Adsorptive desulfurization over hierarchical beta zeolite by alkaline treatment

Hierarchical beta zeolites with SiO2/Al2O3 molar ratios of 16 to 25 were obtained by alkaline treatment in NaOH solution. The effects of treatment temperature on crystallinity, textural properties and chemical composites were studied by XRD, N2 sorption, FT-IR and XRF techniques. The desulfurization performance of parent and alkaline-treated beta zeolites was investigated by static absorption in four model fuels, containing four sulfur compounds of different molecular sizes like thiophene （TP）, 3-methylthiophene （3-MT）, benzothiophene （BT） and dibenzothiophene （DBT）, respectively. The crystallinity was observed to be successfully maintained when the treatment temperature was below 50 ℃. Mesoporosity of beta zeolite was evidently developed with alkaline treatment. The formation of mesopore remarkably improved the desulfurization performance for TP, 3-MT, BT and DBT, especially for DBT with larger molecular diameter. Though the addition of toluene in the model fuels resulted in a significant drop of the desulfurization performance of mesoporous beta zeolite, the introduction of cerium ions to some extent mitigated the effect of toluene, which means that both the adsorbent’s porous structure and the adsorption mode are responsible for the desulfurization performance. The adsorbent of cerium ion-exchanged mesoporous beta showed about 80% recovery of desulfurization after the first regeneration.

Alkaline treatment kinetics of calcium phosphate by piezoelectric quartz crystal impedance

Calcium phosphate film was prepared by electrochemical deposition technology. Subsequently, the alkaline treatment process of calcium phosphate film in 0.1 mol/L NaOH solution was monitored on real time by the piezoelectric quartz crystal impedance （PQCI） technique. The variations of morphology and composition for the alkaline treatment products were characterized by scanning electron microscopy （SEM）, Fourier transform infrared （FT-IR） and X-ray diffraction （XRD）, respectively. The dynamic variations of calcium phosphate can be characterized by the change of equivalent circuit parameters. The results show that the forming process of hydroxyapatite （HA） is composed of three stages： （1） acidic calcium phosphate dissolution; （2） phase transformation; and （3） HA formation. Furthermore, the correlative kinetic equations and parameters are obtained by fitting the static capacitance （C8）-time curves.

Combined alkaline and ultrasonic pretreatment of sludge before aerobic digestion

Alkaline and ultrasonic sludge disintegration can be used as the pretreatment of waste activated sludge （WAS） to promote the subsequent anaerobic or aerobic digestion. In this study, different combinations of these two methods were investigated. The evaluation was based on the quantity of soluble chemical oxygen demand （SCOD） in the pretreated sludge as well as the degradation of organic matter in the subsequent aerobic digestion. For WAS samples with combined pretreatment, the released COD levels were higher than those with ultrasonic or alkaline pretreatment alone. When combined with the ultrasonic treatment, NaOH treatment was more efficient than Ca（OH）2 for WAS solubilization. The COD levels released in various sequential options of combined NaOH and ultrasonic treatments were in the the following descending order： simultaneous treatment 〉 NaOH treatment followed by ultrasonic treatment 〉 ultrasonic treatment followed by NaOH treatment. For simultaneous treatment, low NaOH dosage （100 g/kg dry solid）, short duration （30 min） of NaOH treatment, and low ultrasonic specific energy （7500 kJ/kg dry solid） were suitable for sludge disintegration. Using combined NaOH and ultrasonic pretreatment with optimal parameters, the degradation efficiency of organic matter was increased from 38.0% to 50.7%, which is much higher than that with ultrasonic （42.5%） or with NaOH pretreatment （43.5%） in the subsequent aerobic digestion at the same retention time.

Synergistic Effect of Atmospheric Pressure Plasma Pre-Treatment on Alkaline Etching of Polyethylene Terephthalate Fabrics and Films

Dyeing of PET materials by traditional methods presents several problems.Plasma technology has received enormous attention as a solution for the environmental problems related with textile surface modifications,and there has been a rapid development and commercialization of plasma technology over the past decade.In this work,the synergistic effect of atmospheric pressure plasma on alkaline etching and deep coloring of dyeing properties on polyethylene terephthalate（PET）fabrics and films was investigated.The topographical changes of the PET surface were investigated by atomic force microscopy（AFM）images,which revealed a smooth surface morphology of the untreated sample whereas a high surface roughness for the plasma and/or alkaline treated samples.The effects of atmospheric pressure plasma on alkaline etching of the structure and properties of PET were investigated by means of differential scanning calorimetry（DSC）,the main objective of performing DSC was to investigate the effect of the plasma pre-treatment on the T_g and T_m.Using a tensile strength tester YG065 H and following a standard procedure the maximum force and elongation at maximum force of PET materials was investigated.Oxygen and argon plasma pre-treatment was found to increase the PET fabric weight loss rate.The color strength of PET fabrics was increased by various plasma pre-treatment times.The penetration of plasma and alkaline reactive species deep into the PET structure results in better dyeability and leaves a significant effect on the K/S values of the plasma pre-treated PET.It indicated that plasma pre-treatment has a great synergistic effect with the alkaline treatment of PET.

Investigation of the role of Ca(OH)2 in the catalytic Alkaline Thermal Treatment of cellulose to produce H2 with integrated carbon capture

The Alkaline Thermal Treatment(ATT)of biomass is one of the few biomass conversion processes that has a potential for BECCS(bio-energy with carbon capture and storage).Combining in-situ carbon capture withcreates a carbon-neutral process that has the potential to be carbon-negative.This study has shown that the conversion of cellulose tosuppressedcan be achieved through the reforming of gaseous intermediates in a fixed bed of 10%Ni/ZrO2.Reforming occurs at low temperatures≤773 K,which could allow for improved sustainability.

Key factors governing alkaline pretreatment of waste activated sludge

Alkaline pretreatment is an effective technology to disintegrate sewage sludge, where alkali dosage and sludge concentration are two important factors. p H value or alkali concentration is usually adjusted in order to determine a proper dosage of alkali. Our work has found that this is not a good strategy. A new parameter, the ratio of alkali to sludge(Ra/s), is more sensitive in controlling the alkali dosage. The sludge concentration Csand retention time t are two other important factors to consider. The validity of these arguments is confirmed with modeling and experiments. The individual effect of Ra/s, Csand t was studied separately. Then the combined effect of these three factors was evaluated. The sludge disintegration degree of 44.7% was achieved with the optimized factors. Furthermore, an alkaline-microwave combined pretreatment process was carried out under these optimized conditions. A high disintegration degree of 62.3% was achieved while the energy consumption of microwave was much lower than previously reported.

Study on TEMPO-Mediated Selective Oxidation of Alkaline Natural Cellulose Pulp and Properties of Its Products

It has been reported that natural cellulose （cellulose I） can not be oxidized by TEMPO - NaOCI - NaBr system, one of TEMPO-mediated selective oxidant systems, but regenerated cellulose （cellulose Ⅱ ） can be completely selectively oxidized. In the present work, natural cellulose pulp was treated with NaOH solution, which concentration is lower than 20 wt%. The alkaline celluloses obtained were oxidized by TEMPO - NaOCI - NaBr system and the factors which influence the selective oxidation reaction rate have been investigated. The structure of the oxidized products has been characterized by Fourier transform-infrared （FTIR）, nuclear magenatic resonace （NMR） and wide angle X-ray diffraction （WAXD） methods, and their adsorption properties for Cu^2＋ and Cd^2＋ in aqueous solutions have been preliminarily examined. The results show that after the alkaline treatment, the primary hydroxyl at C6 position of natural cellulose can be selectively oxidized to carboxyl group in the reaction medium at pH 10.8, the oxidation rate becomes greater with the NaOH concentration and alkaline treatment time increasing. The alkaline treatment has a great effect on the crystal structure of natural cellulose, but the crystal structure of alkaline cellulose keeps almost unchanged after oxidation. The adsorption capacity is enhanced by introducing carboxyl groups into the cellulose macromolecular chains.

A green route for hydrogen production from alkaline thermal treatment(ATT)of biomass with carbon storage

Hydrogen,a green energy carrier,is one of the most promising energy sources.However,it is currently mainly produced from depleting fossil fuels with high carbon emissions,which has serious negative effects on the economy and environment.To address this issue,sustainable hydrogen production from bio-energy with carbon capture and storage(HyBECCS)is an ideal technology to reduce global carbon emissions while meeting energy demand.This review presents an overview of the latest progress in alkaline thermal treatment(ATT)of biomass for hydrogen production with carbon storage,especially focusing on the technical characteristics and related challenges from an industrial application perspective.Additionally,the roles of alkali and catalyst in the ATT process are critically discussed,and several aspects that have great influences on the ATT process,such as biomass types,reaction parameters,and reactors,are expounded.Finally,the potential solutions to the general challenges and obstacles to the future industrial-scale application of ATT of biomass for hydrogen production are proposed.

A FACILE APPROACH FOR THE SURFACE MODIFICATION OF POLY(VINYLIDENE FLUORIDE) MEMBRANE VIA SURFACE-INITIATED ATOM TRANSFER RADICAL POLYMERIZATION

A novel approach for the surface modification of poly(vinylidene fluoride)(PVDF)membrane was successfully realized through alkaline treatment,UV-induced bromine addition,and followed by surface-initiated atom transfer radical polymerization(ATRP)of methyl methacrylate(MMA).Chemical changes on the PVDF membrane before and after modification were analyzed with attenuated total reflectance Fourier transform infrared spectroscopy(ATR/FT-IR)and X-ray photoelectron spectroscopy(XPS).Primary kinetic study revealed...

Cellulose Fibre from Schinus molle and Its Characterization

The exploitation of biomass represents a major environmental challenge related to the protection of the environment and the progressive exhaust of fossil resources.In this perspective,the main objective of this work is the extraction and the characterization of natural lignocellulosic fibers from the Schinus molle.The cellulose fibre extraction was investigated employing conditions of alkali treatment.After the alkaline steps,a bleaching treatment was done and let to a yield about 45%pure cellulose.The identification of the chemical composition of Schinus molle reveals that this raw material contains a high level of biopolymers with a cellulose rate of 53.2%.Extracted cellulose fibers have been characterized by several techniques such as scanning electron microscopy,Fourier transform infrared,X-ray diffraction,Morfi,and by the determination of their degree of polymerization.FT-IR results confirm the purity of the cellulosic fibers,and XRD analysis reveals that the crystallinity increases after the delignification and bleaching treatments.

Mechanical Properties of Polypropylene Composites Reinforced with Macadamia Nutshell Fibers

The use of natural fibers as an additive in polymeric matrices has attracted interest of the automotive industries,for its low cost,mechanical properties,biodegradability and lightness.However,the hydrophilic nature of the fiber makes polymer compatibility difficult.Fiber surface treatments can be used to enhance the fiber/matrix interface.In the present work,polypropylene(PP)composites reinforced with fibers from macadamia nutshell were obtained and characterized.Macadamia nutshell fibers were treated by an alkaline treatment with sodium hydroxide(NaOH 4%)to improve adhesion between fibers and matrix.Fibers were characterized by techniques of Scanning Electron Microscopy(SEM)and X-Ray Diffraction(XRD).The PP was mixed with the macadamia fibers(treated and untreated),in proportions of 5 and 10%(wt/wt)using a thermokinetic mixer.Furthermore tensile,flexural and impact specimens(Pure PP and composites)were prepared by an injection molding process and tested for evaluation of mechanical properties.The results showed that the insertion of treated fibers in the PP matrix increased the stiffness of the composites.However,the composites reinforced with untreated fibers presented higher impact energy absorption when compared to composites reinforced with treated fibers.

Alkaline modification of ZSM-5 catalysts for methanol aromatization： The effect of the alkaline concentration

The effects of alkaline treatment on the physical properties of ZSM-5 catalysts and on their activities for methanol to aromatics conversion have been investigated. A mild alkaline treatment （0.2 and 0.3 mol/L NaOH） created mesopores in the parent zeolite with no obvious effect on acidity. The presence of mesopores gives the catalyst a longer lifetime and higher selectivity for aromatics. Treatment with 0.4 mol/L NaOH decreased the number of Bronsted acid sites due to dealumination and desilication, which resulted in a lower deactivation rate. In addition, more mesopores were produced than with the mild alkaline treatment. As a result, the lifetime of the sample treated with 0.4 mol/L NaOH was almost five times that of the parent ZSM-5. Treatment with a higher alkaline concentration （0.5 mol/L） greatly reduced the number of Bronsted acid sites and the number ofmicropores resulting in incomplete methanol conversion. When the alkalinetreated catalysts were washed with acid, some of the porosity was restored and a slight increase in selectivity for aromatics was obtained.

Production and Characterization of High Density Polyethylene Reinforced by Eucalyptus Capsule Fibers

In this work, Eucalyptus Capsule Fibers （ECF） are proposed as a new natural fiber reinforcement to produce bio-composites due to their biological origin, specific smell and color. High Density Polyethylene （HDPE） is used as the matrix to compare three reinforcement types, raw ECF, alkali treated ECF, and ECF treated with PE-graft-maleic anhydride （PE-g-MA） as a coupling agent at three concentrations （5 wt.%, 10 wt%, and 15 wt%）. A complete set of characterization is performed including tension, torsion, hardness, Melt Flow Index （MFI）, Attenuated Total Reflection Fourier Transform Infrared Spectroscopy （ATR-FTIR）, Contact Angle （CA）, Scanning Electron Microscopy （SEM）, Thermogravimetric Analysis （TGA） and Dynamic Mechanical Analysis （DMA）. The results show that the best mechanical and rheological improvements are obtained by using the coupling agent with alkali treated fibers.