CaO-doped tetragonal ZrO2 nanoparticles as an effective adsorbent for the removal of organic dye waste

A new type of calcium-rich biochars derived from spent mushroom substrates and their efficient adsorption properties for cationic dyes

“…For instance, waste eggshell, which contains large amounts of calcium salts, demonstrated the efficacy in adsorbing methylene blue and Congo red in wastewater ( Abdel-Khalek et al, 2017 ). The CaO-doped ZrO 2 nanoparticles were regarded as the brilliant adsorbents for the toxic azo dye of Congo red ( Singh et al, 2022 ). The crab shell-derived biochar (mainly including calcite) showed super adsorption capacities of Malachite green and Congo red, respectively ( Dai et al, 2018 ).…”

Adsorption prospects of ultrafine, cubic 8 mol.% Y2O3‐stabilized ZrO2 nanoparticles

“…This phenomenon is widely observed in the case of MO systems (refer to Equation 3). 1,4,17,59 These defects are responsible for the protonation of hydroxyl groups present on the surface of the adsorbent (confirmed by a broad FTIR peak present at 3344 cm −1 ). 60 The protonated hydroxyl groups (−OH + ) present at the surface of nanoparticles tend to build the hydrogen bonding toward the sulfonic group (SO 3 − ) of the CR dye molecule (as per Equation 4):…”

“…Azo dyes (R−N = N−R′) are highly hazardous due to amine and benzidine emissions, causing asthma, dermal infections, and altering genetic structures. 1,2 Congo red (CR) is a commonly used azo dye for dyeing cellulosebased textiles, biomedical applications, pH indicators, and histochemical applications, but its toxicity is detrimental to the ecosystem. Azo dyes exhibit high water solubility and are typically nonbiodegradable, posing a severe threat to the environment.…”

“…For example, photocatalytic degradation necessarily requires the presence of light for the degradation of dye and also has limited capacities. 1 Reverse osmosis is costly as it uses high power supplies. 7 Ozonation suffers from short ozone half-lives and is less effective for water-dispersed dyes.…”

“…17,21,22 Among MO, zirconia is one such system that can exhibit such chemical stability, and long-term performance, that can allow it to be a promising candidate for such applications. 1,23 In spite of having an abundance of oxygen vacancies in the yttria-stabilized zirconia (YSZ) systems, commercially available powders were incapable of showing any significant sorption capabilities. This work stimulated us to continue our exploration on doped-zirconia systems synthesized in our own laboratory.…”