Iodine Immobilized UiO-66-NH2 Metal-Organic Framework as an Effective Antibacterial Additive for Poly(ε-caprolactone)

Iodine has been widely used as an effective disinfectant with broad-spectrum antimicrobial potency. However, the application of iodine in an antibacterial polymer remains challenging due to its volatile nature and poor solubility. Herein, iodine immobilized UiO-66-NH2 metal-organic framework (MOF) (UiO66@I2) with a high loading capacity was synthesized and used as an effective antibacterial additive for poly(ε-caprolactone) (PCL). An orthogonal design approach was used to achieve the optimal experiments’ conditions in iodine adsorption. UiO66@I2 nanoparticles were added to the PCL matrix under ultrasonic vibration and evaporated the solvent to get a polymer membrane. The composites were characterized by SEM, XRD, FTIR, and static contact angle analysis. UiO-66-NH2 nanoparticles have a high iodine loading capacity, up to 18 wt.%. The concentration of iodine is the most important factor in iodine adsorption. Adding 0.5 wt.% or 1.0 wt.% (equivalent iodine content) of UiO66@I2 to the PCL matrix had no influence on the structure of PCL but reduces the static water angle. The PCL composites showed strong antibacterial activities against Staphylococcus aureus and Escherichia coli. In contrast, the same content of free iodine/PCL composites had no antibacterial activity. The difference in the antibacterial performance was due to the different iodine contents in the polymer composites. It was found that MOF nanoparticles could retain most of the iodine during the sample preparation and storage, while there was few iodine left in the free iodine/PCL composites. This study offers a common and simple way to immobilize iodine and prepare antibacterial polymers with low antiseptic content that would reduce the influence of an additive on polymers’ physical properties.

Removal of Volatile Toluene Using K2CO3-Activated Carbon Adsorbents Prepared from Buckwheat Hull

Carbon adsorbents for use in the removal of gaseous toluene from the air were prepared from buckwheat (Fagopyrum esculentum Moench) hull. A chemically-activated adsorbent was prepared via the impregnation of raw hull powder with potassium carbonate, followed by thermal decomposition. The chemically-activated adsorbent exhibited improved adsorption capacity for toluene compared to the adsorbent prepared without chemical activation. Toluene concentration in the air decreased from 220 ppm to 160 ppm during 24 h of adsorption using unactivated adsorbent. Only a trace amount of toluene remained after the adsorption under the same conditions using K2CO3-activated adsorbent. This improvement was explained based on experimental results, specifically, iodine adsorption tests, methylene blue adsorption tests, and microscopic observations. Chemical activation dramatically increased the specific surface area of the adsorbent and created mesopores capable of adsorbing toluene. This study revealed that a mesoporous adsorbent for use in volatile toluene removal can be prepared from waste biomass (buckwheat hull) by chemical activation using potassium carbonate.

The Physicochemical Characteristic of Activated Carbon Based on Sludge and Preparation Method

To understand the features and best preparation of sludge activated carbon (SAC), and the pore structure, component, adsorption characteristics, and the yield rate of SAC, many tests have been carried out. The study illustrated that the pore structure was mostly mesopore and amorphous pore such as the ink bottle hole. In terms of different preparations to obtain SAC, the yield of SAC in sample No.1 achieved 88.09%. Using the preparation of ZnCl2 as an activator, the iodine adsorption value was significantly higher than other preparations. However, the content of quartz in sample No.1 achieved a maximum of 52.51%. Charcoal was detected in all samples except sample nos 9-12. The adsorption capacity of Cu(II) and Cd(II) reached a maximum of 600.02 mg.kg-1 and 383.2 mg.kg-1. The results showed an optimum preparation condition, which was by using the ZnCl2 as an activator, 2:1 as the impregnated ratio, 40% concentration in activator and at 400ºC reaction temperature could create rich pore structure and charcoal inside.

Preparation of Activated Carbon from Bagasse by Microwave-Assisted Phosphoric Acid Activation

This research focuses on the utilization of bagasse as activated carbon (AC) under microwave-assisted phosphoric acid activation. The AC was activated using various frequencies of microwave energy combined with phosphoric acid before the carbonization process. Results indicated that the AC obtained from bagasse under microwave-assisted phosphoric acid had improved properties, i.e. fixed carbon, surface area, and iodine adsorption capacity. However, the loss of AC properties could be attributed to microwave energy exceeding a limit of 800 W. The optimum activated condition in this research was the use of microwave energy 500 W assisted phosphoric acid, which had fixed carbon, surface area, and iodine adsorption capacity at 88.34 ± 0.67 %, 781 m2/g, and 852 ± 6.0 mg/g, respectively. HIGHLIGHTS Microwave energy and phosphoric acid is applied to pretreat bagasse Bagasse pretreatment by microwave-assisted H3PO4 enhances the properties of AC Optimum condition is pretreatment by phosphoric acid and microwave energy at 500 W GRAPHICAL ABSTRACT