A comprehensive review on LDH-based catalysts to activate persulfates for the degradation of organic pollutants

Abstract

Degradation of organic contaminants into less toxic substances is the best option to remove these compounds rather than using conventional techniques. The sulfate radical-based-advanced oxidation process is an effective strategy that degrades organic contaminants by activating peroxymonosulfate (PMS). Such a strategy generates singlet oxygen (1O2), hydroxyl ($$^ \bullet \!{{{\mathrm{OH}}}}$$ ∙ OH ), and sulfate ($${{{\mathrm{SO}}}}_4^{ \bullet\! - }$$ SO 4 ∙ − ) radicals. $${{{\mathrm{SO}}}}_4^{ \bullet \!- }$$ SO 4 ∙ − is distinguished by its high oxidation selectivity and activity toward the degradation of organic contaminates compared to other radicals. Various catalysts are employed in PMS activation including layered doubled hydroxides (LDHs), which are characterized by their facile synthesis and high catalytic activity. This review article is the first attempt to compile the recent progress in the degradation of common organic pollutants including aromatic compounds, pharmaceutical residues, and dyes via the PMS activation using LDH-based catalysts. The degradation pathways, reaction parameters’ influence, stability of LDHs, and comparisons between different LDH-based catalysts are investigated in this work.

Layered double hydroxides: where should research stress on for massive scaling up?

“…Co-precipitation and mechanosynthesis are well-known approaches for the important production of other types of inorganic (nano)materials, 16,[30][31][32][33][34] and yields of several kilograms (410 kg) are achievable goals for satisfying LDH production, [9][10][11][12][13][14][15][16][17][18]30 taking into account the continuous improvement of reactor design and controlled parameters benefiting from past feedback. One can also note the relatively reduced energy demand involved during the first step of coprecipitation as compared to mechanosynthesis, the first occurring generally at low temperature (typically at room temperature), contributing to a cost-effective approach.…”

“…35 The main drawbacks in co-precipitation and mechanosynthesis generally include more than four synthesis parameters to control. 2,4,[9][10][11][12][13][14][15][16][17] Synthesis times for co-precipitation vary between a few minutes to more than 8 h, depending on the LDH composition, the nature of intercalation compounds and above all, the crystallization degree expected. The synthesis time for mechanosynthesis is longer, typically more than 12 hours, although studies have reported milling times of less than 1 hour.…”

“…[3][4][5][6][7][8][9] Notably, LDHs display a 2D structure, allowing them to be insertion systems for active molecules, pollutants, and so forth, promising numerous smart host-guest materials. For each of these fields, considerable progress has been made recently as highlighted by Kameliya et al 10 with eco-friendly LDH synthesized today for application as catalysts, and in photoelectrocatalysis with amazing results 11 with a strong proof of concept for water decontamination, 12,13 and the sensor-biosensor perspectives are also stemming from these long years of research. Another field where LDHs can be the original material for good solutions is in corrosion protection.…”

Synthesis of Cu1Mg3Sc2(OH)12CO3 layered double hydroxide and its derived catalyst for hydrogenation of DMCD to CHDM

“…Traditionally, x values between 0.20 and 0.33 are more favourable for the formation of well-structured LDH materials. 13,14 A is the anion inserted between the layers of LDHs (see Scheme 1), and this structure can be understood easily via comparison with brucite, Mg(OH) 2 , which is composed of hydroxy-coordinated octahedral units. In the framework of the synthesized LDH materials, partial Mg 2+ could be replaced by M 3+ with a similar radius to Mg 2+ (0.072 nm) and interlayer anions, such as CO 3 2− , NO 3 − , Cl − , etc.…”

Efficient Electron Transfer across Strontium Titanate Decorated Graphene Oxide for High‐Performance Dye‐Sensitized Solar Cells and Photocatalytic Degradation of Dye and Antibiotic

“…In contrast, the Advanced Oxidation Process (AOP) is a promising alternative method for degrading synthetic dyes and organic complexes. Simply, AOPs employ high reactive oxygen species (ROS) such as hydroxyl radicals (*OH) and superoxide radicals (*O 2 ‐ ) to decomposition of organic residuals into less harmful compounds or mineralize them totally into carbon dioxide (CO 2 ) and water vapour (H 2 O) [10,11] . Recently, the semiconducting metal oxide‐based photocatalytic degradation of organic/pharmaceutical contaminants has attracted significant attention due to the formation of plentiful reactive radicals during the photodegradation process.…”