Functionalizing natural polymers to develop green adsorbents for wastewater treatment applications

Curdlan/sodium carboxymethylcellulose composite adsorbents: A biodegradable solution for organic dye removal from water

Composite adsorbent comprised of curdlan (CURD) and sodium carboxymethylcellulose (CMC) were fabricated through a single-step heating process, targeting the removal of methylene blue (MB) from wastewater. The CURD/CMC composite adsorbents had a honeycomb porous structure. The integration of CMC not only increased the storage modulus of the CURD/CMC composite hydrogels but also affected the thermal stability and swelling behavior of the composite adsorbents in different pH solutions. Specifically, the addition of 1.2 % CMC increased the peak temperature (184.73 °C) of CURD/CMC composite adsorbent melting by 5.99 °C compared to CURD adsorbent. The addition of CMC improved the swelling ratio of the composite adsorbent at pH 3,7, and 12 with swelling ratio up to 918.07 %. The synergistic interaction between CURD and CMC led to an enhanced adsorption capacity of the aerogel for MB, achieving a maximum adsorption capability of 385.85 mg/g. Adsorption isotherm assessments further demonstrated that the Langmuir isotherm model well fitted the adsorption data of the composite adsorbent on MB. Collectively, these findings underscore the potential of the developed biodegradable adsorbents as promising adsorbents for efficiently eliminating organic dyes from water.

Sodium carboxymethyl cellulose and MXene reinforced multifunctional conductive hydrogels for multimodal sensors and flexible supercapacitors

With the growing demand for eco-friendly materials in wearable smart electronic devices, renewable, biocompatible, and low-cost hydrogels based on natural polymers have attracted much attention. Cellulose, as one of the renewable and degradable natural polymers, shows great potential in wearable smart electronic devices. Multifunctional conductive cellulose-based hydrogels are designed for flexible electronic devices by adding sodium carboxymethyl cellulose and MXene into polyacrylic acid networks. The multifunctional hydrogels possess excellent mechanical property (stress: 310 kPa; strain: 1127 %), toughness (206.67 KJ m-3), conductivity (1.09 ± 0.12 S m-1) and adhesion (82.19 ± 3.65 kPa). The multifunctional conductive hydrogels serve as strain sensors (Gauge Factor (GF) = 5.79, 0-700 % strain; GF = 14.0, 700-900 % strain; GF = 40.36, 900-1000 % strain; response time: 300 ms; recovery time: 200 ms) and temperature sensors (Temperature coefficient of resistance (TCR) = 2.5755 °C-1 at 35 °C- 60 °C). The sensor detects human activities with clear and steady signals. A distributed array of flexible sensors is created to measure the magnitude and distribution of pressure and a hydrogel-based flexible touch keyboard is also fabricated to recognize writing trajectories, pressures and speeds. Furthermore, a flexible hydrogel-based supercapacitor powers the LED and exhibits good cyclic stability over 15,000 charge-discharge cycles.