A novel remediation method of cadmium (Cd) contaminated soil: Dynamic equilibrium of Cd2+ rapid release from soil to water and selective adsorption by PP-g-AA fibers-ball at low concentration.

The acid-extractable fraction Cd(II) in soil accumulates easily in organisms, migrates and transforms in the ecological environment, which has posed potential health risks to human. This study found that the acid-extractable fraction Cd(II) in soil could be released rapidly into water at very low Cd2+ concentration. Carboxylated polypropylene (PP-g-AA) fibers-ball with high selectivity as adsorbent was used in the Cd(II) contaminated soil-water system. It could remove promptly trace Cd2+ from water even in the presence of interfering metal ions. Moreover, Cd(II) desorbed from soil to water could be continuously adsorbed by PP-g-AA fibers-ball, which kept the Cd2+ concentration always at a low level. This forms a dynamic equilibrium of rapid release- selective adsorption toward the acid-extractable fraction Cd(II) in the soil-water system. Here, the migratory pathway for the acid-extractable fraction Cd(II) to be released from contaminated soil to water and adsorbed simultaneously on the surface of PP-g-AA fibers-ball was established. This work offers a novel protocol that can remove more than 90% of the acid-extractable fraction Cd(II) from contaminated soil within 12 h, thereby contributes better to mitigate the risk of Cd(II) from soil to the food chain without changing the physical and chemical properties of soil.

Synthesis of a new ion-imprinted polymer for selective Cr(VI) adsorption from aqueous solutions effectively and rapidly.

Removing hexavalent chromium (Cr(VI)) from aqueous solution is strategically important. A novel and selective adsorbent was synthesized using a high electron beam irradiation pre-grafting and post-surface ion imprinting method using Cr(VI) and polypropylene (PP) fibers as the template and substrates, respectively. The results obtained using Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TG) indicated that the prepared sorbent was successfully synthesized. At the same time, the adsorption performances were studied through batch experiments. The results exhibited rapid adsorption kinetics, a wide working pH range, and excellent selectivity and regeneration. The equilibrium adsorption was achieved within 30 min, the maximum sorption capacity of Cr(VI)-IIPs was 156.5 mg g-1 and partition coefficients (PC) was 0.591 mg g-1 uM-1 at 400 mg L-1 initial concentration and 298 K. The relative selectivity coefficients of the ion-imprinted polymer (IIP) for Cr2O72-/HPO42- and Cr2O72-/NO3- were 36.7 and 39.9, respectively. In addition, the prepared sorbent has a negligible loss in adsorption capacity after five cycles. IIP has good application prospects in the selective removal of Cr(VI) ions.

Caffeic acid polymer rapidly modified sponge with excellent anti-oil-adhesion property and efficient separation of oil-in-water emulsions.

The efficient treatment of high stability emulsion with small diameter and the prevention of oil contamination of materials are serious issues in the process of emulsion separation. In order to address those issues, we reported a fast and versatile hydrophilic surface coating technology that uses oxidants and diamines to synergistically promote the polymerization of caffeic acid (CA). It was found that amino groups can not only accelerate the polymerization of CA, but also promote the deposition of polymers on the sponge surface. Using silica nanoparticles to improve the roughness, superhydrophilic melamine sponge could be prepared, which exhibited excellent superhydrophlic-underwater superolephobic and anti-oil-adhesion properties. DFT simulation was employed to explore the potential mechanism of the anti-oil adhesion ability. In addition, combined with the mechanical compression strategy, the sponge exhibited a high efficiency of 99.10% with a permeation flux of 19080 ±â€¯700 Lm-2 h-1 in emulsion separation just under the action of gravity. Moreover, based on the interaction between the surfactant and the surface of the material, the separation mechanism was discussed. Overall, this work provided an advanced method for the preparation of superhydrophilic sponge with anti-oil-fouling performance, which showed great potential in dealing with practically challenging emulsified wastewater.

Functional group-rich hyperbranched magnetic material for simultaneous efficient removal of heavy metal ions from aqueous solution.

In order to achieve the purpose of simultaneous removal of coexisting heavy metal ions, in this work, functionalized magnetic mesoprous nanomaterials (Fe3O4-HBPA-ASA) with high density and multiple adsorption sites were designed and prepared. The obtained Fe3O4-HBPA-ASA was characterized by SEM, FTIR, VSM, TGA and zeta potential. Cu(II), Pb(II) and Cd(II) were chosen as the model heavy metal ions, the adsorption experiments showed that Fe3O4-HBPA-ASA showed hightheoretical adsorption capacitiesin individual system, and the maximum adsorption capacity was 136.66 mg/g, 88.36 mg/g and 165.46 mg/g, respectively. In the binary and ternary systems, the competitive adsorption leads to a decrease in the adsorption capacity of Cu(II), Pb(II) and Cd(II). However, in the ternary system with a concentration lower than 15 mg/L, the simultaneous removal rate was still higher than 90%. The adsorption isotherms and kineticswere well fitted by Langmuir and pseudo-second-order models, respectively. The XPS and density functional theory (DFT) analysis have confirmed that the adsorption of metal ions was related to various types of functional groups on the surface of Fe3O4-HBPA-ASA, while the adsorption mechanisms of Cu(II), Cd(II) and Pb(II) were different.