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Adsorption properties of Cr(III) and Cr(VI) on natural (NCS), acid-activated (ACS) and base-activated (BCS) cherry stalks (CS) in Isparta were investigated in aqueous solutions. Batch adsorption studies had been completed with different initial chromium concentrations, pH, temperature, time and biosorbent dosage. Adsorption rapidly approached an equilibrium state between 10 and 60 min. The results displayed that the adsorption system was suitable for pseudo-second-order kinetics. Equilibrium isotherms (Langmuir, Freundlich and Dubinin–Radushkevich) were measured experimentally. The retention characteristics of Cr(III) onto NCS, ACS and BCS and Cr(VI) onto ACS were represented by Langmuir adsorption isotherms, while Cr(VI) ions onto NCS and BCS were compatible with Freundlich adsorption isotherms. The adsorption process was endothermic accompanied by a decrease in entropy and Gibbs energy. An artificial neural network (ANN) model was improved to estimate the efficiency of Cr(III) and Cr(VI) ion's adsorption. The ANN model can predict the behaviour of the Cr(III) and Cr(VI) ion's adsorption under different circumstances. The results have shown that NCS, ACS and BCS biosorbents open up new possibilities and potential commercial uses in the cherry stalks. [ABSTRACT FROM AUTHOR]

Today, the importance of materials produced by natural means or by synthesis is increasing in the prevention of increasing water pollution. Sophora Japonica fruit seeds (SJfs) were pyrolyzed at 450 °C to produce SJfs-biochar (SJfsB) in this study. Iron nanoparticles were immobilized to the SJfsB structure to form a more active biosorbent matrix. SJfsB and the resulting novel biosorbent (nanomagnetic-Sophora Japonica fruit seeds biochar (nM-SJfsB) were used to remove malachite green (MG) from an aqueous solution. Fourier transform infrared analysis (FTIR) and scanning electron microscopy were used to elucidate the details of the biosorbent properties. The effect on removal was investigated using various parameters. A combined strategy was used to define the adsorption parameters such as adsorbent amount, time, initial dye concentration, pH, and temperature. The maximum adsorption capacity determined by the Langmuir model was 51.020 mg/g for SJfsB-MG and 101.010 mg/g was found for nM-SJfsB-MG. The pseudo second order equation made the equilibrium data suitable. After regeneration, nM-SJfsB can be used for re-adsorption studies and reused for multiple cycles in adsorption and desorption applications without discharging nano-iron particles into aqueous medium. [ABSTRACT FROM AUTHOR]

Continuously growing industrial areas cause environmental and water pollution. One of the causes of water pollutants is the dyestuffs released into the environment without being recovered. In this study, biochar and nanomagnetic biochar were obtained from silverberry seeds, and the obtained biochars were used to remove methyl blue, an anionic dye, from the aqueous medium. The effects of pH, initial methyl blue concentration, temperature, amount of adsorbent and time change on the adsorption process were investigated. The maximum adsorption capacity was found to be 55.249 mg/g for biochar (b-EA) and 66.225 mg/g for nanomagnetic biochar (mb-EA). When the adsorption isotherms were examined, it was seen that both adsorbents were more suitable for Langmuir adsorption isotherm (R²=0.963 for b-EA, R²=0.991 for mb-EA). According to the kinetic data, the adsorption rate for both adsorbents is pseudo-second-order. In addition, negative ΔG values indicate that the adsorption process occurs spontaneously and positive ΔH values endothermically. [ABSTRACT FROM AUTHOR]

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