Green formulation for synthetic dye extraction using synergistic mixture of acid-base extractant

Waste Biomass-Mediated Synthesis of TiO2/P, K-Containing Grapefruit Peel Biochar Composites with Enhanced Photocatalytic Activity

In this study, TiO2/P, K-containing grapefruit peel biochar (TiO2/P, K-PC) composites were synthesized in situ biomimetically using grapefruit peel as the bio-template and carbon source and tetrabutyl titanate as the titanium source. This was achieved using the two-step rotary impregnation-calcination method. Adjusting the calcination temperature of the sample in an air atmosphere could regulate the mass ratio of TiO2 to carbon. The prepared samples were subjected to an analysis of their compositions, structures, morphologies, and properties. It demonstrated that the prepared samples were complexes of anatase TiO2 and P, K-containing carbon, with the presence of graphitic carbon. They possessed a unique morphological structure with abundant pores and a large surface area. The grapefruit peel powder played a crucial role in the induction and assembly of TiO2/P, K-PC composites. The sample PCT-400-550 had the best photocatalytic activity, with the degradation rate of RhB, MO, and MB dye solutions reaching more than 99% within 30 min, with satisfactory cyclic stability. The outstanding photocatalytic activity can be credited to its unique morphology and the efficient collaboration between TiO2 and P, K-containing biochar.

Selective extraction and recovery of polyphenols from palm oil mill sterilization condensate using emulsion liquid membrane process

Polluted sterilization condensate discharged from palm oil mill may contain polyphenols that are rich in the antioxidant property. Emulsion liquid membrane (ELM) process is a promising method for polyphenol recovery due to its several attractive features such as high selectivity, simple operation, and low energy consumption. In this study, the condensate was characterized to determine its total phenolic content (TPC), ionic elements, and pH. ELM formulation containing tributylphosphate (TBP) as a carrier, kerosene as a diluent, sorbitan monooleate (Span 80) as a surfactant, and sodium hydroxide (NaOH) as a stripping agent was developed. The results show that sterilization condensate contains 700-1500 mg GAE/L of TPC. During the ELM process, more than 91% of extraction with 83% recovery and 8.3 enrichment were achieved at the favorable condition of 0.1 M TBP, external phase pH 5, 1 M NaOH, 1:5 treat ratio, 5% v/v of octanol as a modifier, and 100 mg GAE/L external phase concentrations. Thus, ELM offers a potential alternative technology to extract and recover polyphenols from palm oil mill sterilization condensate while contributing to sustainable production. Graphical abstract Extraction of polyphenols from palm oil mill sterilization condensate using ELM process.

Supported liquid membrane extraction of nickel using stable composite SPEEK/PVDF support impregnated with a sustainable liquid membrane

A sustainable and stable supported liquid membrane (SLM) extraction of nickel was developed via impregnation of sustainable liquid membrane in the composite membrane support consisting of polyvinylidene fluoride (PVDF) and sulfonated poly (ether ether ketone) (SPEEK). Bis-2-ethylhexyl phosphate (D2EHPA), 1-octanol, refined palm oil and sulfuric acid were employed as extractant, synergist extractant, diluent and strippant, respectively. Variables studied including effect of refined palm oil compositions as well as the configurations and thicknesses of SPEEK. Lifespan of SLM was evaluated by recycling the composite membrane support. Results revealed that upon using 100% refined palm oil, about 100% of nickel was extracted and recovered in 10 and 14 h, respectively. Composite SPEEK/PVDF stabilized SLM by reducing liquid membrane loss from 47 to 23% upon applying SPEEK at the feed side of PVDF support. High permeability and flux values were obtained at 9.26 x 10^-4 cms^-1 and 6.48 x 10^-7 molcm^-2s^-1 when increasing SPEEK thickness from 0.025 to 0.055 mm, respectively. The lifespan of SLM was extended up to ninth cycles with low weight loss percentage of the impregnated composite membrane (8%). In conclusion, the SPEEK/PVDF impregnated with refined palm oil has improved the stability of SLM extraction of nickel ions from industrial wastewater.

Decontamination and disinfection of wastewater by photocatalysis under UV/visible light using nano-catalysts based on Ca-doped ZnO

Nano-catalysts based on ZnO-Ca x% (with x = 0, 0.1, 0.3, 0.5, 0.7, and 1.0 mol % Ca²⁺) were synthesized with a bio-friendly adaptation of the sol-gel method using gelatin as template. These materials were characterized by Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Micro-Raman, transmission electron microscopy (TEM), scanning electron microscopy (SEM), N₂ physisorption, photoacoustic absorption spectroscopy (PAS), and photoluminescence spectroscopy (PL). The Raman results indicated that the signal, attributed to an E₁(LO) mode at 580 cm^-1, was characteristic of oxygen vacancies that decreased with the increased Ca²⁺ content in doped oxides. This agreed with the PL results, which showed that the green emission centered at 510 nm and attributable to structural defects in ZnO decreased for Ca-doped ZnO. Our oxides are constituted by nanoparticles with rod-like and spherical morphologies. All the nano-catalysts exhibited the band gap characteristics of semiconductor materials around 3.0 eV. ZnO-Ca 1.0% exhibited the best photocatalytic performance for degradation of Methyl Orange (MO) model dye, degrading about 82% after 240 min of UV-Vis irradiation at pH 7.0. The reaction mechanism was influenced by hydroxyl (OH) and superoxide (O₂^-) radicals and mainly by active holes (h⁺). This doped oxide also demonstrated efficiency in wastewater disinfection against heterotrophic bacteria and total coliforms, exhibiting a potential use as an antimicrobial agent for the treatment of hospital wastewater. Furthermore, our nanoparticles did not show significant cytotoxic effects on L929 fibroblast cells.