Adsorption behaviors and mechanism of heavy metals onto attapulgite functionalized by polyamine silane

Abstract

Pollution from heavy‐metal ions has become a major challenge to the global fight against environmental pollution. Given the availability of various low‐cost and environmentally friendly adsorbents, adsorption has become the most efficient technology for the removal of heavy metals from water. In this study, attapulgite (ATP) was directly functionalized by coupling with an aminosilane agent. Analysis showed this maneuver provided a suitable adsorbent for the removal of lead ion (Pb2+) from an aqueous solution. The effects of several parameters including solution pH, contacting time, adsorbent dosage, and initial Pb2+ ion concentration were investigated. Batch sorption results showed that the adsorption process was rapid and over 98% of Pb2+ was removed within 30 min at the optimal pH 4.0. The maximum adsorption capacity at 25°C, calculated by the Langmuir isotherm, was 82.17, 78.80, 61.13, and 28.56 mg/g for γ‐divinyltriaminepropyl‐methyldimethoxylsilane‐grafted attapulgite (KH‐103‐ATP), γ‐aminopropyl‐methyldiethoxysilane‐grafted attapulgite (KH‐912‐ATP), N‐(β‐aminoethyl‐γ‐aminopropyl)‐methyl‐dimethoxysilane‐grafted attapulgite (KH‐602‐ATP), and ATP, respectively. Moreover, molecular dynamics simulations of adsorption behaviors of heavy‐metal ions at attapulgite surfaces (010) modified by aminosilane agents were carried out. Both the PMF value and diffusion coefficient of metal ions suggest that KH‐103‐ATP owns the highest rate constant and capacity compared with the other two. And the analysis of free energy and results of XPS characterization revealed that Pb2+ formed covalent bonds with the nitrogen atom of aminosilane agents.

Excellent effect of lubrication performance of chitosan/polyethylene glycol/palygorskite as water‐based lubricating additive on 304 stainless steel and polymer pairs

“…[ 49 ] The absorption peak at 981 cm −1 was attributed to the tensile vibration of SiO bond. [ 33 ] In the absorption spectrum of CS, the peak of CS at 3451 cm −1 resulting from the overlapping of OH and NH stretching vibration. [ 44 ] In the spectrum of CS/PEG, the absorption peak at 2888 cm −1 belonged to the CH stretching vibration of CH 2 in PEG, which was consistent with the previous study.…”

“…This phenomenon can be considered that with the increase of PEG concentration, the formation speed of the friction film on the surface of the friction pair was accelerated, and the hydroxyl groups in PEG can form hydrogen bonds between the hydroxyl groups to form a network structure. [ 33 ] The network structure can play a good role in isolating the friction pair, thus avoiding the direct contact of the friction pair. Due to 10 wt% PEG and 20 wt% PEG have the same lubrication performance, and for the sake of economy, choosing 10 wt% PEG as the experimental object in the later experiment.…”

“…Pal was a silicate clay mineral with nanorod crystalline morphology which can also be used as a nanofiller for reinforcing polymer materials. [ 33–35 ] The experimental results showed that Pal powder dispersed in aqueous solution can play a better anti‐friction performance, [ 18 ] and can reduce friction to a certain extent. In the existing research, Pal has been generally used for rubber, adhesives, thermoplastic polymers, and environmental adsorbents, and so forth.…”

“…In the existing research, Pal has been generally used for rubber, adhesives, thermoplastic polymers, and environmental adsorbents, and so forth. [13,33,36,37] Such as poly (acrylonitrile methacrylate)/attapulgite (AT) nanocomposites were prepared by Yin et al [38] With the increase of AT content, the storage modulus and thermal deformation temperature of nanocomposites increase gradually. Pal as a kind of nonmetallic additive, can enhance the lubrication.…”

Excellent Lubricity of PVA/PEG/CS Composite on Ceramic Surface and Stainless Steel Friction Pair

“…In addition, metal oxides. [ 14 ] silicate materials, [ 15 ] rare earth materials, [ 16 ] and polymers [ 17,18 ] can be used as additive materials. Currently, there are numerous reports on the development of polymer films for lubricating materials.…”