Shrimp Shell Waste Research Articles

Antibody titer after anti-idiotype rabies vaccination with nano-chitosan adjuvant

Background.The rabies virus neutralizing antibodies titers is a public health problem in the world, including Indonesia. Rabies is zoonotic and causes death in humans with a case fatality rate of 100%. Anti-idiotype antibody (Ab2) from chicken immunoglobulin (IgY) can be a substitute antigen for the rabies virus. This research aims to study the potential of rabies vaccine based on anti-idiotype antibody (Ab2) with nano-chitosan as an adjuvant.Materials and methods.The production of Ab2 is derived from purified and characterized chicken immunoglobulins. Nano-chitosan is made from chitosan from shrimp shell waste. Vaccination tests were carried out on rats compared with commercial vaccines as a positive control and physiological solutions as a negative control. The characterization results of IgY Ab2 were IgY rabies with BM ~180 kDa, heavy chains (BM ~60 kDa), and light chains (BM ~30 kDa) of IgY. Nano-chitosan is less than 100 nm in size, can dissolve well, and does not cause side effects in experimental animals.Results.The vaccine formula uses a concentration of 0.5%, where the ratio of nano-chitosan and Ab2 is 1:1. The Ab2 concentration used was about 1000 units per mL of the Ab2 suspension.Conclusion.This study concludes that anti-idiotype antibodies dissolved in nano-chitosan adjuvant can induce the formation of antibodies with titers that are not statistically different from the antibody titers induced by commercial rabies vaccines. Nano-chitosan has a potential vaccine adjuvant candidate, safe to use, and can enhance the immunogenicity of an antigen applied subcutaneously. According to the results of this study, it is recommended that post-vaccination antibody titers be measured regularly: for example, every one week for six weeks after vaccination. This measurement determines the time of the peak of the antibody titer so that the time for revaccination can be determined.

Transforming waste into wealth in sustainable shrimp aquaculture: Effective phosphate removal and recovery using shrimp shell-derived adsorbents

The growing global demand for shrimp has driven the intensification of shrimp aquaculture, leading to significant environmental challenges due to nutrient-rich wastewater and solid waste. This study developed shrimp shell-derived adsorbents (SSs) by pyrolysis and calcium hydroxide (Ca(OH)2) activation to remove phosphate (PO43−) from aqueous solutions. Ca(OH)2 activated adsorbent achieved higher PO43− removal than adsorbent obtained at higher pyrolysis temperature, with adsorption capacities up to 381.24 mg/g of PO43− at 20 °C. The primary mechanism driving PO43− removal was chemical precipitation between Ca and PO43−. SSs were found to release Ca2+ from hydroxylellestadite (HDL), Ca(OH)2, and calcium carbonate (Ca(CO)3). Additionally, ligand exchange of PO43− by Ca(CO)3 and π-π interactions from aromatic rings further enhanced the PO43− adsorption. SEM-EDS showed PO43− dispersed on the SSs surface. XPS revealed that Ca-O bond was shifted to Ca-P bond with a higher binding energy and a new π-π interaction peak appeared at 293.60 eV. FTIR confirmed ligand exchange between PO43− and CO32−, with the 1400 cm−1 band disappearing and a new 870 cm−1 band appearing. The XRD, FTIR, and XPS analyses confirmed the formation of various calcium-phosphate (Ca-P) groups, including calcium apatite (Ca-apatite), monocalcium phosphate (Ca(H2PO4)2), and dicalcium phosphate (CaHPO4), on the saturated SSs. Specifically, all XPS spectra of Ca-O moved to higher binding energy, reflecting Ca-P linkages. This study provides a sustainable alternative for handling shrimp shell waste and suggests a promising approach for PO43− recovery, thereby contributing to a circular system in shrimp aquaculture.

Sustainable ammonia and amines from chitin

Efforts are underway to explore alternative methods to the Haber-Bosch process for sustainable ammonia production, while the potential for ammonia extraction from natural nitrogenous biomass is under-exploited. Here, a synergistic catalytic strategy involving acid and modified Ru-based catalysts is communicated for the direct production of amines and ammonia from chitin. Phosphoric acid promotes the cleavage of ether bonds in biomass polymers and also serves to protect amino groups from being removed. Selective hydrogenation, deoxygenation, and amination can be achieved by controllably adjusting the ratio of Ru0/Run+. The utilization of nitrogen atoms in chitin can reach up to 95 % (21 % amines, 74 % ammonium), and the catalytic process is applicable to waste shrimp shells. This study demonstrates the possibility of efficient production of nitrogen-containing compounds from abundant biopolymers.

Novel Micrococcus unila to Produce Glucosamine by Solid-state Fermentation of Shrimp Shell Waste

This study aimed to assess glucosamine production through enzymatic activity, utilizing actinomycetes sourced from shrimp shell waste (SSW) in a solid-state fermentation (SSF) process. A total of 16 actinomycetes underwent chitinase activity screening, and the strain exhibiting the highest chitinolytic index was chosen for subsequent morphological and phylogenetic analyses. High Performance Liquid Chromatography (HPLC) was employed to analyze glucosamine produced from the bioconversion of SSW via SSF. Optimal conditions for glucosamine production were determined by varying time, pH, and temperature. Isolate 18D36-A2 showed the highest chitinolytic index of 1.02 in the 32-mm clean zone. Phylogenetic analysis revealed 97% similarity to the genus Micrococcus, identifying it as a novel Micrococcus unila strain 18D36-A2 and deposited in GenBank. This isolate effectively converted shrimp shells. The findings showcase the bioconversion of SSW to glucosamine through SSF using the Micrococcus unila 18D36-A2. Furthermore, this study establishes a foundation for future research on environmentally friendly and sustainable designs for glucosamine production.

Extraction and Quality Control of Chitin and Chitosan from Shrimp (Vanami) Litophenause Vanamei Shells Wastes

Objective/Background: The biological value of chitin and chitosan obtained from shrimp, such as physiological compatibility, non-toxicity, bio digestibility, absorption and chelating capacity, depends on qualitative parameters that are directly related to raw material source. This study was carried out to investigate extraction and characterization of chitin and chitosan from shrimp Litophenause vanamei shells wastes. Methods: Chitin and chitosan was extracted and characterized from shrimp L. vanamei shells found in Iran, using conventional methods of pretreatment, demineralization, and deacetylation. In this study, commercial shrimp L. vanamei shell was used to extract chitin and chitosan. Results: The degree of deacetylation of shrimp chitosan (49%) is directly related to solubility of chitosan. Chitosan is considered to have excellent biological value with these qualitative parameters. The yield of shrimp chitosan was 13.96%. Conclusion: These results showed that use of shrimp shell waste to produce chitin and chitosan will have more economic and biological value along with reducing environmental pollution.

Effect of Coating Chemically Derived Chitosan from Shrimp Shell Wastes on Physical, Microbiological and Sensory Characteristics of Chicken Sausages

Sausages have high moisture and protein content, making them extremely vulnerable to microbial deterioration. The antimicrobial qualities of chitosan coating prolong the shelf-life of sausages. The aim of this present study was to evaluate the effect of 0, 0.25, 0.5 and 1% (w/v) of chitosan coatings on microbiological, physical and sensory attributes of chicken sausages in cold storage (-10 °C). Chitosan was extracted from shrimp shell and dissolved in acetic acid to prepare 0.25, 0.5 and 1% of edible chitosan solution and control (0%). Sausages were coated by dipping in chitosan solutions. To find the best percentage of chitosan coating, physical, microbiological and sensory attributes were examined during the storage period. A number of TAB colonies was shown to have increased during the storage; nevertheless, the values were within the acceptable level (5.00 Log (CFU/g) in 0.25, 0.5 and 1% chitosan treated samples in two weeks of storage. The number of TAB colonies was not significantly (P>0.05) reduced between the samples treated with 0.25, 0.5 and 1% of chitosan. Further, hardness values were increased with the chitosan coating, while 1% chitosan-coated sausages had the highest value for hardness (27.93 N). Similarly, the WHC also increased with the chitosan coating. There was no significant difference observed (P>0.05) among 0.25, 0.5, and 1.0% of chitosan coating in WHC. pH values improved with the chitosan coating. Moisture and colour were not significantly (p>0.05) affected by chitosan coating. During storage, deteriorative changes occurred slowly in coated sausages. 1% chitosan coated sausages had the highest overall acceptability and maximum scores for odour, colour, taste, appearance and texture on the day 1 and 4th week of storage. Chitosan coating can be utilized as an edible coating material for the preservation of meat products.

Enhanced oxidation of rhodamine B using Mg-Cu-Al hydrotalcite/chitosan composites as catalysts

A series of Mg-Cu-Al hydrotalcite/chitosan materials have been synthesized via a co‑precipitation method, in which chitosan is synthesized from chitin extraction from waste shrimp shells. The obtained solids were characterized by XRD, BET, EDX, IR techniques. The materials have a well crystallized hydrotalcite structure and medium surface area. It was observed that Mg-Cu-Al hydrotalcite/chitosan catalysts exhibited the high activity in catalyzing enhanced oxidation of rhodamine B solution with H2O2. 95% of 100 mg/L of rhodamine B solution could be decolourized by Mg-Cu-Al hydrotalcite/chitosan composite with the presence of hydrogen peroxide at room temperature for 150 minutes. Therefore, Mg-Cu-Al hydrotalcite/chitosan is a promising and reasonable catalyst for use in the enhanced oxidation of rhodamine B.

Biocomposite Scaffolds Based on Chitosan Extraction from Shrimp Shell Waste for Cartilage Tissue Engineering Application.

Chitosan-based scaffolding possesses unique properties that make it highly suitable for tissue engineering applications. Chitosan is derived from deacetylating chitin, which is particularly abundant in the shells of crustaceans. This study aimed to extract chitosan from shrimp shell waste (Macrobrachium rosenbergii) and produce biocomposite scaffolds using the extracted chitosan for cartilage tissue engineering applications. Chitinous material from shrimp shell waste was deproteinized and deacetylated. The extracted chitosan was characterized and compared to commercial chitosan through various physicochemical analyses. The findings revealed that the extracted chitosan shares similar trends in the Fourier transform infrared spectroscopy spectrum, energy dispersive X-ray mapping, and X-ray diffraction pattern to commercial chitosan. Despite differences in the degree of deacetylation, these results underscore its comparable quality. The extracted chitosan was mixed with agarose, collagen, and gelatin to produce the blending biocomposite AG-CH-COL-GEL scaffold by freeze-drying method. Results showed AG-CH-COL-GEL scaffolds have a 3D interconnected porous structure with pore size 88-278 μm, high water uptake capacity (>90%), and degradation percentages in 21 days between 5.08% and 30.29%. Mechanical compression testing revealed that the elastic modulus of AG-CH-COL-GEL scaffolds ranged from 44.91 to 201.77 KPa. Moreover, AG-CH-COL-GEL scaffolds have shown significant potential in effectively inducing human chondrocyte proliferation and enhancing aggrecan gene expression. In conclusion, AG-CH-COL-GEL scaffolds emerge as promising candidates for cartilage tissue engineering with their optimal physical properties and excellent biocompatibility. This study highlights the potential of using waste-derived chitosan and opens new avenues for sustainable and effective tissue engineering solutions.

Innovative radiation shielding material with flexible lightweight and low cost from shrimp shells waste

This study explores an innovative approach to developing radiation shielding materials using shrimp shell waste. The research investigates the feasibility of incorporating shrimp shells into a silicone rubber matrix to create a flexible, lightweight, and cost-effective radiation shielding material. Shrimp shells, rich in calcium carbonate (CaCO3) content of 13.90%, offers promising properties for radiation attenuation. Through a series of experiments and characterization techniques, including X-ray fluorescence (XRF), X-ray diffraction (XRD), and scanning electron microscopy (SEM), the effectiveness of the composite material in attenuating radiation is evaluated. The results demonstrate that as the shrimp shell concentration rose from 25% to 75%, the absorbed radiation increased from 9.27% to 82.39% (40 kVp) and from 1.88% to 30.22% (120 kVp), while the linear coefficient also increased, attributed to the presence of CaCO3. This novel radiation shielding material presents a sustainable solution by repurposing shrimp shell waste while offering a flexible, lightweight, and cost-effective shielding for various radiation applications.

Advances in extraction, utilization, and development of chitin/chitosan and its derivatives from shrimp shell waste.

Shrimp consumption is in great demand among the seafood used globally. However, this expansion has resulted in the substantial generation and disposal of shrimp shell waste. Through literature search, it has been observed that since 2020, global scholars have shown unprecedented interest in shrimp shell waste and its chitin/chitosan. However, these new insights lack corresponding and comprehensive summarization and analysis. Therefore, this article provides a detailed review of the extraction methods, applications, and the latest research developments on chitin/chitosan from shrimp shells, including micro-nano derivatives, from 2020 to the present. The results indicate that chemical extraction remains the primary technique for the extraction and preparation of chitin/chitosan from shrimp shells. With further refinement and development, adjusting parameters in the chemical extraction process or employing auxiliary techniques such as microwave and radiation enable the customization of target products with different characteristics (e.g., deacetylation degree, molecular weight, and degree of acetylation) according to specific needs. Additionally, in pursuit of environmentally friendly, efficient, and gentle extraction processes, recent research has shifted toward microbial fermentation and green solvent methods for chitin/chitosan extraction. Beyond the traditional antibacterial, film-forming, and encapsulation functionalities, research into the applications of chitosan in biomedical, food processing, new materials, water treatment, and adsorption fields is gradually deepening. Chitin/chitosan derivatives and their modified products have also been a focal point of research in recent years. However, with the rapid expansion, the future development of chitin/chitosan and its derivatives still faces challenges related to the unclear mechanism of action and the complexities associated with industrial scale-up.

Double template synthesis of N/S co-doped shrimp shell derived biochar for efficient sulfadiazine degradation: The role of non-radical pathway

In this work, waste shrimp shells were used to synthesize N/S-co-doped biochar nanomaterials (BC-NS) by simple hard template and soft template. Through the cooperative effect of adsorption and degradation, the BC-NS/PMS system could remove 100 % of SDZ within 30 min. The combination of soft and hard templates produces hierarchical porous structure and provides more reactive sites. The radical quenching tests and electron paramagnetic resonance measurements (EPR) illustrated that the non-radical 1O2 was the dominant reactive oxidative species (ROS) in the BC-NS/PMS system. By density functional theory (DFT) computation, it demonstrated that graphitic N and pyridinic N were the main reactive sites of BC-NS. Finally, intermediate products of SDZ have been identified and four possible pathways for the degradation of SDZ were proposed. Consequently, a novel synthesis strategy of metal-free biochar materials was proposed in this study, which broadened a new prospect for the application of metal-free biochar materials in SR-AOPs.

High Degree of Polymerization of Chitin Oligosaccharides Produced from Shrimp Shell Waste by Enrichment Microbiota Using Two-Stage Temperature-Controlled Technique of Inducing Enzyme Production and Metagenomic Analysis of Microbiota Succession.

The direct enzymatic conversion of untreated waste shrimp and crab shells has been a key problem that plagues the large-scale utilization of chitin biological resources. The microorganisms in soil samples were enriched in two stages with powdered chitin (CP) and shrimp shell powder (SSP) as substrates. The enrichment microbiota XHQ10 with SSP degradation ability was obtained. The activities of chitinase and lytic polysaccharide monooxygenase of XHQ10 were 1.46 and 54.62 U/mL. Metagenomic analysis showed that Chitinolyticbacter meiyuanensis, Chitiniphilus shinanonensis, and Chitinimonas koreensis, with excellent chitin degradation performance, were highly enriched in XHQ10. Chitin oligosaccharides (CHOSs) are produced by XHQ10 through enzyme induction and two-stage temperature control technology, which contains CHOSs with a degree of polymerization (DP) more significant than ten and has excellent antioxidant activity. This work is the first study on the direct enzymatic preparation of CHOSs from SSP using enrichment microbiota, which provides a new path for the large-scale utilization of chitin bioresources.

Kinetic study of in vitro release of curcumin from chitosan biopolymer and the evaluation of biological efficacy

Sustained release of curcumin from the polymeric carrier system chitosan, a natural biopolymer material derived from chitin originated from natural shrimp shell waste, was studied. Six kinetic models, zero order, first order, Korsmeyer–Peppas (KP), Peppas – Sahlin (PS), Higuchi, and Hixson–Crowell, were applied to study the drug release kinetics. The release mechanism of the drug from the curcumin-chitosan composite was evaluated by changing the pH, ionic strength of the release media, and drug concentration. KP and PS models were selected among the studied models to investigate the drug release mechanism from the chitosan biopolymer based on the R2 values (R2 > 0.99). The model constants m in the PS model and n in the KP model stand for the case II relaxation and Fickian diffusion contribution, respectively. The n being < 0.43 in the KP model suggests that the Fickian diffusion governs the drug release. Furthermore, there is a noticeable difference between the values obtained for model parameters m and n in the PS and KP models, indicating that Case II relaxation and Fickian diffusion play crucial roles in the curcumin release mechanism from chitosan. Polymer relaxation has been proven to play a predominant role in releasing curcumin from the composite at lower ionic strengths and higher pH values. Anti-inflammatory activity was tested using the egg-albumin denaturation assay, and the diphenyl-2-picrylhydrazyl assay was carried out to determine the antioxidant activity of the composite. The composite material showed IC50 values of 0.29 mg/ mL and 1.08 mg/ mL for anti-inflammatory and anti-oxidant activities, respectively. The drug composite has shown antibacterial activity against Pseudomonas aeruginosa, Klebsiella pneumoniae, and Staphylococcus aureus, which are highly effective against S.aureus. The resulting inhibition zones for S.aureus were 13.34 ± 0.34 mm, 16.34 ± 0.60 mm, and 13.34 ± 0.73 mm for 5, 10, and 20 mg/ml concentrations, respectively. The drug composite’s minimum inhibitory concentration/ minimum bactericidal concentration ratio for S.aureus, K. pneumoniae, and P.aeruginosa was greater than 4, suggesting that they cause bacteriostatic effects.

Experimental evaluation of the process of protein removal from waste shrimp shells using papaya and pineapple juice solution

This research aims to improve the quality of chitin obtained from process protein extraction for shrimp shells. Previous studies showed that for the synthesis of chitosan, deproteinization, and demineralization is carried out by alkali and acid treatment, combined with heating, which affects the biosecurity of the material. Therefore, this study aims to remove protein from waste shrimp shells to purify chitin using a simple and safe green chemical approach (using pineapple and papaya juice solutions) and safe method. The raw shrimp shells were treated in steps: deproteinization with pineapple and papaya solutions for 12, 24, 36, and 48 h, varying immersion volumes from 10 mL to 60 mL. The experimental results showed that the protein in the shrimp shell was removed at 7.37% for freshwater shrimp (7.14%), higher than that of saltwater shrimp. The pineapple juice solution removed the protein better than the papaya juice.

Development of a Chitosan-Based Film from Shellfish Waste for the Preservation of Various Cheese Types during Storage.

The global concern about the use of disposable plastics has fed the research on sustainable packaging for food products. Among the virtuous materials, chitosan emerges as a valid alternative to conventional polyethylene films because of its abundance in nature. In this work, a novel film for food wrapping was developed by exploiting shellfish waste according to a vision of circular economy. Compared to previous studies, here, novel ingredients, such as polyvinyl alcohol (PVA), fibroin, and essential oils, were used in a synergistic combination to functionally postpone cheese deterioration. The fermentative procedure applied for the obtainment of chitin contributes to filling the existing gap in the literature, since the majority of studies are based on the chemical pathways that dramatically impact the environment. After pretreatment, the shrimp shell waste (SSW) was fermented through two bacterial strains, namely Lactobacillus plantarum and Bacillus subtilis. A deacetylation step in an alkaline environment transformed chitin into chitosan, yielding 78.88 g/kg SWW. Four different film formulations were prepared, all containing chitosan with other ingredients added in order of decreasing complexity from the A to D groups. The novel films were tested with regard to their physico-mechanical and antioxidant properties, including the tensile strength (12.10-23.25 MPa), the elongation at break (27.91-46.12%), the hardness (52-71 Shore A), the film thickness (308-309 μm), and the radical scavenging activity (16.11-76.56%). The performance as a cling film was tested on two groups of cheese samples: the control (CTR), wrapped in conventional polyethylene (PE) film; treated (TRT), wrapped in the chitofilm formulation deemed best for its mechanical properties. The volatiles entrapped into the headspace were investigated by means of the SPME-GC technique. The results varied across soft, Camembert, and semi-hard cheeses, indicating a growing abundance of volatiles during the conservation of cheese. The bacterial growth trends for mesophilic, enterobacteriaceae, and lactic acid bacteria were expressed as the mean colony forming units (CFU)/mL for each type of cheese at different sampling times (day 2, day 8, and day 22): the highest load was quantified as 8.2 × 106 CFU/mL at day 22 in the CTR Camembert cheese. The TRT samples generally exhibited inhibitory activity comparable to or lower than that observed in the CTR samples. The sensory analysis revealed distinctions in cheese taste between the TRT and CTR groups.

Characterization of Chitosan Isolated from Shrimp Shell Waste and Its Ability to Preserve White Tofu

The research has been conducted to characterize chitosan isolated from shrimp shell and also to determine the ability of chitosan in preserving organoleptic parameters of white tofu. Isolation of chitin was performed through two stages, namely deproteination and demineralization. Chitosan is obtained by adding NaOH on chitin in deacetylation process. The obtained chitosan was characterized using several methods. Molecular weight of obtained chitosan is 15 kDa with the degree of deacetylation is 80.3%, whereas analysis of water level, ash, and protein content are 0.3%, 32.1%, 3.79% in consecutively. The optimum concentration to preserve organoleptic parameters of white tofu is 15 minutes in 1% of chitosan.

Antioxidant and cytotoxic activities of protein hydrolysates from shrimp shell wastes, germinated soybean and pigeon pea flour blends: A mixture response surface methodology approach

Cancer has high prevalence rate and mortality with conventional chemotherapy and other management protocols being both expensive and inaccessible especially in low/medium income countries (LMIC). Sourcing alternative cheaper and easily accessible treatment from blends of antioxidants sources can reduce the burden of cancer on patients. This work therefore seeks to produce a blend from the protein hydrolysates of shrimp shell waste, germinated soybean and germinated pigeon pea which not only has high antioxidant activity but also can inhibit cervical cancer cell proliferation. In vitro antioxidant and cytotoxic activities of the mixtures of germinated pigeon pea, germinated soybean, and shrimp shell waste hydrolysates were evaluated using the mixture response surface methodology (MRSM). Fourteen blends were obtained using the simplex centroid design. Total phenolic content (TPC), 2, 2-Diphenyl-1-Picrylhydrazyl (DPPH) and % cytotoxicity of the samples were analysed. Numerical optimization was conducted with the goal of simultaneously maximizing the DPPH scavenging activity and TPC while minimizing % cytotoxicity. The optimized blend consisted of 91.06 % pigeon pea, 8.94 % shrimp shell waste and 0 % soybean. The predicted responses obtained were 74.28 % DPPH scavenging activity, 39.6 GAE mg/dL TPC and 21 % cytotoxicity. The IC50 values for the optimized blend and a standard chemotherapeutic drug were 0.260 mmol/mL and 0.013 mmol / mL respectively. This in vitro study revealed that the pigeon pea - shrimp shell waste blend, as generated by MRSM, was comparable to a standard anticarcinogenic drug with respect to potency. Keywords: pigeon pea, soybean, hydrolysates, shrimp shell waste, cytotoxicity, antioxidants, DPPH

Innovative use of shrimp shell powder in carbon paste electrode for the electrochemical detection of dopamine and paracetamol: Valorization, characterization and application

The present study outlines the design of an innovative, cost-effective, and environmentally friendly electrochemical sensor, based on a carbon paste electrode (CPE) modified by shrimp shell waste (SSW). The developed electrode was used to facilitate the electrocatalytic detection of two compounds, namely dopamine (DA) and paracetamol (PAR). The use of SSW as an electrode material is ground breaking. The results have shown that the addition of shrimp shell (SS) in the CPE has led to a significant increase in the active surface area (0.504 cm2) and has improved electron transfer by decreasing the charge transfer resistance (17.45 Ω.cm2) at the electrode/solution interface. The SSW was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffractometry (XRD), and fourier transform infra-red (FTIR). The results show a fibrous and porous structure with high calcium content and other chemical elements including carbon, oxygen, sulphur, phosphorus and nitrogen. The electrochemical behavior of DA and PAR on the CPE-SS electrode was studied using cyclic voltammetry (CV), chronoamperometry (CA), electrochemical impedance spectroscopy (EIS), and square wave voltammetry (SWV) techniques. Additionally, CPE and CPE-SS electrodes were examined by SEM/EDS and FTIR. The effect of scan rate shows that the electrochemical process is diffusion controlled for DA and PAR. The CPE-SS electrode provide a wide linear range, good selectivity, repeatability, precision (≤5%), and low detection limits 3.6 µM and 5.54 µM for DA and PAR, respectively. In addition, the developed sensor was applied to detect DA and PAR in urine, tap water, and pharmaceutical tablets with apparent recoveries.

Phosphorylated chitin from shrimp shell waste: A robust solution for cadmium remediation

In this work, chitin (CT) was isolated from shrimp shell waste (SSW) and was then phosphorylated using diammonium hydrogen phosphate (DAP) as a phosphorylating agent in the presence of urea. The prepared samples were characterized using Scanning Electron Microscopy (SEM) and EDX-element mapping, Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-Ray Diffraction (XRD), Thermogravimetric Analysis (TGA/DTG), conductometric titration, Degree of Substitution (DS) and contact angle measurements. The results of characterization techniques reveal the successful extraction and phosphorylation of chitin. The charge content of the phosphorylated chitin (P-CT) was 1.510 mmol·kg−1, the degree of substitution of phosphorus groups grafted on the CT surface achieved the value of 0.33. The adsorption mechanisms appeared to involve electrostatic attachment, specific adsorption (CdO or hydroxyl binding), and ion exchange. Regarding the adsorption of Cd2+, the effect of the adsorbent mass, initial concentration of Cd2+, contact time, pH, and temperature were studied in batch experiments, and optimum values for each parameter were identified. The experimental results revealed that P-CT enhanced the Cd2+ removal capacity by 17.5 %. The kinetic analyses favored the pseudo-second-order model over the pseudo-first-order model for describing the adsorption process accurately. Langmuir model aptly represented the adsorption isotherms, suggesting unimolecular layer adsorption with a maximum capacity of 62.71 mg·g−1 under optimal conditions of 30 °C, 120 min, pH 8, and a P-CT dose of 3 g·L−1. Regeneration experiments evidenced that P-CT can be used for 6 cycles without significant removal capacity loss. Consequently, P-CT presents an efficient and cost-effective potential biosorbent for Cd2+ removal in wastewater treatment applications.

Calcium-decorated biochar modified with phosphorus from wastewater to promote U(VI) removal: Adsorption behavior and mechanism

In this study, waste shrimp shell and phosphorous-containing wastewater were used to synthesize calcium-decorated biochar modified with phosphorus (Ca-BC-P) and utilized to remove uranium from aqueous solutions. The results from static adsorption experiment demonstrated that Ca-BC-P exhibited good U(VI) adsorption performance in acidic environments, with a maximum theoretical adsorption capacity of 1074.29 mg g−1. The adsorption behavior perfectly fit Langmuir isotherm and the pseudo-second-order kinetic models, which revealed the nature of monolayer chemical adsorption by Ca-BC-P. Thermodynamic analysis showed that this process was spontaneous and endothermic. Ca-BC-P also displayed excellent selectivity and could be reused for several times while keeping a high U(VI) removal efficiency. When treating simulated acidic uranium mine wastewater, the removal efficiency of uranium reached 99.9 % with Ca-BC-P. The U(VI) removal mechanism was attributed to the precipitation of Ca(UO2)2(PO4)2·6H2O and surface complexation, nHAP on the surface of Ca-BC-P played a pivotal role during the adsorption process. Therefore, Ca-BC-P could be prepared economically and showed great potential for efficiently remove uranium from mining wastewater.