Column efficiency of fluoride removal using Quaternized Palm Kernel Shell (QPKS)

In this research, the adsorption potential of quaternized palm kernel shell (QPKS) to remove F− from aqueous solution was investigated using fixed-bed adsorption column. Raw palm kernel shell waste was reacted with 3-chloro-2-hydroxypropyl trimethylammonium chloride (CHMAC) in order to modify the surface charge. The effects of inlet F− concentrations (2–12 mg/l) and QPKS bed height (2–10 cm) with optimum pH (pH = 3) on the breakthrough characteristics of the adsorption system were determined. In the fixed-bed column, breakthrough time increases with increasing bed height due to increasing amount of active site on adsorbents to adsorb the fluoride ion. Decreasing trend of breakthrough values was obtained with increasing initial fluoride concentration due to greater driving force for the transfer process to overcome the mass transfer resistance in the column. The adsorptions were fitted to three well-established fixed-bed adsorption models, namely, Thomas, Yoon–Nelson, and Adams–Bohart models. The results fitted well to the Thomas and Yoon–Nelson models with correlation coefficient, R2 ≥ 0.96

Equilibrium and kinetic behavior on cadmium and lead removal by using synthetic polymer

It is known that synthetic polymer plays a big role in various applications. One of its potentials is to remove heavy metal ions through single batch adsorption. Adsorption behavior and mechanism of synthetic polymer are the two main focuses in this research. The synthetic polymer of Poly(AN-co-AA) has been successfully polymerized, modified with hydroxylamine hydrochloride and removed Cd2+ and Pb2+. The poly(AN-co-AA) and amidoxime (AO) modified poly(AN-co-AA) were characterized by Fourier Transform Infrared Analysis (FTIR), microanalysis, Scanning Electron Microscopy (SEM) and Thermogravimetry (TGA). At pH 9, the percentage removal for Cd2+ (90%) and Pb2+ (98%) were the highest with adsorbent dosage at 4 gL−1 and 8 g L−1, respectively. The experimental data for Cd2+ (20 mg g−1) and Pb2+ (125 mg g−1) were fitted well by Sips and Freundlich isotherms model, respectively. The adsorption rate for both Cd2+ and Pb2+ were stated by using Lagergren pseudo-first order

Removal of fluoride using quaternized palm kernel shell as adsorbents: equilibrium isotherms and kinetics studies

Palm kernel shell (PKS) core fibers, an agricultural waste, were chemically modified using N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHMAC) as a quaternizing agent. The potential of quaternized palm kernel shell (QPKS) as an adsorbent for fluoride in an aqueous solution was then studied. The quaternized palm kernel shell (QPKS) core fibers were characterized using Fourier transform infrared spectroscopy (FTIR) and a scanning electron microscope (SEM). The effect of various factors on the fluoride sequestration was also investigated. The results showed that with an increase in the adsorbent amount and contact time, the efficiency of fluoride removal was improved. The maximum fluoride uptake was obtained at pH 3 and a contact time of 4 h. The adsorption behavior was further investigated using equilibrium isotherms and kinetics studies. The results from these studies fit well into Freundlich, Redlich-Peterson, and Sips isotherm’s with a coefficient of determination (R2) of 0.9716. The maximum fluoride removal was 63%. For kinetics studies, the pseudo-second order was the best fit for fluoride, with an R2 of 0.999. These results suggest that QPKS has the potential to serve as a low-cost adsorbent for fluoride removal from aqueous solutions

Removal of fluoride using quaternized palm kernel shell as adsorbents: Equilibrium isotherms and kinetics studies

Palm kernel shell (PKS) core fibers, an agricultural waste, were chemically modified using N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHMAC) as a quaternizing agent. The potential of quaternized palm kernel shell (QPKS) as an adsorbent for fluoride in an aqueous solution was then studied. The quaternized palm kernel shell (QPKS) core fibers were characterized using Fourier transform infrared spectroscopy (FTIR) and a scanning electron microscope (SEM). The effect of various factors on the fluoride sequestration was also investigated. The results showed that with an increase in the adsorbent amount and contact time, the efficiency of fluoride removal was improved. The maximum fluoride uptake was obtained at pH 3 and a contact time of 4 h. The adsorption behavior was further investigated using equilibrium isotherms and kinetics studies. The results from these studies fit well into Freundlich, Redlich-Peterson, and Sips isotherm's with a coefficient of determination (R2) of 0.9716. The maximum fluoride removal was 63%. For kinetics studies, the pseudo-second order was the best fit for fluoride, with an R2 of 0.999. These results suggest that QPKS has the potential to serve as a low-cost adsorbent for fluoride removal from aqueous solutions

Performance of amidoxime-modified poly (Acrylonitrile-co-acrylic acid) for the removal of cadmium (II) and lead (II) ions in aqueous solution

The untreated heavy metal ions that were discharged as effluent waste had caused serious impact on the environment and human health. The adsorption process is an alternative way to remove heavy metal ions. The polymer-based adsorbent was chosen as material to remove heavy metal ions due to its economic cost, can be prepared with convenient method and excellent capability to make high adsorption towards metal ions. In this study, the synthesis and modification of amidoxime (AO) modified poly(acrylonitrile-co-acrylic acid) (poly(ANco- AA)) was carried out. Next, the effect of adsorption parameters, equilibrium and kinetic studies of cadmium ion (Cd2+) and lead ion (Pb2+) were investigated. The optimisation of adsorption parameter was analysed using Response surface methodology (RSM). The poly(AN-co-AA) was synthesised via redox polymerisation and was further chemically modified with hydroxylamine hydrochloride to produce AO modified poly(AN-co-AA) as adsorbent. Then, single batch system of adsorption experiments for each heavy metal ions of Cd2+ and Pb2+ were implemented by varying the pH, adsorbent dosage, initial metal ion concentration and contact time. The isotherm and kinetic studies were carried out by using single batch of experimental data. Lastly, the optimisation of adsorption conditions was employed using Central composite design of RSM. The synthesis yield of poly(acrylonitrile) (PAN) was 73% and poly(AN-co-AA) 93:7 obtained the highest yield at 72%. The Fourier transform infrared (FTIR) spectra confirmed the successful of polymerisation due to the appearance of absorption peaks that were assigned to the C≡N and –COOH functional groups on the spectra. The microanalysis showed that the overall trend of elemental percentage for poly(AN-co-AA) copolymers were slightly decreased as the mole ratios of acrylic acid (AA) increased. The thermogravimetric (TG) analysis suggested that the thermal stability of poly(AN-co-AA) was lower as compared to the PAN. On the other hand, the FTIR spectra of AO modified poly(AN-co-AA) proved that the C≡N were successfully converted into amidoxime groups. The microanalysis showed that the increasing trend of nitrogen and hydrogen elements in amidoxime modified polymer. The amine capacity test confirmed the quantity of amidoxime functional groups in modified polymer. The maximum removal percentage based on parameters effect for each Cd2+ and Pb2+ were with an initial adsorbate concentration of 100 mg.L-1 at pH 9 with adsorbent dosage of 4 g.L-1 (Cd2+) and 8 g.L-1 (Pb2+). The Sips isotherms showed good agreement for the adsorption of Cd2+ (R2 of 0.9997) with maximum adsorption capacities of 20 mg.g-1. The adsorption of Pb2+ satisfied the Freundlich isotherms (R2 of 0.9875) with maximum adsorption capacities of 125 mg.g-1. The Lagergren pseudo-first order was observed to have better R2 compared to the other models for both Cd2+ and Pb2+. The RSM shows the removal of Cd2+ (98.33%) was satisfied with predicted value (98.58%) at optimum conditions, 10 mg.L-1 of Cd2+ initial concentration and the 4.66 g.L-1 of adsorbent dosage at pH 9.31. The removal of Pb2+ was 99.41% that fitted well with the predicted value (99.80%) with the optimum conditions, 20 mg.L-1 of Pb2+ initial concentration and 8.27 g.L-1 of adsorbent dosage at pH 9.08. The results suggested that the AO modified poly(AN-co-AA) sorbent is a potential material to capture high quantity of Cd2+ and Pb2+ from aqueous solution under certain conditions

Open-cell copper foam joining: joint strength and interfacial behaviour

A copper (Cu) foam was brazed with Cu-4.0Sn-9.9Ni-7.8P filler foil for joint strength and interface analysis. Brazed 50 pores per inch (PPI) Cu foam yielded a maximum compressive strength of 14.4 MPa with a 127% increment compared to nonbrazed Cu foam. 15 PPI Cu foam produced a maximum shear strength of 2.7 MPa. Scanning electron microscopy showed that the thickness of the brazed seam decreased with increasing the Cu foam’s PPI. The formation of the Cu, Cu3P (P: phosphorus) and Ni3P (Ni: nickel) at the Cu/Cu foam interface was validated using energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction. EDX line scanning analysis revealed the diffusion of P and Ni into Cu foam, which took place via capillary force action. © 2019, © 2019 Institute of Materials, Minerals and Mining

Improved Method for Preparation of Amidoxime Modified Poly(acrylonitrile-co-acrylic acid): Characterizations and Adsorption Case Study

Redox polymerization of poly(acrylonitrile-co-acrylic acid) (poly(AN-co-AA)) is performed at 40 °C under N2 gas by varying the ratio of acrylonitrile (AN) and acrylic acid (AA) in the feed. The yield production of poly(acrylonitrile) (PAN) is 73% and poly(AN-co-AA) with a feed ratio of 93:7 is the highest yield (72%). The PAN and poly(AN-co-AA) are further chemically modify with hydroxylamine hydrochloride. The FTIR spectroscopy is used to confirm the copolymerization of poly(AN-co-AA) and chemical modification of poly(AN-co-AA). Elemental microanalysis shows that the overall trend percentage of carbon, hydrogen, and nitrogen for all feed ratios are slightly decreasing as the feed ratio of AA is increasing except for poly(AN-co-AA) 93:7. The SEM images shows that spherical diameter of poly(AN-co-AA) is smaller compared to the PAN and amidoxime (AO) modified poly(AN-co-AA). The TGA (thermogravimetric analysis) analysis reveals that the poly(AN-co-AA) degrades at lower temperatures compared to the PAN but higher than AO modified poly(AN-co-AA). The case study adsorption test showed that the AO modified poly(AN-co-AA) 93:7 had the highest percentage removal of Cd2+ and Pb2+

Central composite design of heavy metal removal using polymer adsorbent

The industrial effluents of heavy metal become a great concern because of their toxicity. The better design of experimental (DOE) should be applied for an efficient treatment process. The statistical DOE of central composite design (CCD) can be used for the optimization process of heavy metal removal. The cadmium ions (Cd2+) and lead ions (Pb2+) were removed using amidoxime modified poly(acrylonitrile-co-acrylic acid) (poly(AN-co-AA)). The CCD response result (Cd2+ and Pb2+ removal) was obtained by considering independent variables of pH (A), adsorbent dosage (B), and initial concentration (C). The experimental removal of Cd2+ and Pb2+ at optimum conditions was 98.90% and 99.99%, respectively. The regression analysis illustrated the optimum conditions were 10 mg.L−1 Cd2+ concentration with 4.66 g.L−1 adsorbent at pH 9.31, and 20 mg.L−1 Pb2+ concentration with 8.27 g.L−1 adsorbent at pH 9.08. Both of the metal ions yielded insignificant lack of fit of the analysis of variance (ANOVA)

Brazing of porous copper foam/copper with amorphous Cu-9.7Sn-5.7Ni-7.0P (wt%) filler metal: interfacial microstructure and diffusion behavior

In this work, brazing of porous copper foam (PCF) to copper (Cu) using amorphous Cu-9.7Sn-5.7Ni-7.0P (in weight, wt%) filler metal has been performed. PCF with different pore densities of 15 pore per inch (PPI), 25 PPI, and 50 PPI were sandwiched in between amorphous Cu-9.7Sn-5.7Ni-7.0P filler/Cu based plate. A brazed joint of Cu/Cu using amorphous Cu-9.7Sn-5.7Ni-7.0P filler was prepared for comparison purposes. The interfacial microstructures and mechanical properties of the brazed joint were investigated to study the joint ability after the brazing process. Scanning electron microscope (SEM) confirmed the interfacial microstructure by the formation of the diffusion layer (shown in light shaded area) and filler layer (gray island-shaped) for both Cu/Cu and Cu/PCF/Cu brazed joint. The X-ray diffraction (XRD) patterns identified the brittle phases of Cu3P and Ni3P, Cu and Cu6Sn5 phases at the diffusion layer. In the shear test, the strength value decreases with increase in the pore densities of PCF. The decreasing shear strength observed with an increase in the number of PPI in PCF is due to the formation of more cavities in Cu/PCF as the number of PPI in Cu/PCF increases. © 2019, International Institute of Welding