Ultrasound-assisted removal of malachite green from aqueous solution by dead pine needles

The dead needles of Aleppo pine (Pinus halepensis) were tested as a possible sorbent for the removal of malachite green from aqueous solutions in the absence and presence of ultrasound. Batch process was employed for sorption kinetic and equilibrium studies. Sorption experiments indicated that the sorption capacity was dependent of operating variables. Both the rate and the amount of malachite green sorption are markedly increased in the presence of the ultrasonic field. The dye removal with the assistance of ultrasound was enhanced with the increase of sorbate initial concentration and temperature, and with the decrease of sorbent dosage and ionic strength. The combination of stirring and ultrasound leads to an improvement of the removal of dye. The sorption kinetics was controlled by the intraparticle diffusion. The intraparticle diffusion coefficient increased 1.7 times in the presence of ultrasound and up to 3.6 times in the combined process. The sorption capacity, estimated according to the Freundlich model, indicates that ultrasound enhanced the sorption properties of the sorbent. The effect of ultrasound on the improvement of dye sorption is due to a variety of physical and mechanical effects as well as to thermal properties. The combination of ultrasound and stirring for the sorption process was shown to be of interest for the treatment of wastewaters contaminated with malachite green.     

Batch study of arsenate (V) adsorption using Akadama mud: Effect of water mineralization

Akadama mud, consisting mainly of different forms of iron and aluminum oxide minerals, was used for arsenate (V) adsorption from aqueous solutions. The adsorption process fitted the first-order kinetic equation and the Langmuir monolayer model well. The adsorption capacity, estimated by the Langmuir isotherm model, was 5.30 mg/g at 20 ± 0.5 °C. The effects of the solution properties (initial concentration of As (V), pH, temperature, and mineralization degree) on As (V) removal were investigated. Various mineralization degrees in underground water were simulated by adjusting the ionic strength of the solution or adding coexisting ions to the contaminated solution. It was found that mineralization of the water significantly influenced the arsenic adsorption. The existence of multivalent metallic cations significantly enhanced the As (V) adsorption ability, whereas competing anions such as fluoride and phosphate greatly decreased the As (V) adsorption. This result suggests that Akadama mud is more suitable for arsenic adsorption in low-level phosphate and fluoride solutions. The loaded Akadama mud could be desorbed at polar pH conditions, especially in acidic conditions, and more than 65% As (V) sorption has been achieved at pH 1.     

Porous ceramic membrane with superhydrophobic and superoleophilic surface for reclaiming oil from oily water

A porous ceramic tube with superhydrophobic and superoleophilic surface was fabricated by sol-gel and then surface modification with polyurethane-polydimethysiloxane, and an oil-water separator based on the porous ceramic tube was erected to characterize superhydrophobic and superoleophilic surface's separation efficiency and velocity when being used to reclaim oil from oily water and complex oily water containing clay particle. The separator is fit for reclaiming oil from oily water.     

Cobalt-nickel mixed oxide surface: A promising adsorbent for the removal of PR dye from water

A mixed oxide of cobalt (Co) and nickel (Ni) with an approximate composition of Co_0.4Ni_0.4O_0.2 was prepared chemically by precipitating from the corresponding metal carbonates and heating the mixture of carbonates at 650 °C under ambient atmosphere. The mixed (Co-Ni) oxide thus prepared was characterized by IR, SEM and XRD methods. The composition of the mixed metal oxide was obtained by EDX analysis. The surface behavior of the Co-Ni mixed oxide matrix was tested by adsorption studies and pH_pzc measurement. The Co-Ni mixed oxide matrix behaves as a charged adsorbent at the pH media higher and lower than its pH_pzc value (9.50) and thus found to be capable of anchoring the oppositely charged species onto its surface. Removal of cationic and anionic dyestuffs, viz., methylene blue (MB) and procion red (PR), respectively, was attempted using the mixed oxide surface as adsorbent. Although both the dyes can be removed by the mixed oxide, the extent of PR removal (∼70%) seems to be much higher than that of MB (∼20%) demonstrating the superior performance of the Co-Ni mixed oxide for its use as adsorbent in removing the anionic PR dyestuff from water.     

Surface heterogeneity effects of activated carbons on the kinetics of paracetamol removal from aqueous solution

The removal of a compound with therapeutic activity (paracetamol) from aqueous solutions using chemically modified activated carbons has been investigated. The chemical nature of the activated carbon material was modified by wet oxidation, so as to study the effect of the carbon surface chemistry and composition on the removal of paracetamol. The surface heterogeneity of the carbon created upon oxidation was found to be a determinant in the adsorption capability of the modified adsorbents, as well as in the rate of paracetamol removal. The experimental kinetic data were fitted to the pseudo-second order and intraparticle diffusion models. The parameters obtained were linked to the textural and chemical features of the activated carbons. After oxidation the wettability of the carbon is enhanced, which favors the transfer of paracetamol molecules to the carbon pores (smaller boundary layer thickness). At the same time the overall adsorption rate and removal efficiency are reduced in the oxidized carbon due to the competitive effect of water molecules.     

Facile preparation of mesoporous titanium nitride microspheres as novel adsorbent for trace Cd2+ removal from aqueous solution

A simple and facile route is developed for the preparation of mesoporous titanium nitride (TiN) microspheres with a large surface area and a highly porous structure. This method involves the preparation of an amorphous precursor via a solvothermal reaction and subsequent short-time nitridation process to mesoporous TiN. X-ray diffraction and X-ray photoelectron spectroscopy analyses confirm the composition of the resultant sample. The mesoporous structure of the as-prepared TiN sample has been studied by nitrogen adsorption/desorption measurement. The surface area obtained by the Brunauer–Emmett–Teller method is 50.6 m² g⁻¹ and the pore sizes are in the range of 2.0–4.0 nm. In addition, the obtained sample is evaluated as a new sorbent for Cd²⁺ removal. Experimental parameters such as solution pH, contact time and concentration of adsorbate are optimized. The maximum adsorption capacity for Cd²⁺ removal is found to be 12.40 mg g⁻¹ and it is a potentially attractive adsorbent for Cd²⁺ removal from aqueous solution.     

Development and application of ferrite materials for low temperature co-fired ceramic technology

Development and application of ferrite materials for low temperature co-fired ceramic(LTCC)technology are discussed,specifically addressing several typical ferrite materials such as M-type barium ferrite,NiCuZn ferrite,YIG ferrite,and lithium ferrite.In order to permit co-firing with a silver internal electrode in LTCC process,the sintering temperature of ferrite materials should be less than 950°C.These ferrite materials are research focuses and are applied in many ways in electronics.     

The effect of surface modification on heavy metal ion removal from water by carbon nanoporous adsorbent

In this work, chemically oxidized mesoporous carbon (COMC) with excellent lead adsorption performance was prepared by an acid surface modification method from mesoporous carbon (MC) by wet impregnation method. The structural order and textural properties of the mesoporous materials were studied by XRD, SEM, and nitrogen adsorption. The presence of carboxylic functional groups on the carbon surface was confirmed by FT-IR analysis. Batch adsorption experiments were conducted to study the effect of adsorbent dose, initial concentration and temperature for the removal of Pb(II) from aqueous systems. The adsorption was maximum for the initial pH in the range of 6.5-8.0. The kinetic data were best fitted to the pseudo-second order model. The adsorption of chemically oxidized mesoporous carbon to Pb(II) fits to the Langmuir model. The larger adsorption capacity of chemically oxidized mesoporous carbon for Pb(II) is mainly due to the oxygenous functional groups formed on the surface of COMC which can react with Pb(II) to form salt or complex deposited on the surface of MC.     

A numeric model for the kinetics of water vapor sorption on cellulosic reinforcement fibers

Some natural fibers like flax, hemp and others show excellent mechanical properties that make them a promising choice for the reinforcement of polymers. The increasing research on natural fiber reinforced composites has still left important questions open, mainly concerning the fiber–matrix interface. Compared to the well optimized glass fibers, cellulose fibers show very different interaction with matrix polymers and adhesion promoters. The hydrophilic cellulose structure allows for the penetration of a considerable amount of water into the amorphous regions of the fibers, eventually exceeding 20% by mass, depending on fiber type, preparation and environmental humidity. Even embedded in totally apolar polymers the cellulose partly retains its ability for water sorption, which results in unfavorable effects, such as dimensional changes, decrease in strength, roughening of the surface, etc. The interaction of differently prepared fibers with water vapor and the effect of surface treatment is investigated by measuring the dynamics of water vapor sorption. An exponential model is used for the numerical evaluation of the sorption and desorption kinetics. The model not only allows for an excellent fit of the experimental isotherms, but without any further assumptions it immediately gives evidence of the existence of two distinct mechanisms for the exchange of water vapor, related to different sorption sites. These specific mechanisms are represented by individual sorption–desorption isotherms as components of the total isotherms. The model provides a clearer differentiation of the effects of fiber preparation and modification with respect to interfacial interactions.     

Sonocrystallization of a novel ZIF/zeolite composite adsorbent with high chemical stability for removal of the pharmaceutical pollutant azithromycin from contaminated water

Water pollution management, reduction, and elimination are critical challenges of the current era that threaten millions of lives. By spreading the coronavirus in December 2019, the use of antibiotics, such as azithromycin increased. This drug was not metabolized, and entered the surface waters. ZIF-8/Zeolit composite was made by the sonochemical method. Furthermore, the effect of pH, the regeneration of adsorbents, kinetics, isotherms, and thermodynamics were attended. The adsorption capacity of zeolite, ZIF-8, and the composite ZIF-8/Zeolite were 22.37, 235.3, and 131 mg/g, respectively. The adsorbent reaches the equilibrium in 60 min, and at pH = 8. The adsorption process was spontaneous, endothermic associated with increased entropy. The results of the experiment were analyzed using Langmuir isotherms and pseudo-second order kinetic models with a R2 of 0.99, and successfully removing the composite by 85% in 10 cycles. It indicated that the maximum amount of drug could be removed with a small amount of composite.     

Intensified removal of copper from waste water using activated watermelon based biosorbent in the presence of ultrasound

Copper is one of the most toxic heavy metals having significant effects on the living organisms and hence effective removal of copper from waste water is crucial. The current work investigates the application of activated watermelon shell based biosorbent for the removal of copper from aqueous solution. The effect of activation using calcium hydroxide and citric acid as well as the effect of operating parameters like contact time, adsorbent dosage, temperature, pH, initial concentration and ultrasonic power on the extent of removal has been investigated. Experiments performed in the presence of ultrasound to investigate the degree of intensification as compared to the conventional agitation based treatment revealed that the adsorption rate significantly increases in the presence of ultrasound and also the time required for reaching the equilibrium reduces from 60 min in conventional approach to only 20 min in the presence of ultrasound. The extent of adsorption of Cu(II) on adsorbents was found to increase with an increase in the operating pH till an optimum value of 5. The extent of adsorption also increased with a decrease in the initial concentration and particle size as well as with an increase in ultrasonic power till an optimum. Kinetics and isotherm study revealed that all the experimental data was found to best fit the pseudo second order kinetics and Langmuir adsorption isotherm model respectively. Maximum adsorption capacity was found to be 31.25 mg/g for watermelon treated with calcium hydroxide and 27.027 mg/g for watermelon treated with citric acid. Overall present study established that activated watermelon is an environmentally friendly, low cost and highly efficient biosorbent that can be successfully applied for the removal of copper from aqueous solution with intensification benefits based on the ultrasound assisted approach.     

In vitro studies of PBT Nonwoven Fabrics adsorbent for the removal of low density lipoprotein from hyperlipemia plasma

Polyanion ligands such as acrylic acid (AA) and heparin were grafted on PBT Nonwoven Fabrics (PBTNF) to study their effect on the adsorption of low density lipoprotein (LDL). These modified PBTNFs were characterized by Horizontal Attenuated Total Reflectance Fourier Transform Infrared spectroscopy and X-ray Photoelectron spectroscopy. The blood compatibilities of the modified PBTNFs were examined using in vitro hemolysis rate (HR), platelet adhesion, total protein (TP) and activated partial thromboplastin time. The results showed that direct immobilized heparin could improve PBTNF-PAA's blood compatibility and decrease the adsorption capability of useful high density lipoprotein, but would possess so low bioactivity that could not further improve the absorption of LDL and TC. Since the PBTNF-PAA55-Heparin adsorbent had quite good adsorption selectivity for these proteins, it can be an excellent candidate for depletion of LDL with good blood compatibility.     

Nanofibrous membrane of polyacrylonitrile with efficient adsorption capacity for cadmium ions from aqueous solution: Isotherm and kinetic studies

The nanofibrous membrane of polyacrylonitrile (NMP) was successfully synthesized after NaOH and NaHCO₃ treatment aiming its functionalization using electrospinning for cadmium ion (Cd²⁺) adsorption. Field emission scanning electron microscopy (FE-SEM) revealed that small particles attached to the surface of functionalized PAN nanofibers. Equilibrium was attained after 60 min following a rapid uptake of Cd²⁺ with maximum adsorption capacity and percentage removal at an optimum solution pH of 7.0. The adsorbent dose of 0.3 g and 90 mg L⁻¹ of initial Cd²⁺ concentration yielded the maximum adsorption capacity. The pseudo-second-order kinetic model was the best fitted to the adsorption data, indicating that the chemisorption is the controlling mechanism of adsorption. The physisorption was proposed based on the calculated values of the mean free energy of adsorption from the D–R isotherm (E < 8 kJ mol⁻¹). Furthermore, three-parameter isotherm models indicated the homogeneous and heterogeneous Cd²⁺ adsorption onto NMP adsorbent.     

Sonochemical synthesis of amide-functionalized metal-organic framework/graphene oxide nanocomposite for the adsorption of methylene blue from aqueous solution

Graphene oxide-[Zn₂(oba)₂(bpfb)]·(DMF)₅ metal-organic framework nanocomposite (GO-TMU-23; H₂oba = 4,4′-oxybisbenzoic acid, bpfb = N,N′-bis-(4-pyridylformamide)-1,4-benzenediamine, DMF = N,N-dimethylformamide) is prepared through a simple and large-scale sonochemical preparation method at room temperature. The obtained nanocomposite is characterized by Field Emission Scanning Electron Microscopy (FE-SEM), powder X-ray diffraction (PXRD) and FT-IR spectroscopy. Additionally, the absorption ability of GO-TMU-23 nanocomposite toward cationic dye methylene blue was also performed. Significantly, GO-TMU-23 nanocomposite exhibits remarkably accelerated adsorption kinetics for methylene blue in comparison with the parent materials. The adsorption process shows that 90% of the dye has been removed and the equilibrium status has been reached in 2 min by using the nanocomposites as the adsorbent.     

Ultrasound-assisted synthesis of nanocomposites based on aromatic polyamide and modified ZnO nanoparticle for removal of toxic Cr(VI) from water

In this study, novel nanocomposites (NCs) of aromatic polyamide (PA) and surface modified ZnO nanoparticle with s-triazine heterocyclic ring was introduced for efficient removal of toxic hexavalent chromium (VI) from aqueous solution. The surface of ZnO nanoparticle was modified by s-triazine core silane coupling agent (ZnO-TSC) and PA/ZnO-TSC NCs with different amount of ZnO-TSC nanoparticles (0, 5, 10 and 15 wt%) were prepared by ultrasonic irradiation. The synthesized PA/ZnO-TSC NCs were characterized by FT-IR, XRD, FE-SEM, TEM and TGA methods. TEM images showed that ZnO nanoparticles were dispersed homogeneously in the polymer matrix. The adsorption experiments were carried out in batch mode to optimize various parameters like contact time, pH and concentration of metal ion that influence the adsorption rate. The maximum uptakes of Cr(VI) at pH 4.0 was 72%, 81%, 89% and 91% for pure PA, NC5%, NC10% and NC15%, respectively. The kinetic of adsorption was investigated and the pseudo second-order model is an appropriate model for interpretation of adsorption mechanism of Cr(VI) ions.     

An ion-imprinted amino-functionalized silica gel sorbent prepared by hydrothermal assisted surface imprinting technique for selective removal of cadmium (II) from aqueous solution

A new ion-imprinted amino-functionalized silica gel sorbent was synthesized by the hydrothermal-assisted surface imprinting technique using Cd²⁺ as the template, 3-[2-(2-aminoethylamino)ethylamino]propyl-trimethoxysilane (AAAPTS) as the functional monomer, and epichlorohydrin as the cross-linking agent (IIP-AAAPTS/SiO₂) for the selective removal of Cd²⁺ from aqueous solution, and was characterized by FTIR, SEM, nitrogen adsorption and the static adsorption-desorption experiment method. The specific surface area of the IIP-AAAPTS/SiO₂ sorbents was found to be 149 m² g⁻¹. The results showed that the maximum static adsorption capacities of IIP-AAAPTS/SiO₂ sorbents by hydrothermal heating method and by the conventional heating method were 57.4 and 31.6 mg g⁻¹, respectively. The IIP-AAAPTS/SiO₂ sorbents offered a fast kinetics for the adsorption and desorption of Cd(II). The relative selectivity coefficients of IIP-AAAPTS/SiO₂ sorbents for Cd²⁺/Co²⁺, Cd²⁺/Ni²⁺, Cd²⁺/Zn²⁺, Cd²⁺/Pb²⁺ and Cd²⁺/Cu²⁺ were 30.68, 14.02, 3.00, 3.12 and 6.17, respectively. IIP-AAAPTS/SiO₂ sorbents had a substantial binding capacity in the range of pH 4-8 and could be used repeatedly. Equilibrium data fitted perfectly with Langmuir isotherm model compared to Freundlich isotherm model. Kinetic studies indicated that adsorption followed a pseudo-second-order model. Negative values of ΔG° indicated spontaneous adsorption and the degree of spontaneity of the reaction increased with increasing temperature. ΔH° of 26.13 kJ mol⁻¹ due to the adsorption of Cd²⁺ on the IIP-AAAPTS/SiO₂ sorbents indicated that the adsorption was endothermic in the experimental temperature range.     

Application of modificated magnetic nanomaterial for optimization of ultrasound-enhanced removal of Pb2+ ions from aqueous solution under experimental design: Investigation of kinetic and isotherm

Magnetic γ-Fe₂O₃ nanoparticles modificated by bis(5-bromosalicylidene)-1,3-propandiamine (M-γ-Fe₂O₃-NPs-BBSPN) and characterized by field emission scanning electron microscopy (FE-SEM), Fourier transforms infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). This modified compound as novel adsorbent was applied for the ultrasound-assisted removal of Pb²⁺ ion in combination with flame atomic absorption spectroscopy (FAAS). The influences of the effective parameters including initial Pb²⁺ ion concentration, pH, adsorbent mass and ultrasound time were optimized by central composite design (CCD). Maximum removal percentage of Pb²⁺ ion which obtained at 25 mg L⁻¹ of Pb²⁺, 25 mg of adsorbent and 4 min mixing with sonication at pH 6.0. The precision of the equation obtained by CCD was confirmed by the analysis of variance and calculation of correlation coefficient relating the predicted and the experimental values of removal percentage of Pb²⁺ ion. The kinetic and isotherm of ultrasound-assisted removal of Pb²⁺ ion was well described by second-order kinetic and Langmuir isotherm model with maximum adsorption capacity of 163.57 mg g⁻¹.