Abstract
Finding affordable and environment-friendly options to decontaminate wastewater generated with heavy metals and dyes to prevent the depletion of accessible freshwater resources is one of the indispensable challenges of the 21st century. Adsorption is yet to be the most effective and low-cost wastewater treatment method used for the removal of pollutants from wastewater, while naturally derived adsorbent materials have garnered tremendous attention. One promising example of such adsorbents is hydrogels (HGs), which constitute a three-dimensional polymeric network of hydrophilic groups that is highly capable of adsorbing a large quantity of metal ions and dyes from wastewater. Although HGs can also be prepared from synthetic polymers, natural polymers have improved environmental benignity. Recently, cellulose-based hydrogels (CBHs) have been extensively studied owing to their high abundance, biodegradability, non-toxicity, and excellent adsorption capacity. This review emphasizes different CBH adsorbents in the context of dyes and heavy metals removal from wastewater following diverse synthesis techniques and adsorption mechanisms. This study also summarizes various process parameters necessary to optimize adsorption capacity followed by future research directions.
Highlights
Water is the most abundant natural resource on the planet; only about 3%of current water reserves are freshwater, while less than one-third of this freshwater is usable for different household, agricultural, and industrial activities [1,2,3]
For carboxymethyl cellulose sodium (CMCNa)/graphene oxide (GO) hydrogel microparticles, Liu et al [166] suggested that the adsorption mechanism for dyes were due to both electrostatic and π–π interactions, while those for heavy metals were the synergistic effect of electrostatic interactions, surface complexation, and ion exchange
The adsorption capacity of cellulose-based hydrogels (CBHs) for heavy metal ions is higher at the basic pH of the solution; there is a range of pH values for each metal ion wherein the maximum adsorption occurs
Summary
Maimuna Akter 1,† , Maitry Bhattacharjee 2,† , Avik Kumar Dhar 2 , Fahim Bin Abdur Rahman 1,3 , Siddika Haque 4 , Taslim Ur Rashid 5 and S M Fijul Kabir 5, *.
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