A New Approach for Removing Anionic Organic Dyes from Wastewater Based on Electrostatically Driven Assembly

Abstract

A conceptually new approach for an efficient removal of anionic organic dyes from wastewater using layered double hydroxides (LDHs) through their formation is presented. Acid yellow 25 (AY25) was used as anionic organic dye model molecules. As a result of the electrostatic induction, the removal mechanism involved a concurrent incorporation of AY25 molecules into the interlayer of LDHs during their structural arrangement, where Mg(2+) and Al(3+) ions were utilized to construct the base of LDHs in an alkaline solution. It was found that the molar stoichiometry of all precursors was a key factor affecting the removal efficiency. Within 5 min removal time, this method still maintained high removal efficiency of over 97% and provided a removal capacity of ∼186 mg g(-1), comparable to that of other LDH-based methods. Also, almost complete dye recovery was simply achieved by anionic exchange with common anions (Cl(-), NO3(-), and CO3(2-)). Additionally, the present technique is straightforward, cost-effective, and environmentally friendly since it avoids the synthesis step of sorbents, thus significantly saving time, chemicals, and energy. Hence, this strategy not only exhibits the alternative exploitation of LDHs, but also provides new insights into the removal of contaminants from wastewater.

Supramolecular Organization in Confined Nanospaces

“…[779][780][781] Taking inspiration from Blue Maya, the indigo molecule was recently encapsulated into zeolite L microcrystals yielding an exceptionally robust colorant: [782] the insight from simulations [191] was instrumental for the successful blockage of the crystal terminations. An atomistic knowledge of natural host matrices is also important for their use in environmental 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 protection (e. g., absorption of organic pollutants by layered hydroxides, [783,784] sequestration of trace uranium in multiphase iron minerals [785] ) and in the realization of new materials via sustainable fabrication approaches; for instance, using a vaporinduced approach, a direct synthesis of zeolites starting from clay minerals has been recently performed. [786] As regards the concrete use of these composites in optoelectronic applications, the distribution of the guests inside the porous matrix, and the related changes in the photophysical properties remain major issues, nearly for all the considered cases.…”

Hexavalent chromium ion and methyl orange dye uptake via a silk protein sericin–chitosan conjugate

“…[1][2][3] Remediation of these hazardous pollutants can be done by using a variety of techniques, such as adsorption, precipitation, membrane processes, occulation, ion-exchange, chemical coagulation and photo degradation. [4][5][6][7][8][9][10][11][12][13] Among them, adsorption-based technologies are widely recognized as constituting an effective and inexpensive treatment strategy for water tainted with hazardous pollutants. 1,14,15 In recent years, biocomposite materials [16][17][18] have been used for adsorption because of their non-toxic and biodegradable nature.…”

Water–n-BuOH solvothermal synthesis of ZnAl–LDHs with different morphologies and its calcined product in efficient dyes removal

“…Their calcined products, namely layered double oxides (LDO), normally with much higher surface areas than those of LDHs, have good structural memory effect [31]. Thanks to anionexchangeability of LDHs and unique memory effect of LDOs, the LDHs and their calcined products have been used as adsorbents to manage wastewater polluted by dyes, such as congo red (CR) [18,32], methyl orange (MO) [33][34][35], and Acid yellow [36].…”