Catalytic Thermal Treatment Research Articles

Catalytic thermal treatment (catalytic thermolysis) of textile dyeing effluent

During the production of textiles a large amount of wastewater is generated that contains high organics load and color appearance. If it is directly (untreated) discharged into any water-receiving body then it gets fully contaminated, hence its proper treatment is required. The present study deals with the treatment of textile dyeing effluent (TDE) using catalytic thermolysis (CT) for the reduction of color and COD reduction with the help of CuO as a catalyst. The catalyst (CuO) was prepared successfully on the laboratory scale. The CuO preparation is done by alkali precipitation of copper sulfate followed by drying and calcination. Catalyst is characterized in detail including X-ray diffraction, SEM, and TEM analysis. CT treatment of TDE was carried out in a 0.5 dm3 thermolysis batch reactor using CuO as a catalyst at different pH (2.4–10.4), temperatures (70 °C–115 °C), and catalyst loadings (1.5–5.5 g/dm3). The maximum 72 % COD reduction was achieved at the optimum condition of 70 °C temperature, catalyst loading of 1.5 g/dm3, and 4.4 pH. The residues obtained after CT were characterized by TGA, TDA, and TG. In addition, settling characteristics were also observed for CT-treated sludge at different temperatures. CT is a novel treatment technique to treat highly polluted wastewater. During the CT treatment, the addition of chemicals is not required and it has good removal efficiency. Further CT-treated sludge has good heating value hence it can be used as an industrial fuel. In other words, no secondary pollutants are generated during the CT process.

A strategy for industrial waste mitigation—thermal treatment of non-woven polyester fabric debris on ultrahigh-porosity MgO under CO2 atmosphere

Unproperly treated industrial waste creates serious environmental pollution that requires immediate remediation strategies. Non-woven polyester fabrics are widely used in a variety of industrial applications; thus, their debris becomes a major portion of industrial waste. To contribute to advanced industrial waste treatment processes, this study investigated catalytic thermal treatment of non-woven polyester fabric debris on a novel ultrahigh-porosity MgO material under a CO2 environment. The ultrahigh-porosity MgO was synthesized from hydromagnesite via a series of thermal reactions, having a surface area of 208.8 m2 g−1, total pore volume of 0.34 cm3 g−1, and average pore diameter of 2.37 nm. Using the MgO as the catalyst for thermolysis of non-woven polyester fabric debris in CO2 promoted thermal cracking of volatilized species evolved from the non-woven polyester fabric debris thermolysis, thereby increasing the gas product yield and decreasing the liquid product and wax yields. In addition, dehydrogenation and reverse water gas reaction was promoted by the MgO catalyst, leading to more than higher syngas production (up to 16.1 wt% syngas yield) compared to non-catalytic thermolysis (up to 8 wt% syngas yield). The selectivity toward esters was increased, while the selectivities toward benzoic and phthalic acids were decreased, most likely due to the MgO promoting decarboxylation and esterification reactions during the thermolysis. Moreover, the ultrahigh-porosity MgO catalyst was reusable for at least two consecutive cycles. It is hoped that the applicability of the novel material as a catalyst is widened for advanced treatment processes to minimize negative effects of industrial wastes on the environment.

Enabling efficient and economical degradation of PCDD/Fs in MSWIFA via catalysis and dechlorination effect of EMR in synergistic thermal treatment

Catalytic thermal treatment is an efficient and low-energy consumption method for degrading polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in municipal solid waste incineration fly ash (MSWIFA). However, catalysts with high activity are expensive, difficult to separate and reuse from the treated MSWIFA, and they usually pose a risk of heavy metal pollution. Herein, a synergistic thermal treatment method of MSWIFA and electrolytic manganese residue (EMR) at relatively low temperatures was proposed after an in-depth analysis of their mineralogy composition to achieve detoxification of PCDD/Fs in MSWIFA. The mass and WHO-TEQ degradation efficiencies of PCDD/Fs significantly increased from −92.79% and −51.46%–98.57% and 96.10%, respectively, by the addition of electrolytic manganese residue (EMR) with an MSWIFA/EMR ratio of 3:7 in the thermal treatment of MSWIFA at 250 °C for 60 min. The WHO-TEQ concentration of PCDD/Fs in the treated sample decreased to 3.7 ng WHO-TEQ/kg, meeting the European end-of-waste criteria (20 ng WHO-TEQ/kg). The excellent degradation effect of EMR on PCDD/Fs in MSWIFA could be attributed to two aspects: 1) the manganese oxides in EMR has a catalytic effect on the degradation of PCDD/Fs; 2) the NH3 generated by the decomposition of (NH4)2SO4 in EMR is conducive to the degradation and resynthesis inhibition of PCDD/Fs. Besides, the thermodynamic calculations indicated that CaClOH in MSWIFA played a crucial role in the decomposition of (NH4)2SO4 in EMR. In addition, the degradation pathways and mechanisms of PCDD/Fs-homologues under the synergistic effect of manganese oxides, ammonia, and thermal field were investigated through comparative analysis of concentration and fingerprint of PCDD/Fs.

Catalytical thermal conversion of waste fishing nets for a higher added value energy products generation and caprolactam recovery

The ongoing eutrophication processes and water pollution caused by marine plastic waste are relevant ecological problem. Collected wastes are possible alternative feedstock for additional higher added value energy product generation. Moreover, caprolactamis the main compound of nylon-6 waste fishing nets and its recovery conserves natural resources, maximizes waste economic performance, and closes the circular economy loop of the fishing net industry. In order to contribute to the creation of circular economy, investigation of pyrolysis process and the effect of catalyst synergy with different temperatures on the formulated products has been performed. This work aims to analyse the used fishing nets (FN), using TGA-DTG-FTIR systems and mini pyrolysis plant. Experiments were conducted with Y-type zeolite and ZSM-5 as catalysts with a ratio of 1 by 3 and 1 by 8, respectively. Micro-thermal analysis using the TGA-DTG-FTIR system was processed for feedstock characterization purposes, which showed that the fishing gear has one minor decomposition peak around 200 °C, and the major one around 450 °C, with a total weight loss of 88 wt%. Pyro-oils analysis showed that the main fractions could be assigned to aromatic and aliphatic hydrocarbons, such as naphthalene, styrene, and toluene. Moreover, the recovery of caprolactam shows a possibility to obtain not only energy products, but also higher added value chemical derivatives. Temperature and catalyst synergetic approach influence for the recovered products investigation showed the optimum conditions as 700 °C for the highest purity and quality products generation. Based on the results, catalytic thermal treatment at 700 °C with Y-Type could be adapted as a promising technique for extracting of caprolactam with a high yield (96 %).

Catalytic thermal treatment (thermolysis) process of tannery wastewater for the removal of chemical oxygen demand and color

Catalytic thermal treatment (thermolysis) process of tannery wastewater for the removal of chemical oxygen demand and color

Single-Step Formation of Ni Nanoparticle-Modified Graphene-Diamond Hybrid Electrodes for Electrochemical Glucose Detection.

The development of accurate, reliable devices for glucose detection has drawn much attention from the scientific community over the past few years. Here, we report a single-step method to fabricate Ni nanoparticle-modified graphene–diamond hybrid electrodes via a catalytic thermal treatment, by which the graphene layers are directly grown on the diamond surface using Ni thin film as a catalyst, meanwhile, Ni nanoparticles are formed in situ on the graphene surface due to dewetting behavior. The good interface between the Ni nanoparticles and the graphene guarantees efficient charge transfer during electrochemical detection. The fabricated electrodes exhibit good glucose sensing performance with a low detection limit of 2 μM and a linear detection range between 2 μM–1 mM. In addition, this sensor shows great selectivity, suggesting potential applications for sensitive and accurate monitoring of glucose in human blood.

Catalytic graphitization of kraft lignin to graphene-based structures with four different transitional metals

Catalytic graphitization of kraft lignin to nano-materials was investigated over four transitional metal catalysts (Ni, Cu, Fe, and Mo) through a thermal treatment process under an argon flow at 1000 °C. The catalytic thermal process was examined using thermal gravimetric analysis (TGA) and temperature-programmed decomposition (TPD) experiments. The crystal structure and morphology of the thermal-treated metal-lignin samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Raman spectroscopy. Catalytic graphitization of kraft lignin to nano-materials was investigated over four transitional metal catalysts (Ni, Cu, Fe, and Mo) through a catalytic thermal treatment process. It was observed that multi-layer graphene-encapsulated metal nanoparticles were the main products, beside along with some graphene sheets/flakes. The particle sizes and graphene shell layers were significantly affected by the promoted metals. BET surface areas of samples obtained from different metal precursors were in the range of 88–115 m2/g within the order of Ni- > Fe- > Mo- > Cu-. Thermal gravimetric analysis (TGA) and temperature-programmed decomposition (TPD) experimental results showed that adding transitional metals could promote the decomposition and carbonization of kraft lignin. The catalytic activity increased with an order of Mo≅Cu < Ni≅Fe. XRD results show that face-centered cubic (fcc) Cu crystals is formed in the thermal-treated Cu-lignin sample, fcc nickel phase for the Ni-lignin sample, β-Mo2C hexagonal phase for the Mo-lignin sample and α-Fe, γ-iron, and cementite(Fe3C) for the Fe-lignin sample. Average particle sizes of these crystal phases calculated using the Scherrer formula are 52.4 nm, 56.2 nm, 21.0 nm, 23.3 nm, 11.3 nm, and 32.8 nm for Ni, Cu, β-Mo2C, α-Fe, γ-iron, and Fe3C, respectively. Raman results prove that the graphitization activity of these four metals is in the order of Cu < Mo < Ni < Fe. Metal properties such as catalytic activity, carbon solubility, and tendency of metal carbide formation were related to the graphene-based structure formation during catalytic graphitization of kraft lignin process.

Highly stable and regenerative graphene–diamond hybrid electrochemical biosensor for fouling target dopamine detection

Graphene is widely recognized as a promising nanomaterial for the construction of high-performance electrochemical biosensors. However, the lack of strong interfacial forces between graphene and conductive substrates is a bottleneck in the fabrication of highly stable graphene electrodes. In this work, few-layer graphene was directly formed on a high pressure high temperature (HPHT) diamond substrate via sp3-to-sp2 conversion by catalytic thermal treatment and using diamond itself as the carbon source. The hybrid electrode prototype was also highly conductive and had a linear electrochemical response to dopamine in the concentration range of 5 μM – 2 mM, with a low detection limit of 200 nM. After prolonged and repeated exposure to dopamine, electrode fouling was observed which led to sensitivity degradation. Based on the strong interfacial bonding between graphene and HPHT diamond, regeneration of the fouled electrode and full performance recovery would be easily achieved by ultrasonic cleaning. The hybrid electrode is highly robust, and shows potential in its application to the detection of biofouling molecules, food processing and wastewater treatment.

Carbon-Based Nanomaterials from Biopolymer Lignin via Catalytic Thermal Treatment at 700 to 1000 °C.

We report the preparation of carbon-based nanomaterials from biopolymer kraft lignin via an iron catalytic thermal treatment process. Both the carbonaceous gases and amorphous carbon (AC) from lignin thermal decomposition were found to have participated in the formation of graphitic-carbon-encapsulated iron nanoparticles (GCEINs). GCEINs originating from carbonaceous gases have thick-walled graphitic-carbon layers (10 to 50) and form at a temperature of 700 °C. By contrast, GCEINs from AC usually have thin-walled graphitic-carbon layers (1 to 3) and form at a temperature of at least 800 °C. Iron catalyst nanoparticles started their phase transition from α-Fe to γ-Fe at 700 °C, and then from γ-Fe to Fe3C at 1000 °C. Furthermore, we derived a formula to calculate the maximum number of graphitic-carbon layers formed on iron nanoparticles via the AC dissolution-precipitation mechanism.

Catalytic thermal pre-treatments of sugar industry wastewater with metal oxides: Thermal treatment

Water is essential to human health, economic growth, and environmentally sustainable development. Treating sugar industry effluent is one of the important tasks to save the nearby surrounding and recover the fresh water for industrial application. The goal of research work is to treat the sugar industry wastewater by metal catalyst using catalytic thermal treatment. The results show treatment with copper oxide 84.2% chemical oxygen demand and 89.6% color removal at 5kg/m3 catalysis mass loading, optimum pH5, operating temperature 85°C and treatment time 9h can be archives. The settling rate for 6kg/m3mass loading has shown 55% clear liquid and 45% solid interface at 140min of study. The cake resistance was 2.17×1013(m/kg) and filter medium resistance 2.71×109m−1 for 5kg/m3mass loading of copper oxide. The sludge obtained after thermolysis has high heating value and can be used as a fuel.

Degradation of colour and chemical oxygen demand of sugar industry wastewater by thermo-chemical combined processes

Wastewater generated from sugar industries play major role for polluting the environment. It has direct effect on the rural as well as on urban area. Such complex character wastewater required specific and advance technology to bring upto discharge limit. The goal of the research work is treat the sugar industry waste water by catalytic thermal treatment. Ferrous salt has been used as catalysis for the experiment. The result indicated by the combination of thermal and chemical method 95% chemical oxygen demand and 98.5% color can removed at optimum condition. The sludge generated after treatment are fit for construction material. Overall this methodology brings new change from old tradition method used in sugar industry to treat the waste water.

Catalytic thermal treatment (catalytic thermolysis) of a rice grain-based biodigester effluent of an alcohol distillery plant

The catalytic thermolysis (CT) process is an effective and novel approach to treat rice grain-based biodigester effluent (BDE) of the distillery plant. CT treatment of rice grain-based distillery wastewater was carried out in a 0.5 dm3 thermolytic batch reactor using different catalysts such as CuO, copper sulphate and ferrous sulphate. With the CuO catalyst, a temperature of 95°C, catalyst loading of 4 g/dm3 and pH 5 were found to be optimal, obtaining a maximum chemical oxygen demand (COD) and colour removal of 80.4% and 72%, respectively. The initial pH (pHi) was an important parameter to remove COD and colour from BDE. At higher pHi (pH 9.5), less COD and colour reduction were observed. The settling characteristics of CT-treated sludge were also analysed at different temperatures. It was noted that the treated slurry at a temperature of 80°C gave best settling characteristics. Characteristics of residues are also analysed at different pH.

Removal of color and chemical oxygen demand from sugar industry wastewater using thermolysis processes

In the present study, treatment of sugar industry wastewater (SIWW) was investigated for the reduction of chemical oxygen demand (COD) and color using catalytic thermal treatment (thermolysis). Effect of various parameters such as pH 2–10, temperature 55–95°C, catalyst mass loading (Cw) 2–5 kg/m3, and types of catalysts was studied on COD and color reductions of the effluent. Among various catalysts used, copper oxide was found to be the best catalyst giving 74% COD and 80% color reductions with a catalyst concentration of 4 g/dm3 at pH 10 and 75°C temperature. Order of COD degradation rate was found to be 1.5 with respect to COD and 0.805 with respect to catalyst mass loading. Settling rate of the treated effluent was good and was found to be affected by the treatment temperature. The initial pH (pHi) of the effluent played an important role in the treatment process, and optimum value was found to be different for different catalysts. Results show that the process can be applied for the treatment of SIWW.

KINETICS OF CATALYTIC THERMAL TREATMENT (CATALYTIC THERMOLYSIS) OF BIODIGESTER EFFLUENT OF AN ALCOHOL DISTILLERY PLANT

The biodigester effluent (BDE) of a molasses-based alcohol distillery unit was taken for catalytic thermal treatment (catalytic thermolysis) in the presence of CuO catalyst in batch mode in the temperature range of 100° to 140°C and pressure range of 1–9 bar. The catalyst mass loading, Cw, varied between 2 and 5 kg m−3. Thermal treatment at 140°C with a Cw of 3 kg m−3 gave COD reduction of about 70% from its initial value of 34 kg m−3. The BOD reduction was found to be 83% from its initial value of 6.3 kg m−3. The reductions of COD and consequently BOD are due to formation of residues of organics, i.e., carbohydrates, lignin, and proteins, present in the biodigester effluent. The characterization of CuO catalyst through X-ray diffraction shows the presence of the phase of CuO only, at different 2θ values. The kinetic data show two clearly distinct steps, a fast rate process followed by a slower process, adequately described by first-order kinetics with respect to COD. The order with respect to Cw was found to be 0.744 and 0.187 for the first and second steps, respectively.

Treatment of desizing wastewater by catalytic thermal treatment and coagulation

In the present study, the coagulation of the fresh and thermally treated desizing wastewater has been reported. The maximum COD reduction of fresh desizing wastewater using coagulation was observed with commercial alum at initial pH 4. This was followed by aluminum potassium sulfate (pH 4), FeCl 3 (pH 6), PAC (pH 6) and FeSO 4 (pH 4). The maximum COD reduction observed at a coagulant (commercial alum) dose of 5 kg/m 3 and pH 4 was 58% whereas the color reduction at these conditions was 85%. The results reveal that the application of coagulation on the catalytic thermal treated effluent is more effective in removing nearly 88% of COD and 96% of color at above mentioned conditions except at a coagulant dose of 1 kg/m 3. The amount of inorganic sludge generated gets drastically reduced (almost 25%) due to the reduced amount of coagulant. The COD and color of the final effluent were found to be 98.6 mg/l and 2.67 PCU, respectively, and the COD/BOD 3 ratio was 1.36. The settling rate of the slurry was found to be strongly influenced by treatment pH. The slurry obtained after treatment at pH 12 settled faster in comparison to slurry obtained at pH 4. The filterability of the treated effluent is also strongly dependent on pH. pH 12 was adjudged to be the best in giving highest filtration rate.

Decolorization and COD reduction of dyeing wastewater from a cotton textile mill using thermolysis and coagulation

The decolorization and reduction of COD of dyeing wastewater from a cotton textile mill was conducted using catalytic thermal treatment (thermolysis) accompanied with/without coagulation. Thermolysis in presence of a homogeneous copper sulphate catalyst was found to be the most effective in comparison to other catalysts (FeCl 3, FeSO 4, CuO, ZnO and PAC) used. A maximum reduction of chemical oxygen demand (COD) and color of dyeing wastewater of 66.85% and 71.4%, respectively, was observed with a catalyst concentration of 5 kg/m 3 at pH 8. Commercial alum was found most effective coagulant among various coagulants (aluminum potassium sulphate, PAC, FeCl 3 and FeSO 4) tested during coagulation operations, resulting in 58.57% COD and 74% color reduction at pH 4 and coagulant dose of 5 kg/m 3. Coagulation of the clear fluid (supernatant) obtained after treatment by thermolysis at the conditions previously used resulted in an overall reduction of 89.91% COD and 94.4% color at pH 4 and a coagulant dose of 2 kg/m 3. The application of thermolysis followed by coagulation, thus, is the most effective treatment method in removing nearly 90% COD and 95% color at a lower dose of coagulant (2 kg/m 3). The sludge thus produced would contain lower inorganic mass coagulant and, therefore, less amount of inorganic sludge.

Treatment of composite wastewater of a cotton textile mill by thermolysis and coagulation

Catalytic thermal treatment (thermolysis) accompanied with coagulation was used for the removal of COD and color of composite wastewater from a cotton textile mill. CuSO 4, FeSO 4, FeCl 3, CuO, ZnO and PAC were used as catalytic agents during thermolysis. Homogeneous copper sulphate at a mass loading of 6 kg/m 3 was found to be the most active. Similarly during coagulation aluminum potassium sulphate [KAl(SO 4) 2·16H 2O] at a coagulant concentration of 5 kg/m 3 was found to be the best among the other coagulants tested, namely, commercial alum, FeSO 4, FeCl 3 and PAC. During thermolysis, a reduction in COD and color of composite wastewater of about 77.9 and 92.85%, respectively, was observed at pH 12. Coagulation of fresh composite waste using aluminum potassium sulphate resulted in 88.62% COD reduction and 95.4% color reduction at pH 8. Coagulation of the supernatant obtained after treatment by catalytic thermolysis resulted in overall reduction of 97.3% COD and close to 100% color reductions at pH 8 at a lesser coagulant concentration of 3 kg/m 3. The results reveal that the application of coagulation after thermolysis is most effective in removing nearly 100% of COD and color at a lower dose of coagulant. The sludge thus produced would contain lower inorganic mass coagulant and can be used as a solid fuel with high calorific value of about 16 MJ/kg, close to that of Indian coal.

Catalytic thermal treatment of desizing wastewaters

In the present study, catalytic thermal treatment (thermolysis) was investigated for the reduction of COD and color of the desizing wastewater under moderate temperature and atmospheric pressure conditions using various catalysts. The experimental runs were performed in a glass reactor equipped with a vertical condenser. The homogeneous copper sulfate catalyst was found to be the most active in comparison to other catalysts under similar operating conditions. A removal of about 71.6% chemical oxygen demand (COD) and 87.2% color of desizing wastewater was obtained with a catalyst concentration of 4 kg/m 3 at pH 4. The initial pH value of the wastewater showed a pronounced effect on the precipitation process. During the thermolysis, copper gets leached to the aqueous phase, the residue obtained after the treatment is rich in copper and it can be blended with organic manure for use in agricultural fields. The thermogravimetric analysis showed that the thermal oxidation of the solid residue obtained after thermolysis gets oxidized at a higher temperature range than that of the residue obtained from the desizing wastewater. The results lead to the conclusion that thermochemical precipitation is a very fast (instantaneous) process and would need a very small reactor vessel in comparison to other processes.

Catalytic Thermal Treatment (Catalytic Thermolysis) of a Biodigester Effluent of an Alcohol Distillery Plant

The catalytic thermal treatment (catalytic thermolysis) of biodigester effluent from an alcohol distillery unit was studied in the presence of CuO catalyst in batch mode in the temperature range of 100−140 °C and the pressure range of 1−9 bar. The catalyst mass loading, Cw, was varied between 2 and 5 kg/m3. Thermal treatment at 140 °C with a Cw of 3 kg/m3 gave a maximum chemical oxygen demand (COD) reduction of about 70% from its initial value of 34 kg/m3. The biochemical oxygen demand reduction was found to be 83% from its initial value of 6.3 kg/m3. The COD reduction−time profiles show two clearly distinct steps: a fast process followed by a slower process. A good amount of charred solid residue is obtained, which is enriched with carbon, giving a C/H atomic ratio of 1:0.947, versus a C/H atomic ratio of 1:1.146 for the effluent. The charred residue is a good fuel material with a high heating value (∼17.92 MJ/kg) representing 42−47% energy recovery from the digester effluent. During the thermolysis, co...