Competitive removal of heavy metal ions from squid oil under isothermal condition by CR11 chelate ion exchanger

42 Páginas; 11 Figuras; 2 TablasHeavy metal ions (HMIs) are serious threats to the environment. Sub-critical water treatment was used to mimic contamination of squid oil in aqueous, metal-soap and oil phases. Isothermal adsorption of HMIs (Cu2+, Pb2+, Cd2+ and Zn2+) was studied from aqueous phase to oil phase (493, 523, 548, and 573 K) for solutions with different initial concentration of HMIs was studied. Decomposition of glycerides into fatty acids was favored at high subcritical temperatures, with metal-soap phase showing the highest chelation ability toward Cu2+ (96%, isotherm 573 K). The removal-ability of HMIs from contaminated oil was performed by CR11 chelate ion exchanger, showing facilitated removal from metal-soap and oil phases at low temperatures compared to general-purpose PEI-chitosan bead and PEI-chitosan fiber sorbents. The chelation behavior of Pb2+ and Cd2+ was the same in the OIL, with maximum values of 5.7 × 10−3 (mol/l) and 5.0 × 10−3 (mol/l) at 573 K, respectively. By contrast, concentration of Zn2+ ion showed a slight increase with increasing temperature due to electrostatic forces between Zn2+ and active sites of glycerides in oil phase. For oil solution, the selectivity of adsorption for CR11, especially for Zn2+, was at least five-fold larger compared to PEI-chitosan bead and PEI-chitosan fiber adsorbents.Peer reviewe

Visible-Light-Driven Reduced Graphite Oxide as a Metal-Free Catalyst for Degradation of Colored Wastewater

Reduced graphite oxide (rGO)-based materials have demonstrated promising potential for advanced oxidation processes. Along with its distinctive 2D characteristics, rGO offers the prospect of catalytic degradation of various kinds of organic pollutants from aqueous environments. The practical application of rGO as a metal-free catalyst material to promote the Fenton reaction depends on the degree of rGO reduction. In this regard, the rGO was prepared according to oxidation by modified Hummers’ method and two-step reduction via hydrothermal and calcination in the N2 atmosphere. The as-prepared rGO was characterized in terms of X-ray diffraction, Fourier-transform infrared spectroscopy, thermal gravimetric analysis, scanning electron microscopy, UV-vis absorption spectroscopy, and transmission electron microscopy. The effectiveness of as-prepared rGO as a photocatalyst and the metal-free catalyst to decolorize different textile dyes, including basic red 46, basic red 18, and methylene blue, was investigated in visible/rGO and visible/rGO/H2O2 systems. The impact of operational factors such as catalyst dose, pH, and initial dye concentration was examined. The dye degradation process was investigated by the pseudo-first-order kinetic model. In addition, the recyclability of rGO in the visible/rGO/H2O2 system was examined

Adsorption of Malachite Green Dye onto Mesoporous Natural Inorganic Clays: Their Equilibrium Isotherm and Kinetics Studies

Contamination of water with organic dyes is a major environmental concern as it causes serious life-threatening environmental problems. The present research was designed to evaluate the potential of three different natural inorganic clays (NICs) i.e., Pakistani bentonite clay (PB), bentonite purchased from Alfa Aesar (BT), and Turkish red mud (RM) for malachite green (MG) dye removal from an aqueous solution. Various analytical techniques, namely X-ray fluorescence spectrometry (XRF), X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), Brunauer–Emmett–Teller surface area measurement (BET), and thermogravimetric analysis (TGA), were used to investigate the physicochemical properties of the NICs samples. The effect of adsorption operational parameters such as contact time, aqueous phase pH, dye concentration, and amount of NICs on the adsorption behavior of MG onto NICs samples were investigated under the batch adsorption system. The equilibrium and kinetic inspection reflected the best description of MG adsorption behavior by the Langmuir isotherm model and pseudo-first-order kinetic model, respectively. The results indicated that the adsorption was favorable at higher pH. The maximum adsorption capacities calculated by Langmuir isotherm for PB, BT, and RM were found to be 243.90 mg/g, 188.68 mg/g, and 172.41 mg/g, respectively. It can be concluded that natural inorganic clays with a higher surface area can be used as an effective adsorbent material to remove the MG dye from an aqueous solution