Disinfection of water with new chitosan-modified hybrid clay composite adsorbent

Hybrid clay composites were prepared from Kaolinite clay and Carica papaya seeds via modification with chitosan, Alum, NaOH, and ZnCl2 in different ratios, using solvothermal and surface modification techniques. Several composite adsorbents were prepared, and the most efficient of them for the removal of gram negative enteric bacteria was the hybrid clay composite that was surface-modified with chitosan, Ch-nHYCA1:5 (Chitosan: nHYCA = 1:5). This composite adsorbent had a maximum adsorption removal value of 4.07 × 106 cfu/mL for V. cholerae after 120 min, 1.95 × 106 cfu/mL for E. coli after ∼180 min and 3.25 × 106 cfu/mL for S. typhi after 270 min. The Brouers-Sotolongo model was found to better predict the maximum adsorption capacity (qmax) of Ch-nHYCA1:5 composite adsorbent for the removal of E. coli with a qmax of 103.07 mg/g (7.93 × 107 cfu/mL) and V. cholerae with a qmax of 154.18 mg/g (1.19 × 108 cfu/mL) while the Sips model best described S. typhi adsorption by Ch-nHYCA1:5 composite with an estimated qmax of 83.65 mg/g (6.43 × 107 cfu/mL). These efficiencies do far exceed the alert/action levels of ca. 500 cfu/mL in drinking water for these bacteria. The simplicity of the composite preparation process and the availability of raw materials used for its preparation underscore the potential of this low-cost chitosan-modified composite adsorbent (Ch-nHYCA1:5) for water treatment

New micro/mesoporous nanocomposite material from low-cost sources for the efficient removal of aromatic and pathogenic pollutants from water

A new micro/mesoporous hybrid clay nanocomposite prepared from kaolinite clay, Carica papaya seeds, and ZnCl2 via calcination in an inert atmosphere is presented. Regardless of the synthesis temperature, the specific surface area of the nanocomposite material is between approximate to 150 and 300 m(2)/g. The material contains both micro- and mesopores in roughly equal amounts. X-ray diffraction, infrared spectroscopy, and solid-state nuclear magnetic resonance spectroscopy suggest the formation of several new bonds in the materials upon reaction of the precursors, thus confirming the formation of a new hybrid material. Thermogravimetric analysis/differential thermal analysis and elemental analysis confirm the presence of carbonaceous matter. The new composite is stable up to 900 degrees C and is an efficient adsorbent for the removal of a water micropollutant, 4-nitrophenol, and a pathogen, E. coli, from an aqueous medium, suggesting applications in water remediation are feasible

Evaluation of the safety profile and antioxidant activity of fatty hydroxamic acid from underutilized seed oil of Cyperus esculentus

Objective: To evaluate the safety profile and antioxidant activity of fatty hydroxamic acid (FHA) from the seed oil of Cyperus esculentus (C. esculentus). Methods: FHA was synthesized from the seed oil of C. esculentus via a two-step reaction system. The FHA was later subjected to antioxidant activity test using 2, 2-diphenyl-1-picyrl hydrazyl assay. Additionally, adult male Wistar rats were randomly assigned to four groups of five rats each and were orally administered with FHA at 0, 5, 15 and 50 mg/kg for seven days. Clinical observations and serum biochemical parameters were assessed to monitor treatment–related adverse effects in the rats. Results: Fourier transform infrared spectra showed that FHA was synthesised from the seed oil of C. esculentus. The antioxidant property of FHA increased as the concentration reduced below 0.05 μg/mL. Result of oral administration of FHA revealed no adverse effect levels at the dose of 5 mg/kg/day. However, the adverse effects seen in rats receiving 15 mg/kg/day (the least observed adverse effect level) were significant increase in alkaline phosphatase activity, triglycerides, and creatinine levels. Moderate hyperalbuminemia and hypoalbuminemia resulted in an increased albumin/globulin ratio. These effects might be the result of a physiological response to exposure to a very high level of FHA which is not part of the normal diet, and are most likely not toxicologically relevant. Conclusions: C. esculentus has been presented as a potential source of feed stock for the synthesis of a relatively cheap and non toxic FHA which has antioxidant and free-radical scavenging activity

Hybrid materials from agro-waste and nanoparticles: implications on the kinetics of the adsorption of inorganic pollutants

<div><p>This study is a first-hand report of the immobilization of <i>Nauclea diderrichii</i> seed waste biomass (ND) (an agro-waste) with eco-friendly mesoporous silica (MS) and graphene oxide–MS (GO+MS ) nanoparticles, producing two new hybrid materials namely: MND adsorbent for agro-waste modified with MS and GND adsorbent for agro-waste modified with GO+MS nanoparticles showed improved surface area, pore size and pore volume over those of the agro-waste. The abstractive potential of the new hybrid materials was explored for uptake of Cr(III) and Pb(II) ions. Analysis of experimental data from these new hybrid materials showed increased initial sorption rate of Cr(III) and Pb(II) ions uptake. The amounts of Cr(III) and Pb(II) ions adsorbed by MND and GND adsorbents were greater than those of ND. Modification of <i>N. diderrichii</i> seed waste significantly improved its rate of adsorption and diffusion coefficient for Cr(III) and Pb(II) more than its adsorption capacity. The rate of adsorption of the heavy metal ions was higher with GO+MS nanoparticles than for other adsorbents. Kinetic data were found to fit well the pseudo-second-order and the diffusion–chemisorption kinetic models suggesting that the adsorption of Cr(III) and Pb(II) onto these adsorbents is mainly through chemisorption mechanism. Analysis of kinetic data with the homogeneous particle diffusion kinetic model suggests that particle diffusion (diffusion of ions through the adsorbent) is the rate-limiting step for the adsorption process.</p></div

Hybrid Clay: A New Highly Efficient Adsorbent for Water Treatment

New hybrid clay adsorbent based on kaolinite clay and <i>Carica papaya</i> seeds with improved cation exchange capacity (CEC), rate of heavy metal ion uptake, and adsorption capacity for heavy metal ions were prepared. The CEC of the new material is ca. 75 meq/100 g in spite of the unexpectedly low surface area (≈9 m²/g). Accordingly, the average particle size of the hybrid clay adsorbent decreased from over 200 to 100 μm. The hybrid clay adsorbent is a highly efficient adsorbent for heavy metals. With an initial metal concentration of 1 mg/L, the hybrid clay adsorbent reduces the Cd²⁺, Ni²⁺, and Pb²⁺ concentration in aqueous solution to ≤4, ≤7, and ≤20 μg/L, respectively, from the first minute to over 300 min using a fixed bed containing 2 g of adsorbent and a flow rate of ≈7 mL/min. These values are (with the exception of Pb²⁺) in line with the WHO permissible limits for heavy metal ions. In a cocktail solution of Cd²⁺, and Ni²⁺, the hybrid clay shows a reduced rate of uptake but an increased adsorption capacity. The CEC data suggest that the adsorption of Pb²⁺, Cd²⁺, and Ni²⁺ on the hybrid clay adsorbent is essentially due to ion exchange. This hybrid clay adsorbent is prepared from materials that are abundant and by a simple means that is sustainable, easily recovered from aqueous solution, nonbiodegradable (unlike numerous biosorbent), and easily regenerated and is a highly efficient alternative to activated carbon for water treatment

SAPK: A Novel Composite Resin for Water Treatment with Very High Zn²⁺, Cd²⁺, and Pb²⁺ Adsorption Capacity

A new sulfonated aniline-modified poly­(vinyl alcohol)/K-feldspar (SAPK) composite was prepared. The cation-exchange capacity of the composite was found to be 5 times that of neat feldspar. The specific surface area and point of zero charge also changed significantly upon modification, from 15.6 ± 0.1 m²/g and 2.20 (K-feldspar) to 73.6 ± 0.3 m²/g and 1.91 (SAPK). Zn²⁺, Cd²⁺, and Pb²⁺ adsorption was found to be largely independent of pH, and the metal adsorption rate on SAPK was higher than that on neat feldspar. This particularly applies to the initial adsorption rates. The adsorption process involves both film and pore diffusion; film diffusion initially controls the adsorption. The Freundlich and Langmuir models were found to fit metal-ion adsorption on SAPK most accurately. Adsorption on neat feldspar was best fitted with a Langmuir model, indicating the formation of adsorbate monolayers. Both pure feldspar and SAPK showed better selectivity for Pb²⁺ than for Cd²⁺ or Zn²⁺