Characteristics and mechanism of Ni^(2+)and Cd^(2+)adsorption by recovered perlite from agar extraction residue

Ni^(2+)and Cd^(2+)in wastewater accumulated through the ecological chain and could jeopardize human health.Adsorption of Ni^(2+)and Cd^(2+)from wastewater using recovered perlite was an important way to solve the problem of resource utilization of solid waste from agar production.Our previous study confirmed that recovered perlite from agar extraction residue had better pore size and specific surface area than commercial perlite.However,the adsorption efficiency and adsorption mechanism of recovered perlite were the main factors limiting its adsorption application.The adsorption process of Ni^(2+)and Cd^(2+)by recovered perlite in aqueous solution was described by the pseudo-second-order kinetic equation,and the relevant adsorption mechanism was mainly chemisorption.Compared with commercial perlite,the adsorption removal rate of Ni^(2+)and Cd^(2+)by enzymatic recovered perlite could reach 92.9%and 89.2%,respectively,and were improved by 12.63%and 13.03%.Langmuir isothermal adsorption model could better describe the isothermal adsorption process of recovered perlite on heavy metal Ni^(2+)and Cd^(2+),and the relevant adsorption mechanism was mainly monolayer adsorption.The X-ray photoelectron spectroscopy(XPS)results indicated that the decrease of Si—O Si^(2+)hydroxyl coordination bond and the increase of C—Si bond might make the binding effect of recovered perlite with heavy metals stronger.The competitive adsorption of Ni^(2+)and Cd^(2+)by recovered perlite was still dominated by chemisorption and monolayer adsorption.This study was expected to provide a theoretical basis and technical support for the removal of Ni^(2+)and Cd^(2+)from wastewater using recovered perlite from seaweed residue.

Extraction and kinetic analysis of Pb and Sr from the leaching residue of zinc oxide ore

NH4HCO3 conversion followed by HCl leaching was performed and proven to be effective in extracting Pb and Sr from zinc extracted residual.The mechanism and operating conditions of NH4HCO3 conversion,including molar ratio of NH4HCO3 to zinc extracted residual,NH4HCO3 concentration,conversion temperature,conversion time,and stirring velocity,were discussed,and operating conditions were optimized by the orthogonal test.Experimental results indicate that NH4HCO3 conversion at temperatures ranging from 25 to 85°C follows the shrinking unreacted core model and is controlled by inner diffusion through the product layer.The extraction ratios of Pb and Sr under optimized conditions reached 85.15%and 87.08%,respectively.Moreover,the apparent activation energies of Pb and Sr were 13.85 and 13.67 kJ·mol^−1,respectively.

Discharge characteristics of coal and extraction residue from direct coal liquefaction in partial fluidization silo

Gasification of extraction residue(ER) from direct coal liquefaction with pulverized coal is an efficient way for the utilization of carbonaceous wastes, which improve the overall efficiency of direct coal liquefaction technology. The discharge characteristics of ER mixing with pulverized coal is important paraments for its gasification process, which is seldom studied in the literature. In this study, the discharge characteristics of the pulverized coal(M1) as well as its mixture with ER(M2) were systematically investigated in an atmospheric pressure partial fluidization silo with different fluidization apparent velocity. It was observed that although M2 is a viscous powder with lower flowability than M1, the mass flow rate of M2 is 65% higher than M1 at the 3.7 mm·s-1apparent gas velocity. M2 exhibits the properties of Geldart A type powder, which improves the mass flow rate and stability of the discharged material. The mass flow rate of both M1 and M2 first increases and then slowly decreases with the increase of apparent gas velocity of the fluidizing air, which means the discharge process of M1 and M2 can be optimized by the apparent gas velocity.

Oxidation of Lingwu Coal Extraction Residue in Aqueous Sodium Hypochlorite under Mild Conditions

To investigate the structural features and provide an alternative method for high value-added utilization of coal, Lingwu coal was first extracted with organic solvent at room temperature. Then its extraction residue was oxidized in aqueous sodium hypochlorite(ASHC) under mild conditions. The effects of oxidation conditions, such as temperature, reaction time, the ratio of Lingwu coal extraction residue(LCER, g) to ASHC(m L) and p H value, on the product distributions and compositions were investigated. The results of gas chromatography/mass spectrometry(GC/MS) suggested that 53 kinds of methyl esterified products were detected in total, and benzene carboxylic acids were the main oxidation products, while chloro-substituted benzene carboxylic acids were the main by-products. Higher yield and fewer kinds of organic acids could be obtained at lower p H value, especially for the main objective product, benzene carboxylic acids.

Disposal of zinc extraction residues via iron ore sintering process:an innovative resource utilization

Zinc extraction residue,a solid waste generated from the treatment of zinc-containing dust in rotary kilns,is commonly stockpiled in steel companies for extended periods.It poses significant disposal challenges and environmental pollution risks.So far,research on the treatment of zinc extraction residues has been slow,inadequate,and sporadic.For this gap,a novel approach was proposed to effectively treat the zinc extraction residue via the iron ore sintering process.It was feasible to add 1 wt.%of zinc extraction residues to the sintering raw materials.The more adequate mineralization reaction resulted in higher yield and tumbler indexes,despite a slight decrease in sintering speed.Although this may result in a slight decrease in sintering speed,the more complete mineralization reaction leads to improved sintering yield and tumbler index.Interestingly,the addition of zinc extraction residues reduced the CO and NO_(x) concentrations in the sintering flue gas.Thus,the iron ore sintering process provided a viable solution for resource utilization and environmentally friendly treatment of zinc extraction residues.

Autotoxicity of Water Extracts and Decomposition Liquids of Tumorous Stem Mustard(Brassica juncea var.tumida Tsen et Lee) Residues on Seed Germination and Seedling Growth of Tumorous Stem Mustard

[Objective] This study aimed to explore whether there is autotoxicity in tumorous stem mustard through studying the allelopathic effects of water extracts and decomposition liquids of tumorous stem mustard residues on seed germination and seedling growth of tumorous stem mustard.[Method] With Fuza No.2 as the experimental material,the effects of different concentrations of leaf extract,root extract,7-d decomposition liquid,15-d decomposition liquid of tumorous stem mustard on seed germination and seedling growth of tumorous stem mustard were investigated.[Result] Compared with those in the control,the four kinds of 100% treatment solutions all significantly reduced the seed germination rate,seed germination vigor,root length,plant height and fresh weight of tumorous stem mustard(P<0.05),and significantly increased the malondialdehyde(MDA) content,catalase(CAT) activity,peroxidase(POD) activity and superoxide dismutase(SOD) activity of young seedlings of tumorous stem mustard;the allelopathic effects of the four kinds of water extracts and decomposition liquids on seed germination and root length of tumorous stem mustard were weakened with the decreased concentration;for the four kinds of water extracts and decomposition liquids,low-concentration treatment solutions promoted the increase of plant height and fresh weight,while high-concentration treatment solutions inhibited the increase of plant height and fresh weight of young seedlings of tumorous stem mustard;the allelopathic effect of leaf extract on seed germination of tumorous stem mustard was stronger than those of root extract and decomposition liquids,the allelopathic effects of decomposition liquids on seedling growth of tumorous stem mustard were stronger than those of water extracts,the inhibitory effect of leaf extract on seed germination and seedling growth of tumorous stem mustard were stronger than that of root extract,and the inhibitory effect of 15-d decomposition liquid on seed germination and seedling growth of tumorous stem mustard was stronger than that of 7-d decomposition liquid.[Conclusion] The water extracts and decomposition liquids of tumorous stem mustard residues had certain autotoxicity on seed germination and seedling growth of tumorous stem mustard,and their allelopathic effects had a concentration-dependent manner.It could be presumed that the autotoxicity of tumorous stem mustard is the main cause of continuous cropping obstacle.

Study on the corrosion of refractory materials by coal blended with the extraction residue of direct coal liquefaction in a simulated gasification atmosphere

Utilizing the extraction residue(ER)of direct coal liquefaction residue as a gasification feedstock has significant economic value.But the characteristic of high ash and iron in the ER would increase the risk of corrosion of the refractory materials and affect the long-term operation of the gasifier.In this work,corrosion experiments of molten slag derived from a mixture of 20 wt%ER and 80 wt%coal on a high-chromia refractory brick and SiC brick were carried out using a rotary-drum furnace in a simulated gasification atmosphere.The experimental results show that the viscosity of the poured slag is larger as compared to the initial ash sample at the same temperature,which suggests that the viscosity-temperature relationship of the poured slag should be used as the reference for the operation temperature of the gasifier to ensure that the slag can flow during operation.For a high-chromia refractory brick,iron oxides in molten slag could react with Cr_(2)O_(3) in the refractory matrix but,because the aggregate was not found to be damaged,the damage to the matrix structure was the key factor for causing the corrosion of the high-chromia refractory brick.Metallic iron was observed in the exposed SiC brick,which indicated that the reaction between the iron oxides in the slag and SiC occurred,forming metallic iron and SiO_(2).The corrosion of a SiC brick by molten slag depended mainly on the dissolution of Al_(2)O_(3) particles and the reaction between iron oxides in the molten slag and SiC particles.Therefore,the high iron content in coal ash had a serious influence on the corrosion of refractory materials.More efforts need to be made on coal blended with ER as a gasification feedstock in the future.

Fluidized bed combustion of high water content alcohol extracted herb residue and the impacts of blending wasted activated coke

Combustion of herb residues(HRs)for heat recovery is a good way for their utilization,but there exists such a problem as high concentration NOx emission in flue gas.The alcohol extracted herb residue(AEHR),one special type of HRs,was chosen as the object and was subjected to immediate combustion in a fluidized bed reactor to investigate the characteristics of its resulting NOx emission.The results showed that,most of the NOx in the flue gas was produced from the char nitrogen(C-N);as the fuel water content increased,the NOx emission concentration exhibited a trend of first decreasing and then increasing;and a properly low combustion temperature inhibited the NOx emission upon the premise of ensuring full combustion.Air staging combustion was adopted to effectively control NOx:the NOx emission concentration in the flue gas was reduced to 296 mg⋅m􀀀3 and the NOx emission reduction rate reached 46.51%compared to conventional combustion.Co-combustion by blending wasted activated coke(WAC)into the AEHR helped both stabilize the combustion state and reduce further the NOx emission.When the blending ratio of WAC fell within a proper range of 20-30%,the NOx emission concentration in the flue gas was as low as 231.4 mg⋅m􀀀3.In addition to the dilution effect of the combustion flue gas of the blended WAC,the local reducing atmosphere caused by its incomplete combustion as well as its strong absorbability and catalytical effect was accountable for the further decrease of the NOx emission concentration.

Safety and efficacy of VisuMax®circle patterns for flap creation and enhancement following small incision lenticule extraction

Background:The purpose of this case series is to evaluate the safety and efficacy of VisuMax®Circle patterns in eyes that have undergone small incision lenticule extraction,thus creating a flap to perform an enhancement procedure or residual lenticule extraction.Methods:This prospective,single center,case study series evaluated the use of a VisuMax®Circle pattern to create a corneal flap following small incision lenticule extraction.Patients were treated and followed at TRSC International LASIK Center(Bangkok,Thailand)for 3 months to assess the efficacy and safety of the procedure.Efficacy was determined by the surgeon’s ability to lift the created corneal flap.Results:The study enrolled 28 eyes.Twenty-seven underwent the VisuMax®Circle pattern procedure for refractive enhancement,and one for residual lenticule extraction.In 100%of cases(28 eyes)the lifting of the flap was possible,as planned.In all cases of refractive enhancement(27 eyes)by laser in situ keratomileusis(LASIK),the exposure of the stromal bed was sufficient for the necessary excimer laser ablation.No eyes lost two or more Snellen lines of corrected distance visual acuity(CDVA)and no procedure or flap-related complications or serious adverse events occurred.Conclusions:This initial case series demonstrates that VisuMax®Circle pattern is efficacious and a suitable method to create a corneal flap for enhancement,following small incision lenticule extraction.