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The use of phosphonates as antiscalants in membrane processes is common. Before they are discharged into the receiving water, they should be removed from the membrane concentrate to protect the aquatic environment. This study conducted fixed-bed column experiments on the adsorption of diethylenetriaminepenta(methylene phosphonic acid) (DTPMP) and ortho-phosphate on granular ferric (hydr)oxide (GFH). The objective was to investigate the adsorption and desorption performance using real membrane concentrate, while testing both the usability of the GFH and that of the regeneration solutions over multiple cycles. Whereas a synthetic solution with DTPMP allowed almost complete regeneration, the adsorption performance with real membrane concentrate at the original pH ≅ 8 decreased significantly. This could be attributed to the precipitation of calcium compounds which disturbed the adsorption/desorption process. With the introduction of a novel acidic regeneration step to remove the precipitates, an adsorption performance of 95% over 20 cycles was achieved. The hydrochloric acid (HCl) can be reused when its pH is kept constant by a pH control. The sodium hydroxide solution (NaOH) for alkaline regeneration can be reused several times. However, the desorption performance decreased significantly when its electrical conductivity dropped below 90 mS/cm. Replacing the NaOH regularly can significantly improve the desorption performance.

Phosphonates are widely used in various industries. It is desirable to remove them before discharging phosphonate-containing wastewater. This study describes a large number of batch experiments with adsorbents that are likely suitable for the removal of phosphonates. For this, adsorption isotherms for four different granular ferric hydroxide (GFH) adsorbents were determined at different pH values in order to identify the best performing material. Additionally, the influence of temperature was studied for this GFH. A maximum loading for nitrilotrimethylphosphonic acid (NTMP) was found to be ∼12 mg P/g with an initial concentration of 1 mg/L NTMP-P and a contact time of 7 days at room temperature. Then, the adsorption of six different phosphonates was investigated as a function of pH. It was shown that GFH could be used to remove all investigated phosphonates from water and, with an increasing pH, the adsorption capacity decreased for all six phosphonates. Finally, five adsorption–desorption cycles were carried out to check the suitability of the material for multiple re-use. Even after five cycles, the adsorption process still performed well.

This article sets up a dialogue between two bodies of ancient texts, i.e. Jewish wisdom literature and Greco-Roman didactic of the Hellenistic period, with an awareness of the scholarly and interpretive communities that have studied, taught and transformed these bodies of texts from antiquity until the present. The article does not claim direct influence or cross-pollination across intellectual, religious or social communities in the Hellenistic period. Instead, the article suggests four discrete frameworks for thinking about comparative antiquity: creation, the law, the sage and literary form. The comparative model proposed here intends to create the conditions for noticing parallels and kindred concepts. However, the article resists the temptation to repeat earlier scholarly arguments for dependency or priority of influence. Instead, the essay demonstrates remarkable alignments, suggestively similar developments, and synergies. Perhaps, the ideal first reader for this article is none other than Philo of Alexandria.

This paper introduces a procedure to investigate the adsorption of phosphonates onto iron-containing filter materials, particularly granular ferric hydroxide (GFH), with little effort and high reliability. The phosphonate, e.g., nitrilotrimethylphosphonic acid (NTMP), is brought into contact with the GFH in a rotator in a solution buffered by an organic acid (e.g., acetic acid) or Good buffer (e.g., 2-(N-morpholino)ethanesulfonic acid) [MES] and N-cyclohexyl-2-hydroxyl-3-aminopropanesulfonic acid [CAPSO]) in a concentration of 10 mM for a specific time in 50 mL centrifuge tubes. Subsequently, after membrane filtration (0.45 µm pore size), the total phosphorus (total P) concentration is measured using a specifically developed determination method (ISOmini). This method is a modification and simplification of the ISO 6878 method: a 4 mL sample is mixed with H2SO4 and K2S2O8 in a screw cap vial, heated to 148-150 °C for 1 h and then mixed with NaOH, ascorbic acid and acidified molybdate with antimony(III) (final volume of 10 mL) to produce a blue complex. The color intensity, which is linearly proportional to the phosphorus concentration, is measured spectrophotometrically (880 nm). It is demonstrated that the buffer concentration used has no significant effect on the adsorption of phosphonate between pH 4 and 12. The buffers, therefore, do not compete with the phosphonate for adsorption sites. Furthermore, the relatively high concentration of the buffer requires a higher dosage concentration of oxidizing agent (K2S2O8) for digestion than that specified in ISO 6878, which, together with the NaOH dosage, is matched to each buffer. Despite the simplification, the ISOmini method does not lose any of its accuracy compared to the standardized method.