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The main objective of a series of our researches is to develop a novel acoustic-based method for activation of biochar. This study investigates the capability of biochar in adsorbing Ni(II) as a hazardous contaminant and aims at enhancing its adsorption capacity by the addition of extra nitrogen and most probably phosphorous and oxygen containing sites using an ultrasono-chemical modification mechanism. To reach this objective, biochar physically modified by low-frequency ultrasound waves (USB) was chemically treated by phosphoric acid (H3PO4) and then functionalized by urea (CO(NH2)2). Cavitation induced by ultrasound waves exfoliates and breaks apart the regular shape of graphitic oxide layers of biochar, cleans smooth surfaces, and increases the porosity and permeability of biochar’s carbonaceous structure. These phenomena synergistically combined with urea functionalization to attach the amine groups onto the biochar surface and remarkably increased the adsorption of Ni(II). It was found that the modified biochar could remove > 99% of 100 mg Ni(II)/L in only six hours, while the raw biochar removed only 73.5% of Ni(II) in twelve hours. It should be noted that physical treatment of biochar with ultrasound energy, which can be applied at room temperature for a very short duration, followed by chemical functionalization is an economical and efficient method of biochar modification compared with traditional methods, which are usually applied in a very severe temperature (>873 K) for a long duration. Such modified biochars can help protect human health from metal-ion corrosion of degrading piping in cities with aging infrastructure.

The objectives of a series of our researches are to determine the feasibility of applying ultrasonic pretreatment prior to biochar gasification. As per the initial results, the heating value (HV) of biochar significantly increased after acoustic treatment in water with dissolved CO2 (AIChE Journal, 2014;60:1054–1065). Accordingly, emphasis of the current work is placed on the parameters governing the HV of biochar in the early stage of the treatment. Switchgrass and miscanthus biochars were treated under different conditions. The reactant ratio, biochar:water:CO2, exhibited profound impacts on the synergism. The highest (but not yet systematically optimized) ratio of HV increase (or HV Gain, HG) to ultrasound energy supplied (ES) takes place when biochar-to-water ratio, or BC:W, equals 0.06 g/ml. The observed HG/ES is about 10, suggesting that the energy consumption is only a fraction of the acoustic energy supplied. Miscanthus biochar’s HV increases by up to 4.6% after treatment at 5% amplitude for 135 s (HG = 33 cal/g). For the same run, miscanthus biochar's H content increased by 42.7%. Changes in HV can be mediated by mineral leaching, C or H fixation, or O content loss. Mineral leaching is influenced by pH and CO2 concentration. CO2 and water are the sole contributors to C and H gains, respectively. CO2 concentration in the solution during the treatment is also affected by mass transfer limitations, ultrasound power, and design of the three-phase reactor. Increasing the BC:W ratio initially enhances the cavitation nuclei on the fluid/solid surface, and therefore sonolysis. The subsequent decrease in HV with increasing BC:W may be due to the limitation in ultrasound penetration and H supply from water. Carbon and hydrogen fixation may be connected to the formation of H2, CO, formic acid, formaldehyde, and associated radicals during sonolysis of aqueous CO2.

This paper describes a two-stage biochar activation process for CO2 capture, which includes acoustic treatment and amination. Contrarily to traditional carbon activation at temperatures above 700 °C, both stages of the current process are conducted at or near room temperature. It is known that CO2 can be fixed on the edge carbons of polycyclic aromatics hydrocarbons (PAHs) through thermal and reductive photo-carboxylation. Our previous work on biochar suggested that carbon of CO2 could be chemically fixed on biochar through acoustic or photochemical treatment of biochar in water/CO2 systems under ambient conditions. Separately, the graphene oxide (GO) literature reveals that carboxylic acids, epoxy and hydroxyl groups on biochar surface often serve as the active sites for converting GO to a new family of chemicals; amines are commonly grafted on these groups in the functionalization. Biochar has graphite and graphitic oxide clusters that consist of the oxygen functional groups mentioned above. These oxygen functionalities can be utilized for CO2 adsorption when functionalized with amine. Thus, the present study focuses on maximizing the CO2 capture capacity by manipulating the physicochemical structure of a pinewood-derived biochar. In this two-stage process, 30 s sonication at ambient temperature was applied to physically activate biochar prior to functionalization. Low-frequency ultrasound irradiation exfoliates and breaks apart the irregular graphitic layers of biochar, and creates new/opens the blocked microspores, thus enhancing the biochar’s porosity and permeability that are the keys in functionalization and subsequent CO2 capture. The sono-modified biochar was then functionalized with tetraethylenepentamine (TEPA) in the presence of two activating agents. The changes in surface characteristics, functional groups, graphene-like structure, and functionalization using activating agents were examined in detail and the capacity of the final products in CO2 removal was tested. The experimental results revealed that CO2 capture capacity, from a flow containing 10 and 15 vol% CO2, was almost 7 and 9 times higher, respectively, for ultrasound-treated amine-activated biochar, compared to raw biochar. The optimum capacity was 2.79 mmol/g at 70 °C and 0.15 atm CO2 partial pressure. Cyclic adsorption and desorption tests revealed that the CO2 capture capacity decreased 44% after 15 cycles.

Magnetization facilitates the separation and reuse of adsorbents, but significantly reduces the adsorption capacity. In this study, a double layer magnetized/functionalized biochar composite was synthesized through a hybrid post-pyrolysis magnetization which sustained and even significantly increased the adsorption capacity of microporous carbonaceous biochar (BC). The developed process included i) structural modification of biochar under ultrasound waves, ii) magnetization with magnetite (Fe3O4) nanoparticles, and iii) functionalization with 3-aminopropyltriethoxysilane (TES). Ultrasound irradiation exfoliates and breaks apart the irregular graphite layers of biochar, and creates new, or opens blocked, micropores, thus enhancing the BC’s porosity. For its part, TES stabilizes the magnetic nanoparticles on the biochar surface, while it participates in water decontamination through the strong chelation ability of its amino groups toward metal ions. Scanning electron microscopy demonstrated the stable and uniform distribution of Fe3O4 nanoparticles on the surface of microporous biochar, and Fourier-transform infrared spectroscopy indicated effective surface functionalization. In addition, although magnetization usually reduces the porosity of carbonaceous adsorbents, the ultraviolet–visible spectroscopic analysis showed that double layer magnetic biochar composite exhibited a much greater ability to remove Ni(II) and Pb(II), with 139 % and 38 % higher adsorptions than raw biochar. Almost complete removal of Pb (91 %) was observed by magnetic-BC and the adsorbent could easily be separated using a neodymium magnet. This high performance can be attributed to the synergistic effect of ultrasound activation on increasing the porosity and surface area of biochar along with enhanced chelation imparted by amine functionalization. The developed technique can be used for synthesizing advanced adsorbents for removal of nuclear waste-related metal ions from aqueous environments.

Conventional carbon activation requires heating carbon at a temperature greater than 700 °C for over 3 h, consuming 18,600 kcal/kg of activated biochar. In contrast, the ultrasound treatment method is conducted at ambient condition for a very short duration (∼30 s, which requires about 1135 kcal/kg of activated BC produced. The advanced low-temperature acoustic-based surface modification method not only increases the porosity and surface functionality of raw biochar, but also is economically feasible and environmentally friendly. As a sequel of our previous works, this study aims to investigate the interaction between ultrasonic-structural modification with four different pre-treatments including i) control with no pretreatment, ii) EDC/HBOt, iii) alkali using KOH, iv) acid using HNO3 or H3PO4. The process was then followed by amine functionalization with DEA (diethanolamine) for nickel removal. The results demonstrated that all acoustic-based amine-functionalized biochar samples, without any exception, had more amine- and oxygen-containing functional groups as well as micro porosity, compared to those aminated without acoustic-activation, particularly in samples pretreated with HNO3 and H3PO4. Despite an increase in porosity by ultrasonication, metal leaching from US-only samples and those activated with EDC/HOBt was observed during longer adsorption durations. However, the synergism created by the combined effect of ultrasound and KOH and H3PO4, not only enhanced the adsorption capacity of biochar but also significantly reduced the adsorption duration from 8 to 3 h. The highest nickel adsorptions were observed for ultrasonic-amine samples activated with H3PO4 > HNO3 ∼ KOH, which were far higher (60 %, 49 %, and 46 % more adsorption, without any leaching) than raw or US-biochar, or biochar aminated with EDC/HOBt or without pretreatment.

The active, potent, and selective Farnesoid X Receptor (FXR) agonist 6α-ethylchenodeoxycholic acid (6ECDCA) has been synthesized in improved yield compared to the published methodologies. The synthesis employed selective oxidation of one of the two hydroxyls of the readily-available starting material chenodeoxycholic acid (CDCA) as a key step. After protection of the remaining hydroxyl, LDA/HMPA/EtI/PPTS provided an efficient deprotonation/ethylation/deprotection sequence. The two synthetic improvements that allow a productive yield are the use of PCC in the oxidation step, and the use of HMPA/ethyl iodide in the stereoselective alkylation step. This synthesis offers an economical and efficient strategy which provides a simple and cost-effective procedure for potential large-scale production of this promising FXR agonist, which is a research tool and potential drug substance of current interest.

Single molecule spectroscopic characteristics of two organic molecular rectifiers are reported. Composed of pyrene as the donor and perylenebisimide (PBI) as the acceptor, these groups are separated by bridges of one or four carbon atoms. Whereas the solution phase absorption and fluorescence spectra are similar, spectra are much more diverse and exhibit different degrees of photostability at the single molecule level. It was found that the addition of pyrene affects the stability of PBI’s emission and analysis of dipole emission patterns reveal that pyrene functions as an orientational directing group for PBI in polymer thin films.

In the presence of a mixture of n -BuLi and Me 2 S CH 2 reagents, aryl epoxides underwent a novel ring-opening α-methylenation providing conjugated allyl alcohols with an unusual regioselective pattern.

The compounds KZnTiF6, KZnVF6, KVScF6, KCrScF6, and KMnScF6 are fluoride analogs of Tetragonal Tungsten Bronze. M2+–M3+ ionic ordering in these fluorides provided systems which contained linear trinuclear complexes of their respective paramagnetic ions. Magnetic coupling within these linear trimers occurred below 100 K in each of the five systems. Derived magnetic susceptibility equations were fitted to observed magnetic susceptibilities for each of the possible spin systems: KZnTiF6 (S=1/2), J/k=−114 K; KZnVF6 (S=1), J/k=−39 K; KVScF6 (S=3/2), J/k=−16 K; KCrScF6 (S=2), J/k=−4 K; and KMnScF6 (S=5/2), J/k=−7.5 K.

A number of N,N′-disubstituted perylenetetracarboxylic diimides have been reported to bind effectively to DNA that adopts G-quadruplex motifs. In some cases, this binding may actively drive the transition from single-strand DNA to the quadruplex form. The perylenediimides in the reported cases all have amine-containing side chains, which are thought to interact with the grooves of the quadruplex and help dictate the selectivity of these compounds for quadruplex versus duplex DNA. We synthesized a polyethyleneglycol-swallowtailed (PEG-tailed) perylenediimide that is water-soluble even though it is uncharged. Binding to duplex and quadruplex DNA of this perylenediimide was studied by fluorescence quenching titrations under a variety of salt conditions, and the compound’s effect on quadruplex formation was studied by non-denaturing gel electrophoresis. Our results indicate that while the molecule binds to single-stranded DNA quite effectively and with selectivity, it does not drive the transition of the DNA to the tetrameric quadruplex structure, supporting the idea that charge neutralization is a key component of perylene compounds that stabilize tetrameric quadruplexes.

A{sub x}VF{sub 3} (A=K, Rb, Cs; x=0-1.0) and A{sub x}CrF{sub 3} compounds were sealed inside high-temperature DTA molybdenum sample cups using electron beam welding techniques. Melting temperatures of the A{sub x}VF{sub 3} compounds ranged from 1050 to 1400 deg. C; those of A{sub x}CrF{sub 3} from 850 to 1200 deg. C. Reconstructive transitions were observed for A{sub x}VF{sub 3} compounds between 650 and 950 deg. C, and for A{sub x}CrF{sub 3} compounds between 550 and 825 deg. C. A displacive transition was observed to occur in VF{sub 3} at 490 deg. C. Order-disorder transitions were determined by X-ray diffraction techniques. In the A{sub x}VF{sub 3} compounds, electronic ordering and ordering of partially filled A{sup +} sites were observed to occur between 100 and 300 deg. C. Ordering phenomena in the A{sub x}CrF{sub 3} compounds (in addition to electronic ordering and ordering of partially filled A{sup +} sites) included Jahn-Teller cooperative ordering. These compounded transitions occurred between 300 and 500 deg. C.