More Like this

1. Low concentrations of Cu 2+ in synthetic nutrient containing wastewater inhibit MgCO 3 -to-struvite transformation

   https://doi.org/10.1039/D0EW01035A  

   Barčauskaitė, Karolina ; Drapanauskaitė, Donata ; Silva, Manoj ; Murzin, Vadim ; Doyeni, Modupe ; Urbonavicius, Marius ; Williams, Clinton F. ; Supronienė, Skaidrė ; Baltrusaitis, Jonas ( March 2021 , Environmental Science: Water Research & Technology)

   null (Ed.)

   Simultaneous major nutrient nitrogen (N) and phosphorus (P) recovery from wastewater is key to achieving food–energy–water sustainable development. In this work, we elucidate the reaction kinetics, crystalline structure and chemical composition of the resulting solid precipitate obtained from simulated N and P containing wastewater solution using widely abundant low solubility magnesite (MgCO 3 ) particles in the presence of common transition metal ions, such as zinc (Zn 2+ ) or copper (Cu 2+ ). We show that up to 100 ppm Zn 2+ from the simulated wastewater can be incorporated into the struvite lattice as isolated distorted Zn 2+ while even at very low concentrations of ∼5 ppm Cu 2+ ions almost completely inhibit struvite crystal formation. The resulting solid precipitate distinctly affects soil microbial biomass carbon and soil dehydrogenase enzyme activity. These results show a cautionary case where abundant natural mineral MgCO 3 exhibits very different chemistry in Cu 2+ containing simulated wastewater and does not readily adsorb or retain NH 4 + and PO 4 3− ions, unlike less sustainable but more water-soluble magnesium sources, such as MgCl 2 , at the equivalent [Mg 2+ ] : [NH 4 + ] : [PO 4 3− ] molar ratio of 1.4 : 1 : 1. 

   more » « less
2. Synthetic versatility, reaction pathway, and thermal stability of tetrahedrite nanoparticles

   https://doi.org/10.1039/d0tc03599h  

   Fasana, Christine D. ; Jensen, Mitchel S. ; García Ponte, Graciela E. ; MacAlister, Tyler R. ; Kunkel, Grace E. ; Rogers, John P. ; Ochs, Andrew M. ; Stevens, Daniel L. ; Weller, Daniel P. ; Morelli, Donald T. ; et al ( October 2020 , Journal of Materials Chemistry C)

   null (Ed.)

   Copper-antimony-sulfide compounds have desirable earth-abundant compositions for application in renewable energy technologies, such as solar energy and waste heat recycling. These compounds can be synthesized by bottom-up, solution-phase techniques that are more energy and time efficient than conventional solid-state methods. Solution-phase methods typically produce nanostructured materials, which adds another dimension to control optical, electrical, and thermal material properties. This study focuses on a modified-polyol, solution-phase synthesis for tetrahedrite (Cu 12 Sb 4 S 13 ), a promising thermoelectric material with potential also for photovoltaic applications. To dope the tetrahedrite and tune material properties, the utility of the modified polyol synthetic approach has been demonstrated as a strategy to produce phase-pure tetrahedrite that incorporates transition metal (Fe, Co, Ni, Zn, Ag) dopants for Cu, Te dopant for Sb, and Se for S. Six of these reported tetrahedrite compounds have not previously been made by solution-phase methods. For the bottom-up formation of the tetrahedrite nanomaterials, the evolution of the chemical phases has been determined by an investigation of the reaction progress as a function of temperature and time. Digenite (Cu 1.8 S), covellite (CuS), and famatinite (Cu 3 SbS 4 ) are identified as key intermediates and are consistently observed for both undoped and doped tetrahedrites. The effect of nanostructuring and doping tetrahedrite on thermal properties has been investigated. It was found that nanostructured undoped tetrahedrite has reduced thermal stability relative to samples made by solid-state methods, while the addition of dopants for Cu increased the thermal stability of the material. Crystallinity, composition, and nanostructure of products and intermediates were characterized by powder X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy, and transmission electron microscopy. Thermal properties were investigated by differential scanning calorimetry and thermal gravimetric analysis. This synthetic study with thermal property analysis demonstrates the potential of the modified polyol method to produce tetrahedrite and other copper-antimony-sulfide compounds for thermoelectric and photovoltaic applications. 

   more » « less
3. Silver (Ag) doped magnesium phosphate microplatelets as next‐generation antibacterial orthopedic biomaterials

   https://doi.org/10.1002/jbm.b.34450  

   Sikder, Prabaha ; Bhaduri, Sarit B. ; Ong, Joo L. ; Guda, Teja ( July 2019 , Journal of Biomedical Materials Research Part B: Applied Biomaterials)

   This article reports for the first time our successful result in the synthesis of antibacterial single‐phase newberyite (NB, MgHPO₄.3H₂O), an important magnesium phosphate (MgP) bioceramic. The prime novelty lies in the fact that we explore novel MgPs as next‐generation orthopedic biomaterials as opposed to conventional calcium phosphates (CaP). While NB has already shown great promise, unlike its competitor struvite (ST, MgNH₄PO₄.6H₂O), NB is not intrinsically antibacterial. Given the havoc created by surgical site infections (SSI) in orthopedics, it would be worthwhile to explore if antibacterial NB can be synthesized cost‐effectively. To accomplish that central goal, we used silver ion (Ag⁺) containing precursor solutions and exposed those to microwave irradiation. This action resulted in the rapid synthesis of NB microplatelets. Besides, three other specific objectives are addressed. First, Ag‐doping was optimized to preserve the single‐phase nature for sustained dopant release. Second, Ag⁺release kinetics against common infection causing bacterial strains was analyzed. Finally, we inspected for any harmful effect of Ag‐doped NB on MC3T3 preosteoblasts. Interestingly, the single‐phase nature of NB microplatelets can be retained until 2 wt % Ag‐doping and they exhibit good antibacterial and cytocompatible properties. Even though 3 wt % Ag‐doped compositions (composites) were 100% antibacterial; they were cytotoxic.

    

   more » « less
4. Phosphorus recovery from wastewater using pyridine‐based ion‐exchange resins: Role of impregnated iron oxide nanoparticles and preloaded Lewis acid (Cu 2+ )

   https://doi.org/10.1002/wer.1469  

   Beaudry, Jeffrey W. ; Sengupta, Sukalyan ( December 2020 , Water Environment Research)

   Inputs of P into receiving water bodies are attracting increasing attention due to the negative effects of eutrophication. Presently available P treatment technologies are unable to achieve strict P discharge limits from wastewater treatment plants (WWTPs) that may be as low as 10 µg/L as P. Moreover, P is a nonrenewable resource and needs to be recycled in a closed‐loop process for environmental sustainability. This article provides details of a process where a pyridine‐based polymeric ion exchanger is modified with a combination of impregnated hydrated ferric oxide (HFO) nanoparticles and a preloaded Lewis acid (Cu²⁺) to effectuate selective P removal from wastewater and its recovery as a solid‐phase fertilizer. Three such ion exchangers were studied: DOW‐HFO, DOW‐Cu, and DOW‐HFO‐Cu. Each of these materials displays selective phosphate affinity over competing anions chloride and sulfate, and also has the ability to be regenerated upon exhaustion to strip off the P in a concentrated solution. The P in concentrated regenerant can be recovered as struvite, MgNH₄PO₄, a slow‐release fertilizer, after addition of MgCl₂and NH₄Cl. Results of equilibrium and kinetic studies and column experiments with synthetic solutions and a real WWTP effluent are discussed.

   Fixed‐bed columns with DOW‐HFO, DOW‐Cu, or DOW‐HFO‐Cu—can selectively remove phosphorus over competing anions.

   Fixed‐bed columns of above‐listed ion exchangers can produce an effluent P < 6 μg/L.

   DOW‐Cu fixed‐bed column ran for ≈500 Bed Volumes before breakthrough when fed Dartmouth WWTP secondary effluent.

   Regeneration of the exhausted DOW‐Cu column resulted in ≈90% recovery of the phosphorus.

   Regenerant solution was used to generate high‐purity crystals of magnesium ammonium phosphate, MgNH₄PO₄(struvite), a slow‐release fertilizer.

    

   more » « less
5. Remarkable Acid Stability of Polypyrrole‐MoS 4 : A Highly Selective and Efficient Scavenger of Heavy Metals Over a Wide pH Range

   https://doi.org/10.1002/adfm.201800502  

   Xie, Linxia ; Yu, Zihuan ; Islam, Saiful M. ; Shi, Keren ; Cheng, Yahan ; Yuan, Mengwei ; Zhao, Jing ; Sun, Genban ; Li, Huifeng ; Ma, Shulan ; et al ( March 2018 , Advanced Functional Materials)

   The new material polypyrrole/MoS₄²⁻(MoS₄‐Ppy), prepared by ion‐exchange of NO₃‐ of NO₃‐Ppy with MoS₄²⁻, displays high acid stability and excellent uptake for heavy metal ions such as Hg²⁺, Ag⁺, Cu²⁺, and Pb²⁺. The different maximum adsorption capacities (q_m) for Cu²⁺, Pb²⁺, Hg²⁺, and Ag⁺depend on the various binding modes arising from the different thiophilicity of these metal ions. The removals of Ag⁺and Pb²⁺reach >99.6% within 5 min, and for highly toxic Hg²⁺, >98% removal achieves at 1 min. At strong acid limit, the exceptionalq_m(Ag⁺) of 725 mg g⁻¹places the MoS₄‐Ppy at the top of materials for such removal. Uptake kinetics of Ag⁺, Hg²⁺, and Pb²⁺is extremely fast: >99.9% removal rates at wide pH range (0.5–6) within 1–5 min. Also, at strongly acidic conditions (pH ≈ 1), for highly toxic Hg²⁺, <2 ppb concentration can be achieved, accepted as safe limit. The MoS₄‐Ppy demonstrates an outstanding ability to separate low‐concentrated Ag⁺from high concentrated Cu²⁺especially under strong acidic conditions (pH ≈ 1), showing a large separation factor SF_Ag/Cu(K_d^Ag/K_d^Cu) of 10⁵(>100). MoS₄‐Ppy is a superior and novel sorbent material for water remediation applications as well as precious metals recovery.

    

   more » « less