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Response surface methodology (RSM) was used for optimization of the adsorbent dosage, initial solution pH, initial ion concentration, and contact time in removal of Cr (III) with local nanoclay. The adsorption process was modeled by RSM and artificial neural network (ANN). The process was done in batch mode by central composite design (CCD) and the same design was applied for training ANN. The optimum condition was determined to be 500mg/L for adsorbent dosage, initial pH of 5, initial chromium concentration of 180mg/L and 20 min of contact time. In these conditions qRSM = 238.7780mg/g and qANN = 237.5152mg/g which indicate removal percentage of 72.45% and 72.07%, respectively. RRSM2=0.9784 and RANN2=0.9834 indicate that the two models can predict the adsorption of Cr3+ properly. The two parameter Langmuir, Freundlich, Dubinin‐Radushkevich (D‐R), Temkin and three parameter Redlich‐Peterson (R‐PT), Sips and Toth isotherm models were applied to equilibrium data by minimizing the sum of squared errors (SSE), sum of the absolute errors (SAE), average relative errors (ARE), Hybrid fractional error function (HYBRID), Marquardt's percent standard deviation (MPSD), and nonlinear chi‐square test error functions. The results showed that the HYBRID error function gives the lowest value and the R‐PT model fits the data better than other isotherm models.

Simultaneous removal of !" #$ and acidic dye from model tannery wastewater was investigated using local nano clay modified by 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) surfactant. X-ray fluorescence (XRF), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), carbon, hydrogen, nitrogen and sulfur analysis (CHNS), Brunauer-Emmet-Teller (BET) analysis and pH of zero point charge (%& '() ) analyses were carried out for characterization of the adsorbent, and adsorptive properties of the modified clay were investigated by batch experiments. The effects of essential parameters, such as adsorbent dosage, initial solution pH, initial solution concentration, contact time, and temperature, were studied. Maximum adsorption values (99.74% for !" #$ and 83.26% for dye) were obtained in the following conditions: pH of 4, initial concentration of 100 +,/., adsorbent dosage of 15000 +,/., contact time of 30 min. The effect of contaminants' concentration was also investigated through response surface methodology (RSM), central composite face-centered (CCF) design and an empirical model was presented. The results of kinetic models' studies demonstrated that simultaneous adsorption of contaminants follows the pseudo-second-order model, and the adsorption data of single and binary solutions fitted nonlinearly to isotherm models showed that the adsorption of Cr (III) from binary and single solutions follow Langmuir and Dubinin-Radushkevitch (D-R) isotherms, respectively. Adsorption of dye from both single and binary solutions follows Redlich-Peterson (R-PT) isotherm. Maximum adsorption capacities were obtained to be 193.1390 12 2 and 144.1782 12 2for !" #$ and dye, respectively. Synergistic and antagonistic adsorptions were observed in binary solutions.

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Simultaneous removal of Cr^3+ and acidic dye from model tannery wastewater was investigated using local nano clay modified by 3-chloro-2-hydroxypropyltrimethylammonium chloride (CHPTAC) surfactant. X-ray fluorescence (XRF), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), carbon, hydrogen, nitrogen and sulfur analysis (CHNS), Brunauer-Emmet-Teller (BET) analysis and pH of zero point charge (pH_ZPC) analyses were carried out for characterization of the adsorbent, and adsorptive properties of the modified clay were investigated by batch experiments. The effects of essential parameters, such as adsorbent dosage, initial solution pH, initial solution concentration, contact time, and temperature, were studied. Maximum adsorption values (99.74% for Cr^3+ and 83.26% for dye) were obtained in the following conditions: pH of 4, initial concentration of 100 mg/L, adsorbent dosage of 15000 mg/L, contact time of 30 min. The effect of contaminants’ concentration was also investigated through response surface methodology (RSM), central composite face-centered (CCF) design and an empirical model was presented. The results of kinetic models’ studies demonstrated that simultaneous adsorption of contaminants follows the pseudo-second-order model, and the adsorption data of single and binary solutions fitted nonlinearly to isotherm models showed that the adsorption of Cr (III) from binary and single solutions follow Langmuir and Dubinin-Radushkevitch (D-R) isotherms, respectively. Adsorption of dye from both single and binary solutions follows Redlich- Peterson (R-PT) isotherm. Maximum adsorption capacities were obtained to be 193.1390 mg/g and 144.1782 mg/g for Cr^3+ and dye, respectively. Synergistic and antagonistic adsorptions were observed in binary solutions.