Efficient Removal of Pb(Ⅱ) by Highly Porous Polymeric Sponges Self-Assembled from a Poly(Amic Acid)

Lead (II) (Pb(II)) is widespread in water and very harmful to creatures, and the efficient removal of it is still challenging. Therefore, we prepared a novel sponge-like polymer-based absorbent (poly(amic acid), PAA sponge) with a highly porous structure using a straightforward polymer self-assembly strategy for the efficient removal of Pb(II). In this study, the effects of the pH, dosage, adsorption time and concentration of Pb(II) on the adsorption behavior of the PAA sponge are investigated, revealing a rapid adsorption process with a removal efficiency up to 89.0% in 2 min. Based on the adsorption thermodynamics, the adsorption capacity increases with the concentration of Pb(II), reaching a maximum adsorption capacity of 609.7 mg g^-1 according to the Langmuir simulation fitting. Furthermore, the PAA sponge can be efficiently recycled and the removal efficiency of Pb(II) is still as high as 93% after five adsorption-desorption cycles. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses reveal that the efficient adsorption of Pb(II) by the PAA sponge is mainly due to the strong interaction between nitrogen-containing functional groups and Pb(II), and the coordination of oxygen atoms is also involved. Overall, we propose a polymer self-assembly strategy to easily prepare a PAA sponge for the efficient removal of Pb(II) from water.

Synthesis of Nitrogen Containing Biocompatible Non-ionic Surfactants and Investigation for Their Self-Assembly Based Nano-Scale Vesicles

Nonionic surfactants are increasingly interesting because of the solubility and release of drugs. Here, a synthesis of four nonionic nitrogen-containing surfactants is reported. In the synthesis, sulfonamide was reacted with alkyl halides of different lipophilicity. The synthesized nonionic surfactants were characterized by 1H NMR and mass spectroscopy. Their critical micelle concentration (CMC) was determined with a UV spectrophotometer. The self-assembly of surfactants to form drug-loaded, niosomal vesicles with Simvastatin as model drug was investigated. The resulting niosoaml vesicles were characterized by atomic force microscope (AFM), zeta-sizer, and UV spectrophotometer for shape, size, polydispersity index, zeta potential, and drug inclusion efficiency. Their biocompatibility has been determined by blood hemolysis and cell toxicity tests. The synthesized surfactants showed low CMC values and were able to form nano-sized round niosomal vesicles with a homogeneous population and surface negativity. Depending on the lipophilicity, they absorbed an increased amount of drug. The biocompatibility studies show that the surfactants are hemocompatible and non-toxic. The results of the study confirm that the synthesized nonionic surfactants are suitable for the solubilization and release of hydrophobic drugs as efficient novel biocompatible carriers.

Efficient Removal of Polycyclic Aromatic Hydrocarbons, Dyes, and Heavy Metal Ions by a Homopolymer Vesicle

It is an important challenge to effectively remove environmental pollutants such as polycyclic aromatic hydrocarbons (PAHs), dyes, and heavy metal ions at a low cost. Herein, we present a multifunctional homopolymer vesicle self-assembled from a scalable homopolymer, poly(amic acid) (PAA), at room temperature. The vesicle can efficiently eliminate PAHs, cationic dyes, and heavy metal ions from water based on π-π stacking, hydrophobic effect, and electrostatic interactions with the pollutants. The residual concentrations of PAHs, cationic dyes, and heavy metal ions (such as Ni²⁺) in water are lower than 0.60 and 0.30 parts per billion (ppb) and 0.095 parts per million (ppm), respectively, representing a promising adsorbent for water remediation. Furthermore, precious metal ions such as Ag⁺ can be recovered into silver nanoparticles by in situ reduction on the membrane of PAA vesicles to form a silver nanoparticle/vesicle composite (Ag@vesicle) that can effectively catalyze the reduction of toxic pollutants such as aromatic nitro-compounds and be recycled for more than ten times.

Synthesis, Characterizations and Multifunctional Activities of New Thiourea-Based Non-Ionic Surfactants

Six new thiourea-based non-ionic surfactants were prepared from easily existing raw resources in good yield name 1-sec-butyl-3-dodecanoylthiourea, 1-dodecanoyl-3-phenylthiourea, 1,1-dibutyl-3-dodecanoylthiourea, 3-dodecanoyl-1, 1-diphenylthiourea, 1-cyclohexyl-3-dodecanoylthiourea and 1-butyl-3-dodecanoylthiourea. The structural chemistry of these compounds was studied by multinuclear magnetic resonance (1H, 13C), Infrared spectroscopy and UV-Visible spectrophotometry techniques. Their solubility varies according to temperature. They show a low solubility, which increases with the temperature of the water. However, they are not stable. The are soluble in organic solvent like ethanol. These molecules possess a low critical micelle concentration and due to this it shows that they are moderately hydrophobic. These molecules were studied regarding their antimicrobial activities and their antifungal and antibacterial efficiency was tested against five microoganism strains. In all cases, the new compounds show a significant inhibition growth against the tested five bacterial and fungal strains. Due to these behaviors they can be used as future candidates in cleaning as well as in agriculture features. The corrosion inhibition behavior was also studied using chromium and aluminum metals.

Micelles as Soil and Water Decontamination Agents

Contaminated soil and water pose a serious threat to human health and ecosystem. For the treatment of industrial effluents or minimizing their detrimental effects, preventive and remedial approaches must be adopted prior to the occurrence of any severe environmental, health, or safety hazard. Conventional treatment methods of wastewater are insufficient, complicated, and expensive. Therefore, a method that could use environmentally friendly surfactants for the simultaneous removal of both organic and inorganic contaminants from wastewater is deemed a smart approach. Surfactants containing potential donor ligands can coordinate with metal ions, and thus such compounds can be used for the removal of toxic metals and organometallic compounds from aqueous systems. Surfactants form host-guest complexes with the hydrophobic contaminants of water and soil by a mechanism involving the encapsulation of hydrophobes into the self-assembled aggregates (micelles) of surfactants. However, because undefined amounts of surfactants may be released into the aqueous systems, attention must be paid to their own environmental risks as well. Moreover, surfactant remediation methods must be carefully analyzed in the laboratory before field implementation. The use of biosurfactants is the best choice for the removal of water toxins as such surfactants are associated with the characteristics of biodegradability, versatility, recovery, and reuse. This Review is focused on the currently employed surfactant-based soil and wastewater treatment technologies owing to their critical role in the implementation of certain solutions for controlling pollution level, which is necessary to protect human health and ensure the quality standard of the aquatic environment.