Fabrication of a corn stalk derived cellulose-based bio-adsorbent to remove Congo red from wastewater: Investigation on its ultra-high adsorption performance and mechanism.

A cellulose-based bio-absorbent with various and plenty of amino groups was successfully prepared from corn stalk to achieve quantitative removal of Congo red from wastewater with wide pH values (5 ≤ pH ≤ 10). The maximum removal amount was 8.0 mmol·g-1 (5572 mg·g-1) under pH = 6.0 and 45 °C, which was obviously higher than reported absorbents. Investigation on dynamic adsorption and recyclability in authentic wastewater found that the removal efficiency of Congo red was >98 % within 180 min and decreased slightly in industrial water after five cycles, denoting this adsorbent with great potential for environmental application. The characterization results proved that 7.58 mmol·g-1 of different amino groups (-NH2, -NH- and -NR2) were introduced on adsorbent surface by two steps of modification and were the major functional groups for adsorption of Congo red. The inferred adsorption mechanism revealed that Congo red could be adsorbed equivalently on the amino groups by strong electrostatic interactions or hydrogen bonds. Different amino groups played different roles in adsorption due to great differences in protonation ability in 5 ≤ pH ≤ 10. The study was expected to high-efficiently remove Congo red from acidic or alkaline wastewater, and offered an alternative strategy for biowaste treatment of corn stalks in a high value-added manner.

An International Federal Hyperledger Fabric Verification Framework for Digital COVID-19 Vaccine Passport.

The COVID-19 virus has been spreading worldwide on a large scale since 2019, and the most effective way to prevent COVID-19 is to vaccinate. In order to prove that vaccination has been administered to allow access to different areas, paper vaccine passports are produced. However, paper vaccine passport records are vulnerable to counterfeiting or abuse. Previous research has suggested that issuing certificates digitally is an easier way to verify them. This study used the consortium blockchain based on Hyperledger Fabric to upload the digital vaccine passport (DVP) to the blockchain network. In order to enable collaboration across multiple systems, networks, and organizations in different trust realms. Federated Identity Management is considered a promising approach to facilitate secure resource sharing between collaborating partners. Therefore, the international federal identity management architecture proposed in this study enables inspectors in any country to verify the authenticity of the DVP of incoming passengers using the consortium blockchain. Through practical construction, the international federal Hyperledger verification framework for the DVP proposed in this study has shown the feasibility of issuing a global DVP in safety analysis and efficacy testing.