Decolorization of crystal violet from aqueous solutions by a novel adsorbent chitosan/nanodiopside using response surface methodology and artificial neural network-genetic algorithm.

A novel adsorbent of chitosan/nanodiopside nanocomposite (CS-NDIO) was synthesized as a green composite for the removal of crystal violet (CV) and characterized by techniques like XRD, FT-IR, BET, and FESEM analysis. The influence of parameters like molar ratios of CS to NDIO, initial pH of the solution, dosage of adsorbent, initial concentration of CV and contact time was investigated and evaluated by central composite design (CCD; 5 levels and 4 factors). Also, Hybrid model of (ANN) model with genetic algorithm (GA) optimization was applied to the experimental data get through CCD. The optimized molar ratio of CS-NDIO was found: 20/80. Optimal parameter choice for maximum CV adsorption process using CCD and ANN-GA were as follows: pH = 7.50 and 7.499, adsorbent mass: 0.0077 and 0.0077 g, CV concentration: 20.000 and 20.002 mg/L, and contact time: 25.00 and 25.00 min, respectively. The evaluation adsorption equilibrium and kinetic data were fitted with the Langmuir monolayer isotherm model (qmax: 104.66 mg g-1 and R2: 0.9937) and pseudo-second order kinetics mechanism (R2: 0.9978). Thermodynamic parameters (R2: 0.9180, ΔH°: -74.93 kJ mol-1, ΔG°: -12.89 kJ mol-1, and ΔS°: 0.93 kJ mol-1 K-1) were calculated and indicating adsorption to be an exothermic and spontaneous process.

Chitosan /Zeolite Y/Nano ZrO2 nanocomposite as an adsorbent for the removal of nitrate from the aqueous solution.

In the present study, a series of chitosan/Zeolite Y/Nano Zirconium oxide (CTS/ZY/Nano ZrO2) nanocomposites were made by controlling the molar ratio of chitosan (CTS) to Zeolite Y/Nano Zirconium oxide in order to remove nitrate (NO3-) ions in the aqueous solution. The nanocomposite adsorbents were characterized by XRD, FTIR, BET, SEM and TEM. The influence of different molar ratios of CTS to ZY/Nano ZrO2, the initial pH value of the nitrate solution, contact time, temperature, the initial concentration of nitrate and adsorbent dose was studied. The adsorption isotherms and kinetics were also analyzed. It was attempted to describe the sorption processes by the Langmuir equation and the theoretical adsorption capacity (Q0) was found to be 23.58mg nitrate per g of the adsorbent. The optimal conditions for nitrate removal were found to be: molar ratio of CTS/ZY/Nano ZrO2: 5:1; pH: 3; 0.02g of adsorbent and temperature: 35°C, for 60min. The adsorption capacities of CTS, ZY, Nano ZrO2, CTS/Nano ZrO2, CTS/ZY and CTS/ZY/Nano ZrO2 nanocomposites for nitrate removal were compared, showing that the adsorption ability of CTS/ZY/Nano ZrO2 nanocomposite was higher than the average values of those of CTS (1.95mg/g for nitrate removal), ZY, Nano ZrO2, CTS/Nano ZrO2, and CTS/ZY.