New Strategy To Enhance Phosphate Removal from Water by Hydrous Manganese Oxide

Abstract

Hydrous manganese oxide (HMO) is generally negatively charged at circumneutral pH and cannot effectively remove anionic pollutants such as phosphate. Here we proposed a new strategy to enhance HMO-mediated phosphate removal by immobilizing nano-HMO within a polystyrene anion exchanger (NS). The resultant nanocomposite HMO@NS exhibited substantially enhanced phosphate removal in the presence of sulfate, chloride, and nitrate at greater levels. This is mainly attributed to the pHpzc shift from 6.2 for the bulky HMO to 10.5 for the capsulated HMO nanoparticles, where HMO nanoparticles are positively charged at neutral pH. The ammonium groups of NS also favor phosphate adsorption through the Donnan effect. Cyclic column adsorption experiment indicated that the fresh HMO@NS could treat 460 bed volumes (BV) of a synthetic influent (from the initial concentration of 2 mg P[PO4(3-)]/L to 0.5 mg P[PO4(3-)]/L), while only 80 BV for NS. After the first time of regeneration by NaOH-NaCl solution, the capacity of HMO@NS was lowered to ∼ 300 BV and then kept constant for the subsequent 5 runs, implying the presence of both the reversible and irreversible adsorption sites of nano-HMO. Additional column adsorption feeding with a real bioeffluent further validated great potential of HMO@NS in advanced wastewater treatment. This study may provide an alternative approach to expand the usability of other metal oxides in water treatment.

Removal of Phosphorus from Wastewater by Different Morphological Alumina

“…Further research has been done in recent years to search for adsorbent materials suitable for industrial production with high adsorption efficiency [6][7][8][9][10][11][12]. Studies have shown that phosphorus in eutrophic water exists as free phosphate, and a large amount of metal oxide/hydroxide has been used in phosphorus removal because of its specific affinity for phosphate including hydrous ferric oxide [13], magnetite [14], hydrous manganese oxide [15], aluminum hydroxide gel [16], lanthanum hydroxide [17], cerium oxide [18], titanium dioxide [19], hydrous niobium oxide [20], and zirconium oxide/hydroxide [21,22], etc. However, the adsorption capacity of these adsorbents is not high enough (usually <100 mg•g −1 ) and most of them are unsuitable for commercial production due to the complexity of the production process.…”

Adsorption of Phosphate Ions from Aqueous Solution of Nickel Hydroxides Calcined at Different Temperatures

“…To solve these problems, adsorption is being increasingly used in research on phosphorus removal because of its high efficiency and relatively simple application. Thus, diverse adsorbents have been used for phosphorus removal, such as Kanuma mud, Mg 3 -Fe layered double hydroxides, hydrous manganese oxide, and grapheme-nanosheet-supported lanthanum hydroxide nanoparticles [4,[9][10][11]. Nickel hydroxide and nickel oxide materials have received much attention in recent years for application in alkaline secondary batteries, fuel cells, electrochemical capacitors, electrolyzers, electrosynthetic cells, and electrochromic devices [12][13][14][15][16].…”

Anaerobic manganese- or iron-mediated pharmaceutical degradation in water

“…The Fe(III) can also affect the removal and recovery of phosphate in anaerobic sludge digestion [37,288] . Adsorption of phosphate onto MnO2 has also been reported previously [227,228] . In addition, the anaerobic biodegradation with Fe(III) is also efficient in nitrogen (ammonia) removal [232,372] .…”

“…Complete DFC removal is obtained when the concentration is 116 mg P⋅L -1 . PO4 3can adsorb onto the MnO2 surface, which decreases the reactive surface sites for DFC removal [228] . On the other hand, PO4 3can decrease the inhibition effects of Mn 2+ generated from DFC removal by forming Mn3(PO4)2 [127] .…”