Responsive and cellulose-fibre based adsorbents for water clarification and disinfection

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Access to clean water is becoming more challenging due to the pollution from a wide variety of industrial, municipal and agricultural sources, which raises the urgency and need to develop new and alternative technologies for water clarification. Among various technologies for water treatment, using adsorbents is one of the most effective and simplest approaches. However, the work on developing multi-functional (e.g., antimicrobial) and responsive adsorbents is still inadequate. The proposed research aims at developing three types of novel adsorbents based on modified cellulose microfibrils or filaments, nanocapsules and porous polymeric microparticles, which are all associated with green materials - cellulose fibres for innovative water filter systems. The specific sub-projects, to be performed by PhD students, are as follows: 1) Cellulose-fibre based functional absorbent: the functional groups (e.g., carboxyl groups for complexing with heavy metal ions in water) and antimicrobial polymer chains will be grafted on cellulose microfibrils (CMF) and cellulose filaments via proper reactions; and create a novel paper-based filter with long fibres which enable to clarify contaminants in water and deactivate the bacteria entrapped. Moreover, the fibre/inorganic porous filler hybrid adsorbents will be prepared using dissolved cellulose fibres with pore forming agents to facilitate the adsorbent recovery. 2) Responsive or smart nanocapsules: to enhance the performance of cellulose fiber-based absorbents, a range of amphoteric pH-sensitive calixarenes with anionic upper rim and cationic lower rim will be synthesized. Such smart nanocapsules can be well retained with cellulose fibres or used alone for the controllable adsorption/desorption triggered by pH change. 3) Functional polymeric microcapsules or absorbents: to absorb the contaminants with relatively large size, pH-responsive and antimicrobial polymeric microcapsules with tailored pore size and functionality will be prepared via an in-situ free-radical copolymerization using porous calcium carbonate as a template to be removed under appropriate pH, creating the mirrored pore structure of the template. All functional absorbents proposed will be comprehensively characterized for the fundamental understanding of adsorption behaviors, which is of great significance for HQP training. The resulting adsorbents will lead to the value-added products from cellulose fibres and tackle the increasing concern about industrial water contamination and water borne diseases associated with drinking water.