Removal of lead in water by coagulation flocculation process using Cactus-based natural coagulant: optimization and modeling by response surface methodology (RSM)

The aim of this research is to study the ability of Cactus leaves to act as a biocoagulants for the removal of lead in water. Different solvents, such as distilled water, NaCl, NaOH, and HCl, were used as chemical activators to extract the active components from the Cactus. The Cactus was utilized as an organic coagulant in five different forms: (i) Cactus juice (CJ); Cactus extract using (ii) distilled water (C-H2O); (iii) NaCl at 0.5 M concentration (C-NaCl); (iv) NaOH at 0.05 M concentration (C-NaOH); and (v) HCl at 0.05 M concentration (C-HCl). In order to establish the optimal conditions for the coagulation, this study employed the jar test as an experimental technique and the Box-Behnken design (BBD) as an experimental approach. According to BBD, there are three factors (k = 3), namely pH, biocoagulant dosage, and settling time. The R2 and R2 adjusted for all coagulants were close to 100%, confirming the validity of all the mathematical models. The results were significant; the highest lead removal efficiencies were 98.11%, 98.34%, 95.65, 96.19%, and 97.49%, utilizing CJ, C-H2O, C-NaCl, C-HCl, and C-NaOH as natural coagulants. The Cactus has been characterized using FTIR, XRD, and SEM to identify the active components that remove lead.

Preparation and Evaluation of Glucose Based Non-Isocyanate Polyurethane Self-Blowing Rigid Foams

A partially biobased self-blowing and self-hardening polyurethane foam from glucose-based non-isocyanate polyurethanes (g-NIPU) was prepared by reaction of glucose with dimethyl carbonate and hexamethylene diamine. However, these foam types generally require a high foaming temperature. In this paper, a self-blowing foam based on g-NIPU was prepared at room temperature by using maleic acid as an initiator and glutaraldehyde as a crosslinker. Water absorption, compression resistance, and fire resistance were tested. Scanning electron microscopy (SEM) was used to observe the foam cells structure. Middle infrared (ATR FT-MIR) and Matrix Assisted Laser Desorption Ionization Time-of-Flight (MALDI-TOF) mass spectrometry were used to help to analyze the reactions during the foaming process. The results obtained showed that self- blowing rigid foams have good compression, this being directly proportional to the foam density. Increasing the amount of glutaraldehyde or reducing maleic acid thickens the cell walls and increases the density of the foams. MALDI-TOF analysis showed that g-NIPU reacts with both maleic acid and glutaraldehyde. The foams presented poor fire resistance indicating that, as for isocyanate based polyurethane foams, addition of a fire retardant would be necessary.

Melamine⁻Glyoxal⁻Glutaraldehyde Wood Panel Adhesives without Formaldehyde

(MGG') resin adhesives for bonding wood panels were prepared by a single step procedure, namely reacting melamine with glyoxal and simultaneously with a much smaller proportion of glutaraldehyde. No formaldehyde was used. The inherent slow hardening of this resin was overcome by the addition of N-methyl-2-pyrrolidone hydrogen sulphate ionic liquid as the adhesive hardener in the glue mix. The plywood strength results obtained were comparable with those obtained with melamine⁻formaldehyde resins pressed under the same conditions. Matrix assisted laser desorption ionisation time of flight (MALDI ToF) and Fourier transform Infrared (FTIR) analysis allowed the identification of the main oligomer species obtained and of the different types of linkages formed, as well as to indicate the multifaceted role of the ionic liquid. These resins are proposed as a suitable substitute for equivalent formaldehyde-based resins.