Boron Adsorbent Research Articles

Glucose and glycidol grafted polyacrylonitrile particles by hydrothermal synthesis for enriched boron from aqueous solution

The removal of boron from aqueous solution and the enrichment of boron from salt lake have attracted more attention. In this work, ethylenediamine and polyethyleneimine were grafted onto polyacrylonitrile with different degree of polymerization by hydrothermal method, and then reacted with glycidol and glucose to introduce polyhydroxy structure. The chemical composition and surface properties of the four boron adsorbents were characterized by IR, SEM, Mapping, TG-DSC-DTG and BET. The adsorption isotherm and adsorption kinetics of boron adsorption were investigated systematically. The results showed that the maximum boron adsorption capacity of PAN85000/150000-EN-PG and PAN85000/150000-PEI-GLC were 18.43, 15.27, 19.27 and 20.91 mg/g, respectively. The four adsorbents obey Langmuir adsorption model and pseudo-second-order kinetic model. The presence of salt lake brine ions Na+, Mg2+, Ca2+ and Cl− have little interference with boron adsorption. These adsorbents maintained good adsorption performance after 5 times adsorption-desorption processes. They are expected to be ideal environmentally friendly adsorbents for the enrichment of boron from salt lakes.

Facile Fabrication of N-Methyl-D-Glucamine Grafted HDPE Particle as Adsorbent for Boron Removal from Aqueous Solution

Glycidyl methacrylate (GMA) was grafted onto the surface of HDPE particles by radiation grafting and emulsion graft copolymerization. And subsequent ring-opening reaction of expoxy groups in poly-GMA graft chains with N-methylglucamine (NMG) was conducted to synthesis the boron adsorbent. The synthesis condition (radiation dose and NMG concentration) was optimized and characterized by IR and SEM. Adsorption behaviors of the boron adsorbent for boron removal presented that adsorption kinetics was well described by pseudo-second-order kinetic mode. The adsorption isothermal was well fitted with both Langmuir and Freundlich isotherm models. The adsorption capacity for boron reached 15.63 mg/g at optimal pH 8. Dynamic experiment revealed that boron could be efficiently adsorbed by the boron adsorbent and fully desorbed using 13 BV of 1 mol/L HCl.

Adsorption of boron by CA@KH-550@EPH@NMDG (CKEN) with biomass carbonaceous aerogels as substrate

This research reports an innovative boron adsorbent of CA@KH-550@EPH@NMDG (CKEN) via the modification of N-methyl-d-glucosamine (NMDG) on the surface of biomass carbonaceous aerogel, which is environmentally friendly, economically inexpensive, has simple preparation process and good regenerability. SEM and FT-IR characterization results indicate that CKEN has a 3D cross-staggered structure with lots of hydroxyl groups and pore structure, which are beneficial to the diffusion of boron and the chelation interaction between boron and CKEN. The adsorption behavior of CKEN for boron was evaluated. Various parameters affecting adsorption properties, viz., pH, ionic strength, initial concentration of boron, temperature and contact time were investigated. The adsorption kinetics is fitted with pseudo-second-order kinetics model better and the adsorption of boron on CKEN is an exothermic process. The adsorption equilibrium reached within 15 h with the maximum adsorption amount of 1.42 mmol/g (298 K). Moreover, CKEN also showed excellent reusability by consecutive five cycles of adsorption-desorption. It can be used as a potential recyclable adsorbent for efficient enrichment of boron from aqueous solution.

Hydroxyl-enhanced magnetic chitosan microbeads for boron adsorption: Parameter optimization and selectivity in saline water

Hydroxyl-enhanced materials are considered promising for boron adsorption. But, the use of these materials is hindered by issues of selectivity and separation notably in the presence of co-existing ions. Therefore, magnetic chitosan-based microbeads (MC) were synthesized and functionalized with a glycidol to produce boron-selective adsorbent (MCG). The resulting multi-hydroxyl microbeads were found to be a better substitute to the existing boron adsorbents. The adsorbents were characterized by scanning electron microscopy (SEM), and thermal gravimetric analysis (TGA). The BET surface area and vibrating sample magnetometry analyzes confirmed that the functionalized beads had a saturation magnetization, surface area, pore size, and diameter of 46.53Am2/kg, 598m2/g, 2.9nm and ∼150–400μm respectively. Under optimized condition, the MCG showed high adsorption affinity and remarkable selectivity towards boron in the presence of co-existing metal ions (Cu2+, Fe3+, and Ni2+) and salts of Mg2+, Ca2+, Na+ and K+ ions. MCG has 128.5mg/g of boron loading capacity within the first 100min, which is relatively higher than reported values. The spent beads were separated easily from the suspensions by an external magnet and reuse repeatedly.

High boron removal by functionalized magnesium ferrite nanopowders

Hydroxyl-enriched materials are promising boron adsorbents. However, the use of these materials is hampered by issues of separation, recovery, and selectivity, notably due to the presence of interfering ions. Therefore, we synthesized here a cheap magnetic nanopowder, which was further functionalized with polyvinyl alcohol and glycidol to produce boron-selective adsorbents. We studied their selectivity and removal efficiency using batch and fixed-bed systems. Sorption was studied at both concentrated and trace amounts of boron. Results show that nanopowders have 5.3–6.5 nm pore sizes and 145–203 m2/g surface areas, using Brunauer–Emmett–Teller analysis. Polyvinyl alcohol-functionalized particles removed 93 % of boron at 5 mg/L at pH 7 in 30 min, whereas only 68 % of boron was removed by glycidol-functionalized particles. However, at higher boron concentration, of 50 mg/L, glycidol-functionalized particles showed higher adsorption affinity of 68.9 mg/g. We conclude that internal hydroxyl groups of polyvinyl alcohol-functionalized particles are less accessible at higher boron concentration. This is the first report on magnesium ferrites for boron recovery. The spent adsorbents were separated easily from the aqueous media by an external magnet and repeatedly used. Overall, our findings demonstrated that the hydroxyl-enriched magnetic nanopowders are a better alternative to the existing boron adsorbents regarding magnetic separation, reusability, and selectivity.

Synthesis, characterization of salicylic-HCHO polymeric resin and its evaluation as a boron adsorbent

In this study, a novel salicylic-HCHO typed functional polymeric spherical resin (DFP) was prepared by inverse suspension polymerization. Starting with 2,4-dihydroxybenzoic acid, phenol and formaldehyde as monomers, using liquid paraffin as dispersed phase, span 80 as dispersant, 2-methoxyethanol as porogen and HCl as catalyst. The resulted polymer resin containing salicylic acid functions showed a powerful adsorption characteristic towards boron. The boron adsorption behavior of the adsorbent was studied in batch mode by varying different parameters such as pH value, initial concentration of boron and the adsorption time under noncompetitive conditions. It was found that the sorbent always maintained high capacity in neutral and alkaline conditions. The adsorption capacity was considerably increased by an increase in the concentration of boric acid. The existence of sodium ion and calcium ion could promote the boron adsorption to some extent. Langmuir, Freundlich and Dubinin–Radushkevich (D–R) isotherms are applied in order to determine the efficiency of DFP used as a boron adsorbent. Results show that the equilibrium data fits Freundlich model well. Gibbs free energy (ΔG), change in enthalpy (ΔH) and change in entropy (ΔS) were calculated. The adsorption process for boron was proved to be a chemical process of an exothermic nature. Kinetics studies demonstrated that boron uptake onto DFP followed the pseudo-second order model. The load capacity was attributed to specific chemical affinity and physical adsorption.

Magnetic mesoporous silica hybrid nanoparticles for highly selective boron adsorption

Novel core–shell magnetic mesoporous silica hybrid nanoparticles were synthesized and functionalized further with a glycidol reagent to produce boron-specific cis-diol, chelating functional derivatives. The resulting core–shell hybrid nanoparticles were found to be a better alternative to the existing boron adsorbents that had been modified with large molecular weight saccharide moieties and polymer functionalities. The magnetic mesoporous silica hybrid nanoparticles had a surface area, diameter, pore size, and saturation magnetization of 629 m2 g−1, 200–300 nm, 2.5 nm, and 33.25 emu g−1, respectively. The glycidol-modified nanoparticles with cis-diol functional groups showed high adsorption affinity and excellent selectivity towards boron in an aqueous solution, even in the presence of competitive metal ions (Ni2+, Cu2+, Cr2+ and Fe2+) and sulphates and chlorides of Na+, K+, Ca2+ and Mg2+ ions. Adsorption equilibrium could be established within 15–20 min, and the level of boron adsorption was 2.37 mmol g−1, which is much higher than the values previously reported for other boron adsorbent materials. The synthesized magnetic mesoporous silica hybrid nanoparticles showed approximately 97% boron removal capacity from a H3BO3 solution (100 mg L−1), and the used adsorbent particles could be separated easily from the aqueous suspensions by an external magnetic field. The adsorbent could be used repeatedly after a simple acid treatment (0.1 M HCl) and regenerated by an aqueous ammonia solution (3% NH3·H2O).

Preparation of a Solid Adsorbent Derived from Concrete Sludge and its Boron Removal Performance

We prepared a solid adsorbent for boron removal using real concrete sludge. The sludge was diluted with water at dilution ratios from 1 to 15. The diluted concrete sludge was then filtered and dried. Two types of drying methods were examined: natural drying under atmospheric conditions and forced drying in an oven at 105 °C. The boron removal performance was examined using a boric acid solution containing 100 mgB/L. All of the adsorbents prepared showed boron removal capacity. The adsorbent prepared with dilution ratio 10 and forced drying exhibited the highest boron removal capacity; the boron concentration after 24 h was just 3.33 mg/L, which is below the Japanese standard for industrial effluent (10 mg/L), and the maximum adsorption capacity for boron was 50 mgboron/gadsorbent. The drying method had a significant effect on both the rate and capacity of boron removal. With natural drying under atmospheric conditions, the adsorption initially proceeded quickly, but the final amount adsorbed was lower than that for the force-dried adsorbents. The boron removal can be attributed to ion exchange and uptake of boron in the ettringite phase. These results indicate that boron adsorbents prepared from concrete sludge can be applied for the removal of boron from effluents.

Low-cost materials for boron adsorption from water

Knowing the affinity of boron aqueous species for cis-diol organic groups, five different hybrid materials have been prepared by anchoring glucose groups onto the surface of silica matrices with a different surface topology: UVM-7 bimodal mesoporous silica, UVM-11 unimodal non-templated mesoporous silica, commercial silica fume and two silica xerogels with pores within the mesoporous range (13–50 nm). After optimizing the experimental conditions, a comparison was made of the boron adsorption capacities in water. The relationship of the structural and functionalization parameters is discussed and the importance of the surface topology in the final adsorption behaviour is revealed. Hence, despite the UVM-7 based material being the best boron adsorbent, the solid based on one of the xerogels is seen to be a good candidate for preparing low-cost boron adsorbents.

Efficient removal of boron acid by N-methyl-d-glucamine functionalized silica–polyallylamine composites and its adsorption mechanism

A novel boron adsorbent was fabricated by grafting a boric acid chelating group, i.e., N-methyl-d-glucamine, onto the hydrophilic silica–polyallylamine composites (SPC). The boron adsorbent was characterized by scanning electron microscopy (SEM) and TGA method. The adsorption experiment indicated a maximum boron load capacity of ca. 1.55mmolg−1. The high load capacity was attributed to specific chemical affinity and physical adsorption. Highly effective removal of boric acid from aqueous solution was observed for the adsorbent even in the synthetic seawater containing high concentration of foreign ions. Analysis of adsorption thermodynamic and kinetics revealed a spontaneous sorption process that is driven by enthalpy change and limited by chemical reaction. The exhausted adsorbent was regenerated for repeated use by treating with 3% HCl solution, followed by neutralizing with 3% NH3·H2O at ambient temperature. Only 7% capacity loss was observed after five continuous adsorption–regeneration cycles.

Microfiltration of suspensions of microparticulate boron adsorbent through a ceramic membrane

Suspensions of a microparticulate boron adsorbent Dowex XUS can be effectively concentrated by microfiltration (MF) to relatively high concentrations of about 24 mass% of dry adsorbent. This is important for formation of a hybrid process combining adsorption or ion-exchange and MF. A tubular ceramic membrane with the mean pore size of 0.1 μm and the ground boron adsorbent with the mean particle size of 4.7 mm have been used. Analysis of the flux decline data revealed that the dominant membrane fouling mechanism is cake formation. A more detail analysis showed that a pore blocking by initial layer of deposit is dominant at the beginning of MF and the resistance of growing cake becomes more important with increasing filtration time. With the increasing suspension velocity, the permeate flux significantly increases. The velocity of suspension above 2m s −1 should be used to achieve a reasonable flux. The limiting flux was reached at a pressure difference of about 60 kPa at higher suspension concentrations. The critical permeate flux was achieved at pressure difference below about 40 kPa. Even at concentrations as high as 20 mass% of dry adsorbent in the suspension, the permeate flux of about 43 dm −3m −2 h −1 was achieved.

Microfiltration of microparticulate boron adsorbent suspensions in submerged hollow fibre and capillary modules

Suspensions of a microparticulate boron adsorbent can be effectively concentrated to relatively high concentrations of about 11 mass% by microfiltration in aerated submerged modules using hydrophilic capillary and hydrophobic polypropylene hollow fibre membranes. With the increasing trans-membrane pressure difference, the permeate flux increases significantly at suspension concentrations below 7 and 4 mass% for hydrophilic and hydrophobic membrane, respectively. The permeate flux is higher for the hydrophilic membrane than for the hydrophobic one. Concentration dependence of flux for the hydrophilic membrane shows only a slight decrease of the flux with increasing concentration of the suspension, up to 7 mass%, while the flux through the hydrophobic membrane decreases much in this interval. The permeate flux at the trans-membrane pressure of 40 kPa for suspensions with 7 mass% of the adsorbent is about 72 and 14 dm 3m −2h −1 for the hydrophilic and the hydrophobic membrane, respectively. Backwashing of the membrane with a reversed flow of permeate was tested in a module with a hydrophilic membrane and was found successful in keeping the membrane performance stable for a shorter term of operation.

Simulation of the adsorption—microfiltration process for boron removal from RO permeate

Based on experimental data, a simulation and optimisation of the adsorption–microfiltration (AMF) process for boron removal from reverse osmosis (RO) permeate was done. An impressively low flow rate of the dry boron adsorbent of about only 54.3 kg h −1 is needed in the adsorbent recirculation loop of a unit for treatment of 100m 3 h −1 of RO permeate and boron concentration in the feed and raffinate 1.2 and 0.4 mg dm −3, respectively. The optimum concentrations of dry adsorbent in the suspension leaving submerged microfiltration module (MF1) and cross-flow microfilters are 110 and 200 kg m −3, respectively. A diafiltration of regenerated adsorbent suspension is an effective way of decreasing of adsorbent flow rate and consumption of chemicals in the desorption loop. Use of about 0.5% of the raffinate for diafiltration is optimal. Specific consumption of regeneration media per unit volume of raffinate at these conditions are 0.97 and 0.19 mol m −3 for acid and alkali, respectively. Segmentation of submerged MF1 module is a useful way of reducing membrane area needed, which is at an optimal conditions in case of ideal mixing in segmented and non-segmented MF1 modules 1315 and 1695 m 2, respectively. The overall theoretical power input for MF pumps and air blower is of about 0.018 kWh m −3.

Synthesis of Graft Adsorbent with N-Methyl-D-glucamine for Boron Adsorption

It is well known that adsorbents having N-methyl-D-glucamine (NMDG) preferentially adsorb boron. The boron adsorbent developed in this study has promising properties of rapid boron adsorption from the natural water. The adsorbent was prepared by radiation induced graft polymerization of glycidyl methacrylate (GMA) onto non-woven polyethylene fabrics in aqueous medium, and following chemical modification with NMDG The resulting adsorbent was evaluated by column-mode adsorption of boron at various flow rates. Comparison between graft adsorbent and granular resin, graft adsorbent has 4 times higher bed volume (BV) at breakthrough point at space velocity (SV) 50 h-1. The BV at breakthrough point of graft adsorbent at SV 100 h-1 gave the same one with granular resin at SV10 h-1.

Novel organic–inorganic hybrid mesoporous materials for boron adsorption

Amine groups and polyol groups were sequentially grafted on mesoporous SBA-15 and MCM-41 to synthesize novel organic–inorganic hybrid mesoporous materials as boron adsorbents by a two-step post-grafting method. By means of small-angle XRD, N 2 adsorption–desorption, solid-state NMR, Fourier transform infrared (FT-IR) and elemental analysis, the structure and physicochemical properties of the materials were characterized. The behaviors of the resulting adsorbents in adsorption of boron from solutions were investigated. The results show that the organic functional groups are successfully grafted on the SBA-15 and MCM-41, while the quantity and the distribution of the functional groups are varied due to the different pore properties of the materials. The boron adsorption isotherms of the adsorbents are in good accordance with the Langmuir equation. The polyol-functionalized SBA-15 was proved to be a promising adsorbent with the high adsorption capacity of boron up to 0.63 mmol/g as well as the high selectivity towards boron.

Aminopropyl–Glucose Sequentially Grafted Mesoporous Silica Nanocomposite as a Novel Boron Adsorbent

Abstract Aminopropyl groups and glucose molecules were sequentially grafted on mesoporous silica (ca. 5 nm in diameter) to synthesize a glucamine group analogue in the nanospaces. The grafted nanocomposite material showed a high capacity for adsorption of boric acid/borate from water.