Dilek Duranoğlu

Heavy Metal Adsorption by Magnetic Hybrid-Sorbent: An Experimental and Theoretical Approach

This study examined the sorption and desorption behaviors of Cu2+ and Pb2+ ions, which were adsorbed on the vinyl benzene chloride divinylbenzene (VBC-DVB-OH) polymer and magnetic hybrid adsorbent (VBC-DVB-OH-Fe) at pH 5. Batch and fixed bed column experiments were performed to study practical applicability and the breakthrough curves were obtained. The experimental equilibrium data, suitably fitted by the Langmuir and Freundlich isotherms, have shown that ferric oxide loaded magnetic hybrid sorbent (VBC-DVB-OH-Fe) exhibits higher adsorption capacity than vinyl benzene chloride divinylbenzene (VBC-DVB-OH) polymer. The results indicate the following order to fit the isotherms for both metal ions: Langmuir > Freundlich for polymeric sorbent and Freundlich > Langmuir for VBC-DVB-OH-Fe. The maximum adsorption capacity of VBC-DVB-OH adsorbent is 26.39 mg/g for Pb2+ and 7.93 mg/g for Cu2+ whereas it is increased to 45.81 mg/g for Pb2+and 25.64 mg/g for Cu2+ by using VBC-DVB-OH-Fe adsorbent. A series of column experiments were carried out to determine the breakthrough curves. The regeneration efficiency of the column runs was determined using HCl (10% v/v). The elution efficiency was 90% for each adsorbent.

A comparative study of 2-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol adsorption onto polymeric, commercial, and carbonaceous adsorbents

AbstractIn this study, polymeric and carbonaceous type of adsorbents were synthesized and their 2-chlorophenol (2-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) adsorption performances were compared with commercial available XAD-4 resin. Peach stone-based activated carbon (AC) was fabricated by steam activation and porous copolymer of cyanomethyl styrene–divinylbenzene was synthesized by suspension polymerization method. A comparative examination of chlorophenols (CPs) adsorption onto AC, polymeric, and XAD-4 resin was conducted in batch and continuous systems. Zeta potential and potentiometric titration data were analyzed for three adsorbents. The equilibrium data were fitted to the common types of adsorption isotherm and kinetic models. Freundlich model illustrated best fit to the experimental data. The adsorption kinetic obeys the pseudo-second-order model indicating that the chemical sorption is the rate-controlling parameter for chlorophenolic pollutants. The kinetic results...

An experimental design approach for modeling As(V) adsorption from aqueous solution by activated carbon

The present paper discusses response surface methodology as an efficient approach for predictive model building and optimization of As(V) adsorption on activated carbon derived from a food industry waste: peach stones. The objectives of the study are application of a three-factor 2³ full factorial and central composite design technique for maximizing As(V) removal by produced activated carbon, and examination of the interactive effects of three independent variables (i.e., solution pH, temperature, and initial concentration) on As(V) adsorption capacity. Adsorption equilibrium was investigated by using Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models. First-order and second-order kinetic equations were used for modeling of adsorption kinetics. Thermodynamic parameters (ΔG °, ΔH °, and ΔS °) were calculated and used to explain the As(V) adsorption mechanism. The negative value of ΔH (-7.778 kJ mol⁻¹) supported the exothermic nature of the sorption process and the Gibbs free energy values (ΔG°) were found to be negative, which indicates that the As(V) adsorption is feasible and spontaneous.

Cr(VI) Adsorption Onto Biomass Waste Material-Derived Activated Carbon

Activated carbons derived from biomass waste material can be favorable compared to conventional activated carbons with respect to their adsorptive properties, low cost, and renewable sources. Literature about Cr(VI) adsorption onto biomass waste material based activated carbons has been reviewed. Activated carbon derived from peach stone was used for Cr(VI) adsorption from aqueous media. The effects of process parameters like pH, temperature, concentration, and adsorbent amount on Cr(VI) removal were examined with aspect of equilibrium and kinetics. Peach stone based activated carbon showed high Cr(VI) adsorption capacity. Cr(VI) adsorption was strongly pH-dependent and superior at low pH. Freundlich model well expressed Cr(VI) adsorption. Adsorption kinetics followed the pseudo secondorder kinetic model which consists of chemisorption. Possible adsorption mechanism was suggested in three steps: (i) Cr(VI) adsorption onto positively charged groups, (ii) reduction to Cr(III), (iii) adsorption of Cr(III) while a little amount of it releases to the aqueous phase.