Black carbon (BC), a kind of high surface area carbonaceous material (HSACM), was isolated from Andong lake sediment. Sorption and desorption kinetics of naphthalene (Naph) and phenanthrene (Phen) in organic carbon (OC) and BC in the Andong lake sediment were investigated. Several kinetic models such as one-site mass transfer model (OSMTM), two-compartment first-order kinetic model (TCFOKM), and a newly proposed modified two-compartment first-order kinetic model (MTCFOKM) were used to describe the sorption and desorption kinetics. The MTCFOKM was the best fitting model. The MTCFOKM for sorption kinetics showed that i) the sorbed amounts of PAHs onto BC were higher than those onto OC, consistent with BET surface area; ii) the equilibration time for sorption onto BC was longer than those onto OC due to smaller size of micropore ($11.67{\AA}$) of BC than OC ($38.18{\AA}$); iii) initial sorption velocity of BC was higher than OC; and iv) the slow sorption velocity in BC caused the later equilibrium time than OC even though the fast sorption velocity was early completed in both BC and OC. The MTCFOKM also described the desorption of PAHs from the OC and BC well. After desorption, the remaining fractions of PAHs in BC were higher than those in OC due to stronger PAHs-BC binding. The remaining fractions increased with aging for both BC and OC.
Abstract Linear, branched, and grafted polyamine flocculants were synthesized and applied for dye wastewater treatment. The effect of polyamines on color removal was investigated by comparing two treatments: (i) alum alone and (ii) alum/polyamine in combination. Compared to alum alone treatment, the use of polyamine flocculants in combination with alum was highly efficient in color and turbidity removal. Addition of a small amount of polyamine (40 mg/L) reduced alum dosage by 50% while improving color removal efficiency by 20%. Branched polyamines were more efficient than grafted polyamines presumably because branched polyamine has higher charge density than grafted polyamine. Our results indicate that the use of alum/polyamine system is beneficial in dye wastewater treatment. The effects of polyamine flocculants on total organic carbon removal and zeta potential were also discussed. Keywords: Dye wastewaterColor removalPolyamineAlumFlocculant Acknowledgment The authors would like to thank the G7 Project from the Ministry of Environment of Korea for the financial support of this research.
Applicability of the organic acids and cyclodextrin (CD) for the removal of Fe, Co and Ni from the spent electro-decontamination solution was investigated. Oxalic acid showed the highest removal efficiency: 90% for 0.89 M Fe and 95% for 0.0089 M Co and Ni, respectively. The metal–oxalate precipitates were characterized by differential scanning calorimetry/thermogravimetry analysis (DSC/TGA), Fourier transform infrared (FTIR) and X-ray fluorescence (XRF). After thermal decomposition at >300°C, the metal–oxalate precipitates were transformed into metal oxides (Fe2O3, FeO, CoO and NiO) and pure metals (Co and Ni). The results imply that organic acids have a high potential for the removal of heavy metals from electro-decontamination solutions.
The role of carbonaceous sediment oxygen demand (CSOD) due to oxidation of sulfides reduced in oxygen dynamics in crude oil contaminated salt marshes was investigated through a mathematical model. An existing CSOD model was calibrated from laboratory data sets through nonlinear regression. The effect of oil and fertilizer on CSOD was quantified by comparing three treatments (i) control (no oil and fertilizer amended) (ii) fertilized, and (iii) oiled and fertilized sediments. CSOD was directly proportional to sulfate reduction. Higher CSODs under oiled/fertilized and fertilized conditions were primarily due to increased sulfate reduction rates under these conditions. Reaction velocity for oxidation of dissolved sulfide in the aerobic layer, κH2S,d1, was significantly greater than that of particulate sulfide oxidation, κH2S,p1. This indicates that dissolved sulfides are dominant over particulate sulfides and directly related to CSOD in salt marshes. The CSOD was linearly dependent on the overlying dissolved oxygen concentration when crude oil and fertilizer were added.
The aqueous carbonation efficiencies of basic oxygen furnace (BOF) and ladle slags at various pressures, temperatures, and liquid-to-solid (L/S) ratios were investigated to determine optimum conditions. The maximum CO2 carbonated concentrations in slag (0.584 mmol/g for BOF slag and 1.038 mmol/g for ladle slag) was obtained at 10 bars, 40°C, and L/S = 5 mL/g-dry. The L/S ratio was the most critical parameter for carbonation. The effect of carbonated slag amendment on the immobilization of heavy metals in two field-contaminated soils was also investigated. The immobilization efficiencies evaluated by using the toxicity characteristic leaching procedure (TCLP) and the Standards, Measurements and Testing Programme (SM&T) were above 90% for both raw and carbonated slags for all soils. The TCLP-extractable heavy metals concentrations were below the criteria (5.0, 1.0 and 5.0 g/L for Pb, Cd, and Cr, respectively) after immobilizations with both slags except for Pb in soil B. The SM&T analysis showed the decrease in the exchangeable phase but the increase in residual phase after immobilization with raw and carbonated slags. The results of this study imply the promising potential of the carbonated slags on the immobilization of heavy metals in the field-contaminated soils. Keywords: Aqueous carbonation, Contaminated soils, Heavy metals, Immobilization, Slag
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