ [CuCl2 (Mel) 2].2MeOH, 1.5 x 10-5mol/L of initial IC concentration and contact time of 15min. The experimental data were analyzed by the Langmuir, Freundlich, and Tempkin isotherm models. The monolayer adsorption capacity of S/ [CuCl2 (Mel) 2].2MeOHwas found to be 16.8 x 10-3mol/g by using Langmuir isotherm model. The calculation of the thermodynamic parameters such as Gibbs free energy, entropy and enthalpy changes of the ongoing adsorption process indicated the feasibility and endothermic nature of IC adsorption. The kinetics study suggested that the adsorption of IC onto S/ [CuCl2 (Mel) 2].2MeOH proceeds according to the pseudo-second-order model.

One of the toxic element cadmium is environmentally and through water, air and food into the body and be associated with Metallothionein accumulated in the kidneys, causing disturbance in the body are normal activities. In this work, the brown alga (Fucus serratus) used as a low cost sorbent has been studied for the biosorption of Cadmium (II) ions in batch reactors. Cadmium ions adsorption by the biosorbents on tap was selected for high efficiency. In this research it became clear that a key role in the uptake of cadmium ions alginate surface active groups, especially carboxyl foundations are responsible. Firstly, the characterization of the surface functional groups was performed with the method, a qualitatively analysis with the study of FT-IR spectrum. The equilibrium time was about 3. 0 min and the adsorption equilibrium data were well described by the Langmuir’s equation. The maximum capacity has been extrapolated to 0/85 mmol. g-1. Finally; the efficiency of this biosorbent in natural tap water for the removal of cadmium was also investigated.

Background and Aims: Microhardness, sorption, and solubility are useful predictors of a resin composite’ s clinical success. This study aimed to evaluate the effect of 60 days of water storage on the microhardness, sorption, and solubility of 3 commercial nanohybrid resin composites. Materials and Methods: Three nanohybrid composites were evaluated: GC Kalore (GC), Aura (SDI), and G-æ nial Universal Flo Universal Flo (GC). Ten disc-shaped samples were prepared for each material. After baseline weight measurement, the specimens were stored in distilled water for a period of 60 days, and then in desiccators for another 60 days. Specimens were weighed at 24 hours, 7 and 60 days of water storage and desiccation. For the microhardness test, 24 were prepared for each material and divided into 6 groups based on storage media (dry and wet) and storage time (24 hours, 7 days, and 60 days). Specimens were tested by a digital Vickers microhardness tester after storage and data were analyzed using SPSS software. Results: G-æ nial Universal Flo Universal Flo showed the highest sorption and solubility and the lowest microhardness after 60 days of water storage. GC Kalore showed lower sorption and solubility compared to Aura. Also GC Kalore had higher microhardness than Aura after 60 days of storage in water, while Aura had higher microhardness in dry storage. Conclusion: Composites with lower sorption and solubility showed higher microhardnss in wet conditions. Flowable composite resin showed the lowest microhardness and the highest sorption and solubility values. Therefore, the negative effect of water sorption and solubility on surface microhardness should be considered in clinical decisions.

The bio-sorption of ammonium ions using red marine macroalga Gracilaria persica were investigated by response surface methodology. The sorbent was characterized by SEM and FTIR analysis. The influence of various operating parameters such as ammonium concentration (mg L-1), initial solution pH and alga biomass dosage (g L-1) was optimized using Box– Behnken design. A second-order polynomial model successfully described the effects of independent variables on the ammonium ions removal. At the optimum conditions, the maximum removal efficiency was achieved at 100. 01 %. The kinetic results also demonstrated that the bio-sorption of ammonium ions by the dried microalga followed well pseudo-second-order kinetics. FTIR results showed that amide, aliphatic and carbonyl groups might be responsible for the adsorption of ammonium ions in aqueous solution by dried G. persica biomass.

Phosphorus (P) sorption characteristics of soils influence P availability. This study was conducted to investigate P sorption isotherm, standard P requirement (SPR), P buffering capacity (PBC), desorption, and P hysteresis index (PHI) by 10 surface (0-30 cm) and 10 subsurface (30-60 cm) soils in vineyard soils of Malayer area in Hamadan province. Isotherm experiment was carried out by concentrations of P ranging from 0 to 200 mg l-1 of KH2PO4 salt in the presence of 0.01 M CaCl2. Desorption experiments were conducted with 0.01 M CaCl2. Phosphorus sorption characteristics in soil were calculated from isotherm equations. The average values of Olsen's extractable P (Olsen P) in surface and subsurface soils were 24.3 and 19.4 mg kg-1, respectively. In surface and subsurface soils, Olsen P was higher than the optimum concentration of P for most crops (7-10 mg P kg-1). Phosphorus sorption curves were well fitted to the Freundlich, Van-Hay and Temkin equations. The SPR average of surface and subsurface soils, defined as the amount of P sorbed at an equilibrium concentration of 0.3 mgP l-1 was 18.7 mg kg-1 and 19.7 mg kg-1, respectively. The PBC average of surface and subsurface soils, account from Van-Hay equation was 89.2 l kg-1 and 103.5 l kg-1, respectively. The average value of PHI in surface soils (1.7) was greater than subsurface soils (1.6). There was significant negative correlation between SPR with Olsen-P in surface (p£0.01) and subsurface (p£0.05) soils. We found significant positive correlation between PBC with clay (p£0.01) and ECC (p£0.05) of soils. Our finding showed that high level of Olsen P concentration in surface and subsurface soils may decrease the availability of other nutrients. Appropriate P fertilizer management according to isotherm finding is needed.