Rationally engineering magadiite heavy metal adsorbent for p-nitrophenol hydrogenation reduction

In this study, the kinetics modeling for design of adsorbers for multiple adsorption of heavy metal ions was carried out using activated carbon from waste Nigerian bamboo. The bamboo was cut into sizes, washed, dried and was carbonized at 350°C-500°C. It was then activated at 800°C using nitric acid. Simultaneous batch adsorption of different heavy metal ions (Cd2+, Ni2+, Pb2+, Cr3+,Cu2+and Zn2+) in same aqueous solution using activated carbon from Nigerian bamboo was carried out at different initial concentration till equilibrium was reached. In order to determine the mechanism of sorption for multiple adsorption of these heavy metals ions, the kinetic data were modeled using the pseudo first order, pseudo second order kinetic equations, and intra-particle diffusion models. The pseudo first order did not fit well into the kinetic data. The pseudo second order equation was the best applicable model to describe the sorption process. Hence the pseudo second order kinetic reaction is the rate controlling step with some intra particle diffusion taking place. An empirical model was also developed which can then be used for predicting and designing adsorber for the multiple removal of 99% heavy metal ions at any given initial heavy metal ions concentration and the adsorption time required for any multi-stage adsorption system using Nigerian Bamboo activated carbon.

Phase control and its mechanism of CuInS2 nanoparticles

Polymer metal nano‐composites (PMNC) were synthesized by integrating different weight percentage of chitosan (CS), N,N′‐methylenebisacrylamide (MBA) crosslinked poly(acrylic acid‐co‐hydroxyethyl methacrylate) copolymer and Cu nanoparticles (CuNPs). CuNPs were generated in situ during polymerization by reducing CuSO4.5H2O with ascorbic acid. The presence of the CuNPs in the polymer network, functionality, crystallinity, morphology, size distribution of the CuNPs, elemental composition, thermal characteristics, network parameters, pH sensitivity, and strength of the composites was evaluated. The CuNP‐loaded PMNC4 composite prepared with 10:1 acrylic acid : hydroxyethyl methacrylate molar ratio, 1 wt% each of initiator and MBA crosslinker and 4 wt% CS showed a photodegradation efficiency of 64% in 5 h for 50 mg/L methyl violet dye in water. The same polymer showed a rejection of 91.45% and a mass transfer coefficient of 4.14 × 10−5 cm/s for continuous adsorption of 20 mg/L Pb(II) ion in water in a fixed bed of height 22 mm for an inflow rate of 30 ml/min.

Investigation of the adsorption of heavy metals (Cu, Co, Ni and Pb) in treatment synthetic wastewater using natural clay as a potential adsorbent (Sale-Morocco)

This manuscript describes the preparation and characterization of silica-nickel oxide (SiO2-NiO) xerogel nanocomposite and its catalytic application in the hydrogenation of p-nitrophenol. Hydrochloric acid and ammonium hydroxide were used as the acid and base catalyst, respectively during the synthesis of SiO2-NiO. The Fourier Transformation Infra-Red spectroscopic results supported the formation of the silica xerogel skeleton structure with corresponding characteristic peaks of siloxane linkage. The surface of SiO2-NiO xerogel nanocomposite was observed to be porous along with some irregular cracks. The X-Ray diffraction analysis showed that the SiO2-NiO xerogel nanocomposite was amorphous in nature. The synthesized xerogel nanocomposite was employed as a catalyst for the hydrogenation of p-nitrophenol with sodium borohydride in water. The rate of hydrogenation of p-nitrophenol was observed to be increased with the increased amount of catalyst as well as the temperature. The maximum reduction rate of p-nitrophenol was found as high as 0.26 min-1.

Cu-SSZ-39 zeolite nanosheets-heterogeneous catalyst for the decarboxylative cross-coupling of cinnamic acids with ethers

Novel insights into adsorption of heavy metal ions using magnetic graphene composites

The removal performance and the selectivity sequence of separate metal ions (Fe2+, Cr3+, Cu2+, Zn2+ and Ni2+) in aqueous solution were studied by adsorption process on untreated and natural volcanic tuff. A series of experiments were conducted in batch-wise and fixed-bed columns to investigate the removal efficiency of natural Jordanian volcanic tuff as low cost and an effective adsorbent for heavy metal ions and to examine its economical application in water purification and treatment practices.Water and wastewater samples containing metal ions with concentrations ranging from 1 to 15 mg/L were used. The plexi glas columns were filled with natural occurring volcanic tuff particles ranging between (0.350 – 3.000) mm. Photometric methods were used for laboratory analysis of samples.The experiments were carried out under changing conditions as a function of different pH-values (2,4,6 and 7), initial solute concentrations (1, 5, 10, 15) mg/L, and different room temperatures (20, 25 and 30 Cº ), and varying tuff particle sizes (0.35 -3.0) mm. The breakthrough curves were derived by plotting the normalized effluent metal concentrations (C/C0) versus bed volume.Obtained results showed that natural Jordanian volcanic tuff has an adsorption capacity of 0.417 mg/g for Fe 2+ and 0.151mg/g for C 2+. Factors in the reaction medium such as pH and ionic strength influenced the adsorption process. The quantity of particular ionic species (Cu2+, Pb2+, Cr2+ ,Fe2+, Zn2+) bound in dependence on the initial concentrations, indicates that the removal efficiency from the liquid phase follows the sequence Fe2+>Cu2+>Pb2+> Cr2+>Zn2+ when keeping the pH at 4 and follows the sequence Cu2+>Zi2+>Fe2+>Cr2+>Pb2+ when keeping the pH at 6. Equilibrium modeling of the removal showed that the adsorption of the metal cations Cr2+, Pb2+, Zn2+ , Cu2+ and Fe2+ were fitted to one of the adsorption isotherms.

Chapter 12 - Nano-Array Catalysts for Energy and Environmental Catalysis

Site- and Spatial-Selective Integration of Non-noble Metal Ions into Quantum Dots for Robust Hydrogen Photogeneration

In this work adsorption of heavy metal ions (Cu2+, Pb2+, Zn2+and Ni2+) from aqueous solution by chitosan was investigated in a batch reactor. Three commercially different viscosity chitosans were used as adsrobents. pH value, adsorption temperature, time and initial concentration had affected adsorption efficiency of metal ions. The results showed that low viscosity chitosan has the highest adsorption capacity among the low, middle and high viscosity chitosans. The amounts of adsorbed metal ions decreased with increased adsorption temperature and decreased pH value. The highest adsorbed amount at the equilibrium time (7.5mg/g) of Cu2+was observed among Cu2+, Pb2+, Zn2+and Ni2+.

Various heavy metals have been released into the waters, causing serious pollution of water resources and endangering human health. Therefore, it is very important to study the removal of heavy metals from water. In this work, the adsorption of heavy metal ions including Pb(II), Cu(II), and Fe(II), onto Dennettia tripetala from aqueous solutions was investigated in mixed systems. The batch adsorption experiment for heavy metal ions on Dennettia tripetala mixed system was studied at different conditions including contact time, initial concentration, initial pH and adsorbent dosage. The results indicated that the adsorption kinetics followed the pseudo-first order model base on R2 for Fe(II) which is 0.907, and pseudo-second order for Pb(II) with R2 = 0.70 respectively. Hence the freundlich isotherm model is the best fit for Fe(II) with R2 = 0.979 and for the Pb(II), it fits Temkin model with R2 = 0.930. The final removal efficiencies and maximum adsorption capacity followed the order of Pb(II) > Cu(II) > Fe(II) at room temperature. The bio-sorption of heavy metals determined by the pH of the solution and the adsorbent dose, was found that the initial pH of 7 was optimal for the removal of Pb(II) and Fe(II), which was different from the optimum initial pH below or above 7. The results demonstrated that the electrostatic interaction between the surface of the Dennettia tripetala and heavy metal ions played an important role in the adsorption of heavy metal ions. In addition, compared to other researches, the results in mixed system showed that the adsorption of Cu(II), Pb(II) and Fe(II) was promoted since none of the metal co-exist with one another.

When considering the importance of mesoporous materials as adsorbent for heavy metal ions, this study concerns on the preparation, characterization and application of a SBA-15 mesoporous silica material functionalized with a Schiff base ligand N-propylsalicylaldimine (SBA/SA). The properties of this adsorbent were compared with two SBA-15 mesoporous silica materials modified with aminopropyl (SBA/NH2) and ethylenediaminopropyl (SBA/En) groups. These materials were characterized by XRD, SEM, TEM, TGA techniques and FTIR spectroscopy. The potential of the prepared modified mesoporous materials, as metal ion adsorbents, was evaluated by their application for removal of Pb(II), Cd(II) and Ag(I) ions from aqueous solutions. The assessments were conducted by investigating the effect of sample aqueous pH, contact time, adsorbent dose and initial concentration of the metal ions in batch systems. Flame atomic absorption spectroscopy (FAAS) was used for metal ions measurements. It is found that after 4 h of mechanical agitation of the adsorbents and solution, under optimum conditions, lead ions can be quantitatively removed from 10 mg L−1 Pb(II) solution using 0.03 g of SBA/NH2, 0.005 g of SBA/En or 0.005 g of SBA/SA. Under same conditions, silver ions can be quantitatively removed from 10 mg L−1 Ag(I) solution using 0.04 g of SBA/SA. In addition, all the studied ions can be eliminated from solution (initial concentration 10 mg L−1) using 0.06 g of SBA/En adsorbent. Based on the calculated values from the Langmuir isotherm, the maximum adsorption capacities of the adsorbents SBA/NH2,SBA/En and SBA/SA for Pb(II), Cd(II) and Ag(I) were found to be 29.4, 111.1 and 100.0 mg g−1, 8.0, 14.0 and 5.6 mg g−1, and 7.3, 31.2 and 28.5 mg g−1, respectively. The equilibrium data were analyzed using the Langmuir and Freundlich isotherms. The proposed method was applied for removing Pb(II), Cd(II) and Ag(I) ions from real samples under selected experimental conditions.

The present study was undertaken to investigate the ability of granulated charcoal activated carbon (AC) and multiwalled carbon nanotubes (MWNTs) as adsorbents in adsorption process of removing heavy metals from aqueous solutions. The analyses of heavy metal removal are performed on three operational parameters which are agitation time, initial ion concentration and pH. The experiments were carried out at room temperature (25°C) and metal solutions were agitated on a rotary shaker at constant speed range between 200 to 240 rpm. BET surface area of AC and MWNTs were found to be 898 m2/g and 213 m2/g, respectively. Metals adsorptions by both adsorbents were well fitted to Freundlich isotherm. Batch adsorption test showed that metal uptake increases as agitation time increases which are the optimum time are 3 hours and 4 hours by using AC and MWNTs, respectively. Cadmium adsorption by both adsorbents showed the same behaviour where as initial metal ion concentration increases, cadmium adsorption percentage increases. As for nickel, when using AC as adsorbent, as the initial ion concentration increases, the nickel adsorption percentage decreases. Adsorption was found to be low at acidic pH and kept on increasing as pH increased.

Adsorption of lead, copper and zinc in a multi-metal aqueous solution by waste rubber tires for the design of single batch adsorber