Glyphosate, the most widespread organophosphorus herbicide, enters lakes, rivers and groundwater through rainwater and surface runoff. It is very important to remove glyphosate from neutral water bodies. A new strategy for the development of glyphosate adsorbent was implemented through in situ nanoconfinement of hydrated ferric oxide (Fe 2 O 3 ·nH 2 O) in an anion exchange resin D201 (D201/Fe 2 O 3 ·nH 2 O). Fe 2 O 3 ·nH 2 O was confined within the 12–140 nm pores of D201/Fe 2 O 3 ·nH 2 O, exhibiting uniform distribution, nanoscale and amorphous state. Benefiting from the cross-linked polystyrene network, D201/Fe 2 O 3 ·nH 2 O featured excellent chemical stability in weakly acidic (pH > 3), alkaline and salt solutions. Compared with its host D201, D201/Fe 2 O 3 ·nH 2 O exhibited larger rate constant k 1 , larger glyphosate capacity and superior selectivity at pH = 7.0 ± 0.05. Corresponding its bifunctional groups of -N + (CH 3 ) 3 and Fe 2 O 3 ·nH 2 O, D201/Fe 2 O 3 ·nH 2 O could adsorb glyphosate through the two mechanisms of the ligand exchange between glyphosate anion and hydroxyl group, as well as the anion exchange between Cl − and glyphosate anion. D201/Fe 2 O 3 ·nH 2 O showed the commendable reusability and maintained constant glyphosate adsorption capacities at 161.5–164.5 mg/g in five consecutive adsorption-regeneration cycles. At the injection glyphosate concentration of 1.1 mg/mL, the effective processing volumes of D201/Fe 2 O 3 ·nH 2 O were 3.81 and 3.21 times that of D201 at two breakthrough points.
D201@S-nZVI was synthesized to remove Cr(VI) from aqueous solution. Batch experiments demonstrate it has excellent removal performance, recycling performance and longevity. Its removal efficiency and maximum adsorption capacity reaches 89.67% and 137.35 mg·g −1 for 100 mg·L −1 Cr(VI) solution, respectively. This is because S-nZVI (nZVI@FeS x ) has a core-shell structure. The FeS x layer prevents the leaching of iron and has excellent reduction and electron transport capability. In addition, the functional groups of D201 can electrostatically attract Cr(VI), and its unique skeleton structure well disperses S-nZVI. The adsorption is a spontaneous exothermic process. This research provides an effective remediation material for Cr(VI) wastewater.
Shen Zhang,Wencai Cheng,Congcong Ding,Ze Qiu,Junwen Tan,Xirui Lu,Jun Wen,Hao Li
Developing an efficient uranium enrichment process for large-scale eluates from marine-tested fibers is crucial for filling the gap in the downstream of seawater uranium extraction. Alkaline elution of 10 kg real marine-tested fibers yielded 33 L of clear eluate after pretreatment, where uranium existed mainly as [UO 2 (CO 3 ) 2 ] 2− , [UO 2 (CO 3 ) 3 ] 4− , and [UO 2 (O 2 )(CO 3 ) 2 ] 4− species with a concentration of 11.98 mg/L, while magnesium concentration was up to 352.48 mg/L.MIP analysis selected D201 resin with more and larger pores, which showed better uranium adsorption due to a maximum electrostatic potential of 114.93 kcal/mol via simulation. 1 kg of D201 resin was used in a self-developed ion exchange equipment (maximum 100 L eluate per run) for concentration and purification. After 5 days of enrichment, 3 L of uranium concentrate was obtained, with uranium concentration increased to 121.48 mg/L and magnesium reduced to 14.9 mg/L. Ammonia water was added to the concentrate for precipitation, collecting 1112.45 mg of uranium product. The uranium precipitation rate was 99.27 %, and that of magnesium was only 31.1 %. The overall enrichment efficiency reached 93.13 % for uranium. ICP results showed the uranium mass fraction in the product was 33.1 %. TI-MS results indicated the U-235 abundance (≈0.72 %) was consistent with natural levels, and U-234 abundance (0.0064 %) was, slightly higher than natural, but still qualified it as natural uranium. This study provides an innovative enrichment process and theoretical support for efficient downstream uranium recovery in seawater uranium extraction.
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