Sustainable adsorptive removal of antibiotics from aqueous streams using Fe3O4-functionalized MIL101(Fe) chitosan composite beads.

In this study, we synthesized recyclable Fe3O4-functionalized MIL101(Fe) chitosan composite beads for the removal of tetracycline (TC), doxycycline (DC) and ciprofloxacin (CFX) antibiotics from aqueous streams. More than 99% removal efficiency for each antibiotic was achieved at optimum pH, dosage, concentration and contact time. Langmuir adsorption isotherms and pseudo-second-ord er kinetic model were suitable with correlation coefficient values close to 1 for all the antibiotics. Adsorption capacities of 45.33, 33.20 and 31.30 mg g-1 for TC, DC and CFX, respectively, were reported by the synthesized Fe3O4-functionalized MIL101(Fe) chitosan composite beads. The Fe3O4-functionalized MIL101(Fe) chitosan composite beads were also tested for their regeneration ability, and a remarkable regeneration ability over up to 5 cycles was observed. The adsorption of TC, DC and CFX on the surface of Fe3O4-functionalized MIL101(Fe) chitosan composite beads was governed by the π-π interaction, H-bonding and electrostatic interaction between the antibiotics and adsorbent due to protonation, deprotonation and cation exchange in the aqueous solution. These results showed a good prospect for applying the reported beads towards removing antibiotics from pharmaceutical industry wastewater.

Adsorption of cupric, cadmium and cobalt ions from the aqueous stream using the composite of iron(II,III) oxide and zeolitic imidazole framework-8.

In recent research, the composite of Fe3O4 and metal-organic frameworks have shown great potential in removing potentially toxic metals from water. We conducted the adsorption studies of potentially toxic metal ions (Cu2+, Co2+ and Cd2+) using the composite of Fe3O4 and zeolitic imidazole framework-8 (Fe3O4@ZIF-8) for the first time. The solvothermal technique was used to synthesize the Fe3O4. The magnetic ZIF-8 offers high thermal stability, greater adsorption surface, good removability, and high chemical and thermal stability. Characterization techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) were used to characterize the synthesized samples. The SEM and XRD results revealed the high purity and structural integrity of ZIF-8 crystallites. To remove potentially toxic metals (Cu2+, Co2+ and Cd2+), the influence of adsorbent dosage, contact time, pH, and adsorbate concentration on the adsorption performance of Fe3O4@ZIF-8 was investigated. The Langmuir isotherm accurately represented the adsorption processes, with absorption magnitudes of Fe3O4@ZIF-8 determined to be 46.82 mg g-1, 71.29 mg g-1 and 54.49 mg g-1 for Cu2+, Co2+ and Cd2+, respectively. According to the adsorption mechanism analysis, the primary Cu2+, Co2+ and Cd2+ removal methods of Fe3O4@ZIF-8 were ion exchange and coordination bonds. The uptake capacity of Cu2+, Co2+ and Cd2+ solution by Fe3O4@ZIF-8 were not significantly affected by the presence of counter ions. The material exhibited superior regenerative properties for Cu2+, Co2+ and Cd2+ ions from water for up to three cycles. This study concluded that the Fe3O4@ZIF-8 could be a viable candidate for eliminating potentially toxic metals (Cu2+, Co2+ and Cd2+).

Implementation of water safety plan for a large-piped water supply system.

A water safety plan for the city of Nagpur was developed by the National Environmental Engineering Research Institute (NEERI) and Nagpur Municipal Corporation (NMC). Possible hazards were identified through field visits. Based on this, an improvement plan was drawn up to suggest corrective actions and a time frame for implementation. The findings of this study are being used to modify or repair components of the water supply system and upgrade management procedures. This paper highlights the lessons learnt during implementation of the WSP and the key challenges faced.