Nickel adsorption from waters onto Fe3O4/sugar beet pulp nanocomposite.

In this study the magnetic nanocomposite material was synthesized with Fe3O4 impregnated to sugar beet pulp using chemical precipitation technique. Ni(II) removal performance of magnetic nanocomposite was investigated under different environmental conditions such as contact time, adsorbent dose, pH, initial heavy metal concentration, etc. The experimental studies have shown that, 81.2% Ni(II) removal efficiency was achieved at optimal conditions (25 mg/L initial Ni(II) concentration at 40 minute contact time, 200 rpm shaking speed, 5 g/L nanocomposite dose and pH 6.6). Freundlich and Langmuir isotherm experiments were performed and correlation coefficients were determined as 94.5% and 99.4%, respectively. The maximum adsorption capacity of material was achieved as 9.36 mg/g. These findings indicate that the adsorption that takes place is a monolayer process. The results of the pseudo-second order kinetic model (R2 = 0.9947) indicate the chemisorptions process is used for Ni(II) removal using the electrostatic interaction. Thermodynamic studies illustrated that Ni(II) adsorption onto nanocomposite are exothermic and causes a decrease in the entropy. The adsorption of Ni(II) ions is non-spontaneous except for at low temperature and low initial concentrations. Nanocomposite characterization was illuminated with XRD, FT-IR, BET, TGA, TEM, SEM/EDX analysis.

In this study, it was aimed to synthesis new adsorbent using sugar beet pulp together with Fe₃O₄ under suitable conditions, obtain a magnetic nanocomposite, and examine the reusability and recovery properties of the produced material. The use of industrial wastes as an adsorbent material provides both a solution to the problem of the removal of wastes and a reuse method for the use of wastes as a low cost adsorbent for a useful purpose. Therefore, it has two advantages: There is a need to investigate the feasibility of investigating all possible industry-based cheap adsorbent sources as well as the removal of heavy metals for the production of a reliable and harmless adsorbent.

Simultaneous nitrate, nickel ions and phosphorus removal in a bioreactor containing a novel composite material.

This study presents the novel composite material TMCC/PAA/SA@Fe(TPSA), a bacteria immobilized carrier for use in bioreactor systems to enhance the simultaneous removal efficiency of nitrate, Ni(II) and phosphorus. The influence of various operational factors were evaluated on the performance of nitrate, phosphorus and Ni(II) removal. Results demonstrate that under optimum conditions of an hydraulic retention time (HRT) of 8 h and pH 7.0, nitrate and phosphorus removal reached nearly 100% and 61.7%, respectively. When the initial Ni(II) concentration was 1 mg/L, approximately 100% Ni(II) removal efficiency was achieved. Furthermore, the morphology and components of the TPSA immobilized bacterial pellets were analyzed to investigate the mechanism of simultaneous nitrate, Ni(II) and phosphorus removal. Microbial metabolism was more active in the experimental reactor compared with control, although high concentrations of Ni(II) could inhibit bacterial activity.

Adsorption of Ni(II) ions by magnetic activated carbon/chitosan beads prepared from spent coffee grounds, shrimp shells and green tea extract.

Magnetic activated carbon/chitosan composite (MACCS) beads from spent coffee grounds and shrimp shells were synthesized using green tea extract as a crosslinker. The adsorbent was then applied for removal of Ni(II) ions from aqueous solution after carefully characterizing it by various techniques (XRD, FTIR, FE-SEM, EDX, VSM and BET). The adsorption kinetics, isotherms, thermodynamics, the effects of key adsorption factors such as the pH value, initial Ni(II) concentration, contact time, adsorbent dose and temperature were investigated in detail. A possible adsorption mechanism was proposed. The results indicated that the adsorption process was thermodynamically favourable, spontaneous, endothermic, and was best described by the Langmuir isotherm and pseudo-second-order kinetic models. The MACCS beads with an optimum CS to MAC weight ratio estimated as 60:40 gave the maximum monolayer adsorption capacity for Ni(II) ions of 108.70 mg g-1 at 25°C, pH of 6, adsorbent dose of 1.0g L-1 and a contact time of 6 h. The recycling study confirmed that the adsorption ability of MACCS beads towards Ni(II) ions maintained well after five consecutive cycles with the removal efficiency greater than 86.25%. Eventually, the MACCS beads could be used as an environmentally-friendly and highly efficient adsorbent for removal of Ni(II) ions from wastewater due to the advantages of high efficiency, rapid separation and good reusability.

Development of carbon adsorbents with high surface acidity and basicity from polyhydric alcohols with phosphoric acid activation for Ni(II) removal.

In this study, polyhydric alcohols, including glycerol, erythritol, xylitol, mannitol, and inositol, were chosen as carbon precursors for preparation of carbon adsorbents via phosphoric acid activation. The thermal behaviors of phosphoric acid-treated polyhydric alcohols revealed the formation and decomposition of organic phosphates at low temperatures, which enhanced the creation of functional groups on activated carbon. In general, the activated carbons showed relative low surface area (the highest one of 509 m2/g for AC-xylitol) due to the low activation temperature, and low yields (the highest one of 36.6% for AC-xylitol) due to the volatilization and decomposition of organic phosphates. The activated carbons contained 50-90% larger total amount of surface groups than the reference activated carbon derived from lignocellulose material, which mainly resulted in their 40-75% higher Ni(II) adsorption capacity. These results also indicated that the polyhydric alcohols-based activated carbons can be promising candidates for Ni(II) removal.

The nickel ion removal prediction model from aqueous solutions using a hybrid neural genetic algorithm.

Prediction of Ni(II) removal during ion flotation is necessary for increasing the process efficiency by suitable modeling and simulation. In this regard, a new predictive model based on the hybrid neural genetic algorithm (GANN) was developed to predict the Ni(II) ion removal and water removal during the process from aqueous solutions using ion flotation. A multi-layer GANN model was trained to develop a predictive model based on the important effective variables on the Ni(II) ion flotation. The input variables of the model were pH, collector concentration, frother concentration, impeller speed and flotation time, while the removal percentage of Ni(II) ions and water during ion flotation were the outputs. The most effective input variables on Ni(II) removal and water removal were evaluated using the sensitivity analysis. The sensitivity analysis of the model shows that all input variables have a significant impact on the outputs. The results show that the proposed GANN models can be used to predict the Ni(II) removal and water removal during ion flotation.

Effective removal of Ni(II) from aqueous solutions by modification of nano particles of clinoptilolite with dimethylglyoxime.

In this work an Iranian natural clinoptilolite tuff was pre-treated and changed to the micro (MCP) and nano (NCP) particles by mechanical method. Modification of micro and nano particles and also their Ni-exchanged forms were done by dimethylglyoxime (DMG). The raw and modified samples were characterized by XRD, FT-IR, SEM, BET, TG-DTG and energy dispersive analysis X-ray spectroscopy (EDAX). Removal of Ni(II) by modified and unmodified samples was investigated in batch procedure. It was found that NCP-DMG has higher capacity for removal of Ni(II). The effects of analytical parameters such as pH, dose of DMG, concentration of nickel solution, contact time and selectivity were studied and the optimal operation parameters were found as follows: pHPZC: 7.6, CNi(II): 0.01 M, contact time: 360 min and DMG dosage: 5mM. The results of selectivity experiments showed that the modified zeolite has a good selectivity for nickel in the presence of different multivalent cations. Langmuir and Freundlich isotherm models were adopted to describe the adsorption isotherms. Adsorption isotherms of Ni(II) ions could be best modelled by Langmuir equation, that indicate the monolayer sorption of Ni(II). Comparison of two kinetic models indicates that the adsorption kinetic can be well described by the pseudo-second-order rate equation that indicates that the rate limiting step for the process involves chemical reaction. The negative ΔH and ΔG indicate an exothermic and spontaneously process. The negative ΔS indicates that the adsorption of nickel cations from solution occurs with lower amount ion replacement, thus chemisorptions due to complex formation are dominant process in nickel removal.