Bio-waste corn–cob cellulose supported poly (amidoxime) palladium nanoparticles for Suzuki-Miyaura cross-coupling reactions

Waste corn-cob cellulose supported poly(amidoxime) palladium nanoparticles (PdNs@PA) were prepared by the surface modification of waste corn-cob cellulose through graft co-polymerization and subsequent amidoximation. The supported nanoperticles showed high catalytic activity (45-400 mol ppm) towards Suzuki-Miyaura cross-coupling of aryl bromides/chlorides with organoboronic acids to give the corresponding biaryl products up to 99 % yield with high turnover number (TON) 19777 and turnover frequency (TOF) 4944 h−1. The PdNs@PA was easily recovered from the reaction mixture and reused several times without significant loss of its catalytic activity

Highly active kenaf bio-cellulose based poly (hydroxamic acid) copper catalyst for Aza-Michael addition and click reactions

Bio-heterogeneous kenaf cellulose supported poly(hydroxamic acid) Cu(II) complex and corresponding copper nanoparticles (CuN@PHA) were synthesized and characterized. Cellulose supported poly(hydroxamic acid) copper nanoparticles was successfully applied to the Aza-Michael addition reaction of amines with α,β-unsaturated carbonyl/cyano compounds and poly(hydroxamic acid) Cu(II) complex was applied to the Click reactions of organic azides with alkynes in presence of sodium ascorbate as highly active catalysts under mild reaction conditions. The copper nanoparticles (50 mol ppm) selectively boosted Aza-Michael addition reaction to give the corresponding alkylated products in up to 96 % yield, whereas poly(hydroxamic acid) Cu(II) complex (0.25 mol%) efficiently promoted Click reaction to give the corresponding 1,2,3-triazoles in up to 94 % yields. Excellent reusability of the supported copper catalysts were found with no significant loss of catalytic activity for several cycles having high turnover number (TON) 18000 and turnover frequency (TOF) 3000 h−1 in the Aza-Michael addition reaction

Synthesis of poly(hydroxamic acid) ligand from polymer grafted corn-cob cellulose for transition metals extraction

Poly(hydroxamic acid) ligand was synthesized using ester functionalities of cellulose-graft-poly(methyl acrylate) copolymer, and products are characterized by Fourier transform infrared spectroscopy, field emission scanning electron microscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy analysis. The poly(hydroxamic acid) ligand was utilized for the sensing and removal of transition metal ions form aqueous solutions. The solution pH is found a key factor for the optical detection of metal ions, and the reflectance spectra of the [Cu-ligand]n+ complex were observed to be the highest absorbance 99.5% at pH?6. With the increase of Cu2+ ion concentration, the reflectance spectra were increased, and a broad peak at 705?nm indicated that the charge transfer (p-p transition) complex was formed. The adsorption capacity with copper was found to be superior, 320?mg?g-1, and adsorption capacities for other transition metal ions were also found to be good such as Fe3+, Mn2+, Co3+, Cr3+, Ni2+, and Zn2+ were 255, 260, 300, 280, 233, and 223?mg?g-1, respectively, at pH?6. The experimental data show that all metal ions fitted well with the pseudo-second-order rate equation. The sorption results of the transition metal ions onto ligand were well fitted with Langmuir isotherm model (R2?>?0.98), which implies the homogenous and monolayer character of poly(hydroxamic acid) ligand surface. Eleven cycles sorption/desorption process were applied to verify the reusability of this adsorbent. The investigation of sorption and extraction efficiency in each cycle indicated that this new type of adsorbent can be recycled in many cycles with no significant loss in its original detection and removal capability

Assessment of the Level and Health Risk of Fluoride and Heavy Metals in Commercial Toothpastes in Bangladesh

Toothpaste is one of the daily essentials, and good quality control practices over it are very important to protect the oral public health from adverse effects. The current study aimed to assess the concentration of fluoride and heavy metals, physicochemical properties in ten different toothpaste samples in Bangladesh, followed by related health risk analysis. pH, moisture content, F–, As, Cu, Pb contents were measured by membrane electrode, thermogravimetric, SPADNS, HG-AAS, flame-AAS methods, respectively. The results were compared to the specification of the packet and Bangladesh Standard and Testing Institute (BSTI) standard. The physicochemical properties well-matched the formulation standard values. The moisture content was 27.18 ± 2.20 to 52.10 ± 5.01%, with 50% of the samples in permissible limit but the pH of all the samples (6.40-8.60) was within the standard limit. Available F–, Cu, Pb, and As content ranged from 803–1617, 2.78–13.10, 0.27–2.12, and 0.027–0.637 mg/Kg, respectively. F– content in 80% toothpaste did not meet the packet specification and was higher than BSTI standard, though heavy metals were within the BSTI limit. Hazard quotient (HQ) and HI (Hazard Index) analysis revealed that toothpaste safe from heavy metal related to health risk

Synthesis of tapioca cellulose-based poly (hydroxamic acid) ligand for heavy metals removal from water

A graft copolymerization was performed using free radical initiating process to prepare the poly(methyl acrylate) grafted copolymer from the tapioca cellulose. The desired material is poly(hydroxamic acid) ligand, which is synthesized from poly(methyl acrylate) grafted cellulose using hydroximation reaction. The tapioca cellulose, grafted cellulose and poly(hydroxamic acid) ligand were characterized by Infrared Spectroscopy and Field Emission Scanning Electron Microscope. The adsorption capacity with copper was found to be good, 210 mg g¡1 with a faster adsorption rate (t1/2 D 10.5 min). The adsorption capacities for other heavy metal ions were also found to be strong such as Fe3C, Cr3C, Co3C and Ni2C were 191, 182, 202 and 173 mg g¡1, respectively at pH 6. To predict the adsorption behavior, the heavy metal ions sorption onto ligand were well-fitted with the Langmuir isotherm model (R2 > 0.99), which suggest that the cellulose-based adsorbent i.e., poly(hydroxamic acid) ligand surface is homogenous and monolayer. The reusability was checked by the sorption/desorption process for six cycles and the sorption and extraction efficiency in each cycle was determined. This new adsorbent can be reused in many cycles without any significant loss in its original removal performances

Poly(hydroxamic acid) functionalized copper catalyzed C–N bond formation reactions

Highly active poly(hydroxamic acid) functionalized copper catalysts were synthesized by the surface modification of khaya cellulose through graft copolymerization and subsequent hydroximation processes. The prepared catalysts were well characterized by FTIR, FESEM, HRTEM, ICP-AES, UV-vis and XPS analyses. The supported catalysts effectively promoted C–N bond formation reactions and provided excellent yields of the corresponding products under mild reaction conditions. The catalysts were easy to recover from the reaction mixture and were reused several times without any significant loss of their catalytic activity

Synthesis of poly (hydroxamic acid) ligand from polymer grafted khaya cellulose for transition metals extraction

A cellulose-graft-poly(methyl acrylate) was synthesized by free radical initiating process and the ester functional groups were converted into the hydroxamic acid ligand. The intermediate and final products are characterized by FT-IR, FE-SEM, HR-TEM and XPS technique. The pH of the solution acts as a key factor in achieving optical color signals of metal complexation. The reflectance spectra of the [Cu-ligand]n+ complex was found to be a highest absorbance at 99.8 % at pH 6 and it was increased upon increasing of Cu2+ ion concentrations and a broad peak at 700 nm was observed which indicated the charge transfer (π-π transition) metals-Cu complex. The adsorption capacity of copper was found to be superior (336 mg g−1) rather than other transition metals such as Fe3+, Co3+, Cr3+, Ni2+, Mn2+ and Zn2+ were 310, 295, 288, 250, 248 and 225 mg g-1, respectively at pH 6. The experimental data of all metal ions fitted significantly with the pseudo-second-order rate equation. The transition metal ions sorption onto ligand were well fitted with the Langmuir isotherm model (R2>0.99), which suggested that the cellulose-based adsorbent known as poly(hydroxamic acid) ligand surface is homogenous and monolayer. The reusability of the poly(hydroxamic acid) ligand was checked by the sorption/desorption process up to ten cycles without any significant loss in its original sensing and removal performances

Kenaf Cellulose Supported Highly Active Poly(Amidoxime) Palladium Complex as a Reusable Heterogeneous Catalyst For Allylic Arylation Reactions

A highly active kenaf cellulose supported poly(amidoxime) palladium catalyst was synthesized and characterized with FTIR, UV-Vis, FESEM, XPS and TEM analyses. The catalyst (65 mol ppm to 6.5 mol ppm) was found to promote efficiently the allylic arylation of allylic ester with sodium tetraarylborates in ethanol at 60 °C temperature. Outstanding yields of the corresponding products as well as significant reusability of the catalyst were obtained. The total turnover number (TON) and frequency (TOF) were 144615 and 9641 h–1 respectively

Synthesis of Kenaf Cellulose Supported Highly Active Poly(amidoxime) Palladium Complex and Its Application as a Reusable Catalyst for Allylic Arylation reactions

A highly active kenaf cellulose supported poly(amidoxime) palladium catalyst was sythesized and the catalyst (65 mol ppm to 6.5 mol ppm) was found to promote efficiently allylic arylation of allylic ester with sodium tetraarylborates and arylboronic acids in ethanol at 60 °C temperature. Oustanding yields of the corresponding products as well as significant reusability of the catalyst were obtained. The total turnover number(TON) and frequency(TOF) were 144615 and 9641 h–1 respectively