Hydrated Aluminum Sulfate Research Articles

Experimental investigation and Monte Carlo simulation of landfill leachate treatment using physicochemical method and a non-thermal plasma reactor

ABSTRACT Leachate treatment is one of the challenging subjects in the field of waste management. Leachate as a dumpling sites hazardous byproduct due to the high concentration of chemical oxygen demand (COD) and toxic compounds with dark colour is a potential pollutant of the environment, causing a lot of problems in the absence of treatment and direct discharge to the environment. In this study, the combinatory performance of sequential chemical flocculation and coagulation process and non-thermal plasma (NTP) technology on leachate from the Sarāvān city former controlled landfill, Iran, was investigated. The outcomes of Jar test illustrated that hydrated aluminium sulphate (PAC) was selected the best coagulant compared with hydrated aluminium sulphate (HAS) and ferric chloride (FC) to remove suspended solids and colour. The optimised parameters for 10% PAC pre-treatment were obtained 3 g lime and cationic 0.1 g polyelectrolyte per 1 litre of leachate. After pre-treatment by using jar test, NTP was used to remove turbidity, colour, COD and so forth. The sequential system-based all stages of pretreatment and NTP diminished the turbidity and colour removal to 98.6% and 99.2%, respectively. Furthermore, COD, BOD5, TSS, and TDS were also reduced. As a result, combination of pre-treatment and NTP technology are able to remove the landfill leachate effectively. Monte Carlo calculations exhibited that Al3+ and H2O2 had the most effects to decompose HA (Humic acid) compound in physicochemical pre-treatment and treatment stages.

Modified trichrome stain for faster and improved detection of intestinal protozoan parasites.

Permanent stains such as trichrome have better sensitivity but are time-consuming and the fixative includes toxic mercuric chloride. Thus, a newer modification was tested and found to be a superior, faster and safer staining technique for intestinal parasitic detection. Our study lasted 9 months and a single stool sample was collected from each enrolled patient. We evaluated classical trichrome (T1 - using Schaudinn fixative) with newer modifications, which involved different fixatives with mordant combinations (T2 - acetic acid + hydrated aluminium sulphate, T3 - citric acid + copper sulphate hydrate). Conventional PCR targeting Entamoeba histolytica, Giardia lamblia and Cryptosporidium spp. was taken as the reference. Out of 175 stool samples, 25.1% protozoa were identified by wet mount, 24% by each T1 and T2, 25.7% by T3. Statistically, T3 and T2 had higher sensitivity as compared to T1 and wet mount when PCR was used as reference.

Preparation of mullite whiskers from high alumina fly ash and its reinforced porous structure

Porous has been formed in samples when mullite whiskers are prepared by firing compacts of high-aluminum fly ash and ammonium aluminum sulfate hydrate with a small amount of sodium dihydrogen phosphate and SiO2 at high temperature for 4 h. The effects of the particle size of fly ash, the firing temperature, and the content of sodium dihydrogen phosphate on the porous structure and the formation of whiskers are discussed. The results show that the smaller the particle size of fly ash, the more uniform porous in sample after fired, which is more conducive to the nucleation of mullite whiskers. Additionally, the amount of whiskers formation increased significantly with the firing temperature increasing, nonetheless, the pore size of porous reduced and the aspect ratio of whiskers gradually increased by reducing the content of sodium dihydrogen phosphate; owing to the reduction of glass melt in the matrix, the Al2O3/SiO2 ratio of the formed mullite whiskers gradually decreased. Thus, in order to obtain mullite whiskers self-reinforcement porous ceramics with the relatively low cost and no pollution to the environment, through the above preparation process, the addition amount of sodium dihydrogen phosphate and calcination temperature should be properly controlled.

A novel approach for the defluorination of groundwater using trivalent-metal hydroxide/bone-char composite adsorbent

The adsorption capacity of trivalent-metal hydroxide-bone char composite (TMH/BC) for defluorination of ground water was investigated. The operating parameters for the bone char (BC) production process were optimized. The best adsorption efficiency of 88%, was recorded for the BC produced at 450 °C for 3 h of thermal treatment. The BC impregnated in hydrated aluminum sulfate and coated with the trivalent metal oxide (Al(OH)3) showed higher fluoride removal efficiency of 99% compared to BC (88%) and hydroxyapatite (HAP) (87%). The SEM and EDS characterization for the modified BC confirmed the effect of thermal treatment and aluminum dispersion on the surface of the BC. The core elements determined in TMH/BC were calcium, carbon, phosphorus, oxygen, aluminum, and sodium. The fluoride was identified to be linked with the aluminum composites. The TMH/BC composite has improved specific surface area of 379 m2/g compared to GBC with 350.2 m2/g. The adsorption kinetic model of TMH/BC was fitted to the Temkin isotherm model while BC and HAP were fitted with Langmuir and Freundlich isotherms. Due to its higher adsorption ability compared to the tested adsorbents, TMH/BC was more suitable adsorbent to remove excess fluoride present in the groundwater.

Kinetic analysis of poly-aluminum sulfate hydrate for low-temperature thermochemical heat storage

A summary of the research undertaken on poly-aluminum sulfate is performed revealing several disagreements on important thermal properties of the material. Nevertheless, the energy density reported highlights that the material is promising for thermochemical heat storage (THS). A thorough thermal analysis (TA) of (Al2(SO4)3·xH2O) is conducted using TA devices and the ICTAC kinetics committee recommendations, to identify its thermal properties, its most stable form (Al2(SO4)3·18H2O, and the conditions of its use for low-temperature THS (80 °C and 125 °C under atmospheric pressure. The material decomposes in four endothermic stages as shown in the thermal curves and illustrated by possible reaction formulas, three of which are dehydrations followed by a final decomposition. The non-isothermal kinetics of the dehydration for PAS has been determined by the methods of Coats-Redfern (CR) and Achar-Brindley-Sharp (ABS) with 19 different reaction models. It is found that most reaction models exhibit a linear trend. The Janders reaction model is appropriate for the first dehydration with an activation energy of ca. 33.248 kJ/mol by CR and 30.759 kJ/mol by ABS, respectively. Both the power law and the Avrami-Erofeev model can be used for the second stage with an activation energy of ca. 235 kJ/mol. The overall kinetics modeling for aluminum sulfate hydrate is successful for PAS implying the substitution of aluminum sulfate with PAS in applications.

Fluoride pollutants removal from industrial wastewater

BackgroundThe main object of the present study is the industrial wastewater effluent treatment resulting from a solar cell manufacturing process, which is a Joint Egyptian Chinese Renewable Energy laboratory, in Sohag Governorate. Fluoric and hydrochloric acids are the main pollutants causing a pH of 1 to 3. The effluent is neutralized by the addition of both potassium hydroxide and calcium hydroxide to permit the precipitation of the resulting sparingly soluble calcium fluoride. The chlorides are partially precipitated as calcium chloride, and the further addition of hydrated aluminum sulfate is used to precipitate the remaining extra chloride as an insoluble complex to reach the allowable chloride concentration in the treated effluent. Set of experiments at bench and pilot scales were run to achieve the optimum conditions for defluorination and dichlorination taking into consideration not exceeding the allowable ranges of pollutants as soluble salts in the final effluent.ResultsExperimental results showed that the performance of a pilot scale was satisfactory in fluorides, chlorides, and dissolved solids by 97.64, 78.85, and 79.4% removal, respectively. Based on these results a full-scale industrial treatment unit was designed for construction and operation as a treatment unit for industrial wastewater contaminated with fluorides as main pollutant.ConclusionsThe recommended treatment procedure succeeded in the removal of fluorides and chlorides as main contaminants in the effluent which permit the use of treated water in the irrigation of non-edible plants, according to Egyptian Code No. (501/2015).

The influence of environmental factor on the coagulation enhanced ultrafiltration of algae-laden water: Role of two anionic surfactants to the separation performance

With the acceleration of urbanization and the improvement of people's living standards, more chemicals that humans rely on are entering the city and surrounding water bodies. Anionic surfactants are one of the essential products for human beings. It is also one of the inducements that cause the eutrophication. The algae-laden water caused by eutrophication is a headache in the traditional water treatment process. To solve the problem, ultrafitration combined process was widely investigated to treat the algae-laden water. The presence of stimuli, low concentration anionic surfactant, probably interfere the performance of ultrafiltration process during algae-laden water treatment. In this study, the influence of two typical anionic surfactants, sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (LAS), on the performance of coagulation-enhanced ultrafiltration was investigated. The aluminum sulfate hydrate and iron sulfate hydrate were respectively employed as coagulant. Based on the residual turbidity and zeta potential, 4 mg/L Al and 8 mg/L Fe were determined as the optimal coagulant dosage. The floc morphology confirmed that Al-algae flocs with lower fractal dimension (Df) were looser and more porous compared to Fe-algae flocs. More coagulant was depleted by LAS due to the better hydrophobicity of LAS. During the filtration process, LAS caused a larger flux reduction compared with SDS regardless of the coagulant that was used. More organic compounds penetrate into membrane pores and block the pores with the presence of LAS since algal cell aggregation was weakened. Finally, the rejection of organic compounds by the coagulation-enhanced ultrafiltration process was studied, and the co-existing surfactants can cause effluent deterioration. Therefore, the presence of surfactants has a negative effect to the ultrafiltration treatment of algae-laden water.

Sodium hydroxide substitution in slag activating mixes: A potential pathway to more sustainable slag-based binders

Alkali-activated slag is commonly used as a cement substitute to reduce the environmental footprint of construction materials. Nonetheless, the use of significant amount of alkaline activators, such as sodium silicate or sodium hydroxide, can be detrimental in terms of global warming potential impact. The aim of this work is to use complementary activators as partial replacement of sodium hydroxide, and therefore reduce the environmental footprint of the activated slag binder. Calcium hydroxide, calcium carbonate, calcium sulfate and magnesium oxide are used as complementary activators in binary or ternary activating mixes. The compressive strength at 28 days are higher (up to 18%) for the calcium carbonate and calcium sulfate-activated samples as compared to the reference activated with sodium hydroxide only. The characterization of the microstructure shows that the proportion of activated slag and the nature of hydrates formed depend on the nature of complementary activators. Calcium aluminum silicate hydrates and hydrotalcite are favored by the presence of calcium carbonate and magnesium oxide, and a sodium calcium aluminum sulfate hydrate is formed in the presence of calcium sulfate. The life cycle impact assessment (LCIA) performed on the different formulations shows that a partial substitution of sodium hydroxide is a potential option to develop more sustainable slag-based binders.

Chitosan dressings containing inorganic additives and levofloxacin as potential wound care products with enhanced hemostatic properties

Despite the progress in the development of hemostatic products, efficient treatment solutions to control hemorrhage upon wounding are still necessary. Chitosan (CS) is a natural hydrogel-forming polysaccharide, easy to modify for specific applications. Inorganic compounds in turn possess documented hemostatic properties. In this study, innovative hemostatic products based on CS, containing the inorganic additives aluminum chloride, aluminum sulfate hydrate or iron(III) sulfate and the antibiotic Levofloxacin were prepared, and their potential use as hemostatic materials was investigated. Structural characteristics, physical state and drug loading/release properties were examined. Strong interactions developed between CS and the additives, the pore size in the resulting products was affected, swelling increased up to 2500% and the stability of the wound dressings improved. The crystallinity of Levofloxacin reduced, and its release was immediate. The materials showed biocompatibility upon contact with cultured keratinocytes, hemocompatibility and hemostatic efficacy in vitro and in vivo.

Recovery of scandium and neodymium from blast furnace slag using acid baking-water leaching.

The current study puts the emphasis on developing a pyro-hydrometallurgical process, called acid baking–water leaching, to recover scandium and neodymium from blast furnace slag produced by the ironmaking industry. In this process, the feed is mixed with concentrated sulfuric acid, digested at 200–400 °C, and leached in water at ambient conditions. This process offers several advantages including less acidic waste generation and rapid kinetics. With fundamental investigations into the digestion mechanism, acid to slag mass ratio and baking temperature are determined to have the most significant positive and negative impacts, respectively. At low acid to slag ratio, the silicate bearing phases in the feed do not digest, resulting in low extraction. At 200 °C baking temperature, a hydrated aluminum sulfate ((Al(H2O)6)2(SO4)3(H2O)4.4) phase with weak hydrogen bonds is formed that leaches in water rapidly (<10 min); while at 400 °C, Al2(SO4)3 with strong ionic bonds is formed that leaches at slower kinetics (>4 h). Fundamental investigations into the water leaching process indicate that the diffusion of water through the firm solid product (ash layer) is the rate determining step. We expect the results of this study would help enable valorization of industrial byproducts, in particular ironmaking slag.

Alternative Staining Method for Four Parasites that are Difficult to Identify through Direct Inspection.

The aim of the present study was to identify Blastocystis spp. (particularly the granular form), Dientamoeba fragilis, and Entamoeba histolytica/dispar trophozoites, which are difficult to identify using wet mount, as well as Giardia intestinalis cysts, which are difficult to identify by unexperienced researchers, in fresh fecal samples within 5 min using a different fixative employing trichrome staining. The slides were fixed by fixatives based ethyl alcohol, formalin, acetic acid, and distilled water including four different mordants (divalent or polyvalent metals that form coordination complex with some dyes) consisted of zinc sulfate hydrate, copper sulfate hydrate, aluminum sulfate hydrate, and ferric sulfate hydrate using a modification of Gomori's trichrome staining. Samples fixed by Schaudinn fixative including mercury chloride were stained using Wheatley modification of Gomori's trichrome staining as gold standard for control and comparison. Regarding D. fragilis and E. histolytica/dispar trophozoites, similar results were obtained among the slides stained by classical fixation/staining method and those stained by the alternative method. However, regarding Blastocystis spp. and Giardia intestinalis cysts, classical fixation/staining method was relatively superior to the alternative method. Although the alternative method is slightly inferior to the classical fixation/staining method, it seems to be a good option with respect to the process time.

Mechanochemical synthesis of α‐Al2O3‐Cr3+ (Ruby) and χ‐Al2O3

AbstractIn this work we present a unique method to synthesize χ‐Al2O3 and α‐Al2O3 doped with Cr3+ (ruby). The ruby is synthesized by mechanical milling of pseudoboehmite that is doped in‐situ with chromium. The doping is carried by adding chromium sulfate hydrate to an aqueous solution rich in aluminum sulfate hydrate. The pH in the solution is controlled to be between 9 and 10 by using ammonia, which induces the pseudoboehmite precipitation. The Cr3+ is added for its remarkable effects on the detectability of ruby emitting luminescent R1 and R2 bands that are traceable in Raman spectroscopy. The formation of ruby is detected at milling times as short as 5 hours and increased with the milling time. Ruby phase is further confirmed by means of true atomic resolution Transmission Electron Microscopy (TEM).

Atmospheric corrosion comparison of antirust aluminum exposed to industrial and coastal atmospheres

The atmospheric corrosion behavior of antirust aluminum alloys 3A21 and 5A05 in industrial and coastal atmospheres was investigated and compared. Weight loss results, together with corrosion morphology characterization, suggest that the coastal atmosphere is much more corrosive to antirust aluminum than the industrial atmosphere. 5A05 alloy has better localized corrosion resistance than 3A21 alloy, and the corrosion rate shows a decreasing tendency with exposure time. After 3 years of exposure, the antirust aluminum samples only suffer pitting corrosion attack and retain their mechanical properties well. In the two atmospheres, the corrosion products are mainly oxides, aluminum hydroxychloride, aluminum sulfate hydrate, and basic aluminum sulfate. Besides, the atmospheric corrosion mechanism and the corrosion comparison between the two atmospheres were also discussed.

Tunable morphology of aluminum oxide whiskers grown by hydrothermal method

Hydrothermal method was used to grow α-Al2O3 whiskers by using hydrated aluminum sulfate, urea and poly ethylene glycol as precursors. X-ray diffraction (XRD), selected area electron diffraction (SAED), and high resolution transmission electron microscope (HRTEM) were used to characterize morphology of the whiskers. By increasing the pH of the solution (by adding extra NaOH), by adjusting calcination times and atmospheres it was possible to tune the whiskers morphology and their aspect ratio. Aspect ratio as high as 25 was obtained after hydrothermal treatment of a solution having pH 3 followed by calcination in Ar or N2 atmosphere at 1200 °C for 6 h.

Chemical and physical transformations of aluminosilicate clay minerals due to acid treatment and consequences for heterogeneous ice nucleation.

Mineral dust aerosol is one of the largest contributors to global ice nuclei, but physical and chemical processing of dust during atmospheric transport can alter its ice nucleation activity. In particular, several recent studies have noted that sulfuric and nitric acids inhibit heterogeneous ice nucleation in the regime below liquid water saturation in aluminosilicate clay minerals. We have exposed kaolinite, KGa-1b and KGa-2, and montmorillonite, STx-1b and SWy-2, to aqueous sulfuric and nitric acid to determine the physical and chemical changes that are responsible for the observed deactivation. To characterize the changes to the samples upon acid treatment, we use X-ray diffraction, transmission electron microscopy, and inductively coupled plasma-atomic emission spectroscopy. We find that the reaction of kaolinite and montmorillonite with aqueous sulfuric acid results in the formation of hydrated aluminum sulfate. In addition, sulfuric and nitric acids induce large structural changes in montmorillonite. We additionally report the supersaturation with respect to ice required for the onset of ice nucleation for these acid-treated species. On the basis of lattice spacing arguments, we explain how the chemical and physical changes observed upon acid treatment could lead to the observed reduction in ice nucleation activity.

Effect of iron/aluminum hydrolyzed precipitate layer on ultrafiltration membrane

In order to fully understand the effect of iron/aluminum hydrolyzed precipitate layer on ultrafiltration (UF) membrane, both hydrolyzed precipitate layers on a flat sheet UF membrane surface were investigated. The results showed that the aluminum hydrolyzed precipitate layer was much better than that of the iron hydrolyzed precipitate layer on protecting the UF membrane. X-ray diffraction (XRD) demonstrated that the structure of the aluminum precipitate layer was amorphous. Although the precipitate layer of aluminum sulfate hydrate could cause a slight flux decline, it improved the protection of the UF membrane to some extent. The rejection of different pollutants with Al precipitate layer was much higher than that without Al precipitate layer and many humic acid (HA)/bovine serum albumin (BSA) with different molecular weights could be adsorbed by the Al precipitate layer, especially for those with larger molecular weight. The rejection of 1:1 (by weight) HA/BSA mixture was higher than that of only HA or BSA in the presence of the precipitate layer of aluminum sulfate hydrate.

Foaming control in activated sludge treatment plants by coagulants addition

This paper presents the results of an investigation that aimed to evaluate the efficiency of various inorganic coagulants and organic polymers to combat filamentous foaming and bulking problems, caused by the proliferation of M. parvicella and/or Gordona amarae. The duration of the investigation covered 14 months. During this period foam samples were taken from the aeration basins of two full-scale wastewater treatment plants that contained high concentrations of M. parvicella and/or Gordona amarae. Bench scale batch experiments were conducted to evaluate the efficiency of the following coagulants: ferric chloride, ferrous chloride, polyaluminium chloride, hydrated aluminium sulphate, cationic polymer. In addition bench scale batch experiments (ammonia uptake rate (AUR) and oxygen uptake rate (OUR) measurements) were conducted to evaluate the toxicity effects of the most promising coagulants on nitrification and organic matter removal. Polyaluminium chloride (PAX) and cationic polymer proved to be the most efficient among all the coagulants investigated. By adding PAX (aluminium application of 6.6 – 11.5 g Al3+ kg-1 MLSS) a general improvement of the settling properties of the activated sludge was achieved. High foaming control was also achieved with cationic polymer addition at doses in the 3.5 to 4.5 g kg-1 MLSS. According to microscopic analysis of the sludge samples following PAX or polymer addition, the floc strength was improved and flocs appeared more compact and dense. In addition both M. parvicella and Gordona amarae filamentous organisms were embedded inside the floc material, making access to particulate and colloidal substrates more difficult due to increased diffusional resistance. PAX or polymer addition, at the above specified doses, resulted in a 75 – 100 % reduction of the sludge foaming potential. PAX potential toxicity was investigated in the context of this study. PAX addition caused no inhibition on autotrophic and heterotrophic bacteria that perform nitrification and organic carbon removal, respectively. The estimated operational costs of PAX and polymer addition for foaming control, are approximately 0.0057 euros m-3 and 0.0026 euros m-3 of wastewater treated, respectively.

Physico–chemical properties of CdO–Al2O3 catalysts. I – Structural characteristics

Alumina gels AN6 and AN7 were prepared by precipitation with NaOH from hydrated aluminum sulfate at pH 6 and 7, respectively. A third alumina gel AA7 was similarly prepared, but by precipitation with 30% ammonia. Pure cadmia C8 and C9 were precipitated from cadmium sulfate at pH 8 and 9 using NaOH. Five mechanically mixed gels ACM (1:0.25), ACM (1:0.5), ACM (1:1), ACM (0.5:1) and ACM (0.25:1) were prepared by thoroughly mixing the appropriate molar ratios of AN7 and C8. Also, five coprecipitated gels ACC (1:0.25), ACC (1:0.5), ACC (1:1), ACC (0.5:1) and ACC (0.25:1) were coprecipitated by dropping simultaneously the appropriate volumes of 1M aluminum sulfate, 1M cadmium sulfate and 3M NaOH. Calcination products at 400, 500, 600, 800 and 1000°C were obtained from each preparation.TG–DTA patterns of uncalcined samples were analyzed and the XRD of all 1000°C-products and some selected samples calcined at 400–800°C were investigated. The thermal behaviors of pure and mixed gels depend on the precipitating agent, pH of precipitation, chemical composition and method of preparation. Generally, calcination at temperatures below 800°C gave poorly crystalline phases. Well crystalline phases are obtained at 800 and 1000°C. For pure alumina γ-Al2O3 was shown as 400°C-calcination product that transforms into the δ form around 900°C and later to θ-Al2O3 as a major phase and α-Al2O3 as a minor phase at 1000°C. CdO was shown by 500°C-calcined cadmia gel that showed color changes with rise of calcination temperature. The most stable black cadmium oxide phase (Monteponite) is obtained upon calcination at 1000°C. Thousand degree celsius- calcined mixed oxides showed θ-Al2O3, α-Al2O3, CdAl2O4 and monteponite which dominate depending on the chemical composition.

Hydrothermal synthesis of Al-doped ZnO nanorod arrays on Si substrate

Abstract High-density, single-crystal, quasi-aligned, Al-doped ZnO nanorod arrays were grown on a silicon substrate using a low temperature hydrothermal process. Different Al atomic concentrations have been successfully doped into the ZnO lattice using different Zn and Al precursors in the synthesis solution. The effects of Al doping on the microstructure characteristics, elemental composition and optical properties of the nanorod arrays were studied. It has been shown that the morphology, density, and surface compositions of ZnO nanorod arrays are sensitive to the concentration and variety of zinc and aluminum precursors. The ratio of ultraviolet to visible emission peak (IUV/IVis) increases as the aluminum nitrate concentration increases up to 5 mM. The best optical property was obtained for Al-doped ZnO nanorods grown in a 0.04 M zinc acetate dihydrate solution with 5 mM of aluminum sulfate hydrate. The improved optical property in Al-doped ZnO nanorods can be attributed to the decrease in oxygen deficiency after Al doping.

Natural organic matter removal from Tigris River water in Baghdad, Iraq

Experimental measurements were conducted to determine the level of natural organic matter (NOM) and its disinfection by-products formation potential (DBPFP) for Tigris River water in Baghdad. The results showed that raw water total organic carbon (TOC) levels have a potential to produce concentrations of trihalomethanes (THM) exceeding the USEPA stage 1 guideline of 80 μg/l during 7 months of the year comprising spring, summer and early autumn (March–September). Treatment options were tested for their efficacy to reduce raw water NOM; namely granular activated carbon (GAC) adsorption, enhanced coagulation (EC), and combination of both. With a raw water TOC concentration of 2.2. mg/l, GAC adsorption was found to be capable of treating 3300 be volumes up to breakthrough at UV 254 absorbance removal of 99%. EC treatment achieved TOC removal efficiencies of 18% and 23% with hydrated aluminum sulfate dose of 4 mg/l as Al and ferric chloride dose of 8 mg/l as Fe respectively. These TOC removal values increased to 22% and 24% respectively when raw water initial pH was reduced from 7.9 to 6.5 prior to coagulation. GAC-treated water volume was increased by 12% when a column was fed with either coagulated-only or acidified-only raw water. However, this volume-increase reached 59% when the GAC column was fed with acidified-coagulated raw water. Presently, EC without raw water acidification is capable of reducing NOM to an acceptable level according to USEPA requirements. Use of GAC (with/without pretreatment) is a future option dependent on the raw water trophic state.