Adsorption mechanism of 2-mercaptobenzothiazole on chalcopyrite and sphalerite surfaces:Ab initio and spectroscopy studies

Interaction mechanism of the collector,2-mercaptobenzothiazole（MBT）,with chalcopyrite and sphalerite surfaces were investigated by Fourier transform infrared（FTIR） and density functional theory,Results of FTIR showed that some characteristic peaks of MBT were observed on the chalcopyrite surface,including C=N,C=N-S and C-S stretching vibration peaks,and the adsorption product was CuMBT.But there were no characteristic peaks of MBT on the sphalerite surface.The thione molecular form of MBT was the most efficient and stable,N and exocyclic S were the more favourable reactive sites for nucleophilic attacked by metal atoms.Compared with ZnS（110）,MBT is more readily adsorbed on CuFeS2（112）.Attachment of MBT occurs due to strong bonding through exocyclic S p and s orbits with Cu d orbit on CuFeS2（112） and electron transfer from Cu atom to S atom.Under the vacuum condition,MBT in the form of thione molecular cannot be adsorbed on ZnS（110） spontaneously.

Collecting performances of N-dodecylethylene-diamine and its adsorption mechanism on mineral surface

The collecting performances of N-dodecylethylene-diamine （ND） to quartz and hematite were studied via single mineral flotation. Experimental results show that ND has stronger collecting ability to quartz than hematite. Different floatability of quartz and hematite was presented in the existence of depressant. Compared with lauryl amine, ND has stronger collecting performances to quartz. Satisfied separation result of artificially mixed sample was acquired with iron grade of concentrate of 59.92% and iron recovery of 88.85% when pulp pH value was 7.27 with 41.7 mg/L collector and 3.33 mg/L starch. Polar group properties calculation results indicated that ND has stronger collecting capability and better selectivity than lauryl amine. Measurement results of zeta-potentials and infrared spectrum showed that hydrogen bonding adsorption and electrostatic adsorption occur between the surface of ND and quartz.

Flotation performance and adsorption mechanism of novel 1-(2-hydroxyphenyl)hex-2-en-1-one oxime flotation collector to malachite

A novel collector 1-(2-hydroxyphenyl)hex-2-en-1-one oxime(HPHO)was synthesized from 2-hydroxy acetophenone and butyraldehyde.Its flotation performance and adsorption mechanism to malachite were investigated by flotation test,zeta potential,Fourier transform infrared(FTIR)and X-ray photoelectron spectroscopy(XPS)analysis techniques.Compared with benzohydroxamic acid(BA),1-(2-hydroxyphenyl)ethan-1-one oxime(HPEO)and sodium isobutyl xanthate(SIBX),HPHO exhibited excellent collecting power to malachite without additional reagents,such as Na2S regulator and methyl isobutyl carbinol(MIBC)frother.Results of zeta potential indicated that HPHO was coated on malachite surfaces through a chemisorption process.FTIR and XPS data gave clear evidence for the formation of Cu−oxime complex on malachite surfaces after HPHO adsorption through the linkage between C=C,—OH,N—OH group and Cu species.

Adsorption mechanism of sodium oleate and styryl phosphonic acid on rutile and amphibole surfaces

A reagent combination of sodium oleate(NaOl)and salicyl hydroximic acid was employed as the roughing and scavenging collectors,whereas styryl phosphoric acid(SPA)and octanol were employed as the cleaning collectors.Results of bench-scale flotation demonstrate that the dosage of SPA can be reduced by about 80%,and that a better flotation index can be obtained using the proposed reagent system.The results of adsorption amount and contact angle measurements indicate that the rutile surface adsorbed not only a large amount of residual NaOl but also SPA and a small amount of NaOl remained on the amphibole surface in strong acidic solution.The hydrophobic difference between rutile and amphibole surfaces was therefore amplified in cleaning,and their further separation became much easier consequently.

Synthesis of novel thionocarbamate for copper-sulfur flotation separation and its adsorption mechanism

As a novel collector, O-isopropyl-N,N-diethyl thionocarbamate(IPDTC) was designed and synthesized for copper-sulfur flotation separation. Density functional theory calculations were performed to investigate the electronic structures of IPDTC. The results showed that IPDTC had higher energy of the highest occupied molecular orbital but lower electronegativity than O-isopropyl-N-ethyl thionocarbamate(Z-200). It was predicted that IPDTC had strong collection ability according to the reaction energy criteria. Flotation results demonstrated that the collecting ability of IPDTC to chalcopyrite and pyrite was stronger than that of Z-200. Then, the flotation mechanism was analyzed by measurements of surface tension, adsorption capacity, XPS, FTIR and zeta potential. These results indicated that IPDTC could reduce the solution surface tension. The adsorption capacity of IPDTC on chalcopyrite was higher than that on pyrite, consistent with the results of the flotation tests. FTIR, zeta potential and XPS results also demonstrated that IPDTC was strongly absorbed on the chalcopyrite surface by formation of Cu—S—C bonds, but showed a weak affinity on the pyrite surface.

Fluoride Removal by Lanthanum Alginate Bead: Adsorbent Characterization and Adsorption Mechanism

Lanthanum alginate bead is a new, highly active adsorbent. In the present study, we investigated its ad- sorption performance and its adsorption mechanism. The adsorption isotherm for fluoride onto lanthanum alginate b ead fits the Langmuir model well, and the maximum adsorption capacity is 197.2 mg·g-1. X-ray diffraction shows the amorphous nature of lanthanum alginate bead, which allows for better accessibility to fluoride and thus better activity. Infrared spectra of lanthanum alginate bead before and after adsorption confirm its stable skeletal structure. Scanning electron microscopy shows that the dense surface structure of the adsorbent appear cracks after adsorption. T he adsorption mechanism of lanthanum alginate bead is considered as an ion exchange between F- and Cl- or OH-, as verified from the adsorbent and the solution by pH effect, energy dispersive X-ray, and ion chromatography.

Adsorption Mechanisms of Mesoporous Adsorbents in Solutions

Sieve effect, complexation, ionic exchange, electrostatic interaction, hydrogen bonding, hydrophobic interaction, and molecular recognition based on molecular imprinting are comprehensively discussed.

Trimethylamine Adsorption Mechanism on Activated Carbon and Removal in Water and Oyster Proteolytic Solution

In this study,seven coal-based activated carbons(ACs)were adopted to remove trimethylamine(TMA)in an aqueous solution as environmentally friendly and harmless adsorbents.The results showed that columnar AC(CAC)had a clear scale and honeycomb structures with few fragments and micropores,contributing to superior TMA removal capacity compared to granular AC(GAC)(71.67%for 6.0 mm CAC and 69.92%for 40–60 mesh GAC).In addition,the process of adsorption was accompanied by desorption,and the recommended absorbed time was 120–180 min.The short time to achieve equilibrium indicated that adsorption was kinetically controlled,and pseudo-second-order kinetics was more appropriate than pseudo-first-order kinetics in explaining the adsorption mechanism in both water and oyster enzymatic hydrolysate.The intraparticle diffusion model presented that the adsorption processes could be divided into three steps for GAC and two steps for CAC.The adsorption processes were consistent with the Freundlich model,indicating the existence of physisorption and chemisorption as multilayer adsorption.The results indicated that AC,especially CAC,has great potential for TMA elimination in aquatic product processing.

Research on adsorption mechanism of wall climbing robots based on internally balanced theory

The internally balanced theory proposed by the Japanese researchers,solved the contradiction between adsorption ability and moving capability of the permanent magnetic adsorption mechanism.However,it still has some problems when applied to wall climbing robots.This paper analyzes and improves this theory,and the improved internally balanced theory satisfies the requirements of the adsorption mechanism significantly.Finally,a practical prototype is proposed based on this method,and both the analysis using ANSYS and the experiment results justify the design validity.

Prediction of Henry Constants and Adsorption Mechanism of Volatile Organic Compounds on Multi-Walled Carbon Nanotubes by Using Support Vector Regression

Support vector regression （SVR） combined with particle swarm optimization for its parameter optimization is employed to establish a model for predicting the Henry constants of multi-walled carbon nanotubes （MWNTs） for adsorption of volatile organic compounds （VOCs）. The prediction performance of SVR is compared with those of the model of theoretical linear salvation energy relationship （TLSER）. By using leave-one-out cross validation of SVR test Henry constants for adsorption of 35 VOCs on MWNTs, the root mean square error is 0.080, the mean absolute percentage error is only 1.19~, and the correlation coefficient （R2） is as high as 0.997. Compared with the results of the TLSER model, it is shown that the estimated errors by SVR are ali smaller than those achieved by TLSER. It reveals that the generalization ability of SVR is superior to that of the TLSER model Meanwhile, multifactor analysis is adopted for investigation of the influences of each molecular structure descriptor on the Henry constants. According to the TLSER model, the adsorption mechanism of adsorption of carbon nanotubes of VOCs is mainly a result of van der Waals and interactions of hydrogen bonds. These can provide the theoretical support for the application of carbon nanotube adsorption of VOCs and can make up for the lack of experimental data.

Adsorption mechanism of styryl phosphonate ester as collector in ilmenite flotation

A styryl phosphonate ester(SPE) collector was used to improve the flotation performance of ilmenite, and the adsorption mechanism and model were revealed and established, respectively. Microflotation tests showed that SPE exhibited a stronger collecting ability for ilmenite than the traditional collector styrene phosphonic acid(SPA). Zeta potential measurements revealed that both SPE and SPA could negatively shift the zeta potential of ilmenite, while SPE had more effects than SPA, suggesting the stronger adsorption of SPE. The analysis of X-ray photoelectron spectroscopy confirmed the chemisorption of SPA and SPE onto the Fe/Ti sites of ilmenite. According to frontier orbital theory, the chemical activities of SPE are greater than those of SPA. The partial densities of states analysis indicated that the PO—H groups of the collectors could interact with the Ti/Fe atoms of the ilmenite surface to generate a stable four-membered ring. The bonding model of the collector and(104) ilmenite surface showed that the adsorption energy of SPE was higher than that of SPA. Overall, SPE presented a better collecting ability and interaction effect for ilmenite flotation than SPA, and had the potential to replace SPA in the industry.

Adsorption mechanism of expanded graphite for oil and dyes

Expanded graphite （r-;G） shows higher adsorption capacity for oils than for dyes. To illustrate the different adsorption mechanism of EG for these pollutants, adsorption capacities of dyes and oil on EG were firstly studied. And then stepwise adsorption for oils was carried out with EG which has been saturated firstly by dyes, the difference between adsorbance of oil on EG was checked with deviation analysis. Scanning electronic microscopy （SEM） analysis was used to show structure difference of EG adsorbed different adsorbates. These used adsorbates were SD300 oil, basic fuchsine, Auramine lake yellow O and acid brilliant red 3B. The adsorption isotherm of dyes on EG is type 11 or type 1, and their equilibrium adsorbances are less than 1.0 g/g. While, adsorbance for SD300 oil can reach 104.5 g/g. Deviation analysis for stepwise adsorbances of oil shows no statistical significance. EG saturated firstly by dyes, still has an average adsorption capacity of 35 g/g for SD300 oil, and it does not change with the initial dyes concentration. SEM photos illustrate the adsorption of oil on EG is mainly filling, In the adsorption of dyes, there is severe breakage of the V-type pore and shrinkage of the particle. Kinetic difference is analyzed also.

Adsorption Mechanism of Disperse Dye on Elastic Polyurethane Fibre

In this paper, the adsorption isotherms of two disperse dyes, C.I. Disperse Red 60 and C.I. Disperse orange 76, on two kinds of PU fibers at 90℃ were measured respectively. It was found that these adsorption isotherms followed a dual model, Nernst and Langmuir. Based on the parameters obtained in studying, the relationship between the chemical structure of dyes and their adsorption behaviors was arialyzed. Through the measurement of washing fastness of dyed sample with two dye concentrations, 1% （o.w. f） and 3% （o. w. f）, it was found that the pale shade dyeing possessed better wet-fastness than the dark. This phenomenon confirmed further that the disperse dyes were sorbed on the PU fiber by langmuir sorption and the partition mechanism.

Multilayer adsorption mechanism of coal surface adsorption to three oxygen molecule

Compared chemical bonds change situation of coal surface and oxygen mole- cules before and after coal surface adsorption to three oxygen molecules,after adsorption each oxygen molecule's chemical bond got longer,but had not broken,the coal surface's chemical bonds changed a little.It proves that the coal surface adsorption to five oxygen molecules is the physical adsorption and is the multilayer adsorption according to the op- timized geometry structure.The oxygen molecule's bond length that adsorbed by the side chain of coal surface changes most from 1.258 2×10^(-10) m to 1.316 8×10^(-10) m,which indi- cates this oxygen molecular to be the liveliest.The analysis of charge population reveals that how many electrons shift in the atom is directly proportional to the change of chemical bonds.The more electrons shift in the atom,the more molecule chemical bond changes. In the adsorption state,which is composed of coal surface and five oxygen molecules,the vibration frequency of oxygen molecules drops off,and the adsorption energy reached by calculation is 202.11 kJ/mol.

Biomass Carbon Improves the Adsorption Performance of Gangue-Based Ceramsites:Adsorption Kinetics and Mechanism Analysis

The large accumulation of coal gangue,a common industrial solid waste,causes severe environmental problems,and green development strategies are required to transform this waste into high-value-added products.In this study,low-cost ceramsites adsorbents were prepared from waste gangue,silt coal,and peanut shells and applied to remove the organic dye methylene blue from wastewater.We investigated the microstructure of ceramsites and the effects of the sintering atmosphere,sintering temperature,and solution pH on their adsorption performance.The ceramsites sintered at 800℃under a nitrogen atmosphere exhibited the largest three-dimensional-interconnected hierarchical porous structure among the prepared ceramsites;further,it exhibited the highest methylene blue adsorption performance,with an adsorption capacity of 0.954 mg·g^(−1),adsorption efficiency of over 95%,and adsorption equilibrium time of 1 h at a solution pH of 9.The removal efficiency remained greater than 75%after five adsorption cycles.The adsorption kinetics data were analyzed using various models,including the pseudosecond-order kinetic model and Langmuir equation,and the adsorption was attributed to electrostatic interactions between the dyes and ceramsites,n-interactions,and hydrogen bonds.The prepared coal gangue ceramsites exhibited excellent adsorption capacities,removal rates,and cyclic stabilities,demonstrating their promising application prospects for the comprehensive utilization of solid waste and for wastewater treatment.

A new liquid membrane diffusion model for characterizing the adsorption kinetics of europium by using a continuous measurement of adsorption platform

To explore the kinetic adsorption under continuous and nonequilibrium states, an integration of continuous measurement and adsorption platform kinetics method was proposed, which was initially called the ICM-AP kinetics method, and a corresponding kinetic adsorption experimental method was developed. Adsorption experiments of europium(Eu) on Ca-bentonite,Na-bentonite, and the D231 cation exchange resin were performed using the ICM-AP kinetics method and continuous measurements. Because the kinetic experimental results observed in this study were different from those of traditional batch adsorption data, pseudo-first-order or pseudo-second-order kinetic models were unsuitable for fitting the experimental data.Hence, a liquid membrane diffusion(LMD) model was developed based on the assumption of simultaneous adsorption/desorption to discuss the mechanism of kinetic adsorption. The kinetic adsorption mechanism was also studied by using XPS.The results indicated that the proposed adsorption model can fit the experimental data more suitably, and the adsorption/desorption behaviors of Eu on bentonite and the D231 resin were simultaneously observed, suggesting that the adsorption kinetics of Eu(Ⅲ) was mainly dominated by hydrated Eu(Ⅲ) ions on the liquid membrane.

Characterization of adsorptive capacity and mechanisms on adsorption of copper, lead and zinc by modified orange peel

A novel adsorbent was prepared by modifying orange peel with sodium hydroxide and calcium chloride. The morphological and characteristics of the adsorbent were evaluated by infrared spectroscopy （IR）, scanning electron microscopy （SEM） and N2-adsorption techniques. The adsorption behavior of Cu^2＋, Pb^2＋ and Zn^2＋ on modified orange peel （SCOP） was studied by varying parameters like pH, initial concentration of metal ions. Equilibrium was well described by Langmuir equation with the maximum adsorption capacities for Cu^2＋, Pb^2＋ and Zn^2＋ of 70.73, 209.8 and 56.18 mg/g, respectively. Based on the results obtained in batch experiments, breakthrough profiles were examined using a column packed with SCOP for the separation of small concentration of Pb^2＋ from an excess of Zn^2＋ followed by elution tests. Ion exchange with Ca^2＋ neutralizing the carboxyl groups of the pectin was found to be the predominant mechanism.

Highly Efficient Adsorption of Copper Ions by a PVP-Reduced Graphene Oxide Based On a New Adsorptions Mechanism

Polyvinylpyrrolidone-reduced graphene oxide was prepared by modified hummers method and was used as adsorbent for removing Cu ions from wastewater. The effects of contact time and ions concentration on adsorption capacity were examined. The maximum adsorption capacity of 1689 mg/g was observed at an initial p H value of 3.5 after agitating for 10 min. It was demonstrated that polyvinylpyrrolidone-reduced graphene oxide had a huge adsorption capacity for Cu ions, which was 10 times higher than maximal value reported in previous works. The adsorption mechanism was also discussed by density functional theory. It demonstrates that Cu ions are attracted to surface of reduced graphene oxide by C atoms in reduced graphene oxide modified by polyvinylpyrrolidone through physisorption processes, which may be responsible for the higher adsorption capacity. Our results suggest that polyvinylpyrrolidone-reduced graphene oxide is an effective adsorbent for removing Cu ions in wastewater. It also provides a new way to improve the adsorption capacity of reduced graphene oxide for dealing with the heavy metal ion in wastewater.

Experimental determination of Cd^2＋ adsorption mechanism on low-cost biological waste

Carbonate shells have an astonishing ability in the removal of Cd^2＋ in a short time period with emphasis on being a low cost adsorbent. In the present study, the sorption capacity of carbonate shells was studied for Cd^2＋ in batch experiments. The influence of different carbonate shell sizes and physico-chemical factors were evaluated and the results were analyzed for its correlation matrices by using Predictive Analytics Software （PASW）. The miner- alogy state of aqueous solution regarding the saturation index was simulated using PHREEQC to identify the Cd^2＋ uptake mechanism. The Cd uptake rates were calculated as well as Ca^2＋, HCO3- concentration, pH, ambient humidity and temperature were measured. Cd2＋ removal of 91.52% was achieved after 5 h adsorption. The adsorption efficiencies were significantly influenced by pH as they increased with the increase of pH from acidic solution （5.50±0.02） to slightly alkaline （7.60±0.05）. In addition, the mineralogy state of aqueous solution calculated from PHREEQC confirmed that the increment of Ca^2＋ and HCO3- concentrations in solution was attributed to the dissolution of carbonate shells. Moreover, the ion exchange adsorption mechanism of Cd^2＋ toward Ca^2＋ was identified as the process involved in Cd^2＋ uptake.

Adsorption and flotation mechanism of a ketoxime-dithiocarbonate surfactant to chalcopyrite

The adsorption mechanism of O-isopropyl-S-[2-(hydroxyimino) propyl] dithiocarbonate ester(IPXPO) to chalcopyrite was investigated by using contact angle, in-situ atomic force microscopy(in-situ AFM), cyclic voltammetry(CV) and X-ray photoelectron spectroscopy(XPS). The results of contact angle and in-situ AFM demonstrated that IPXPO adsorbed on chalcopyrite increases surface hydrophobicity and roughness. It was found by CV experiments that a layer passive film was formed. The results of XPS spectra further revealed that the thiol S atom, oxime N atom, and O atom in the IPXPO molecule might react with copper atoms to form Cu-S, Cu-N, and Cu-O bonds, respectively. An artificial mixed minerals flotation test indicated that under the condition of pH=6.79 and IPXPO initial concentration 5×10^(-5)mol/L, the flotation recovery of chalcopyrite reached about 90%, while for pyrite only 25%, suggesting that IPXPO is an excellent collector for flotation separation and enrichment of chalcopyrite.