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Sun-light driven CoO–CuFe2O4 photocatalyst was fabricated successfully from a layered double hydroxide via a modified co-precipitation and calcination method at 500°C, for the decontamination of azo dye-laden wastewater. The CoO–CuFe2O4 was characterized and the results demonstrated that it is composed of face-centered cubic CoO and cubic spinel CuFe2O4, which has a specific surface area and pore volume of 348.5 m² g–1 and 0.715 cm³ g–1, respectively; and pH point zero charges of 5.8. The photocatalytic activity is enhanced at acidic pH level and achieved ~99.4% decolorization of Eriochrome black T dye (EBT) within 90 min in the presence of 0.05 g of CoO–CuFe2O4. Notably, •OH and •O2− radicals played a role while h+ significantly participated during the EBT photodegradation. Reusability experiments confirm that the CoO–CuFe2O4 possesses high stability and exhibits efficient photocatalytic reusability with almost the same efficiency for degrading EBT dye. [ABSTRACT FROM AUTHOR]

Health concerns have been raised over the excessive occurrences of antibiotics such as tetracycline in aquatic environments. Adsorption is a simple and cheap technique for the removal of pharmaceuticals from industrial wastewater. To date, limited information exists on the fate, economical treatment and safe disposal of spent adsorbents in the environment, and this is often considered as the main drawback of adsorption. In this article, an alternative strategy to dispose and reuse spent inorganic adsorbents is proposed. We synthesized CoO/CuFe2O4 mixed metal oxide from layered double hydroxides by a modified co-precipitation and calcination method at 500 °C for 5 h. CoO/CuFe2O4 has a 348.5 m2/g surface area, pH point zero charge of 5.8 and an average pore diameter of 5.8 nm. Results show that the tetracycline removal efficiency at pH 6 reached 96.6% and 84-87.3% in the absence and in the presence of 4 g/L competing ions (Cl− and NO3−), respectively. Moreover, CoO/CuFe2O4 retained stable activities, of about 90%, over five consecutive recycling runs. Spent CoO/CuFe2O4 was reused as a catalyst in the presence of sunlight for degradation of azo dye, and this is the first report of achieving ~ 77% discolouration of eriochrome black T dye using a recycled adsorbent. [ABSTRACT FROM AUTHOR]

Magnetic chicken bone biochar (MCB) was fabricated and characterised. The specific surface area, magnetisation value and pH pzc of the MCB were found to be 328 m 2  g −1 , 64.7 emu/g and 8.3 respectively. The adsorptive performance of MCB for rhodamine B dye (RB) and tetracycline (TC) removal in a single and two-stage stirred adsorber (TSA) was evaluated. The TSA reduced the pressure drops, mass transfer resistances, and fouling of the adsorbent. 63.0 g MCB is required to remove 75% of RB and TC in a single-stage system within 12 h. However, the optimised TSA confirmed that 33.2 g of MCB is needed to achieve 96% removal of TC and 22.2 g for RB within 180 min of 100 mgL −1 effluent solutions. The sorption was suitably described by the Freundlich mechanism. Based on the comparative performance, the MCB is considered a viable efficient and magnetically separable alternative adsorbent. [ABSTRACT FROM AUTHOR]

Magnetic chicken bone-based biochar (MCBB) was successfully prepared and efficiently adsorbed rhodamine-B (RB) dye and tetracycline (TC) in multi-component systems. The magnetisation value, surface area, and pHpzc of the MCBB were found to be 66.5 emu/g, 328 m2/g, and 8.3, respectively. RB has higher saturation capacity (96.5 mg/g) and occupies more active sites on MCBB, thus limiting the sorption of TC with lower saturation capacity (63.3 mg/g). Langmuir isotherm suitably describes the sorption process in a single-component system; however, the multi-component system was well fitted to the Sheindorf-Rebhun-Sheintuch model. The selectivity factor values confirmed that MCBB had higher adsorption affinity toward RB than TC. The intraparticle diffusion model played a significant role in the sorption process. The MCBB can be easily desorbed with base-spiked H2O and reused without loss in stability or structural integrity. [ABSTRACT FROM AUTHOR]

Adsorption of a binary mixture of anionic dyes onto chitosan-based hydrogel (SAH) was investigated. Erichrome black T (EBT) and reactive blue 2 (RB2) were used as a model azo and anthraquinone dyes respectively. Adsorption potential of SAH was investigated under laboratory conditions as a function of initial concentration (50–400 mg/L), temperate (25–55 °C) and solution pH. In a single dye system, adsorption trend follows the Langmuir and pseudo second-order kinetics models. The overall rates of EBT and RB2 were noted to be controlled by film, pore and particle diffusions throughout the adsorption period. For binary dye-system, selectivity factor ( A ) was introduced into the extended Langmuir model, and the equilibrium data fitted well with the modified isotherm model ( R 2 = 0.96–0.99). The values of Δ G ° (−17.012 to −22.473 kJ/mol) of the binary dye system are within the ranges of physisorption mechanism. Box-Behnken model was utilized to estimate the competitive effects of the variables in binary dye system, and the experimental data indicates higher affinity for EBT (520.21 mg/g) compared with RB2 (407.05 mg/g). The reusability of SAH has proven that the adsorbent is durable and cost-effective. [ABSTRACT FROM AUTHOR]