Purpose The purpose of this paper is to screen out environmental mordants with good performance and less wastewater pollution by studying the mordanting effects and environmental problems of six different types of mordants in the natural curcumin dyeing of wool fabric. Design/methodology/approach In this study, the one-bath two-step post-mordant dyeing method was used for the dyeing of wool fabrics with natural curcumin pigment. The dyeing properties of the dyed wool fabric and the comprehensive indicators of the dyeing wastewater were tested. The mordanting effects and environmental problems of six kinds of mordants were compared. Based on this, the most effective and eco-friendly mordant was selected. Findings The test results of wool fabrics mordanted with citric acid exhibited high K/S values (second only to potassium dichromate) and color difference values (>25), surpassed only by darker mordants (potassium dichromate and pomegranate peel). Citric acid generated dyeing wastewater with the lowest chemical oxygen demand, ammonia nitrogen and hexavalent chromium among six mordants, significantly reducing environmental impact. Color fastness tests showed excellent results (= 4 for all except sunlight fastness). Given its colorless, easily degradable nature and superior eco-friendly performance alongside effective mordanting, citric acid is identified as the optimal environmentally sustainable mordant for curcumin-dyed wool fabrics. Originality/value At present, there are few reports on the systematic research of screening eco-friendly mordants for the dyeing of natural dyes, and the application of eco-friendly mordants in the dyeing of natural dyes belongs to the clean production process, which is beneficial to environmental protection and sustainable development.

Allergic contact dermatitis (ACD) is a rare but significant cause of hand eczema (HE). To evaluate positive patch test reactions in HE patients, focusing on frequency, clinical/occupational relevance and sources of exposure at a tertiary referral centre in Turkey. Retrospective analysis of 1499 HE patients from 2533 consecutively patch-tested individuals (1996-2021). Positive patch test reactions occurred in 55.6% of HE patients, most commonly to nickel sulphate, potassium dichromate and thiuram mix. ACD was diagnosed in 34.2% of cases, with 54.1% being occupational, mainly in males. Occupational ACD was predominantly associated with potassium dichromate/cement among construction workers, and thiurams/rubber gloves among construction and healthcare workers. Non-occupational ACD (45.9%) was more frequent in females, typically associated with methylchloroisothiazolinone/methylisothiazolinone (MCI/MI), MI and fragrances in cosmetics and personal care products. Nickel was not a leading cause of HE; however, it was the inducer of systemic allergic dermatitis in 2.7% (14/512) of patients with hand ACD. Recurrent vesicular HE and bilateral dorsal, periungual, or wrist involvement were significantly associated with ACD. Nickel was a frequent sensitiser but an uncommon cause of hand ACD, often triggering systemic allergic dermatitis. Occupational ACD and male gender predominated. Recurrent vesicular HE and bilateral dorsal, periungual, or wrist involvement were key patterns helping identify patients for patch testing.

IntroductionUnderstanding the dynamics of soil organic carbon (SOC) in sloping farmlands is critical, as they play a vital role in the global carbon cycle and soil health. Although prior research has focused on physical carbon loss due to erosion, the biological mechanisms by which slope gradients affect microbial carbon cycling remain poorly understood.MethodsSoil samples were collected from maize fields with three slope gradients (30°, 45°, and 60°) across different growth stages. Key indicators were determined as follows: SOC by potassium dichromate oxidation (external heating method); DOC by ultrapure water extraction (1:5 ratio) and organic carbon analyzer; POC by sodium hexametaphosphate dispersion, 53-μm sieving, and chromic acid oxidation; soil Ca2+, Mg2+, and Cl− by EDTA complexometric titration and silver nitrate titration, respectively; invertase (SUC) by 3,5-dinitrosalicylic acid colorimetry; polyphenol oxidase (SPPO) and peroxidase (SPOD) by commercial kits with L-dopa as substrate. Statistical analyses were performed using IBM SPSS 26 (One-way ANOVA with LSD post-hoc test, Pearson correlation analysis) and Origin 2024 (Principal Component Analysis, PCA). Normality of data was verified prior to analysis, and significance was set at P < 0.05.ResultsResults showed that SOC levels decreased with increasing slope steepness, while DOC peaked at 45°. SPPO and SPOD activities (involved in recalcitrant carbon decomposition) were significantly elevated at 60°. SUC activity was positively correlated with DOC, while oxidase activities were positively associated with POC and negatively with Mg2+.DiscussionThis study identifies a critical slope threshold (30°–45°) for DOC loss: DOC availability on steeper slopes stimulates microbial synthesis of SPPO and SPOD, enhancing recalcitrant carbon degradation and potentially intensifying long-term SOC depletion. The identification of this threshold provides insights for designing microbiome-informed strategies to mitigate soil degradation and safeguard ecological security.

ABSTRACT Aggregation‐induced emission fluorogens (AIEgens) functionalized mesoporous silica SBA‐15 was synthesized through the simple post‐grafting method, then abundant amino groups were modified via a soaking and evaporation process in order to enhance the material's fluorescence intensity. The prepared fluorescent sensor AFSBA15 emitted strong blue light centered at 490 nm, and could detect furazolidone and potassium dichromate with low LOD values as 1.08 and 3.65 µM, respectively. What's more, AFSBA15 could selectively detect furazolidone and potassium dichromate without disturbed by other pollutants such as phenol, glyphosate, chlorfluazone, AlCl 3 , PbCl 2 , CuCl 2 ·2H 2 O, KOH, KCl, K 2 CO 3 , and K 2 SO 4 , exhibiting potential application in water quality monitoring and pollutant treatment.

Intestinal parasitic (IP) species with zoonotic significance are major public health issues, mostly prevalent in developing countries, leading to high morbidity and mortality. The present study aimed to assess the prevalence of IP species in humans and domestic animals, compare and contrast the zoonotic potentialities and investigate the associated factors in the Solukhumbu District, Nepal. The fresh faecal samples from humans (N = 200), cattle (N = 20), dogs (N = 20) and pigs (N = 20) were collected using a non-invasive purposive sampling method, preserved in 2.5% potassium dichromate, and examined by direct wet mount, flotation and modified acid-fast techniques. Sociodemographic data were obtained through a structured questionnaire, interviews and focal group discussions. The overall prevalence rate of IP species in all hosts was recorded as 70.77% (184/260), with infection rates of 65.5% in humans, 100% in cattle and pigs and 65% in dogs, with a total of 23 species. Cryptosporidium spp., Balantidium coli, Ascaris spp., taeniid and Acanthocephala spp. were shared by all hosts. Taeniid (18.5%) in humans, Entamoeba spp. (85%) in cattle, Strongyle (70%) in pigs and Cryptosporidium spp. (30%) in dogs were the most prevalent species. Significant associations were observed between a few IP species and participants' characteristics like education status, drug intake history, occupation type, feeding habit and disease checkup priorities (p<0.05). These findings reinforce the need to consider deworming campaigns for both humans and domestic animals. Further, one-health approaches involving extensive datasets of faecal samples from animals and humans living nearby and environmental samples would address zoonoses more effectively.

A simple, cost-effective, and highly sensitive spectrophotometric method was developed for the determination of folic acid (vitamin B9). The method is based on an oxidative coupling reaction with a synthetic reagent, (E)-N’-(1-(2-nitrophenyl)ethylidene)quinoline-6-carbohydrazide (M4), in the presence of potassium dichromate as the oxidizing agent and sodium hydroxide in a basic medium. This reaction produces a yellow, water-soluble compound with an absorbance at 380 nm. The Beer-Lambert law was applied over the concentration range of 0.5 to 7.5 μg/mL. The recovery was 98.71%, and the correlation coefficient was 0.9955. It was determined that the Sandell sensitivity was 0.0085 μg/cm² and the molar absorptivity was 51599.66 L mol cm. The limits of detection (LOD) and quantification (LOQ) were 0.059 μg/mL and 0.196 μg/mL, respectively. Using the suggested technique, the amount of folic acid found in pharmaceutical formulations has been successfully determined.

Cyclospora spp. causes intestinal cyclosporiasis and exists as a globally emerging pathogen in humans. However, the infection has also been reported from various animal hosts, including domestic canids. Very few articles have highlighted the presence of this coccidian in dogs, but interestingly, in each case; the oocyst morphology resembles that of human strains (C. cayetanensis). Here within, we have addressed a new description of the oocyst morphology of Cyclospora-like coccidian reported in the feces of a young female free-ranging street dog in Lalitpur Metropolitan City in central Nepal. Sporulation of oocyst is exogenous and completed within a week at 28°C with a 1:4 ratio in a 2.5% potassium dichromate solution. A mature oocyst was spherical, measuring 22.5 μm × 21.5 μm (22-23 μm × 21-22 μm, n = 10), with a shape index of 1.03 (1.0–1.05), an oocyst thickness of 0.5 μm, and a smooth and bilayered oocyst wall. Similarly, the oocyst was dizoic and was broadly elliptical sporozoites (average size: 9.9 μm × 8.3 μm, shape index: 1.2) with an inconspicuous nipple shaped stieda body and sporocyst residuum.

Introduction.Today, due to the growth of idiopathic male infertility, the problem of the impact of chemical and physical factors on the reproductive function in men remains very relevant.Studies on the effect of radiation and hexavalent chromium on male fertility in small doses deserve special attention.Literature data on gonadotoxicity and embryotoxicity under exposure to factors in small doses are very contradictory.Materials and methods. The experimental study was conducted on sexually mature BALB/c mice and Wistar rats of both sexes (a total of 189 animals). The animals were divided into groups according to the received dose of training and potassium dichromate. In mice, group 1 was a control, group 2 consisted of males who received a dose of 0.25 Gy, and group 3 received a dose of 0.5 Gy. In rats, group 1 was a control, group 2 consisted of males who received potassium dichromate (K2Cr2O7) at a dose of 0.028 mg/kg, and group 3 – at a dose of 0.28 mg/kg for 48 days. The state of spermatogenesis was assessed in smears from testicular cell homogenate. To analyze embryonic losses, experimental animals were mated with intact females.Results. Analysis of the testicles of animals after irradiation and chromium intoxication revealed the following: a 20% decrease in the relaxation index, an increase in multinucleated cells by 40% (dose 0.5 Gy) and 25% (dose 0.28 mg/kg), in aberrant germ cells by 1.5–2 times (dose 0.028 mg/kg and 0.5 Gy, respectively), and an almost 2-fold increase in the number of spermatids with micronuclei. The number of spermatozoa with abnormal heads increases: by 15–20% with irradiation and by 1.5–2 times with chromium intoxication. Mating of experimental males with intact females indicates an increase in the overall embryonic mortality in fetuses by 1.5–2 times with chromium intoxication.Limitations. In the study, when using the quantitative cytological express method in assessing spermatogenesis disorders under the influence of radiation and xenobiotics in small doses, there are no data on remote effects (90–120 days), which would allow determining the prognostic significance of these indicators in solving reproductive problems.Conclusions. For the first time, based on quantitative, morphological indicators, the degree of spermatogenesis impairment and the level of embryonic losses during irradiation and chromium intoxication in low doses were shown. The most pronounced degree of spermatogenesis impairment during chromium intoxication leads to a higher level of embryonic mortality.Compliance with ethical standards. The experimental study was approved by the Bioethics Committee of the Institute of Plant and Animal Ecology of the Ural Branch of the Russian Academy of Sciences (protocol No. 13 dated 03/12/2025).Conflict of interest. The authors declare no conflict of interest.Funding. The study was carried out within the framework of State Assignment to Institute of Plant and Animal Ecology (No. 122021000085-1).Received: April 28, 2025 / Accepted: June 26, 2025 / Published: December 19, 2025

New insights into the electron-transfer mechanism of Cr(VI) activation by carbon materials for simultaneously enhanced Cr(VI) detoxicate and acetaminophen oxidation: the role of defect structures.

Broiler chickens are chickens that have been specifically bred for high meat production. The increase in chicken meat consumption has become both an opportunity and a challenge for farmers, one of which is coccidiosis. Coccidiosis is caused by the Eimeria protozoa, which commonly infect chickens and target their digestive tract. This study aims to calculate the proportion and identify Eimeria species that often cause coccidiosis in broiler chickens in Malang Regency and Batu City. A total of 180 fecal samples from 6 different farms were used. The examination was conducted using the McMaster method and sporulation for 2-7 days on positive samples by immersing feces in a 2% potassium dichromate solution. Identification of Eimeria species was based on morphology and morphometry and was then were analyzed using descriptive statistics. The relationship between risk factors and coccidiosis occurrence was analyzed using Chi-square. The distribution of coccidiosis infections in Malang was depicted on an epidemiological map. The results showed that there were 4 Eimeria species infecting the six subdistricts in Malang Regency and Batu City, namely E. necatrix, E. acervulina, E. praecox, and E. maxima. The proportion of coccidiosis incidence in Malang Regency and Batu City was 18.89%. The highest proportion was in Dau District (43.33%), followed by Pagelaran District (36.67%), Kromengan District (23.33%), Wagir District (6.67%), Junrejo District (3.33%), and lastly Batu District (0%). Chi-square analysis showed that altitude and temperature had a significant effect (p&lt;0.05) on the coccidiosis incidence rate in Malang Regency and Batu City.

A limited-domain ion-imprinted fluorescence sensor (LDIFS) was developed by integrating aptamers with ion-imprinted polymers, achieving exceptional sensitivity and selectivity. Aptamers were immobilized on silanized ZnS quantum dots, after which pre-polymerized potassium dichromate and functional monomers were introduced. The polymerization process generated selective imprinted cavities and stabilized the active conformation of aptamer. LDIFS achieves the detection within 15min by leveraging the inner filter effect. A dual-recognition mechanism, which integrates conformational locking and imprinted cavity memory, synergistically improves the analytical performance of the sensor. The sensor achieves an ultralow detection limit of 0.43 nmol/L, exhibiting 1-3 orders of magnitude higher sensitivity than conventional approaches. A high selectivity factor of 17.9 was attained, ensuring excellent anti-interference capability. The method was successfully applied to the analysis of real squid samples, yielding recoveries ranging from 85.39% to 102.5% with RSD < 3%. This work presents a highly sensitive and selective strategy for chromium ion detection, showcasing its promising applications in environmental monitoring and food safety analysis.

BackgroundThe Yangai tea farm was established in 1952, with a long history of cultivating tea plants. The tea plant can activate Al3+ of the soil and affect soil physicochemical properties. Understanding soil physicochemical properties is crucial for studying soil fertility, nutrient retention, and long-term agricultural sustainability. Therefore, we investigated the distribution characteristics of soil pH, exchangeable acid, soil organic matter (SOM), and cation exchange capacity (CEC) in the surface soil and soil profile to assess their interaction in the managed tea garden.MethodsWe collected surface soil and soil profile samples from the managed tea garden and three land-use types (i.e., managed tea garden, unmanaged tea garden, and Pinus massoniana forest), respectively. We measure soil pH value with a laboratory pH meter. We measured the SOM, soil exchangeable acid, and CEC content, respectively, with potassium dichromate heating, potassium chloride leaching, and spectrophotometric methods.ResultsThe average soil pH value, exchangeable Al3+ content, and exchangeable H+ content were 4.50 (ranging from 3.95 to 5.88), 6.11 (0.04 to 9.32) cmol kg−1, and 0.30 (0.03 to 0.62) cmol kg−1, respectively. The surface soil acidification is severe, and the exchangeable acids in the tea garden were mainly exchangeable Al3+. The surface soil of the Yangai tea farm had a high ability to keep and supply fertilizer due to its enriching SOM content (average 55.94g kg−1) and soil CEC (24.06 cmol(+) kg−1). Surface soil exchangeable acid and CEC contents were higher after spring tea picking than before spring tea picking in the Yangai tea farm, while their SOM content was just the opposite. Therefore, it was recommended to supplement organic fertilizers after tea-picking because the surface SOM of the Yangai tea farm would decompose and be consumed more during the spring, summer, and autumn tea-picking periods than in winter. In addition, the SOM contents and soil pH values decreased and then increased with the increasing soil depth of the soil profile in three land-use types. The soil acidification rate of the managed tea garden was faster than that of the unmanaged tea garden and Pinus massoniana forest, and the difference in the acidification rate between the unmanaged tea garden and Pinus massoniana forest was slight. Therefore, there should be attention to preventing excessive soil acidification in the later tea garden management.

Studies on redox behavior of inorganic and organic substrates is an important area of research. Potassium dichromate (K2Cr2O7), the orange crystalline solid is an excellent oxidant for inorganic substrates. Nevertheless, this issue arises with organic substrates because of their inadequate solubility in organic solvents, prompting efforts to substitute the K+ cation with alternative cations. A range of onium ions has been used to design several Cr(VI) oxidants, with di-tertiary butyl chromate (TBC) being the key oxidant utilized in this study.

This study investigates the synthesis and characterization of biochar derived from the slow pyrolysis of industrial digestate (IDT), a byproduct of anaerobic digestion. The biochars were characterized by their water uptake capacity, surface characteristics (BET), and its sorption capacity against model molecules (e.g. methyl violet (MV) and potassium dichromate (K2Cr2O7) in aqueous solutions. The results showed that the water uptake capacity was ~38.3% for all tested biochars independent of pyrolysis processing procedure. However, a linear relationship between biochar surface area and pyrolysis temperature was attained where greater surface area was observed for higher pyrolysis temperature. Biochars presented mesoporous structure independent of pyrolysis temperature. The MV removal efficiency reached 63.9% for C350-22.5 and 74.6% for C550-22.5 at 25 °C. The kinetic data was best described by the Pseudo-second order (PSO) model. Nevertheless, the study found that the biochars had no significant adsorption capacity for K2Cr2O7, indicating specificity in their adsorption capabilities. Biochars obtained from pyrolyzed IDT represents a sustainable alternative to the design of sorbent platforms, contributing to improved water quality and resource recovery.

Leguminous green manure plays a vital role in improving soil quality and enhancing soil carbon sequestration within agricultural ecosystems. This study focused on young rubber plantations in Hainan and employed five treatments: Pueraria phaseoloides (Roxb.) Benth. (GT), Tephrosia candida DC. (SMD), Stylosanthes guianensis (Aubl) Sw. (ZHC), Crotalaria pallida Ait. (ZSD), and weed control (CK). We measured soil water-stable aggregates and soil organic carbon (SOC) content at the 0-20 cm and 20-40 cm depths using wet sieving and potassium dichromate heating methods and further analyzed the relationships of aggregate stability and SOC. Compared to that under the CK treatment, the SMD covering treatment significantly increased SOC at depths of 0-20 cm and 20-40 cm by 19.8% and 25.3%, respectively. The GT covering treatment also significantly increased SOC in the 20-40 cm layer by 26.7%, while the ZHC and ZSD treatments had no significant effect on the SOC in either soil layer. The GT and SMD treatments significantly improved the aggregate stability indicators [mean weight diameter (MWD) and geometric mean diameter (GMD)], the proportion, and SOC associated with &gt;2 mm size aggregates, while the ZHC and ZSD treatments markedly reduced the MWD and GMD in the 20-40 cm soil layer, as well as the proportion of &gt;2 mm size aggregates. The GT treatment significantly enhanced the SOC enrichment coefficients of 0.25-2 mm size aggregates in the 0-20 cm soil layer and 1-2 mm size aggregates in the 20-40 cm soil layer. The SMD treatment also substantially increased the SOC enrichment coefficient of 1-2 mm size aggregates in the 20-40 cm soil layer. Both the GT and SMD treatments notably improved the contribution rate of SOC from &gt;2 mm size aggregates by 65.7% and 105.5% in the 0-20 cm layer and 58.6% and 79.1% in the 20-40 cm layer, respectively, while significantly reducing the contribution rate of SOC from &lt; 0.25 mm size aggregates. Spearman correlation analysis revealed a significant positive correlation between the total SOC and MWD and GMD of aggregates at both depths of 0-20 cm and 20-40 cm. In summary, GT and SMD coverings in young rubber plantations can enhance the proportion of soil macro-aggregates, increase organic carbon content, and improve the stability of soil aggregates. The findings provide a theoretical basis for implementing perennial green manure covering practices in the tropical rubber plantation regions, as well as for enhancing soil fertility and erosion control.

Chromium (Cr) may cause contact allergy with leather being the most important exposure. To reduce contact allergy to Cr, the European Union (EU) implemented a regulation in 2015 limiting the maximum amount of hexavalent Cr in leather that comes into contact with the skin to 3 mg/kg. To investigate prevalences, trends, and clinical and demographic characteristics of patients with contact allergy to Cr following the EU regulation. A cross-sectional study was conducted. Patients aged ≥ 18 years, who were consecutively patch tested with potassium dichromate 0.5% in petrolatum at Gentofte hospital, Denmark, from 2016 to 2024, were included. A total of 4830 patients were included. The overall prevalence of contact allergy to Cr was 2.1% with stable trends across test years. Contact allergy to Cr was associated with hand, leg and foot dermatitis, and age > 40 years. The most frequent exposure was leather shoes. Contact allergy to Cr was found to be frequent and stable. The 2015 EU regulation on the content of Cr in leather does not yet appear to significantly reduce the prevalence of contact allergy to Cr, when compared with previous Gentofte data from 2006 to 2009 (2.3%, p = 0.65) and from 2010 to 2013 (1.9%, p = 0.41).

Many laboratory studies in cryptosporidial research require a source of purified oocysts. Sources can include experimentally infected laboratory animals or from samples collected from naturally infected animals and from clinical cases of human cryptosporidiosis. Purification of oocysts can be accomplished with readily available laboratory equipment including table-top centrifuges and microcentrifuges. Following purification, oocysts can be stored in antibiotic-supplemented buffers or in 2.5% aqueous potassium dichromate for over 6months. Ultimately, oocyst viability and infectivity declines to less than 10% after 1year, so if isolates are expected to be maintained, serial passage in a suitable host at ≤6-month intervals is recommended. Oocysts purified as described in this chapter are suitable for animal infection studies, cell culture studies, and a wide range of molecular biological studies, environmental studies, drug testing, and disinfection studies.

Heinrich Stilling, the third son of the German anatomist Benedict Stilling (1810-1879), received his medical doctorate from the Georg-August-Universität of Göttingen in 1876 under Franz König (1832-1910). After several periods of training in Kiel with Johannes von Esmarch (1823-1908) and in Strassburg with Friedrich Daniel von Recklinghausen (1833-1910) and Adolf Kussmaul (1822-1902), in 1890 Stilling became the first chair of Pathological Anatomy, General Pathology and Bacteriology at the newly founded medical school in Lausanne. In 1891, he founded there the Institute of Pathological Anatomy, which he directed until his death in 1911. Although he made numerous important contributions to the scientific literature on pathological anatomy, his main scientific interest was the study of the adrenal glands. In this field, he made significant contributions to the histology and physiology of the gland in various animal species. He first demonstrated the compensatory hypertrophy of adrenals after extirpation of the glands. Furthermore, he first coined the name 'chromophile' for the cells brown stained by potassium dichromate. Unfortunately, these achievements are not always adequately remembered in current literature.

Eimeria bovis is a protozoan disease-causing coccidiosis, a which affects significantly on the global cattle industry. Nonetheless, the control measures implemented have not been entirely effective, thus prompting the search for alternative methods for the parasitic and/or environmental control of the infecting forms (sporulated oocysts). The study aimed to evaluate the effect of papaya (Carica papaya) latex and pure papain on both sporulated and non-sporulated E. bovis oocysts. Oocysts were collected from the feces of calves previously inoculated with E. bovis and stored in a potassium dichromate solution. Subsequently, the oocysts were assessed for the application of aqueous solutions (both active and denatured) of latex and papain at concentrations of 10%, 15%, and 30% (w/v), alongside a control group (water), which were incubated at 28 °C for 48h. A reduction in oocyst counts was observed in the treatments compared to the control group. However, a significant difference (p < 0.01) was noted only at the concentration of 30% papain (m/v) in relation to the control. The findings suggest that extracts of C. papaya, rich in papain, hold considerable potential for future applications in the control of E. bovis.

We investigated the application of an adsorbent fabricated from satsuma mandarin peel biomass using coating with poly(glycidyl methacrylate) followed by sequential treatment with hydroxylamine and hydrochloric acid for the remediation of hexavalent chromium-polluted water. The adsorbent was characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Batch adsorption experiments were conducted wherein initial solution pH, initial chromium concentration, contact time, and temperature were varied. The adsorption equilibrium experimental data were well simulated by the Langmuir and Jovanovic models, pointing toward the formation of a monolayer of adsorbed chromium ions. The total chromium adsorption capacity of the functionalized satsuma mandarin peel adsorbent reached 219.28 mg g−1 at initial pH 1.4 and 60 °C, markedly higher than 110.23 mg g−1 at 30 °C. Where Cr(VI) was the sole chromium oxidation state in the initial solutions synthesized from potassium dichromate, the presence of Cr(III) ions in the final solutions confirmed Cr(VI) reduction. The results of this study show that the functionalized satsuma mandarin peel biomass is a potential candidate for use in the removal of hexavalent chromium from aqueous solution through reduction-coupled adsorption.