Treatment of chromium-laden aqueous solution using CaCl2-modified Sargassum oligocystum biomass: Characteristics, equilibrium, kinetic, and thermodynamic studies

Rauf Foroutan,Reza Mohammadi,Bahman Ramavandi 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.1

Biosorption properties of a CaCl2-modified Sargassum oligocystum algae biomass for removal of Cr(VI) from aqueous solutions were investigated. Experimental parameters affecting the biosorption process such as pH, contact time, biosorbent dosage, and temperature were studied. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), mapping test, energy-dispersive X-ray spectroscopy (EDX), and specific surface area were used to assess the physico-chemical properties the biosorbent. The surface area of biosorbent was found to be 35.64m2/g. FTIR test revealed that the active groups of -OH, -NH2, -C-H, C-O, -C-N, and S=O were present on the surface of CaCl2-modified S. oligocystum biomass. The kinetic behavior of the chromium biosorption by modified S. oligocystum biomass followed well pseudo-second order kinetic (R2>0.999). The biosorption equilibrium occurred at 100th min of contact time. The Langmuir, Freundlich, and Dubinin-Radushkevich models were applied to describe the biosorption isotherm of Cr(VI) onto modified S. oligocystum biomass. According to the RL and n parameters of the studied isotherms, the Cr(VI) biosorption process was physical and desirable. The chromium biosorption capacity of modified S. oligocystum biomass was found to be 34.46mg/g. The calculated thermodynamic parameters (ΔGo, ΔHo, and ΔSo) indicated that the biosorption of Cr(VI) onto modified S. oligocystum biomass algae was feasible, spontaneous, and exothermic under examined conditions.

Removal characteristics of chromium by activated carbon/CoFe2O4 magnetic composite and Phoenix dactylifera stone carbon

Rauf Foroutan,Reza Mohammadi,Bahman Ramavandi,Maryam Bastanian 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.11

Activated carbon (AC) was synthesized from Phoenix dactylifera stones and then modified by CoFe2O4 magnetic nanocomposite for use as a Cr(VI) adsorbent. Both AC/CoFe2O4 composite and AC were fully characterized by FTIR, SEM, XRD, TEM, TGA, and VSM techniques. Based on the surface analyses, the addition of CoFe2O4 nanoparticles had a significant effect on the thermal stability and crystalline structure of AC. Factors affecting chromium removal efficiency like pH, dosage, contact time, temperature, and initial Cr(VI) concentration were investigated. The best pH was found 2 and 3 for Cr adsorption by AC and AC/CoFe2O4 composite, respectively. The presence of ion sulfate had a greater effect on the chromium sorption efficiency than nitrate and chlorine ions. The results illustrated that both adsorbents can be used up to seven times to adsorb chromium. The adsorption process was examined by three isothermal models, and Freundlich was chosen as the best one. The experimental data were well fitted by pseudo-second-order kinetic model. The half-life (t1/2) of hexavalent chromium using AC and AC/CoFe2O4 magnetic composite was obtained as 5.18min and 1.52min, respectively. Cr(VI) adsorption by AC and AC/CoFe2O4 magnetic composite was spontaneous and exothermic. In general, our study showed that the composition of CoFe2O4 magnetic nanoparticles with AC can increase the adsorption capacity of AC from 36mg/L to 70mg/L.

Effect of interfering ions on phosphate removal from aqueous media using magnesium oxide@ferric molybdate nanocomposite

Hossein Esmaeili,Rauf Foroutan,Dariush Jafari,Mohammad Aghil Rezaei 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.5

The removal efficiency of phosphate ion from aqueous media using magnesium oxide/iron molybdate (MgO/Fe2(MoO4)3) nanocomposite was investigated. MgO nanoparticles were chemically modified by ferric molybdate. Then, the structure and morphology of the nanocomposite was completely investigated using different analyses such as SEM, EDX/Map, FTIR, XRD, TGA, BET, and TEM. The TEM analysis demonstrated that the particles in the mentioned nano-composite were on a nanoscale. BET analysis proved that the nanocomposite was mesoporous with mean pore size of 9.4 nm. The sorption outcomes demonstrated that the highest phosphate sorption yield was achieved at 98.38%, exhibiting remarkable sorption efficiency. Carbonate ions showed to have the highest interfering impact compared to sulfate and nitrate ions, since phosphate ion removal efficiency decreased significantly when carbonate and phosphate ions were simultaneously available in the solution. The thermodynamic studies demonstrated that the current sorption process was spontaneous, possible, and exothermic. The sorption equilibrium investigation showed that the Freundlich isotherm model can describe the adsorption of phosphate ion better than can the Langmuir model, and the maximum sorption capacity was obtained as 30.21mg/g. Additionally, the adsorbent was successfully regenerated four times and was able to perform the sorption and desorption process well.

Adsorptive performance of calcined Cardita bicolor for attenuating Hg(II) and As(III) from synthetic and real wastewaters

Abolfazl Teimouri,Hossein Esmaeili,Rauf Foroutan,Bahman Ramavandi 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.2

The first application of calcined Cardita bicolor oyster shell (CCBS) for Hg(II) and As(III) adsorption from synthetic and real wastewaters was tested. The main elements in CCBS structure were carbon, oxygen, magnesium, phosphor, and calcium. Effects of different parameters like initial pH, contact time, temperature, and CCBS dosage were assessed. The results showed that the maximum recovery of Hg(II) and As(III) adsorption was determined as C0=10mg/L, t=80 min, T=25 oC, CCBS dosage=5 g/L, and pH=6 (for mercury ion) and 7 (for arsenic ion). In these conditions, 95.72% Hg(II) and 96.88% As(III) were removed from aqueous solution. The correlation coefficient (R2) values for both adsorbates were obtained >0.98 and >0.96 for Langmuir and Freundlich isotherm models, respectively. Pseudo-second-order kinetic model was more capable to describe kinetic behavior of adsorption process of both metal ions in comparison with pseudo-first-order model. The half life (t1/2) value for Hg(II) and As(III) with initial concentration of 10mg/L was 4.032 and 4.957 min, respectively. Moreover, thermodynamic parameters of enthalpy (ΔHo), entropy (ΔSo), and Gibbs free energy (ΔGo) were investigated. Two real wastewaters obtained from a leather factory and a landfill leachate were successfully treated using CCBS. The results confirmed that adsorption process of metals ions was exothermic and spontaneous.

Ultrasonic-assisted synthesis of Populus alba activated carbon for water defluorination: Application for real wastewater

Ziaeddin Bonyadi,Ponnusamy Senthil Kumar,Rauf Foroutan,Raheleh Kafaei,Hossein Arfaeinia,Sima Farjadfard,Bahman Ramavandi 한국화학공학회 2019 Korean Journal of Chemical Engineering Vol.36 No.10

Efficient activated carbon was ultrasonically synthesized from the Populus alba tree, and fluoride ions were removed from samples of synthetic and real wastewaters. The effects of various parameters including pH (2-10), time (5-180 min), contaminant concentration (10-100mg/L), sorbent dose (1-7 g/L), and co-existing ions on the fluoride removal using Populus alba activated carbon (PAAC) were revealed. The physico-chemical characteristics of PAAC were determined using SEM, FTIR, BET, XRD, and EDX mapping. The specific surface area and pore volume of the mesoporous PAAC were obtained as 707.39m2/g and 0.40m3/g. The study found that the maximum removal efficiency of fluoride (93.37%) occurred under the fluoride concentration of 10mg/L, PAAC of 4 g/L, pH of 6, and contact time of 100 min. The isotherms and kinetics data could be suitably reflected by the Freundlich and the pseudosecond- order kinetic models, respectively. Langmuir maximum monolayer adsorption capacity of the ultrasonicassisted PAAC was measured as 77.12mg/g. Sorption of fluoride ions onto PAAC is feasible and an exothermic process. According to the field test, PAAC can significantly remove fluoride and other pollutants like BOD5, COD, Ni, Co, and Pb from glass and shipyard wastewater samples.