The electrochemical degradation of agri-based paper mill wastewater (black liquor) was investigated in a 2 dm3 electrolytic batch reactor using iron plate electrodes. Of the four-, six-, and ...eight-plate configurations, a current density of 55.56 A/m2 at neutral pH with a six-plate arrangement was found to be optimal, achieving a maximum chemical oxygen demand (COD) and color removal of 80% and 90% (175 platinum−cobalt units (PCU)), respectively. The chemical dissolution of iron was strongly influenced by pH0. Electrochemical treatment at higher pH0 (pH0 ≥ 9) increases the dissolution of iron electrodes by an order of magnitude. At the optimal current density, the iron electrode consumed is 31.27 g/m2·h, achieving maximum COD removal. An increase in salinity reduces the treatment time significantly, and the sludge settling characteristics also improve. The addition of polyacrylamide (10 mg/dm3) to the electrochemical reactor enhances the COD removal rate with a very short treatment time with excellent sludge settleability. Specific energy consumption (SEC) reduces from 6.64 to 5.73 kWh/kg of COD removed with the addition of NaCl (625 mg/dm3). The posttreatment of electrochemically treated wastewater by chemical coagulation using alum (360 mg/dm3) along with 20 mg/dm3 polyacrylamide (PAA) further reduced COD values to <180 mg/dm3 and a near 100% (<5 PCU) color removal. An overall COD removal of 91% and color removal of near 100% could be achieved by electrochemical treatment followed by coagulation/flocculation.
This paper presents the physico-chemical characteristics of low-cost fertilizer plant waste carbon (WC) for the adsorption of different dyes. The particle size analysis showed an average particle ...size of 167.35
μm. Proximate and CHN analysis showed the presence of high amount of carbon in WC. Bulk density and heating value of WC were found to be 308.03
kg/m
3 and 22.3
MJ/kg, respectively. The pore size distribution results showed that the WC was predominantly mesoporous. The BET surface area was 357
m
2/g. The average pore diameter by BET was 6.483
nm. The mesoporous surface area for adsorption was 96% of the total pore surface area. The polar groups present on the WC surface imparted considerable cation exchange capacity to it. WC was further used as an adsorbent for the removal of Auramine-O (AR), Congo red (CR), Orange-G (OG) and methyl violet (MV) dyes from aqueous solutions. Optimum initial pH (pH
0) was found to be 7.0. WC dose of 1
g/l was found to be optimum for the adsorption of all dyes at a concentration of 20
mg/l. The adsorption of dyes on WC was found to be gradual process and quasi-equilibrium reached in 5
h. The adsorption kinetics followed pseudo-second-order kinetics. The effective diffusion coefficient was of the order of 10
−12
m
2/s. Error analysis showed that Redlich-Peterson (R-P) isotherm best represented the equilibrium adsorption data for all the dyes. Thermodynamics showed that the adsorption of CR on WC was most favourable in comparison to other dyes. The desorption study showed that the recovery of dyes and the regeneration of the WC using different solvents viz. water, acids and alkalies were not feasible. Spent WC can, however, be used as a fuel to recover its high energy content and the bottom ash obtained after its combustion/incineration can be blended with clay/cement–concrete mixture to make bricks and building blocks for its safe disposal. WC has been found to have high potential as an adsorbent for the removal of AR, CR, OG and MV dyes from aqueous solutions.
The present study deals with the competitive adsorption of cadmium (Cd(II)) and nickel (Ni(II)) ions onto bagasse fly ash (BFA) from single component and binary systems. BFA is a waste material ...obtained from the flue gas of the bagasse-fired boilers of sugar mills. Equilibrium adsorption is affected by the initial pH (pH
0) of the solution. The pH
0
≈
6.0 is found to be the optimum for the individual removal of Cd(II) and Ni(II) ions by BFA. The pH of the system, however, increases during the initial sorption process for about 20
min and, thereafter, it remains constant. The equilibrium adsorption data were obtained at different initial concentrations (
C
0
=
10–100
mg/l), 5
h contact time, 30
°C temperature, BFA dosage of 10
mg/l at pH
0 6. The single ion equilibrium adsorption data were fitted to the non-competitive Langmuir, Freundlich and Redlich–Peterson (R–P) isotherm models. The R–P and the Freundlich models represent the equilibrium data better than the Langmuir model in the studied initial metal concentration range (10–100
mg/l). The adsorption capacity of Ni(II) is higher than that for Cd(II) for the binary metal solutions and is in agreement with the single-component adsorption data. The equilibrium metal removal decreases with increasing concentrations of the other metal ion and the combined action of Cd(II) and Ni(II) ions on BFA is generally found to be antagonistic. Equilibrium isotherms for the binary adsorption of Cd(II) and Ni(II) ions onto BFA have been analyzed by using non-modified Langmuir, modified Langmuir, extended Langmuir, extended Freundlich and Sheindorf–Rebuhn–Sheintuch (SRS) models. The competitive extended Freundlich model fits the binary adsorption equilibrium data satisfactorily and adequately. Desorption with various solvents showed that the hydrochloric acid is the best solvent; the maximum elution being about 65% for Cd(II) and about 42% for Ni(II). Since BFA is a waste material obtained at almost no cost, the spent BFA can be combusted to recover its energy value and the bottom ash can be blended with cementitious mixture for making building blocks.
Sorptive removal of phenol from synthetic aqueous solutions by bagasse fly ash (BFA) was investigated at 303 K under dynamic conditions in a packed bed. The effects of sorbent bed length (Z = 40−90 ...cm), flow rate (Q = 0.01−0.04 dm3/min), bed diameter (D = 2−4 cm), and initial concentration (C 0 = 50−500 mg/dm3) on the sorption characteristics of phenol were investigated at an influent pH of 6.5. More than 99.5% of phenol was removed in the column operated at C 0 =100 mg/dm3 of phenol. The column performance improved with increasing Z and decreasing Q. The Bohart−Adams, Thomas, Yoon−Nelson, Clark, and Wolborska models were applied to the experimental data to represent the breakthrough curves and determine the characteristic design parameters of the column. The bed depth service time (BDST) model at 50% breakthrough provided a good fit to the experimental data, and the sorption capacity of the adsorbent was close to the value predicted from a batch study. The sorption performance of the BFA columns could be well described by the Thomas, Yoon−Nelson, and Clark models at effluent-to-influent concentration ratios (C/C 0) higher than 0.08 and lower than 0.99. Application of the Wolborska model to the experimental data for C/C 0 <0.5 enabled the determination of the kinetic coefficients for mass transfer in these systems. All of the models can be applied to describe the dynamic behavior of the column sorption with respect to bed length and flow rates. The sorptive capacity of BFA for phenol was found to be 9.93 mg/g.
The present study deals with the adsorption of pyridine (Py) from synthetic aqueous solutions by rice husk ash (RHA) and commercial grade granular activated carbon (GAC) and reports on the kinetic, ...equilibrium and thermodynamic aspects of Py sorption. Batch sorption studies were carried out to evaluate the effect of various parameters, such as adsorbent dose (
m), initial pH (pH
0), contact time (
t), initial concentration (
C
0) and temperature (
T) on the removal of Py. The maximum removal of Py is found to be ∼96% and ∼97% at lower concentrations (<50
mg
dm
−3) and ∼79.5% and ∼84% at higher concentrations (600
mg
dm
−3) using 50
kg
m
−3 and 30
kg
m
−3 of RHA and GAC dosage, respectively, at 30
±
1
°C. Adsorption of Py is found to be endothermic in nature and the equilibrium data can be adequately represented by Toth and Redlich–Peterson isotherm equations. Py can be recovered from the spent adsorbents by using acidic water and 0.1
N H
2SO
4. The overall adsorption of Py on RHA and GAC is found to be in the order of GAC
>
RHA. Comparative assessment of adsorbents used by various investigators available in literature showed the effectiveness of BFA and RHA over other adsorbents. Spent RHA can simply be filtered, dried and used in the boiler furnaces/incinerators. Thus, its heating value can be recovered.
Context.
Following a multi-year minimum of solar activity, a solar energetic particle event on 2020 Nov. 29 was observed by multiple spacecraft covering a wide range of solar longitudes including ...ACE, the Solar Terrestrial Relations Observatory-A, and the recently launched Parker Solar Probe and Solar Orbiter.
Aims.
Multi-point observations of a solar particle event, combined with remote-sensing imaging of flaring, shocks, and coronal mass ejections allows for a global picture of the event to be synthesized, and made available to the modeling community to test, constrain, and refine models of particle acceleration and transport according to such parameters as shock geometries and particle mass-to-charge ratios.
Methods.
Detailed measurements of heavy ion intensities, time dependence, fluences, and spectral slopes provided the required test data for this study.
Results.
The heavy ion abundances, timing, and spectral forms for this event fall well within the range found in prior surveys at 1 au. The spectra were well fitted by broken power law shapes; the Fe/O ratio was somewhat lower than the average of other events. In addition,
3
He/
4
He was very low, with only the upper limits established here.
In this paper, we report the characteristics and the management of the sludge generated by the batch electrochemical (EC) treatment of the black liquor (BL) of a small paper mill based on ...agricultural waste as raw material. The study shows that the sludges obtained from the EC treatment of the BL at its natural pH without any additive and with 625 mg dm-3 sodium chloride (NaCl) or 10 mg dm-3 polyacrylamide (PAA) during the EC process had very good settling characteristics. PAA addition hastens the EC process, and the sludge settling rate improves considerably. The settling velocity of the sludge obtained from the EC treatment without any additive could be satisfactorily correlated with the model of Richardson and Zaki. The results of the gravity filtration of the treated BL showed that the addition of NaCl (625 mg dm-3) improved the filtration characteristics and reduced the values of the specific cake resistance (α). The values of the specific cake resistance (α) and the resistance of the filter medium (R m) were in the range of 3.25−4.67 × 1011 m kg-1 and 2.37−2.98 × 109 m-1, respectively. Prolonged use of iron anodes produces a large number of dents on their surface. SEM images of the electrodes show that the dents formed because of the anode dissolution during the EC process. The sludge has lower ash content and fixed carbon and higher volatile matter than that of Indian coal. Thermal analysis showed good combustion characteristics and complete oxidation of the EC process sludge at about 400 °C, with a heating value of 11.33 MJ kg-1. The sludge can be dewatered, dried, and used in the furnace/incinerators for its heat recovery, and the ash may either be blended with organic manure for use in agriculture/horticulture or may be blended with clay/coal fly ash to make bricks/ceramic tiles for the building industry.
The present study deals with the use of poly aluminium chloride (PAC) as a coagulant and bagasse fly ash (BFA), which is generated in sugar mills, as an adsorbent for the removal of chemical oxygen ...demand (COD) and colour of pulp and paper mill effluents. Under optimal conditions of pH 3 and initial PAC dosage of 3
g/l, about 80% COD removal and 90% colour removal were obtained. The optimal conditions for the adsorptive removal of COD and colour with BFA were pH 4 and BFA dosage of 2
g/l. Under these conditions, COD and colour removal were, respectively, 50 and 55%. Adsorptive removal of COD by BFA followed second-order kinetics. Intra-particle diffusion was found to be rate controlling. Freundlich and Langmuir adsorption isotherms were found to fit the equilibrium adsorption data with BFA. Two-stage treatment using PAC (3
g/l) as a coagulant in the first stage and BFA (2
g/l) as an adsorbent in the second stage gave the combined COD and colour removal of nearly 87 and 95%, respectively, for different effluents without any pH adjustment. Two-stage adsorptive treatment using BFA (2
g/l) in both the stages gave a combined COD and colour removal of about 70%. The sludge obtained can be dewatered by centri-clarifiers, dried, briquetted and incinerated to recover its energy content.
PANIC7 is the new PAnoramic Near-Infrared Camera for Calar Alto and is a project jointly developed by the MPIA in Heidelberg, Germany, and the IAA in Granada, Spain, for the German-Spanish ...Astronomical Center at Calar Alto Observatory (CAHA; Almería, Spain). This new instrument works with the 2.2 m and 3.5 m CAHA telescopes covering a field of view of 30 × 30 arcmin and 15 × 15 arcmin, respectively, with a sampling of 4096 × 4096 pixels. It is designed for the spectral bands from Z to KS, and can also be equipped with narrowband filters. The instrument was delivered to the observatory in 2014 October and was commissioned at both telescopes between 2014 November and 2015 June. Science verification at the 2.2 m telescope was carried out during the second semester of 2015 and the instrument is now at full operation. We describe the design, assembly, integration, and verification process, the final laboratory tests and the PANIC instrument performance. We also present first-light data obtained during the commissioning and preliminary results of the scientific verification. The final optical model and the theoretical performance of the camera were updated according to the as-built data. The laboratory tests were made with a star simulator. Finally, the commissioning phase was done at both telescopes to validate the camera real performance on sky. The final laboratory test confirmed the expected camera performances, complying with the scientific requirements. The commissioning phase on sky has been accomplished.
Fourier Transform Infrared Spectroscopy (FTIR) is a non-destructive analytical technique that has been employed in this research to characterize the biochemical make-up of various rat brain regions. ...The sensorimotor cortex, caudate putamen, thalamus, and the hippocampus were found to have higher olefinic content—an indicator of a higher degree of unsaturated fatty acids—rich in short-chain fatty acids, and low in ester and lipid contents. While the regions of the corpus callosum, internal, and external capsule were found to contain long-chained and higher-esterified saturated fatty acids. These molecular differences may reflect the roles of the specific regions in information processing and can provide a unique biochemical platform for future studies on the earlier detection of pathology development in the brain, as a consequence of disease or injury. Laser Ablation Inductively Coupled Plasma Mass Spectroscopy (LA-ICP-MS) is another vital analytical technique that was used in this work to analyze the elements’ distribution patterns in various regions of the brain. The complementary data sets allowed the characterization of the brain regions, the chemical dominating groups, and the elemental composition. This set-up may be used for the investigation of changes in the brain caused by diseases and help create a deeper understanding of the interactions between the organic and elemental composition.
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