Preparation of an amphoteric adsorbent from cellulose for wastewater treatment

In many types of organic wastewater, the majority of organic pollutants have a negative potential and the minority of pollutants have a positive potential. Hence, an amphoteric adsorbent can be used to enhance the efficiency of adsorbing contaminants. To exploit the abundance of cellulose resources, the preparation of an amphoteric adsorbent from cellulose-grafted calcium hydroxide is proposed for use in wastewater treatment. Experiments were carried out to verify the hypothesis that an amphoteric adsorbent can adsorb both negatively and positively charged contaminants in simulated wastewater. The maximum adsorption efficiency and maximum adsorption capacity of the proposed adsorbent at 303 K were 96.95 ± 0.0058% and 2552.67 mg/g, respectively, for Congo red (CR, an anionic dye) and 84.48 ± 0.0058% and 756.50 mg/g, respectively, for methylene blue (MB, a cationic dye). In addition, the amphoteric adsorbent can be reused several times, retaining 74.38 ± 6.16–79.01 ± 3.06% and 45.69 ± 0.0074–51.75 ± 0.022% of the initial adsorption capacity for CR and MB, respectively. Therefore, cellulose-grafted calcium hydroxide is an effective amphoteric adsorbent for wastewater treatment. [Display omitted] •Successful valorization of cellulose-based adsorbent via facile water bath grafting approach.•Cellulose grafted calcium hydroxide successfully adsorbs cation and anion organic matter.•High uptake capacity of ~2552.67 mg/g demonstrated by adsorbent for CR dye.•High uptake capacity of and ~756.50 mg/g demonstrated by adsorbent for MB dye.•Great adsorption capacities of the amphoteric absorbent have been identified.