Adsorption removal of styrene on C-Cl grafted silica gel adsorbents

Green synthesis of azo-linked porous organic polymer for enrichment of nitroimidazoles from water, shrimp and Basa fish

Reliable monitoring of nitroimidazoles (NDZs) is of great significance to public health. Herein, an azo-linked porous organic polymer (Res-POPs) was prepared by green synthesis method using natural resveratrol as monomer for the first time. Using Res-POPs as sorbent, a facile method coupling solid-phase extraction with high performance liquid chromatography-diode array detection was developed for effective detecting NDZs. The method achieved good linearities (0.06 ∼ 100 ng mL-1 for water, 1.8 ∼ 200 ng g-1 for shrimp, and 1.5 ∼ 200 ng g-1 for Basa fish) with determination coefficients above 0.995, low detection limits (0.02 ∼ 0.05 ng mL-1, 0.60 ∼ 1.00 ng g-1 and 0.50 ∼ 0.90 ng g-1 for water, shrimp and Basa fish), high method recovery (85 %∼114 %) and relative standard deviations below 8.2 %. The results demonstrated the superiority and the promising potential of the established method for detection of NDZs compared with the reported method.

Conversion of PET Bottle Waste into a Terephthalic Acid-Based Metal-Organic Framework for Removing Plastic Nanoparticles from Water

Micro- and nanoparticles of plastic waste are considered emerging pollutants with significant environmental and health impacts at high concentrations or prolonged exposure time. Here we report the synthesis and characterization of a known metal-organic framework (MOF) using terephthalic acid (TPA) recovered from the hydrolysis of polyethylene terephthalate (PET) bottle waste. This approach adds value to the existing large amounts of bottle waste in the environment. Fully characterized zinc-TPA MOF (MOF-5) was used for the extraction and removal of engineered polyvinyl chloride (PVC) and polymethylmethacrylate (PMMA) nanoparticles from water with a high efficiency of 97% and 95%, respectively. Kinetic and isotherm models for the adsorption of polymer nanoparticles (PNPs) on the MOF surface were investigated to understand the mechanism. The Qmax for PVC and PMMA NPs were recorded as 56.65 mg/g and 33.32 mg/g, respectively. MOF-5 was characterized before and after adsorption of PNPs on the surface of MOF-5 using a range of techniques. After adsorption, the MOF-5 was successfully regenerated and reused for the adsorption and removal of PNPs, showing consistent results for five adsorption cycles with a removal rate of 83-85%. MOF-5 was characterized before and after adsorption of PNPs on the surface using a range of techniques. The MOF-5 with PNPs on the surface was successfully regenerated and reused for the adsorption and removal of polymer nanoparticles, showing consistent results for five extraction cycles. As a proof of concept, MOF-5 was also used to remove plastic particles from commercially available body scrub gel solutions. Such methods and materials are needed to mitigate the health hazards caused by emerging micro- and nanoplastic pollutants in the environment.

Preparation of a phenylboronic acid and aldehyde bi-functional group modified silica absorbent and applications in removing Cr(vi) and reducing to Cr(iii)

Cr(vi) is a great threat to the ecological environment and human health, so it is urgent to remove Cr(vi) from the environment. In this study, a novel silica gel adsorbent SiO₂-CHO-APBA containing phenylboronic acids and aldehyde groups was prepared, evaluated and applied for removing Cr(vi) from water and soil samples. The adsorption conditions including pH, adsorbent dosage, initial concentration of Cr(vi), temperature and time were optimized. Its ability in removing Cr(vi) was investigated and compared with three other common adsorbents, SiO₂-NH₂, SiO₂-SH and SiO₂-EDTA. Data showed SiO₂-CHO-APBA had the highest adsorption capacity of 58.14 mg g^-1 at pH 2 and could reach adsorption equilibrium in about 3 h. When 50 mg SiO₂-CHO-APBA was added in 20 mL of 50 mg L^-1 Cr(vi) solution, more than 97% of Cr(vi) was removed. A mechanism study revealed that a cooperative interaction of both the aldehyde and boronic acid groups is attributed to Cr(vi) removal. The reducing function was gradually weakened with the consumption of the aldehyde group, which was oxidized to a carboxyl group by Cr(vi). This SiO₂-CHO-APBA adsorbent was successfully used for the removal of Cr(vi) from soil samples with satisfactory results which indicates a good potential in agriculture and other fields.