Influence of synthesis approach on controlled microstructures and photocatalytic properties of ag/agbr-activated carbon composites on visible light degradation of tetracycline

The influence of the synthesis approach (thermal polyol and deposition–precipitation) regarding the dispersion of Ag/AgBr nanoparticles dispersed on activated carbon prepared from chemical impregnated pinecone (TP-AABR-ACK, and DP-AABR-ACK) was studied, to increase their photocatalytic efficiency on the degradation of tetracycline (TC). The physicochemical characterization evidenced the significance of the ACK catalyst promoter in enhancing controlled microstructures (morphologies and particle size distributions), synergistic interface interaction between AABR NPs and the carbonaceous support, and efficient photogenerated charge carriers separation within TPAABR- ACK, and DP-AABR-ACK composites. The results revealed 92% removal of TC within 180 min under the LED visible light irradiation, which was achieved using TP-AABR-ACK when compared to DP-AABR-ACK composite and other catalysts in this study. Such superior results achieved with TP-AABR-ACK composite were attributed to controlled morphologies, reduced particle size and agglomeration, improved absorptivity, and superior cooperative effect between the AABR and ACK catalyst promoter as evidenced from SEM, EDX, TEM, UV-DRS, and electrochemical characterizations, respectively. Furthermore, enhanced TOC removal and abundance of reactive superoxide anion generation were achieved with the TP-AABR-ACK composite in this study.Supplementary Materials: Figure S1: Thermogravimetric analysis of ACK, DP-AABR-ACK, and TP-AABR-ACK, Figure S2: Photocatalytic degradation efficiencies of (A) ciprofloxacin, and (B) rhodamine B as a function of irradiation time for (a) TP-AABR-ACK, (b) DP-AABR-ACK, (c) TPAABR, (d) DP-AABR and (e) photolysis, Figure S3: Reusability test AABR-ACK nanocomposites for the degradation of TC under LED visible light illumination, and (b) XRD patterns of the AABR-ACK nanocomposites prior, and then afterward test.The Sasol University Collaboration Program, National Research Foundation of South Africa, the Vaal University of Technology and the Built Environment and Information Technology Department, University of Pretoria.https://www.mdpi.com/journal/catalystsam2022Chemical Engineerin

Surfactant-modified Macadamia nutshell for enhancement of methylene blue dye adsorption from aqueous media

This study reported the synthesis of a low-cost, and efficient adsorbent through surfactant modified macadamia nutshells (SMS) by a facile sodium dodecyl sulfonate (SDS) treatment approach. The SDS treatment resulted in increased functionalities, and ion exchangeable sites of macadamia nutshells leading to enhanced the removal of methylene blue (MB) dye from water. Factors such as pH (2-11), contact time (1-360 min), initial MB dye concentration (30-385 mg/L), and adsorbent mass (0.02 – 0.18 g/L), were tested in this study. The enhanced removal of MB removal (≥ 90%) was synergistically influenced by pH, with optimum adsorption removal around pH 7 to 11 for the SMS adsorbent. The results showed that MB removal was fast with SMS, and that the equilibrium was reached in 80 min. The batch adsorption results showed a good fit with pseudo-first-order kinetics, and the Langmuir isotherm model, in agreement with the experimental values, with a maximum adsorption capacity of 195.97 mg/g for MB. Surfactant modified macadamia nutshells (SMS) composed of surface functional groups: –OH, –C = O, -C-O, and multiple carbon-carbon bond, all contributed to synergistic mechanism interaction between the adsorbent and MB dye in this study. This study thus suggested that the SMS could be highly beneficial for eliminating anionic dye from polluted water-based solutions, thus highlighting its potential for practical usage in large pollutants removal

One-Step Green Synthesis of Water-Soluble Fluorescent Carbon Dots and Its Application in the Detection of Cu2+

Renewable biowaste-derived carbon dots have garnered immense interest owing to their exceptional optical, fluorescence, chemical, and environmentally friendly attributes, which have been exploited for the detection of metals, non-metals, and organics in the environment. In the present study, water-soluble fluorescent carbon dots (CDs) were synthesized via facile green microwave pyrolysis of pine-cone biomass as precursors, without any chemical additives. The synthesized fluorescent pine-cone carbon dots (PC-CDs) were spherical in shape with a bimodal particle-size distribution (average diameters of 15.2 nm and 42.1 nm) and a broad absorption band of between 280 and 350 nm, attributed to a π-π* and n-π* transition. The synthesized PC-CDs exhibited the highest fluorescent (FL) intensity at an excitation wavelength of 360 nm, with maximum emission of 430 nm. The synthesized PC-CDs were an excellent fluorescent probe for the selective detection of Cu2+ in aqueous solution, amidst the presence of other metal ions. The FL intensity of PC-CDs was exceptionally quenched in the presence of Cu2+ ions, with a low detection limit of 0.005 μg/mL; this was largely ascribed to Cu2+ ion binding interactions with the enriched surface functional groups on the PC-CDs. As-synthesized PC-CDs are an excellent, cost effective, and sensitive probe for detecting and monitoring Cu2+ metal ions in wastewater