Heavy Metals Removal in Aqueous Solution by two Delta-diketones

Light-activated g-C3N4 photoelectrodes with a selective molecular sieve for in vivo quantification of oxygen levels in the living mouse brain

A novel micro-photoelectrode with a selective molecular sieve was created for in vivo monitoring of O2 levels in the mouse brain. An ITO optical fiber modified by graphitized carbon nitride (g-C3N4) in situ was employed as the light activated substrate to provide rich photo-induced electrons for the catalytic reduction of O2. Meanwhile, the porous hybrid layer composed of zeolitic imidazolate framework-8 and polysulfone was constructed over the g-C3N4 surface as the molecular sieve to synergically enhance the selectivity of O2 detections. By advantage of this useful tool, the real time variation of the O2 level was successfully determined in the mouse brain upon ischemia.

Extraction and separation feasibility of cerium (III) and lanthanum (III) from aqueous solution using modified graphite adsorbent

Graphite (GR) and graphite/alginate (GRA) composite were synthesized utilizing the thermal annealing technique and used as a new adsorbent material for the selective separation and removal of La(III) and Ce(III) from aqueous solutions. Fourier transform infrared (FTIR) spectroscopy, thermal analysis (DTA, TGA), X-ray diffraction (XRD), surface area, porosity, and scanning electron microscope (SEM) were also used to characterize the generated material. Distinct experiments were performed to test the ability of the GRA to La(III) and Ce(III) removal, which include the effect of pH, shaken time, initial concentration of La(III), and Ce(III) at different temperatures range. After 20 min, both ions have reached equilibrium. The pseudo second-order kinetic model was chosen as one which best fits the experimental evidence and better reflects the chemical sorption process. Adsorption isotherm was studied using the Langmuir, Freundlich, and D-R models. The Langmuir model was used to better fit the results obtained. At 25 °C, Ce(III) and La(III) have maximum monolayer capacities of 200 and 83.3 mg/g, respectively. The sorption was endothermic reaction and spontaneous, as illustrated by the data of thermodynamics studies. GRA has the ability to be used as a novel lanthanide adsorbent material, especially for selective separation between Ce(III) and La(III).

A Mass Transfer Analysis of Competitive Binding of Pb, Cd, and Zn from Binary Systems onto a Fixed Zeolite Bed

The low-cost natural zeolite clinoptilolite was successfully applied for the competitive removal of Pb, Cd, and Zn from binary (Pb + Zn) and (Cd + Zn) aqueous solutions at different Pb/Zn and Cd/Zn concentration ratios. The obtained efficiency was in the range of 79.0⁻85.0%, and was similar for both systems, indicating that no loss in capacity was observed for six successive sorption-desorption cycles. In both systems, after the breakthrough, competition between the ions occurs, leading to overshooting in the Zn's initial concentration, indicating displacement of already-bound Zn with Pb and Cd from the feeding solutions. The Zn exceeded its initial concentration up to 2.3 times in the presence of Pb, and up to 1.2 times in the presence of Cd. The film diffusion was pronounced as the slowest step responsible for the overall process rate. The overall mass transfer coefficient (K_a) shows higher values for the (Cd + Zn) system compared to the (Pb + Zn) one due to reduced competition and ions migration. An SEM-EDS analysis confirmed a higher amount of bound Pb and Cd compared to Zn, and a mapping analysis revealed the equal distribution of all ions onto the zeolite surface.

Modification of bio-based β-diketone from wheat straw wax: synthesis of polydentate lipophilic super-chelators for enhanced metal recovery

Bio-derived lipophilic polydentate chelators have been synthesized and tested for their chelating ability using a range of metal salts of Cu, Co, Ni, Fe, and Cr. These novel molecules were produced by the Michael addition reaction of 14,16-hentriacontanedione, isolated from wheat straw wax, with methyl acrylate or bio-derived dimethyl itaconate via microwave heating. The Michael adducts could either be used directly as esters or be hydrolysed to their acid form. Critically, the creation of additional binding sites via the carboxylate moieties leads to an enhanced metal uptake over both a non-renewable commercially available lipophilic β-diketone (dibenzoylmethane) and the unmodified hentriacontane-14,16-dione, for the chelation of Fe(iii), Cr(iii) and Ni(ii). The modified β-diketone containing a single carboxylic acid functionality was able to extract 167 mg L⁻¹ of Fe(iii) from an FeCl₃ solution with no pH adjustment. In comparison, no chelation was observed with dibenzoylmethane, while unmodified hentriacontane-14,16-dione was able to extract 81 mg L⁻¹. The modified chelators containing one and two ester carboxylates extracted 255 and 305 mg L⁻¹ Cr(iii) from a solution of CrCl₃ at pH 5–6, 238 mg L⁻¹ was extracted by the unmodified β-diketone whilst no extraction was observed using dibenzoylmethane. This suggest some minor contribution or positive effect to chelation due to neighbouring ester groups. The chelator containing two carboxylic acid groups (tetra-dentate when combined with the diketone) was the most proficient in this study for removal of Ni from an NiCl₂ solution (140 mg L⁻¹). It was also found that at higher pH almost quantitative extraction was achieved using the polydentate chelators.

Bio-derived lipophilic polydentate chelators have been synthesized and tested for their chelating ability using a range of metal salts of Cu, Co, Ni, Fe, and Cr.

Nitrogen-Doped Nanoporous Carbon Nanospheroids for Selective Dye Adsorption and Pb(II) Ion Removal from Waste Water

In the presence of melamine and block copolymers, namely, F108, F127, and P123, nitrogen-doped nanoporous carbon nanospheroids (N@CNSs) were synthesized by the hydrothermal process. The F127-modified sample (CNF127) exhibits the maximum Brunauer-Emmett-Teller (BET) surface area of 773.4 m2/g with a pore volume of 0.877 cm3/g. The microstructural study reveals that nanospheroids of size 50-200 nm were aggregated together to form a chainlike structure for all triblock copolymer-modified samples. The X-ray photoelectron spectroscopy study shows the binding energies of 398.33 and 400.7 eV attributed to sp2 (C-N=C)- and sp3 (C-N)-hybridized nitrogen-bonded carbons, respectively. The synthesized N@CNS samples showed selective adsorption of organic dye methylene blue (MB) in the presence of methyl orange (MO) as well as Pb(II) ion removal from contaminated water. The adsorptions for MB and Pb(II) ions followed pseudo-first-order and pseudo-second-order kinetic models, respectively. The sample CNF127 showed the highest adsorption of 73 and 99.82 mg/g for MB and Pb(II) adsorptions, respectively. The adsorption capacity for MB of the copolymer-modified samples follows the order CNF127 > CNP123 > CNF108, which corroborated with the mesoporosity as well as nitrogen content of the corresponding samples. The maximum % adsorption of Pb(II) follows the order CNF127 (99.82%) > CNF108 (98.74%) > CNP123 (91.82%), and this trend is attributed to the BET surface area of the corresponding samples. This study demonstrates multicomponent removal of water pollutants, both organic dyes and inorganic toxic metal ions.

Synthesis of a functionalized fibrous adsorbent of high uptake capacity: a study on Pb(ii) uptake and simple acidic site model development

Development and exposure of acidic functional groups on lignocellulose biomaterials through destruction of lignin barrier by acid treatment.

Rapid and efficient biphasic liquid extraction of metals with bio-derived lipophilic β-diketone

A bio-derived lipophilic β-diketone (14,16-hentriacontanedione) was isolated from wheat straw wax and tested in the liquid biphasic removal of Ni²⁺, Co²⁺, Cu²⁺ and Cr³⁺ in comparison to dibenzoylmethane and acetylacetone.