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In this study a novel activated carbon derived from Raffia palm shells was synthesized firstly by activating the precursor with phosphoric acid to produce Raffia Palm Shell Activated Carbon (RPSAC) and further functionalized by coating its surface with aluminium hydroxide to produce a composite called Aluminium Oxide-coated Raffia Palm Shell Activated Carbon (ACRPSAC). These adsorbents were extensively characterized and tested for fluoride adsorption in aqueous media using batch adsorption experiment in comparison with a commercially available activated carbon (CAC). ACRPSAC demonstrated excellent qualities and fluoride adsorption capacity as compared to RPSAC. SEM/EDX revealed that ACRPSAC developed both micro and meso-pores on its surface with BET-surface area and pore volume of 715.80 m2/g and 0.47 cm3/g respectively. FTIR and XRD proved that ACRPSAC was largely amorphous and had sufficient functionality for fluoride uptake in solution. Batch adsorption studies showed that the fluoride removal abilities were in the order of ACRPSAC > RPSAC > CAC with maximum Langmuir adsorption capacity of 4.10 > 2.26 > 2.24 mg/g. respectively. The experimental data was well described by the Langmuir (R2 = 0.8802–0.9751) and the pseudo-second order kinetic (R2 = 0.9974–0.9999) models, signifying that fluoride uptake by the adsorbents was a chemisorption process. Thermodynamic studies revealed that the process was spontaneous, endothermic and feasible for ACRPSAC and RPSAC but was non-spontaneous for CAC. It was concluded that ACRPSAC is an excellent activated carbon for eliminating fluoride from groundwater and can be further studied for its commercialization.

Accidental freezing of aluminum-based vaccines occurs during their storage and transportation, in both developed and developing countries. Freezing damages the freeze-sensitive aluminum adjuvanted vaccines, through separation of lattice between aluminum adjuvant and antigen, leading to formation of aluminum aggregates, and loss of potency. In this study, we examined Alhydrogel™ ([AlO(OH)]xnH2O, aluminum hydroxide, hydrated for adsorption) stored under recommended conditions, and exposed to freezing temperature until solid-frozen. The main purpose of our research was to determine the destruction areas of the solid-frozen Alhydrogel™ using selected methods of scanning electron microscopy, energy dispersive X-ray spectroscopy, Raman spectroscopy, Fourier-transform infrared spectroscopy and transmission electron microscopy working in diffraction mode. The Zeta potential evaluation, measurements of albumin adsorption power, thermogravimetric analysis and estimation of the mass loss after drying indicated significant structural (physical) and chemical differences between the freeze-damaged and non-frozen vaccine adjuvant. The presented results are important to better understand the type and nature of damages occurring in freeze-damaged aluminum-based vaccines. These results can be used in future studies to improve the temperature stability of aluminum adjuvanted vaccines.

In eutrophication management, many phosphorus (P) adsorbents have been developed to capture P at the laboratory scale. Existing P removal practice in freshwaters is limited due to the lack of assessment of the possibility and feasibility of controlling P level towards a very low level (such as 10 &mu, g/L) in order to prevent the harmful algal blooms. In this study, a combined external and internal P control approach was evaluated in a simulated pilot-scale river&ndash, lake system. In total, 0.8 m3 of simulated river water was continuously supplied to be initially treated by a P adsorption column filled with a granulated lanthanum/aluminium hydroxide composite (LAH) P adsorbent. At the outlet of the column (i.e., inlet of the receiving tanks), the P concentration decreased from 230 to 20 &micro, g/L at a flow rate of 57 L/day with a hydraulic loading rate of 45 m/d. In the receiving tanks (simulated lake), 90 g of the same adsorbent material was added into 1 m3 water for further in situ treatment, which reduced and maintained the P concentration at 10 &micro, g/L for 5 days. The synergy of external and internal P recapture was demonstrated to be an effective strategy for maintaining the P concentration below 10 &micro, g/L under low levels of P water input. The P removal was not significantly affected by temperature (5&ndash, 30 &deg, C), and the treatment did not substantially alter the water pH. Along with the superior P adsorption capacity, less usage of LAH could lead to reduced cost for potation eutrophication control compared with other widely used P adsorbents.

In this study, the adsorption potential of aluminium-iron-amended activated bamboo charcoal (AIAABC), prepared from waste bamboo, for defluoridation of drinking water was investigated. The adsorbent (AIAABC) in which ABC was impregnated in AlCl3/FeCl3 solution and treated at 400 °C showed higher fluoride uptake capacity. The samples obtained were characterized and tested in batch mode. Inorganic particles were dispersed on the surface of carbon as indicated by SEM images and EDS. The main elements found in AIAABC were carbon, oxygen, aluminium, iron, sodium, and sulfur. Fluoride was associated with the aluminium hydro(oxide) (AO) particles in the pore spaces of ABC after adsorption. Specific surface area (SSA) was reduced from 80.5 to 3.7 m2/g, when ABC was impregnated with AO, indicating that the AO particles might cover the surface or pore spaces found in ABC. Maximum adsorption occurred at pH range from 5 to 9. The adsorption data were well fitted to Langmuir isotherm model with a maximum adsorption capacity of 21.1 mg/g. The adsorption process obeyed a pseudo–second–order rate equation. The adsorbent was effectively regenerated (85.7%) by 0.1% NaOH. Due to its high adsorption capacity compared to commercially available aluminium hydroxide–based adsorbents, AIAABC is a highly promising material for defluoridation of drinking water.

It is unclear to what extent sorption of antimony (Sb) in soils occurs over long time scales. This study was set up to monitor slow reactions (7 days to 6 months) of Sb in Sb(V)‐spiked soil samples during aerobic incubation. The solid–liquid distribution coefficients (KD) increased by factors of 3 to 6 between 7 and 190 days after spiking, depending on the soil. This increase in the KD value, hereafter named the Sb ageing factor, increased with increasing amorphous iron and aluminium hydroxide concentration and decreasing pH of the soil samples. Finally, ageing factors were highest in topsoils and could be important in preventing Sb from migrating downwards into groundwater bodies. HIGHLIGHTS: Quantification of antimonate ageing in soils. Topsoils could prevent downward leaching of Sb in the long‐term. Ageing of Sb increased in soils with increasing amorphous iron and aluminium hydroxide concentration and decreasing pH. Slow sorption reactions reduce Sb mobility in soils.

Exposure to fluoride beyond the recommended level for longer duration causes both dental and skeletal fluorosis. Thus, the development of cost-effective, locally available, and environmentally benign adsorbents for fluoride removal from contaminated water sources is absolutely required. In the present study, diatomaceous earth (diatomite) locally available in Ethiopia, modified by treating it with an aluminum hydroxide solution, was used as an adsorbent for fluoride removal from aqueous solutions. Adsorption experiments were carried out by using batch contact method. The adsorbent was characterized using FT-IR spectroscopy. Effects of different parameters affecting efficiency of fluoride removal such as adsorbent dose, contact time, initial fluoride concentration, and pH were investigated and optimized. The optimum adsorbent dose, contact time, initial fluoride concentration, and pH values were 25 g/L, 180 min, 10 mg/L, and 6.7, respectively. The performance of the adsorbent was also tested under optimum conditions using groundwater samples taken from Hawassa and Ziway. Langmuir and Freundlich isotherm models were applied to describe the equilibrium data. Compared to Langmuir isotherm (R2 = 0.888), the Freundlich isotherm (R2 = 0.985) model was better fitted to describe the adsorption characteristics of fluoride on Al-diatomite. The Langmuir maximum adsorption capacity was 1.67 mg/g. The pseudosecond-order model was found to be more suitable than the pseudofirst-order to describe the adsorption kinetics. The low correlation coefficient value ofR2 = 0.596 for the intraparticle diffusion model indicates that the intraparticle diffusion model does not apply to the present studied adsorption system. The maximum fluoride removal was observed to be 89.4% under the optimum conditions which indicated that aluminum hydroxide-modified diatomite can be used as efficient, cheap, and ecofriendly adsorbents for the removal of fluoride from contaminated water.

The purpose of the research was to develop a new pigment from teak leaves, an agricultural waste material from the teak industry. Teak leaves were extracted by various polarity solvents to provide a variety of color extracts. The ethyl acetate extract gave reddish-brown with the highest intensity. The ethyl acetate extract was selected to develop the pigment by adsorption method. It was found that the type of substrate affects the color and the intensity of the obtained pigments. Using aluminium hydroxide Al(OH)3 as a substrate provided the purple pigment with the highest color intensity because Al(OH)3 could adsorb both flavonoids and anthraquinones contained in the extract. The other substrates showed a lighter color because they could adsorb only flavonoids. Increasing the mass ratio between Al(OH)3 and the extract, when preparing the pigment, increased the color intensity of the pigment, with a mass ratio of 10:5, resulting in the color compounds in the pigment being in the range of 12–20%, which meets commercial requirements. The pigments also exhibited higher thermal and light stability than the extract. These results demonstrate the possibility of teak leaves being used as a new source for the development of natural pigments in cosmetic products.

Adsorption properties of aluminium hydroxide γ-modification towards toxic copper(II) and zinc(II) ions were studied. In a neutral medium at pH=7.6, the ion adsorption capacity was 264 mg/g for copper(II) and 338 mg/g for zinc(II). The study of the temperature effect on the absorbability of toxic ions established that the adsorption capacity is characterized by an increase followed by a decrease as the equilibrium value is reached. The absorbability increase in the initial moment is caused by an increase in the formation rate of hydroxo aqua complexes of copper(II) and zinc(II) ions. The differential heat of adsorption was determined. It demonstrated a decrease from 27 to 20 kJ/mol during the process, which is caused by the fact that, as the most active centres of nanostructured form of aluminium hydroxide γ-modification are saturated, heavy metal ions are adsorbed by decreasingly active regions of its surface.

A novel aluminium hydroxide modified porous cellulose aerogel was prepared and used as an effective adsorbent for the removal of fluoride from aqueous solution. The adsorbent was prepared by freeze-drying of cellulose nanofibrils gel followed by impregnation with AlCl3 solution and washing with water. The ensuing sorbent was characterized by SEM observation, XPS, TGA and BET measurement for specific-surface evaluation. The CNF-Al(OH)3 modified aerogel was shown to be an effective adsorbent for fluoride in water, with an adsorption capacity ranging from 20 to 35 mg.g−1, depending on the Al(OH)3 loading. The spent CNF-Al(OH)3 adsorbent was regenerable by washing with NaOH solution and could be reused up to five adsorption-desorption cycles without significant loss of its adsorption capacity. The CNF-Al(OH)3 aerogel showed a great promise to be applied as a reusable adsorbent from a renewable resource for defluorination.

Electrocoagulation (EC) is an electrochemical technique for removal of various pollutants – in particular metal cations – from waste or groundwaters. In comparison with other metal cations, iron can be under divalent and trivalent forms, with different physicochemical properties, so various physicochemical phenomena are to occur for its removal. For the case of Fe2+ ions removal from a synthetic aqueous solution by EC with aluminium electrodes, we investigated both occurrence and significance of the various phenomena encountered e.g. formation of divalent iron hydroxide, adsorption of Fe species on Al(III) flocs formed and oxidation phenomena. Designed experiments have been conducted with an electrochemical cell at various current densities below 10 mA cm−2 and pH, and depending on the nature of the gaseous atmosphere, or in an electroless stirred vessel. Analysis of the data showed that, in addition to direct Fe2+ adsorption on generated solid aluminium hydroxide, Fe(II) hydroxide formed near the cathode surface, precipitates jointly on the Al flocs. Fe(II) oxidation by air oxygen in the liquid phase in EC runs was predicted to be little significant, whereas solid Fe(OH)2 is oxidized more efficiently to Fe(OH)3. However, Fe(II) oxidations improve only little its removal from the water treated by electrocoagulation, as shown by EC tests in anoxic conditions.

Lepidolite has an Al 2 O 3 content of greater than 22%. Using it efficiently will be very important for the economic extraction of lithium from this low-grade lithium ore if an industrial-scale extraction process is to be developed. This paper presents a novel technique for recovering aluminium and lithium from the gypsum residue generated during the extraction of lithium from lepidolite. The alkali digestion conditions were considered based on the principles behind the Bayer process. Maximum extraction of aluminium (100%) and 96.4% extraction of lithium were recorded at caustic ratio (Na 2 O/Al 2 O 3 molar ratio) of 1.7, digestion temperature of 136 °C and digestion time of 60 min. After digestion, aluminium hydroxide was precipitated by cooling and seeding of the digestion solution. Li + ion was not adsorbed by aluminium hydroxide during this process. Therefore, Li could easily be recovered by adding sodium phosphate (Na 3 PO 4 ). In addition, the precipitation of lithium at several different molar ratios of Li + /PO 4 3 − was performed to investigate its influence on the recovery process.

Alumina-activated carbon composite has been synthesized and studied for adsorption procion red dye. Composite was prepared by precipitation method aluminium hydroxide on the surface of activated carbon followed by calcinations. The Fourier transform Infra Red (FTIR), Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDS) and Brunaeur Emmet Teller (BET) surface are being used to characterize the adsorbent. Batch adsorption experiments were carried out for the adsorption of procion red dye. Effect of the mass of composite, stirrer speed, contact times and pH of the solution on the adsorption capacity were studied. The obtained optimum conditions applied to adsorp of procion red dye from wastewater songket industry. The result showed that the adsorption optimum at mass of alumina-activated carbon composite 0.1 g, stirrer speed 150 rpm, contact times 2 hours at pH of the solution 9. The adsorption isotherm data according to Langmuir isotherm. The alumina-activated carbon composite can be removal of procion red dye from wastewater songket industry with effectiveness adsorption of 88.21 %.

The in vitro interaction between zidovudine and three antacids and a commercial product was investigated. The extent of adsorption of zidovudine by the antacids, and the effects of the antacids on the disintegration time and dissolution of the drug from tablets were studied. Adsorption of the drug by the antacids followed the order; magnesium trisilicate > aluminium hydroxide > magnesium hydroxide. Retardation of dissolution amongst the antacids and commercial product was of the order; Jawasil® > magnesium trisilicate > aluminium hydroxide > magnesium hydroxide. Also, the degree of retardation of dissolution from the tablets increased as the amount of adsorbent increased. Co-administration of zidovudine and adsorptive antacid formulations should be avoided in clinical practice since it can lead to a decrease in the bioavailability of zidovudine, ultimately leading to therapeutic failure. DOI: http://dx.doi.org/10.3329/dujps.v13i1.21853 Dhaka Univ. J. Pharm. Sci. 13(1): 1-6, 2014 (June)

Steel slag, which makes up a gigantic amount of metallurgical industrial solid waste, was in this experiment successfully synthesized an inexpensive adsorbent used to remove nitrate pollution from aqueous solution. This adsorbent was obtained by mixing steel slag, aluminium hydroxide and deionized water, and aging this at a mass ratio of 3:0.45:2, and then activating it at 800 °C. The physicochemical characteristics of the steel slag before and after modification were investigated to compare the effect of their surface properties on the adsorption behaviour of nitrate. The effects of adsorbent dosage, pH, and contact time on the adsorption process were investigated. The results showed that an increase in specific surface area and the formation of a positive surface of the modified steel slag (MSS) compared with the original steel slag (OSS) could effectively increase the number of the active adsorption sites and nitrate removal ability. The optimum parameters for nitrate removal were as follows: the concentration of nitrate was 20 mg/L, the dosage was 1 g/100 mL, the pH was four, and the reaction time was 180 min. The adsorption capacity of the MSS was approximately 1.9 times that of the OSS. The nitrate adsorption of the MSS was in accordance with the pseudo-second-order model and the Freundlich model, which indicated that the adsorption of nitrate on the MSS was mainly single layer chemical adsorption. The mechanism of nitrate removal mainly included ion exchange, hydrogen bonding, electrostatic interactions and intermolecular interactions. In addition, regeneration experiments indicated that the MSS after regeneration still had the capacity to remove nitrate.

Several methods to remove arsenic from water have been considered, including co-precipitation with Fe and Al (hydr)oxides. Such compounds are considered very effective to remove As from contaminated water due to strong bindings between them. Three Fe:Al molar ratios (100:0, 80:20, and 60:40) were used to synthesize aluminum, ferrous, and ferric (hydr)oxides by precipitation in water highly contaminated with arsenite (50 and 500 mg L−1). The method was very efficient for all treatments (> 93%) at the beginning of the incubation period, excepted the one with 60:40 Fe(II):Al molar ratio at the higher As concentration (500 mg L−1) in which gibbsite was identified in precipitated phases. In spite of the high efficiency, however, the threshold for drinking water was not attained, mainly to the higher As concentration, even 84 days after precipitation. At this high concentration of arsenite, even the required threshold for effluent discharge was not attained in some treatments. The sludge resulting from treatments with higher As concentration were considered hazardous according to results from leaching test and corroborated by BCR extractions. Arsenic associated with Al and adsorbed phases were also assessed by extractions with NH4F and KH2PO4, respectively. In general, the presence of Al increased the efficiency as well as the stability of the sludge resulting from Fe (II) treatments, but did not affect Fe (III) treatments, which were more efficient for As removal.

Filtration of aqueous liquids has wide implications, for example for provision of clean drinking water. Nevertheless, many people still lack access to safe water and suffer from preventable water-borne microbial diseases. This study reports a new ultrafiltration-range separation technology using a gelatinous layer of aluminium hydroxide polyhydrate as a secondary membrane on a retaining fabric that enables simple and cost-effective production of filtered water. Properties include at least 4-fold higher flux rates than currently available membranes, pressure-resistance, impenetrability to filtered particles, easy cleaning by backwashing and simple, cost-effective replacement by gel injection. Depending on the substrate, filtration is achieved through a packed bed of 1–2 nm hydrate gel globules, partly by mechanical straining with a size exclusion of approx. 10 nm and partly by physical adsorption. As a result, filtration of water (e.g. turbid river water) contaminated with colloids and microorganisms, including viruses, yields clear water that is free of measurable particles or detectable microorganisms. However, small water-soluble molecules (salts, sugars, proteins) remain in the filtrate. The findings demonstrate the potential for wide applicability of hydrate gels in high-flux and low-cost water purification devices.

The aim of this research was to estimate the possibility of using synthesized hydrous iron oxide/aluminium hydroxide composite loaded on coal fly ash (FA3) as an efficient sorbent for Cr(VI) sorption from aqueous solution. In this regard, dissolution and precipitation processes were performed to rearrange and load the intrinsic iron and aluminum on the surface of fly ash. Different characterization techniques including XRD, XRF, FT-IR, SEM, LPS and BET surface area were applied to analyze the sorbent properties. Moreover, sorption kinetics were studied using Morris–Weber intra-particle diffusion, Lagergren pseudo-first-order and pseudo-second-order models. The kinetic analyses indicated that pseudo-first-order model controlled the sorption process. In order to estimate the sorbent capacity, Langmuir, Freundlich and D–R models were applied. The thermodynamic parameters of Cr(VI) sorption were also studied. In addition, removal efficiency of Cr(VI) was predicted using the developed fuzzy logic model. The fuzzification of four input variables including pH, contact time, adsorbent dose and initial Cr(VI) concentration versus removal efficiency as output was carried out using an artificial intelligence-based approach. A Mamdani-type fuzzy interface system was employed to fulfill a collection of 24 rules (If-Then format) using triangle membership functions (MFS) with seven levels in fuzzy sets. The proposed fuzzy logic model demonstrated high predictive performance with correlation coefficient (R2) of 0.95 and acceptable deviation from the experimental data, confirming its suitability to predict Cr(VI) removal efficiency. Based on experimental data and statistical analysis, the synthetized sorbent was effective for treating wastewater containing Cr(VI).

In the present study high surface area amorphous boehmite and γ-alumina were synthesised using walnut shell as template. This green, simple and useful synthetic protocol was based on the precipitation of aluminium hydroxide as the source of aluminium on biomass in an aqueous phase followed by calcination. The influence of walnut shell was evaluated by varying the calcination atmosphere. N2 adsorption/desorption porosimetry exhibited high surface area for boehmite and γ-alumina. Furthermore, the pore size and surface area of these mesoporous materials can be adjusted by varying the experimental conditions. Additionally, boehmite was studied as the support of vanadium catalyst for the oxidation of alcohols by hydrogen peroxide. We have found that resulting V-loaded material act as an effective catalytic system for the oxidation of a wide range of alcohols in 1,4-dioxane. The catalyst can be recovered and reused four times without loss of activity.

Intake of excess fluoride (beyond 1.5 mg/L, WHO guideline) for long periods can result in the incidence of fluorosis. Adsorption is widely considered the most appropriate technology for water defluoridation, if a suitable adsorbent is available. Several studied adsorbents have shown certain degrees of adsorption capacity, however, applicability of most is limited either due to lack of socio-cultural acceptance, high cost or effectiveness only in extreme pH conditions. The search for alternative adsorbents thus remains of interest. Modification of pumice particle surfaces by aluminum oxide coating was found effective in creating hard surface sites for fluoride adsorption, in accordance with the hard and soft acids and bases (HSAB) concept. Aluminum oxide coated pumice (AOCP) reduced fluoride concentration in model water from 5.0 ± 0.2 mg/L to 1.5 mg/L in approximately 1 h, using an adsorbent dose of 10 mg/L. Contrary to expectations, thermal treatment of AOCP aimed at further improving its performance, instead reduced the fluoride removal efficiency. The equilibrium adsorption of fluoride by AOCP conformed reasonably to five isotherm models in the order: Generalized model > Langmuir type 2 > BET > Temkin > Dubinin–Radushkevich; with a maximum capacity of 7.87 mg/g. AOCP exhibited good fluoride adsorption within the pH range, 6–9, which makes it possible to avoid pH adjustment with the associated cost and operational difficulties, especially if it is to be used in remote areas of developing countries. Based on results from kinetic adsorption experiments, it was observed that at a neutral pH of 7.0 ± 0.1 which is a more suitable condition for groundwater treatment, fluoride adsorption by AOCP was quite comparable or perhaps fairly faster in the initial period of contact than that of activated alumina (AA), the commonly used adsorbent for water defluoridation. AOCP is thus promising and could also possibly be a useful fluoride adsorbent.

Arsenic-contaminated waters can be remediated by adsorption of the As onto an amorphous Al(OH) 3 sludge precipitated using poly-aluminium chloride, which is a widely used, very effective polymeric coagulant. Investigation of the atomic near-range order and structure of As adsorbed to this sludge using X-ray Absorption Spectroscopy showed that the EXAFS spectrum of the sludge samples is very similar to that of mansfieldite (AlAs V O 4 ·2H 2 O), indicating that As in the sludge is present as As V , and that the atomic near-range structure of As is similar in the two materials. In the sludge, the first As–O coordination shell is populated with ∼4 oxygen neighbours at 1.70 ± 0.01 A, and As has ∼2 Al neighbours at 3.18 ± 0.02 A, consistent with bidentate binuclear As–O–Al bonding (two O atoms from an AsO 4 unit bonded individually to two Al atoms). Previous studies have shown that As bonding on crystalline Al oxides and hydroxides is also bidentate binucleate, contrasting with the variable As bonding on ferric oxy-hydroxides. In particular, the bidentate mononucleate bonding reported for As sorption on amorphous ferric oxy-hydroxide sludges suggests that As is more strongly bonded to Al(OH) 3 sludges. The latter may, therefore, have an advantage over ferric oxy-hydroxide coagulants for treatment of As-enriched waters.

Adsorption of fluoride ion from aqueous solutions by using different silico-aluminous natural products was studied. Preliminary batch tests indicated how bauxite shows a high removal efficiency. Such optimum efficiency is due to the elevated presence of aluminium hydroxide (gibbsite) and aluminium oxide hydroxide (boehmite). Both batch and continuous experiments were performed: Freundlich equation well described batch equilibrium data. In continuous-flow column experiments, the effects of inlet fluoride concentration (5–50 mg L–1) and flow rate (up to 2.5 mL min–1) on breakthrough time and adsorption capacity were studied. Column studies showed that the dynamic adsorption capacity depends on the inlet fluoride concentration and the flow rate. After adsorption of fluorides, saturated bauxite, was regenerated by using two different solutions containing NaOH and H2SO4. Column tests indicated a different behaviour of original respect to regenerated bauxite.

To better understand the sequestration of toxic metals such as nickel (Ni), zinc (Zn), and cobalt (Co) as layered double hydroxide (LDH) phases in soils, we systematically examined the presence of Al and the role of mineral dissolution during Zn sorption/precipitation on γ-Al(2)O(3) (γ-alumina) at pH 7.5 using extended X-ray absorption fine structure spectroscopy (EXAFS), high-resolution transmission electron microscopy (HR-TEM), synchrotron-radiation powder X-ray diffraction (SR-XRD), and (27)Al solid-state NMR. The EXAFS analysis indicates the formation of Zn-Al LDH precipitates at Zn concentration ≥0.4 mM, and both HR-TEM and SR-XRD reveal that these precipitates are crystalline. These precipitates yield a small shoulder at δ(Al-27) = +12.5 ppm in the (27)Al solid-state NMR spectra, consistent with the mixed octahedral Al/Zn chemical environment in typical Zn-Al LDHs. The NMR analysis provides direct evidence for the existence of Al in the precipitates and the migration from the dissolution of γ-alumina substrate. To further address this issue, we compared the Zn sorption mechanism on a series of Al (hydr)oxides with similar chemical composition but differing dissolubility using EXAFS and TEM. These results suggest that, under the same experimental conditions, Zn-Al LDH precipitates formed on γ-alumina and corundum but not on less soluble minerals such as bayerite, boehmite, and gibbsite, which point outs that substrate mineral surface dissolution plays an important role in the formation of Zn-Al LDH precipitates.

The aggregation of tetanus toxoid leads to reduced bioavailability of the vaccine and failure of immunization programmes in many parts of the globe. One of the main reasons for denaturation and aggregation of tetanus toxoid formulations is agitation of the protein during transport. We have identified that agitation leads to collapse of the gel matrix of aluminium hydroxide which is used as an adjuvant in these preparations. This results in desorption of the toxoid from the matrix, which then loses its antigenicity due to agitation-induced denaturation of the protein. We show that incorporation of some compatible osmolytes like sorbitol, glucose and arginine, but not trehalose, is able to protect the adjuvant matrix from degradation, and retain the integrity of the vaccine preparation in terms of its antigenicity.

Aluminium-containing adjuvants are often used to enhance the potency of vaccines. In the present work we studied whether adsorption of diphtheria toxoid to colloidal aluminium hydroxide induces conformational changes of the antigen. Diphtheria toxoid has a high affinity for the aluminium hydroxide particles based on a high adsorption degree, adsorption rate and adsorptive capacity. The conformation and stability of diphtheria toxoid in solution and adsorbed to aluminium hydroxide adjuvant were characterized using five physicochemical techniques: intrinsic and extrinsic fluorescence spectroscopy, circular dichroism, infrared spectroscopy and differential scanning calorimetry. Diphtheria toxoid adsorbed to aluminium hydroxide resulted in a minimal shift of the tryptophan fluorescence spectrum, whereas a large increase in the emission of the Bis-ANS probe was observed, indicating that hydrophobic sites of the protein became accessible due to adsorption. In addition, circular dichroism and infrared spectroscopy revealed that adsorption to aluminium hydroxide caused an increase of beta-sheet content and a decrease of a-helix content in diphtheria toxoid. Differential scanning calorimetry demonstrated a major decrease in the enthalpy of denaturation upon adsorption. In conclusion, the adsorption of diphtheria toxoid to aluminium hydroxide adjuvant leads to substantial conformational changes in the antigen. Since physicochemical methods can be used to monitor these conformational changes, these analytical methods might offer a tool in regulatory required vaccine quality control by demonstrating consistency in production. (C) 2012 Elsevier Ltd. All rights reserved.

Adsorption phenomena of AlCl3 on silica in aqueous suspensions have been studied by means of micro-electrophoresis and titration techniques. In neutral and alkaline suspensions, pH > 4-5, aluminium hydroxide precipitates on the outer surface of the silica particles and in the course of time may migrate through the pores of the particles. The rate, of migration is highest in alkaline solution. Evidence is presented that an acid alumino-silica complex is formed.

In our previous studies, iron and aluminium based mixed hydroxides were prepared in different molar ratios and fluoride removal efficiencies were evaluated. It was found that the Fe/Al sample with 1:1 molar ratio exhibited maximum adsorption capacity for fluoride. In the present work detailed studies were carried out to understand the effect of fluoride concentration on kinetics, adsorbent dose and competing anion concentrations. Characterisation studies on the adsorbent by XRD, TGA, SEM-EDX, TEM and FT-IR analysis before and after fluoride adsorption were carried out to understand the adsorption mechanism. The particles were irregular in shape

Although highly effective, venom immunotherapy (VIT) may be responsible for local and systemic allergic reactions. There is a good theoretical basis for believing that purified aqueous and purified aluminium hydroxide adsorbed (so-called depot) extracts, commercially available in Europe, have the potential to reduce the incidence of VIT's side effects. The aim of this article is to review the literature on safety and effectiveness of purified preparations as well as compare them with nonpurified extracts.Old and new noncomparative studies reveal good tolerance of purified aqueous and purified depot extracts. In comparative trials purified extracts appear to be better tolerated than nonpurified extracts, whereas depot extracts seem to be safer than the corresponding purified aqueous preparation, especially in the prevention of severe large local reactions. The efficacy of purified aqueous and depot extracts is supported by studies using both sting challenge and in-field stings and is comparable to that of nonpurified preparations.The theoretical basis of the safer profile of purified extracts is supported by a number of clinical studies, making the use of purified depot preparations preferable for conventional treatment also by specialists with less experience in managing VIT. In specialized centres purified aqueous extracts may be preferred for faster build-up protocols. However, further prospective controlled studies are needed in order to evaluate the ability of purified extracts to reduce the frequency of severe systemic reactions over the corresponding nonpurified preparation.

In vitro interaction between artemether and some antacids and edible clay was investigated. Adsorption studies using three antacids namely, magnesium trisilicate, aluminium hydroxide, magnesium hydroxide as well as edible clay were carried out to determine extent of adsorption of artemether onto the adsorptive materials. A commercial artemether tablet brand was evaluated for some tablet properties and used to determine the effects of the adsorptive materials on tablet disintegration time and dissolution. Adsorption of artemether by the adsorbents followed the rank order; magnesium trisilicate (79.98%) > magnesium hydroxide (74.21%) > aluminium hydroxide (70.90%) > edible clay (37.10%). The adsorption of the drug onto the adsorptive materials was proportional to the drug concentration. The tablet parameters (weight, hardness, friability and content of active) of the commercial tablets met official BP specifications. There was significant increase ( p = 0.0012) in the disintegration times of the tablets in the presence of the antacids, edible clay and a commercial antacid suspension Emtrisil ® , however there was retardation of dissolution in the presence of the adsorptive materials. The percentage amount of artemether dissolved in 60 min and the order of dissolution retardation was as follows: Emtrisil ® (49.58%) > magnesium trisilicate (52.20%) > magnesium hydroxide (58.92%) > aluminium hydroxide (62.67%) > edible clay (67.42%) as against 88.86% in 0.1 N HCl solution. Co-administration of artemether with adsorptive antacid formulations and concomitant consumption of edible clay with artemether should be strongly discouraged. Keywords : artemether, adsorption, antacids, edible clay, dissolution

A series of layered double hydroxides (LDHs) with different metal cations were synthesized to remove phosphate in waste sludge filtrate from a municipal wastewater treatment plant for phosphorus recovery and to help control eutrophication. The highest phosphate adsorption capacity was obtained by using Zn-Al-2-300, that is LDHs with Zn/Al molar ratio of 2 and calcined at 300 degrees C for 4h. Circumneutral and mildly alkaline waters appeared suitable for the possible application of Zn-Al LDHs due to the amphoteric nature of aluminum hydroxide. Phosphate adsorption from the sludge filtrate by the LDHs followed pseudo-second-order kinetics, and the adsorption capacity at equilibrium was determined to be approximately 50 mg P/g. Adsorption isotherms showed that phosphate uptake in this study was an endothermic process and had a good fit with a Langmuir-type model. The absorbed phosphate can be effectively desorbed (more than 80%) from LDHs particles by a 5 wt% NaOH solution. The regeneration rate of used LDHs was approximately 60% after six cycles of adsorption-desorption-regeneration.

BACKGROUND: The present study has concentrated on investigating the fluoride removal potential of nano-scale aluminum oxide hydroxide (nano-AlOOH). A series of batch adsorption experiments were carried out to assess parameters that influence the adsorption process. The different parameters investigated include the effect of contact time, initial fluoride concentration, adsorbent dose, pH of the solution and co-existing anions. RESULTS: Most of the adsorption took place during the first 30 min and kinetic and equilibrium adsorption data show that the process obeys a pseudo-second-order kinetic equation and the Langmuir adsorption model. The fluoride removal efficiency is greater than 90% between pH 6 and 8 and decreases as pH values increase to 11. The presence of SO42− or PO43− in aqueous solution was found to reduce the fluoride uptake. Desorption studies showed that the fluoride can easily be desorbed at pH 13. CONCLUSION: Nano-AlOOH possesses a maximum fluoride capacity of 3259 mg F− kg−1, which is comparable with that of activated alumina. Maximum adsorption occurred at around pH 7, which makes nano-AlOOH a potential adsorbent for drinking water treatment. Copyright © 2009 Society of Chemical Industry

The adsorption of fluoride on lime stone (LS) and aluminium hydroxide impregnated lime stone (AlLS) was investigated using a batch adsorption technique. A series of experiments were under taken in an agitated batch adsorber to assess the effect of the system variables such as solution pH, dye concentration and temperature. Removal of fluoride was observed to be the most effective at pH 8. The langmuir and Freundlich isotherm models were applied to the equilibrium data. The results showed that the Freundlich equation fits better than the Langmuir equation. The maximum sorption capacities for the LS and AlLS adsorbents were found to be 43.10 mg/g and AlLS 84.03 mg/g respectively. The FTIR studies indicate that the adsorption of fluoride is physiorption. The adsorption of fluoride onto AlLS proceeds according to a pseudo-first-order model. The results reveal that the LS and AlLS can be economical for the removal of fluoride compared to many other expensive adsorbents.

This study evaluates the forces involved in the adsorption of abagovomab onto an aluminium hydroxide adjuvant in interstitial fluid and the influences of interstitial fluid and its components on this process. Abagovomab is a monoclonal, anti-idiotypic antibody developed as an immunovaccine for the treatment of ovarian cancer. Partial elution of abagovomab by a change in ionic strength indicates that electrostatic interactions influenced adsorption. Studies on the role of phosphate and simulated interstitial fluid on the adsorption demonstrated that ligand exchange is the main force of adsorption. A comparison of the adsorption capacity of abagovomab in the formulation with that in an environment imitating the in vivo environment using simulated interstitial fluid showed the adsorption capacity to decrease, the more the conditions resemble the in vivo environment after subcutaneous or intramuscular administration.

We experimentally determined the adsorption characteristics of natural, freshly precipitated Al(OH)3 for SO4 and PO4. The fresh Al precipitate occurred in stream sediment of Jachymov Stream (Czech Republic). The Al-rich sediment strongly adsorbed added PO4 prior to acidification experiment; this sorbed PO4 was released only after substantial dissolution of the sediment, at pH

Research on arsenate adsorption by Al hydroxides is common; however, relatively little is known on the kinetics of arsenate desorption from these Al hydroxides. The batch method was used to compare the phosphate-induced desorption kinetics of preadsorbed arsenate from the crystalline and amorphous Al(OH) 3 at pH 5.0, background electrolyte of 0.01 M NaNO 3 at 298 and 318 K. The results showed that both the amount of arsenate adsorbed by the amorphous Al(OH) 3 and the mole fraction of arsenate remaining adsorbed on the amorphous Al(OH) 3 after desorption were substantially greater than those in the crystalline Al(OH) 3 system. The second-order rate equation was chosen to compare the rates of arsenate desorption. The rate constant of arsenate desorption from the crystalline Al(OH) 3 was 3.8 to 15.5 times greater than that from the amorphous Al(OH) 3 in the reaction period, suggesting that, compared with the crystalline Al(OH) 3 , the arsenate adsorbed on the amorphous Al(OH) 3 was much more difficult to be desorbed by phosphate. The rate constant of arsenate desorption increased with the increase of phosphate concentration from 0.1 to 1.0 mM and the increasing temperature. Although the activation energy for arsenate desorption from the crystalline Al(OH) 3 in the fast reaction was greater than that from the amorphous Al(OH) 3 , the much greater frequency factor for the desorption from the former resulted in a higher desorption rate of arsenate from the crystalline Al(OH) 3 . This information is of fundamental significance in understanding the dynamics of remobilization and fate of arsenate in soil and related environments.

This study examined the potential reuse of powdered wastes (PW) generated during the sanding and sawing process in a local chemical company in Korea with the viewpoint of the recycling these wastes and minimizing the level of contamination. As the aluminium hydroxide inside the PW could be thermally converted to various types of aluminium oxides depending on the calcination temperature, the adsorptive properties could be changed and it may affect on adsorption ability. Calcination of the PW was performed for 3 h at 550 degrees C, 750 degrees C, and 950 degrees C. From the results, amorphous aluminium oxide was thermally generated by calcinating the PW at 550 degrees C and with further increase of temperature to 950 degrees C, the crystallinity of amorphous aluminium oxide was gradually increased. The physicochemical analysis of calcined powdered wastes (CPW) at various temperatures showed that more developed porosity was noted in the CPW as the calcinations temperature increased, whereas surface area was significantly decreased from 175.5 m2 g(-1) to 46.5 m2 g(-1). The removal efficiency of arsenate on the CPW decreased as the calcinations temperature increased from 550 degrees C to 950 degrees C. The CPW550 exhibited the highest adsorption capacities toward arsenate over pH range of 2-8 and showed a complete removal of the arsenate (10.0 mg L(-1)) within the first 10 min. Adsorption kinetic studies showed that the rate of arsenic adsorption on the CPW decreased with the increase of the calcination temperature. When the maximum adsorption capacity of arsenic onto the CPW was calculated by Langmuir equation, the CPW550 has the highest value as 43.9 mg g(-1).

The purpose of this study was a preliminary evaluation of mineral-carbon sorbents preparation possibility by the method of thermal decomposition of a mixture of aluminium oxide or hydroxide and acenaphthene and determination of their physicochemical properties. The conditions of carbonization were established and the changes of physicochemical properties of obtained materials as a function of organic substance content in the mineral-carbon mixture before the process of carbonization were tracked. In these investigations the methods of thermal analysis, low-temperature nitrogen adsorption and benzene vapors adsorption were applied.

Solubility, structure and position of charges in a peptide antigen sequence can be mentioned as being amongst the basic features of adsorption. In order to study their effect on adsorption, seven analogue series were synthesized from a MSP-1 peptide sequence by systematically replacing each one of the positions in the peptide sequence by aspartic acid, glutamic acid, serine, alanine, asparagine, glutamine or lysine. Such modifications in analogue peptide sequences showed a non-regular tendency regarding solubility and adsorption data. Aspartic acid and Glutamic acid analogue series showed great improvements in adsorption, especially in peptides where Lysine in position 6 and Arginine in position 13 were replaced. Solubility of position 5 analogue was greater than the position 6 analogue in Aspartic acid series; however, the position 6 analogue showed best adsorption results whilst the Aspartic acid in position 5 analogue showed no adsorption in the same conditions. Nuclear Magnetic Resonance structural analysis revealed differences in the -helical structureextension between these analogues. The Aspartic acid in position 6, located in the polar side of the helix, may allow this analogueto fit better onto the adsorption regions suggesting that the local electrostatic charge is responsible for this behavior.

The interaction of water and the alumina surface is comprehensively reviewed. Water can be incorporated in the alumina crystal structure resulting in the formation of aluminum hydroxides such as gibbsite. Alumina dissolves into water to an extent that depends primarily upon the solution pH and temperature. The soluble Al (III)aq species (hydrolysis products) likewise depend upon the solution pH, temperature, aluminum, and other salt concentrations. The development of charge on the surface of alumina is controlled by amphoteric surface ionization reactions. The charging behavior of both alumina powders and single crystal faces is compared. The differences can be explained by the reactivities of different types of surface hydroxyl groups. The substantial difference in surface charging behavior of single crystal sapphire and alumina powders indicates that experiments and modeling conducted on single crystals is of limited use in predicting suspension behavior. The atomic scale structure of the hydroxylated sapphire (0001) basal plane is nearly identical to the gibbsite (001) basal plane. The observed surface structures are consistent with the charging behavior of the surfaces. The role of surface charge on the adsorption of processing additives is briefly discussed. How surface charge and processing additives at the alumina aqueous solution interface influence surface forces between particles is reviewed. The influence of these forces on suspension properties such as rheological behavior is outlined. The importance of controlling these behaviors to improve colloidal ceramic powder processing is stressed.

Polystyrene sulfate (PSS) particles (301 nm mean diameter) were covered with single cationic dioctadecyldimethylammonium bromide (DDA) bilayers and used for antigen adsorption and presentation. The antigen was a mixture of purified 18/14 Taenia crassiceps proteins (18/14-Tcra). Firstly, the DDA/PSS assembly was characterized at 1 mM NaCl and 5 × 109 PSS particles/mL over a range of DDA concentrations (0.001–1 mM) by means of dynamic light scattering for particle sizing and zeta-potential analysis. 0.01 mM DDA is enough to produce homodisperse and cationic bilayer-covered particles. Secondly, under these experimental conditions, 18/14-Tcra adsorption isotherms onto biomimetic particles or aluminium hydroxide (Al(OH)3) yield limiting adsorption of 0.36 and 1.32 mg protein/mg biomimetic particles or Al(OH)3, respectively. Finally, in mice, superior humoral and cellular immunoresponse from serum IgG and footpad swelling was obtained for antigen/biomimetic particles in comparison to conventional Al(OH)3. Cationic bilayer-covered particles are a novel, highly organized and, possibly, general immunoadjuvant for antigen presentation and subunit vaccine design.

Aluminium hydroxide gels with a range of textures have been prepared by the hydrolysis of aluminium s- butoxide with water, aqueous ethanol and aqueous glycerol. Crystallisation was permitted to take place to varying extents by ageing of precipitates in their mother liquors at room temperature. Adsorption isotherms on the outgassed gels were of Types II and IV of the Brunauer classification. An examination of the data by plotting reduced isotherms (V/Vmversus P/Po) revealed the existence of reversible capillary condensation on some of the hydroxides, although the isotherms were of Type II. The Lippens de Boer t method has been found useful in locating the onset of capillary condensation in an adsorption isotherm, but the t-plot can be misleading with samples that have a spread of pore dimensions extending into both the micro- and transitional-pore regions. This situation appears to arise in pseudoboehmites aged for extended periods so that cementation is extensive. The principal factors influencing the texture of the gels appear to be the extent of crystallisation and the amount of inter-particle cementation. Thus amorphous material prepared in water was found to be porous whereas that precipitated in glycerol, which apparently protects the surface of the primary particles, was non-porous (or macro-porous). Transitional pore systems with the best definition were obtained with pseudoboehmites, especially with those formed by ageing in aqueous ethanol. In water, the ready conversion of pseudoboehmite to low-area, non-porous, bayerite is a complicating factor.