Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Environmental fate and pathways

 

 

Aluminum sulphate is stable and having a high melting point of 770 deg °C .Aluminim sulphate is stable in air, sunlight and to metals.

Solid product is stable for long periods if kept dry and at ambient temperatures. Legal shelf-life of aluminim sulphate is 60 months.

 

Aluminum sulphate cannot be oxidized and atmospheric transformations would not be expected to occur during transport. If aluminum metal particulates were released to air during metal processing, they would be rapidly oxidized. It is not applicable for an inorganic compound wich dissociates

 

Aluminum sulphate is an inorganic substance with a relatively large number of oxygen atoms per molecule but no hydrogen or carbon atoms. There are no structural alerts with regard to oxidising potential of the substance.

 

In air,hydratedaluminum sulfate will react with moisture and produce sulfuric acids, and aluminum oxide. Since these aluminum sulfate is usually not emitted to air, the amount of aluminum present in air would be negligible compared with the amount coming from natural erosion of soil.

 

Aluminum sulphate which, as an inorganic compound, would not be expected to biodegrade.

Biodegradable matter is generally organic material such as plant and animal matter and other substances originating from living organisms, or artificial materials that are similar enough to plant and animal matter to be put to use by microorganisms.

 

 

Hydrolysis is a chemical reaction during which molecules of water (H2O) are split into hydrogen cations (H+, conventionally referred to as protons) and hydroxide anions (OH−) in the process of a chemical mechanism).

 

When released into water, the aluminum sulphate hydrolyses to form aluminum hydroxides.

Reactions between aluminum sulphate, water and associated “impurities” result in the formation of a floc, which separates from the water phase to form alum sludge. A small fraction of the aluminum can stay in the water in either colloidal or dissolved form.The different reactions involved in the formation of aluminum hydroxide in aqueous solutionwasdescribed; the overall reaction can be represented by the following equation:

Al2(SO4)3+ 6H2O<=>2Al(OH)30+ 3H2SO4

The aluminum hydroxide present in sludge is expected to remain mostly solid following release into surface water.Experiments wereshowed that less than 0.2% of the aluminum hydroxide present in sludge was released in supernatant water at a pH of 6 and less than 0.0013% was released at pH 7.65. In both cases, aluminum hydroxide was present mostly in particulate form. At these pH values, aluminum solubility is low and kinetics favour the formation of solid aluminum hydroxide.

 

When used to treat sewage water, alum will also react with phosphate, as shown in the following reaction:

Al2(SO4)3+ 2PO43– <=>AlPO4(s) + 3SO42–

 

This process has been used for many years to treat phosphorus in wastewaters, as well as to reduce phosphorus levels in runoff from land fertilized with poultry litter and restore phosphorus-enriched eutrophic lakes .

Aluminum is a strongly hydrolysing metal and is relatively insoluble in the neutral pH range (6.0–8.0) . In the presence of complexing ligands and under acidic (pH < 6) and alkaline (pH > 8) conditions, aluminum solubility is enhanced. At low pH values, dissolved aluminum is present mainly in the aquo form (Al3+).

 

Hydrolysis occurs as pH rises, resulting in a series of less soluble hydroxide complexes (e.g., Al(OH)2+, Al(OH)2+). Aluminum solubility is at a minimum near pH 6.5 at 20°C and then increases as the anion, Al(OH)4–, begins to form at higher pH.

 

Temperature has been shown to influence the solubility, hydrolysis and molecular weight distribution of aqueous aluminum species as well as the pH of solutions.There wasreported a higher degree of aluminum hydrolysis and greater polymerization to high molecular weight species in inorganic aluminum solutions stored for one month at 25°C compared with those stored for an equivalent period at 2°C. The researchers hypothesized that more advanced polymerization evident at the higher temperature resulted in more deprotonation and condensation reactions, possibly accounting for the observed lower pH of the 25°C test solutions (range 4.83 to 5.07 versus 5.64 to 5.78 in the solutions at 2°C).

 

 

In water, Aluminum sulphate is likely to disappear rapidly, because of its high water solubility and non- volatility; 

 

Chemical decomposition or phototransformation induced by light or other radiant energy is not possible because Aluminium sulphate as an inorganic compound cannot broken down by photons.

 

 

Aluminum sulphate will not degrade in surface water and goes into solution without undergoing chemicals decomposition. Aluminium ions will remain as aluminium ions.

When released into water, the aluminum sulphate hydrolyses to form aluminum hydroxides.

Reactions between aluminum sulphate, water and associated “impurities” result in the formation of a floc, which separates from the water phase to form alum sludge. A small fraction of the aluminum can stay in the water in either colloidal or dissolved form.The different reactions involved in the formation of aluminum hydroxide in aqueous solution was described; the overall reaction can be represented by the following equation:

Al2(SO4)3+ 6H2O<=> 2Al(OH)3 0+ 3H2SO4

The aluminum hydroxide present in sludge is expected to remain mostly solid following release into surface water.Experiments were showed that less than 0.2% of the aluminum hydroxide present in sludge was released in supernatant water at a pH of 6 and less than 0.0013% was released at pH 7.65. In both cases, aluminum hydroxide was present mostly in particulate form. At these pH values, aluminum solubility is low and kinetics favour the formation of solid aluminum hydroxide.

When heated between 770 and 860°C Aluminum sulphate decomposes to produce Aluminium oxide and Sulfur trioxide. It combines with water forming hydrated salts of various compositions

Al2(SO4) 770 - 860°C    2Al2O3 + 6SO2 + 3O2

Al2(SO4)3 + 6 NaHCO3 → 3 Na2SO4 + 2 Al(OH)3 + 6 CO2

Levels of background oxygen in surface water also indicate a lack of significant degradation.

 

Aluminium sulphate will bioaccumulate in aquatic and terrestrial species

Numerous field and laboratory studies have demonstrated that fish accumulate aluminum (as aluminium sulphate) in and on the gill. It has been suggested that the rate of transfer of aluminum (as aluminium sulphate) into the body of fish is either slow or negligible under natural environmental conditions . The initial uptake of aluminum (as aluminium sulphate) by fish essentially takes place not on the gill surface but mainly on the gill mucous layer.

Fish may rapidly eliminate mucus and the bound aluminum following the exposure episode.There wasfound that depuration of aluminum from the gills of Atlantic salmon (Salmo salar) was extremely rapid once fish were transferred into clean water. The authors suggested that the rapid loss is due to expulsion of aluminum bound to mucus.

 

In Atlantic salmon (Salmo salar), steady state BCFs of 76 and 190 were reported after a 60-day exposure and BCFs of  362 after a45-day exposure to aluminium (aluminium sulphate) at pH 5.6 to 5.8.

A BCF of 155 has also been reported in rainbow trout (Oncorhynchus mykiss) gill tissue after a 3-day exposure to aluminium (as aluminium sulphate).

Steady-state BCF values as high as 14,000 have been reported in Asellus aquaticus after a 20-day exposure to aluminium (as aluminium sulphate). However, much of the accumulation was due to passive adsorption of aluminium onto the cuticle. Therefore, these BCFs are not representative of the internal concentration of aluminium and over estimate accumulation in this species.

 

A steady state BCF of 19,000 has been reported for the gut tissue of the fresh water snail Lymnaea stagnalis. However, the gut of the snail contains mucus that has a high affinity for metals such as aluminium. The mucus can be excreted and may be a primary route for the removal of metals from the snails. It was reported that mucus may have remained during the analysis of the gut and so this BCF may overestimate the accumulation of aluminium A BCF of 155 has also been reported in rainbow trout (Oncorhynchus mykiss) gill tissue after a 3-day exposure to aluminium (as aluminium sulphate) in this species.

A BCF of 0.13 to 0.5 in the whole body for the snail Helix aspersa has been reported.

 

BCFs for terrestrial plants were calculated based on data cited in the review by Bélanger et al. (1999). For both hardwood and coniferous species, the calculated BCF ranged from 5 to 1,300 for foliage and from 20 to 79,600 for roots in studies done with aluminum solutions. For those conducted with soil, BCFs were lower for both foliage (0.03–1.3) and roots (325–3,526). BCFs calculated for grain and forage crops ranged from 4 to 1,260 infoliage and from 200 to 6,000 in roots for experiments done with solutions. For soil experiments, the foliar BCF varied from 0.07 to 0.7.

 

The estimated BCF of 3.16 L/kg wet-wt was measured by calculation from EPI SuiteTM v4.0 Program. This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency) .

 

BCFBAF Program (v3.00) Results:

==============================

SMILES : [Al](O)S(=O)(=O)O(=O)S(O(=O))(=O)=OS(O([Al]))(=O)=O

CHEM  :aluminium sulphate

MOL FOR: H4 O12 S3 Al2

MOL WT : 346.17

--------------------------------- BCFBAF v3.00 --------------------------------

Summary Results:

Log BCF (regression-based estimate): 0.50 (BCF = 3.16 L/kg wet-wt)

Biotransformation Half-Life (days) : 1.48e-005 (normalized to 10 g fish)

Log BAF (Arnot-Gobas upper trophic): -0.05 (BAF = 0.893 L/kg wet-wt)

 

Log Kow (experimental): not available from database

Log Kow used by BCF estimates: -7.82

 

Equation Used to Make BCF estimate:

Log BCF = 0.50

 

Correction(s):                   Value

Correction Factors Not Used for Log Kow < 1

 

Estimated Log BCF = 0.500 (BCF=3.162 L/kg wet-wt)

 

 

 

The estimated BCF (upper trophic) of 0.893 L/kg wet-wt was measured by calculation from EPI SuiteTM v4.0 Program. This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency) .

 

Summary Results:

Log BCF (regression-based estimate): 0.50 (BCF = 3.16 L/kg wet-wt)

Biotransformation Half-Life (days) : 1.48e-005 (normalized to 10 g fish)

Log BAF (Arnot-Gobas upper trophic): -0.05 (BAF = 0.893 L/kg wet-wt)

 

Log Kow (experimental): not available from database

Log Kow used by BCF estimates: -7.82

 

Equation Used to Make BCF estimate:Log BCF = 0.50

 

Correction(s):                   Value

Correction Factors Not Used for Log Kow < 1

Estimated Log BCF (upper trophic) = -0.049 (BCF = 0.893 L/kg wet-wt)

 

 

 

 Adsorption of aluminium occurs only under pH conditions where it hydrolyzes togive various hydrolysis products.Progressive hydrolysis leads to the formation of colloidalaluminium hydroxide.

 

The rate at which soluble aluminium sulphate are gradually leached away is dependent upon the water supply. In humid regions, the upper layers of soil and rock are kept thoroughly leached, and as fast as they are formed the soluble products are removed in the drainage water. In semi-arid regions, the soils are not fully leached and soluble substances tend to accumulate.

 

When dissolved in a large amount of neutral or slightly-alkaline water, aluminium sulfate hydrolyzes to form the aluminium hydroxide precipitate(Al(OH)3) and a dilute sulfuric acid solutionandreduce the pH of soil.

 

The anhydrous form occurs naturally as a rare mineral millosevichite, found e.g. in volcanic environments and on burning coal-mining waste dumps. Aluminium sulfate is rarely, if ever, encountered as the anhydrous salt. It forms a number of different hydrates, of which the hexadecahydrate Al2(SO4)3•16H2O and octadecahydrate Al2(SO4)3•18H2O are the most common. The heptadecahydrate, whose formula can be written as [Al(H2O)6]2(SO4)3•5H2O, occurs naturally as the mineral alunogen.

 

 The above information indicates that aluminium sulphate has a propensity to leach through soil if water is applied, i.e. it does have mobility through soil, and providing sufficient water is present. As it moves downwards into layers where the water content is low, the leaching will stop.

 

On this basis, it does not have a high potential for adsorption to soil if water is not present andonly part of thealuminium sulphatein the solid phase is adsorbed.

 

On the other basis if water is present aluminium sulphate as aluminium hydroxide precipitate (Al(OH)3) have a high potential for adsorption to soil.

-          soil, the colloidal surface can adsorb large quantities of aluminium

 

Selectivity of cation adsorption

The affinity of most cations for an adsorbing surface is greater for divalent than for monovalent ions, and for large cations than for small ones of the same charge because the larger the cation the less hydrated it is. The usual affinity is:

 

Al3+> Ba2+>Sr2+>Ca2+>Mg2+= Cs+>Rb+>K+= NH4+>Na+

 

The soil cations that are readily adsorbed onto soil colloids can be divided ino two groups. Firstly there are the base catoins, which include the important plant nutrients Ca2+, Mg2+ ,K+and Na+. Secondly there are acid cations, which include Al3+and H+. Related to this distinction in cations is the term base saturation, which is defined as the proportion of exchange sites occupied by base cations. A soil with a high base saturation (greater than 35%) is more fertile than a soil with a low base saturation.

Al3+, Ca2+and H+are the commonly adsorbed cations in humid regions. This reflects the long-term leaching loss of basic cations and their replacement by acidic cations. In contrast, Ca2+,Mg2+, K+and Na+are the commonly adsorbed cations in arid regions.

 

Aluminium influences of soil acidity

As clay minerals weather and break down, the aluminium in the octahedral layer is released into the soil solution, where it either reacts with water or is adsorbed onto the exchange sites of negatively charged clay minerals. Al3+ions are adsorbed in preference to all the other major cations. The influence that aluminium has on soil acidy is itself dependant on the acidity of the soil. At Ph less 5, aluminium is soluble and exists as Al3+. When Al3+enters the soil solution it reacts with water (it is hydrolysed) to produce H+ions:

 

                   Al3++ H2O <===> AlOH2++ H+

 

Thus the acidity of the soil increases (pH falls). In soils with a pH of between 5 and 6.5, aluminium also contributes H+oins to the soil solution but by different mechanisms, as aluminium can no longer exist as Al3+ions but is converted to aluminium hydroxyl ions:

 

Al3++ OH-<===> AlOH2+

AlOH2++H-<===> Al(OH)2+ 

                                      ALUMINIUM HYDROXY IONS

 

These hydroxyl aluminium ions act as exchangeable cations just like Al3+, and are adsorbed by the clay minerals. They are in equilibrium with hydroxyl aluminium ions in the soil solution, where they produce H+ions by the following reactions:

 

              AlOH2++H20 <===> Al(OH)2+   + H+

 

              Al(OH)2++H20 <===> Al(OH)3+   + H+

 

In soils where the pH is above 7 Ca2+and Mg2+dominated the exchange sites and most of the hydroxyl aluminium ions have been converted to gibbsite (Al(OH)3), is insoluble and cannot be by the negative clay minerals as no charge. In a neutral soil the exchangeable cations that dominate the cation exchange sites are the base cations, whereas in an acidics soils aluminium and hydrogen ions dominate the exchange sites.

 

On this basis if water is present aluminium sulphate as aluminium hydroxide precipitate (Al(OH)3) have a high potential for adsorption to soil.

 

The estimated Soil Adsorption Coefficient was 31.82L/kg measured by calculation from EPI SuiteTM v4.0..This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency).

Inorganic compounds are outside the estimation domain.

For Soil Adsorption Comparison Purposes:

 

Koc Estimate from MCI:

---------------------

First Order Molecular Connectivity Index ........... : 1.732

Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 1.5027

Fragment Correction(s) --> NONE                     :  ---

Corrected Log Koc .................................. : 1.5027

 

Estimated Koc: 31.82 L/kg  <===========