The cellulose of Boehmeria nivea as natural flocculants: synthesis, modification, and flocculation analysis

Due to their non-toxicity and biodegradability, natural polymeric flocculants have gained popularity in water and wastewater treatment in recent years. Because of its broad availability, renewability, sustainability, and surface modification potential, cellulose, the most common polymer on the planet, is regarded as one of the foundation polymers for flocculant production and modification. The following article consists of a review of the latest developments regarding biopolymers, in particular, cellulose as a natural flocculant. One of the plants that can be developed in Indonesia is Boehmeria nivea, or what is known as Ramie, which contains cellulose that is still not utilized optimally. There is a method of isolation of alpha-cellulose derived from Boehmeria nivea and its application as a flocculant in synthetic wastewater presented in this paper. The alpha-cellulose of Boehmeria nivea was used as a flocculant in jar testing using kaolin suspension (5 g/L). The study shows that adding alpha-cellulose as an aid to PAC slightly increased the turbidity removal efficiency, and further modification of alpha-cellulose by cationic grafts into cationic cellulose is needed.

Sustainable Cationic Cellulose for Highly Efficient Flocculation of Suspended Particles

Sustainable, cationic cellulose bio-flocculants with various amino group contents were successfully prepared by a feasible chemical crosslinking with polyethyleneimine (PEI). The flocculation performances of diverse PEI-grafting cellulose (CE-PEI)were evaluated topurify sewage sludge treatment. Further, the preparation conditions and flocculation mechanismof CE-PEI were investigated. Benefiting from the high surface positive charges and the supramolecular structure of PEI, the results indicate that CE-PEI could remove the turbid Kaolin suspension effectively. The efficiency of CE-PEI for removing the turbid in Kaolin suspension is 98.2%.Flocculation kinetic results indicated that charge neutralization was the dominant mechanism for the flocculation process. And then, the small Kaolin particles agglomerate together to form large flocs by the function of adsorbing, gathering, and enwrapping. Thus, this work not only exploits a promising application of cellulose as a bio-flocculantbut also provides a feasible approach to efficiently purify high turbidity wastewater.

Synthesis, Surface Tension, Flocculation and Antibacterial Properties of Cationic Copolymer Methacryloxyethyl Trimethyl Ammonium Chloride-Butyl Acrylate-Acrylamide

Three cationic copolymers methacryloxyethyl trimethyl ammonium chloride-butyl acrylate-acrylamide (MTAC-BA-AM terpolymer) were designed and synthesized by emulsion polymerization. Their structures were confirmed by FT-IR and 1H NMR. The effect of content of hydrophobic monomer butyl acrylate (BA) in MTAC-BA-AM terpolymer on surface activities, flocculation and antibacterial properties were investigated. The study of surface tension shows that MTAC-BA-AM terpolymer has good surface activity due to the introduction of hydrophobic monomer BA. The flocculation experiment showed that the light transmittance of the kaolin suspension supernatant was 98.13% when the dose of MTAC-BA-AM terpolymer in the kaolin suspension was 0.03 mg/L, which was obviously better than the P(MTAC-AM) (91.02%) without hydrophobic modification of BA. The bacteriostatic experiment of MTAC-BA-AM terpolymer showed that as the content of hydrophobic monomer BA in MTAC-BA-AM terpolymer increased the inhibitory rate of MTAC-BA-AM terpolymer aginst Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus)

Synthesis and Characterization of Novel Hybrid Flocculants Based on Potato Starch Copolymers with Hollow Carbon Spheres

Novel carbon nanofiller-based starch-g-polyacrylamide hybrid flocculation materials (St-PAM-CS) were in situ prepared using potato starch (St), acrylamide (AM), and hollow mesoporous carbon spheres (CSs; diameters of 300–400 nm). Structures of different St-PAM-CS systems were characterized by Fourier transform infrared (FTIR) spectroscopy, X-Ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), laser scanning microscopy (LSM), and particle size analysis. The flocculation tests were evaluated by removing high turbidity kaolin suspension—initial absorbance 1.84. The effect of the St to AM molar ratio, doses, and content of CSs in hybrids on flocculation efficiency were examined. Satisfactory flocculation efficiency was obtained for all hybrids with 1 wt.% of the CS component. The highest reduction of the kaolin suspension absorbance (to 0.06) was observed for a 3 mL dose of the starch hybrid with the highest AM content. Additionally, St-PAM-CS showed a reduction in the sludge volume in time. The hybrids reached better flocculation efficiency in relation to the reference systems without CSs. The proposed flocculation mechanism (considering bridging, patching, and formation of hydrogen bonds) has been confirmed by the recorded results.

Survival, development and reproduction of Phenacoccus solenopsis (Hemiptera: Pseudococcidae) on kaolin-treated cotton

The mealybug, Phenacoccus solenopsis Tinsley (Hemiptera: Pseudococcidae) is a cotton pest widespread in several cotton growing regions of Brazil, particularly in the semi-arid region of southwestern Bahia. The impact of kaolin on survival, development and reproduction of P. solenopsis was evaluated in the laboratory. The experiment was developed in a completely randomized design with two treatments: immature or newly emerged adults of P. solenopsis sprayed with kaolin and fed with cotton leaf discs treated with kaolin suspension (with kaolin) (T1) and immature or newly emerged adults of P. solenopsis sprayed with distilled water and fed with cotton leaf discs treated with distilled water (without kaolin) (T2). The kaolin suspension shortens the life cycle, increases the reproductive potential and population growth of the cotton mealybug, P. solenopsis and, therefore, it should be used with caution on cotton plants in regions with a history of occurrence of this pest.

Using Sulfobutylated and Sulfomethylated Lignin as Dispersant for Kaolin Suspension

Kraft lignin is an abundant natural resource, but it is underutilized. In this study, sulfoalkylated lignin derivatives with similar charge densities but with different alkyl chain length were produced via sulfobutylation and sulfomethylation reactions. The contact angle studies revealed that sulfobutylated lignin (SBL) with longer alkyl chains had a higher hydrophobicity than sulfomethylated lignin (SML) did. The adsorption behavior of sulfoalkylated lignins was studied using a Quartz crystal microbalance with dissipation (QCM-D) on Al2O3 coated surface as representative of positively charged sites of kaolin particles. The results of adsorption studies showed that SBL deposited more greatly than SML did on the Al2O3 surface, and it generated a thicker but less viscoelastic adlayer on the surface. The adlayer thickness and configuration of molecules on the surface were also related to the zeta potential and stabilization performance of the polymers in the kaolin suspension system. The results also confirmed that both lignin derivatives were very effective in dispersing kaolin particles at neutral pH, and their effectiveness was hampered under alkaline or acidic pH.