In this review, we discuss the rich chemistry of helicenes and helicenoids containing main-group elements. Enantioenriched helicenic derivatives containing main-group elements B, Si, N, and P, either incorporated within the helical backbone or grafted to it, will be thoroughly presented. We will describe their synthesis, resolution, and asymmetric synthesis, their structural features, electronic and chiroptical properties, and emission, together with other photochemical properties and applications.

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Enantioenriched Helicenes and Helicenoids Containing Main-Group Elements (B, Si, N, P).

Biochar shows great promise for use in adsorbing pollutants. However, a process for enhancing its adsorption capacity and re-collection efficiency is yet to be further developed. Hence, in this study, we developed a type of biochar coated with magnetic Fe3O4 nanoparticles (i.e., magnetic biochar (MBC)) and assessed its use for crystal violet (CV) adsorption as well as its recycling potential. The coating of Fe3O4 nanoparticles, which was not only on the surface, but also in the interior of biochar, performed two functions. Firstly, it produced a saturation magnetization of 61.48 emu/g, which enabled the biochar being efficiently re-collected using a magnet. Secondly, it significantly enhanced the adsorption capacity of the biochar (from 80.36 to 99.19 mg/g). The adsorption capacity of the MBC was determined to be the largest by so far (349.40 mg/g) for an initial CV concentration of 400 mg/L, pH of 6.0 and temperature of 40 °C and the adsorption capacity of re-collected MBC was 73.31 mg/g. The adsorption of CV by the MBC was found to be a spontaneous and endothermic physical process in which the intraparticle diffusion was the limiting step. These findings inspire us to use other similar materials to tackle the menace of pollutions.

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Efficient removal of crystal violet using Fe3O4-coated biochar: the role of the Fe3O4 nanoparticles and modeling study their adsorption behavior.

A novel cellulose-based adsorbent (CGS) was synthesized by a facile, two-step modification route. It was characterized by the FTIR, XRD, and SEM technique. The adsorption characteristics of CGS were compared with those of native cellulose using crystal violet (CV) as an adsorbate in this work. The effects of contact time, temperature, pH, and initial concentration on the sorption were all investigated. The adsorption kinetics for both CGS and cellulose were found to follow a pseudo-second-order (P-S-O) kinetic model. The equilibrium data of CGS fitted well with the Langmuir isothermal model, and the maximum theoretical adsorption capacity of CGS for CV was 218.82 mg g–1 at 50 °C; the adsorption increased by 70.8% compared to that of native cellulose. A thermodynamics study was also performed. The comparative study confirmed that the structure of CGS is more conducive for the adsorption of CV than cellulose. Furthermore, adsorption/desorption experiments showed that CGS could be reused for at least eight c...

Removal of Crystal Violet by a Novel Cellulose-Based Adsorbent: Comparison with Native Cellulose

Isotherms and kinetic study of ultrasound-assisted adsorption of malachite green and Pb2+ ions from aqueous samples by copper sulfide nanorods loaded on activated carbon: Experimental design optimization.

Microwave–ultrasound-assisted facile synthesis of a dumbbell- and flower-shaped potato starch phosphate (PSP) polymer, hereafter PSP, was carried out by cross-linking the hydroxyl groups of native ...

Enhanced and Selective Adsorption of Zn(II), Pb(II), Cd(II), and Hg(II) Ions by a Dumbbell- and Flower-Shaped Potato Starch Phosphate Polymer: A Combined Experimental and DFT Calculation Study.

Preparation and characterization of 5-sulphosalicylic acid doped tetraethoxysilane composite ion-exchange material by sol-gel method.

Density functional theory prediction of geometry and vibrational circular dichroism of bridged triarylamine helicenes

We report batch adsorption studies for the removal of Malachite green from an aqueous solution using 5-sulphosalicylic acid doped tetraethoxysilane (SATEOS) composite material, prepared in our laboratory previously. Various variables studied were the initial dye concentration, adsorbent concentration, pH, contact time and temperature. The maximum percentage of colour was removed at the basic pH of 9. The removal data were fitted to Langmuir and Freundlich adsorption isotherm equations. The values of their corresponding constants were determined from the slope and intercepts of their respective plots. The monolayer adsorption capacity of SATEOS at 323 K was found to be 657.89 mg g−1. The values of various thermodynamic parameters, such as ΔG°, ΔS° and ΔH°, were also determined. A pseudo second-order kinetic model and Lagergren first-order kinetic model were also applied to study the adsorption process. The effective diffusion parameter Di values were estimated at different initial dye concentrations. The mechanism of adsorption was studied using Rechienberg's equation where a linearity test indicates a film diffusion controlled adsorption mechanism. The maximum interaction (IE = 1432.54 kJ mol−1) between SATEOS and the dye molecule, calculated using B3PW91 functional and LanL2MB basis set, was observed when the nitrogen atom of the dye lies at a distance of 1.57 A from the hydrogen of the hydroxyl group present on SATEOS molecule.

Suhail-ul Rehman

Papers

Preparation and characterization of 5-sulphosalicylic acid doped tetraethoxysilane composite ion-exchange material by sol-gel method.

Density functional theory prediction of geometry and vibrational circular dichroism of bridged triarylamine helicenes

Adsorption studies of Malachite green on 5-sulphosalicylic acid doped tetraethoxysilane (SATEOS) composite material