Adsorption of Nitrite Ions Using Activated Carbons Derived from Walnut Shells | Chapter 3 | Chemical and Materials Sciences: Research Findings Vol. 3

In this paper, activated carbons obtained from walnut shells were used as adsorbents to remove nitrite ions from aqueous solutions. In the Republic of Moldova, walnut shells are chosen as a raw material for obtaining activated carbons in research due to their local abundance, low cost, and favorable chemical composition, which allows for the production of an efficient adsorbent material for removing pollutants from water. The novel adsorbent was obtained by modification with hydrochloric acid. The physical-chemical characteristics of activated carbons were determined from nitrogen sorption isotherms, SEM-EDX, elemental analysis, FTIR, thermal analysis, and temperature-programmed decomposition (TPD). According to the results obtained, chlorine is retained on the surface in an amount of 2%. Chlorine increases the positive charge of the surface by forming –C–Cl or –C–OH⁺ groups, the electrostatic attraction towards nitrite ions can be improved, thus increasing the adsorption efficiency. The effect of pH on the adsorption of nitrite ions was investigated for both activated carbons CAN and CAN-Cl. For activated carbon CAN, an increase in pH resulted in a significant decrease in adsorption, from 0.13 mg/g at pH 3 to 0.07 mg/g (approximately 1.8 times lower). Similarly, for activated carbon CAN-Cl, adsorption values decreased from 2.85 mg/g to 0.68 mg/g as the pH increased. These results suggest that pH plays a critical role in the adsorption capacity of activated carbons, with lower pH levels enhancing the adsorption of nitrite ions. The results of batch experiments indicate that maximum adsorption/ removal of nitrite ions can be achieved at pH = 3, being of 0.2 mg/g for CAN and 4.7 mg/g for CAN-Cl. The modification of the surface of activated carbons with chloride ions leads to an increase in the rate and adsorption capacity of nitrite ions by approximately 50 times.

To study the adsorption of nitrite ions on activated carbons the following mathematical models were used: pseudo-first-order, pseudo-second-order, and intraparticle diffusion kinetic models, and Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin-Pyzhev isotherm models. These models were chosen to provide a comprehensive understanding of the adsorption kinetics and equilibrium behavior, allowing for the identification of the dominant adsorption mechanisms and the efficiency of the adsorbent material. The results indicate that the adsorption of nitrite ions onto activated carbons CAN and CAN-Cl follows the pseudo-second-order kinetic model and also aligns with the intraparticle diffusion model, suggesting that the process is primarily governed by chemisorption.

Future studies should explore strategies to mitigate the impact of electrolytes on adsorption efficiency and optimize surface modifications to enhance nitrite ion removal. Additionally, investigating the regeneration potential of the modified adsorbents could improve their practicality for long-term water treatment applications.

 

Author (s) Details

 

Irina Ceban
Institute of Chemistry, Moldova State University, 3, Academiei Str., MD-2028 Chisinau, Republic of Moldova.

Raisa Nastas
Institute of Chemistry, Moldova State University, 3, Academiei Str., MD-2028 Chisinau, Republic of Moldova.

 

 

Please see the book here:- https://doi.org/10.9734/bpi/cmsrf/v3/5161

Plant-Based Activated Carbons for Cobalt and Strontium Removal: Insights into Adsorption Mechanisms | Chapter 8 | Chemical and Materials Sciences: Research Findings Vol. 2

Aims: To investigate the adsorption behavior of Co(II) and Sr(II) ions on the surface of plant-based activated carbons (obtained from walnut shells (CA-N) and apple wood (CA-M), and modified by oxidation with nitric acid and nitric acid/urea mixture).

Methodology: Activated carbons were chemically modified using nitric acid (sample CA-Mox) and a nitric acid/urea mixture (samples CA-Mox-u, CA-Nox-u). Their physicochemical properties were characterized through nitrogen adsorption isotherms, SEM-EDX, FTIR spectroscopy, pH metric titrations, Boehm titration, and elemental analysis. Batch adsorption experiments were conducted to evaluate the removal efficiency of Co(II) and Sr(II) ions over a pH range of 2–10. Kinetic models (pseudo-first-order, pseudo-second-order, intraparticle diffusion) and isotherm models (Langmuir, Freundlich, Dubinin–Radushkevich, Temkin-Pyzhev) were applied to study adsorption mechanisms and estimate maximum adsorption capacities.

Results: On the surface of activated carbons the following functional groups have been identified: strongly acidic groups (CA-Mox, 0.95 meq/g; CA-Mox-u, 0.44 meq/g; CA-Nox-u, 0.32 meq/g) and weakly acidic and phenolic groups, while the pH_pzc value of the studied activated carbons increase as follows:
CA-Mox (2.3) < CA-Mox-u (3.3) < CA-Nox-u (3.9) < CA-M (6.9) < CA-N (8.3).

The results of batch experiments indicate that maximum adsorption can be achieved in broad pH ranges: 4–8 for Co(II) and 4–10 for Sr(II). The maximum adsorption capacities of Co(II) and Sr(II) on oxidized activated carbons at pH = 4 are: CA-Mox, 0.085 and 0.076 mmol/g; CA-Mox-u, 0.056 and 0.041 mmol/g; and CA-Nox-u, 0.041 and 0.034 mmol/g, respectively.

The experimental data are best described by the pseudo-second kinetic model, suggesting that the adsorption of metal ions (cobalt(II) and strontium(II)) onto oxidized activated carbons is based on chemisorption. The constants determined for the Freundlich and Langmuir models and the energy values estimated by Dubinin–Radushkevich demonstrate that the adsorption process of strontium(II) and cobalt(II) ions onto oxidized activated carbons is favorable and dominated by chemisorption of the energetically homogenous surface in the modeled system.

Conclusion: The investigations highlight the important role of the solution pH, of the activated carbons' functional groups, and the pH_pzc value for the adsorption process of cobalt(II) and strontium(II) ions. By summarizing the obtained results, the adsorption mechanisms of toxic metal ions on activated carbons were proposed.

 

 

Author (s) Details

Raisa Nastas
Institute of Chemistry of Moldova State University, 3, Academiei Str. Chisinau, MD-2028, Republic of Moldova.

 

Irina Ceban
Institute of Chemistry of Moldova State University, 3, Academiei Str. Chisinau, MD-2028, Republic of Moldova.

 

Tudor Lupascu
Institute of Chemistry of Moldova State University, 3, Academiei Str. Chisinau, MD-2028, Republic of Moldova.

 

Please see the book here:- https://doi.org/10.9734/bpi/cmsrf/v2/5160

 

Assessment of Agricultural Wastes in the Removal of Hexavalent Chromium | Chapter 3 | Novel Aspects on Chemistry and Biochemistry Vol. 1

 The present study climaxes the assessment of Agricultural Wastes in the Removal of Hexavalent Chromium. Hexavalent chromium is a big pollutant produced by a difference of industrial processes. Adsorbents came from waste agricultural byproducts have been used to erase hexavalent chromium. Study mainly directed on comparing certain agro located products for the chelation of Cr(VI) ions. An far-reaching list of agricultural based fruit such as Coconut Coir, Prunus amygdalus, Cissus quadrangularis, Soapnut Acacia, Justicia adhatoda, Bhringraj, Aerva lanata, Trianthema portulacastrum, Tephrosia purpurea, Solanum nigrum, Datura metel, Cleome viscous, Asparagus racemosus employed for Cr(VI) trapping from liquid solutions and the fulfilled industrial effluents are inspected in this work. Chemically altered matters have greater adsorption volumes and are therefore used to modify the stated materials in the research items in particular ways. For further examination into the extensive use of the secondhand materials, the results reported apiece authors have been distinguished and summarized. The comparative study on biosorbents explaines that they possess extreme potential in full- scale for the removal of poisonous metal ions.

Author(s) Details:

N. Muthulakshmi Andal,
Department of Chemistry, PSGR Krishnammal College for Women, Affiliated to Bharathiar University, Coimbatore-641 004, Tamil Nadu, India.

S. Charulatha,
Department of Chemistry, PSGR Krishnammal College for Women, Affiliated to Bharathiar University, Coimbatore-641 004, Tamil Nadu, India.

Please see the link here: https://stm.bookpi.org/NACB-V1/article/view/10244

Research New Ways of Processing Polymer Waste that was Formed as a Result of Operation | Chapter 2 | Novel Perspectives of Geography, Environment and Earth Sciences Vol. 1

 In this study, the reasons for the decommissioning of polymer matters are shown and recycling orders are analyzed. Polymer matters do not rot, corrode, etc. if their characteristics are captured into account, their reusing is an economic problem in addition to an ecological problem that needs expected solved. Taking into account all this, the arrangements of obtaining purposeful arrangements from some polymer wastes have been intentional. its demolition mainly occurs on account of high hotnesses. As a result, the molecular mass of RS (elastic scrub) decreases. When studying this in an aerate and non-oxygenated atmosphere, the maximum stability of RS is observed in the hotness interval of 180°C. Therefore, we selected the temperature of 180°C to modify highway oil bitumen accompanying RS waste. The most effective field valuable of polymer materials is the modification of highway bitumen.

Author(s) Details:

Shixaliyev Kerem Seyfi,
Department of Organic Substances and Technology of Macromolecular Compounds, Azerbaijan State Oil and Industry University, Academician of the European Academy of Natural Sciences, Baku, Azerbaijan.

Please see the link here: https://stm.bookpi.org/NPGEES-V1/article/view/8939

Oxygen Electroreduction on Catalysts Containing Platinum Deposited on Carbon Nanotubes Modified by O, N and P Atoms| Chapter 8 | Research Aspects in Chemical and Materials Sciences Vol. 4

 Platinum established on scattered fabrics has been the most standard catalyst for produce cathodes for a variety of electrochemical capacity sources. The purpose of this research search out look into the effect of O, N, and P atoms on the fundamental, electrocatalytic, and corrosion possessions of as-synthesised monoplatinum catalysts. The examined Pt/CNTmod incentives demonstrated improved electrochemically active light surface area and electrical generated power, as well as raised catalytic activity in soluble electrolytes during the oxygen reduction response (ORR). The half-wave potential reaches 0.89 V for nitrogen-doped and 0.88 V for planet seen at dawn-doped CNTs, that is comparable to a commercial stimulant. The increased characteristics of Pt/CNT catalysts are related by changes in the composition and amount of groups produced on the CNT surface, in addition to their electronic construction. Pt/CNTHNO3+N and Pt/CNTHNO3+NP are the most hopeful catalysts for use as cathode materials in salty medium based on the total of the major possessions.  The influence of the platinum mass (10, 20, 40, 60 wt %) on the balance, electrochemical characteristics and the backlash path of ORR in an soluble electrolyte has been studied. The capital selectivity in ORR to water is noticed for catalysts combined on nitrogen-doped CNTs and increases due to the tumor of the Pt surface on the electrode. The closeness of hydrogen peroxide and a decrease in stability are noticed at a low content of light. Thus, according to the entirety of the results of this study, catalysts accompanying 60 and 40 wt. % Pt/CNTNaOH+N, as well as Pt/CNTHNO3+N and Pt/CNTHNO3+NP are ultimate promising stimulants for alkaline fuel cells.

Author(s) Details:

Vera Bogdanovskaya,
A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia.

Inna Vernigor,
A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia.

Marina Radina,
A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia.

Vladimir Andreev,
A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia.

Oleg Korchagin,
A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, Russia.

Please see the link here: https://stm.bookpi.org/RACMS-V4/article/view/8697

Studies on Developing a Neuro Fuzzy Model to Predict the Properties of AlSi12 Alloy | Chapter 7 | Emerging Trends in Engineering Research and Technology Vol. 11

 The results of alteration and vibration are investigated and compared with unmodified alloy during solidification of Aluminum-Silicon eutectic alloy (AlSi12). As modifiers, Sodium and Strontium are used. Using a vibration table, horizontal sinusoidal vibration was imposed at various frequencies. Modification treatment has been found to enhance characteristics such as ultimate tensile strength (UTS), percentage elongation, stiffness, durability, cutting power, electrical conductivity, thermal conductivity, fluidity, porosity and fatigue strength, and optimum values have been found for modifier sodium and strontium weight addition. The network model of a self-organized feature map (SOFM) is created The kit uses Neuro Solutions. To optimise the model generated, genetic algorithms are used. In addition, the neuro fuzzy model (CANFIS) was developed and the results were compared with the developed neural network model. Sensitivity analysis is carried out to measure the relative value of the model's inputs and how the output of the model differs in response to an input variance. The models developed were experimentally tested.

Author (s) Details

Dr. K. Srinivasulu Reddy
Mechanical Engineering Department, Sreenidhi Institute of Science and Technology, Hyderabad, Telangana-501 301, India.

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