Color removal for large-scale interbasin water transfer: Experimental comparison of five sorption media

The increasing needs of drinking water due to population growth requires seeking for new tap water sources. However, these large-scale tap water sources are oftentimes abundant with dissolved natural organic matter (NOM), such as tannic acid issue causing color in water. If not removed at the source locations beforehand, NOM would impact coagulation and flocculation unit, and/or become precursors to prompt the production of disinfectant by-products after chlorination in drinking water treatment. This study focuses on developing and testing a suite of cost-effective, scalable, adaptable, and sustainable sorption media that can be implemented near the source locations of tap water as a pretreatment option to remove color for a long-distance interbasin transfer. Within the five tested sorption media, a media recipe of Zero-valent-Iron and Perlite based Green Sorption Media (ZIPGEM) with ingredients of 85% sand, 5% clay, 6% zero-valent-iron (ZVI) and 4% perlite by volume stood out as the best option for color removal. Findings showed that ZIPGEM can maintain a color removal of ∼77% for about 14,080 min, maintaining the effluent concentration below 40 Pt-Co units given the influent condition of 175 ± 10 Pt-Co units. A recovery on the adsorption capacity of ZIPGEM was observed around 40,000 min due to synergetic effects among several different ingredients of recycled ZVI, clay, sand, and perlites. ZIPGEM can be applied to industrial wastewater treatment for dye removal as well.

Research progress of adsorption and removal of heavy metals by chitosan and its derivatives: A review

Chitosan has received widespread attention as an adsorbent for pollutants because of its low cost and great adsorption potentials. Chitosan has abundant hydroxyl and amino groups that can bind heavy metal ions. However, it has defects such as sensitivity to pH, low thermal stability, and low mechanical strength, which limit the application of chitosan in wastewater treatment. The functional groups of chitosan can be modified to improve its performance via crosslinking and graft modification. The porosity and specific surface area of chitosan in powder form are not ideal, therefore, physical modification has been attempted to generate chitosan nanoparticles and hydrogel. Chitosan has also been integrated with other materials (e.g. graphene, zeolite) resulting in composite materials with improved adsorption performance. This review mainly focuses on reports about the application of chitosan and its derivatives to remove different heavy metals. The preparation strategy, adsorption mechanism, and factors affecting the adsorption performance of adsorbents for each type of heavy metal are discussed in detail. Recent reports on important organic pollutants (dyes and phenol) removal by chitosan and its derivatives are also briefly discussed.

Structural diversity of six metal–organic frameworks from a rigid bisimidazole ligand and their adsorption of organic dyes

Six entangled coordination polymers from a bisimidazole ligand and versatile carboxylate acids have been synthesized and structurally characterized. Their adsorption behaviors to organic dyes have also been evaluated.

A microporous cationic metal–organic framework for the efficient removal of dichromate and the selective adsorption of dyes from water

A microporous anionic metal–organic framework has been synthesized, which can be used as the effective adsorbent to methyl orange and Cr₂O₇²⁻ from aqueous solutions.

Solvothermal synthesis of magnetic CoFe2O4/rGO nanocomposites for highly efficient dye removal in wastewater

Magnetic CoFe₂O₄/rGO nanocomposites were fabricated via a solvothermal process and used as environmentally-friendly adsorbents for the adsorption of organic dyes.